xfs: more sensible inode refcounting for ialloc

[pandora-kernel.git] / fs / xfs / xfs_inode.c

/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include <linux/log2.h>

#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_trans_priv.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_buf_item.h"
#include "xfs_inode_item.h"
#include "xfs_btree.h"
#include "xfs_btree_trace.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_bmap.h"
#include "xfs_error.h"
#include "xfs_utils.h"
#include "xfs_quota.h"
#include "xfs_filestream.h"
#include "xfs_vnodeops.h"
#include "xfs_trace.h"

kmem_zone_t *xfs_ifork_zone;
kmem_zone_t *xfs_inode_zone;

/*
 * Used in xfs_itruncate().  This is the maximum number of extents
 * freed from a file in a single transaction.
 */
#define XFS_ITRUNC_MAX_EXTENTS  2

STATIC int xfs_iflush_int(xfs_inode_t *, xfs_buf_t *);
STATIC int xfs_iformat_local(xfs_inode_t *, xfs_dinode_t *, int, int);
STATIC int xfs_iformat_extents(xfs_inode_t *, xfs_dinode_t *, int);
STATIC int xfs_iformat_btree(xfs_inode_t *, xfs_dinode_t *, int);

#ifdef DEBUG
/*
 * Make sure that the extents in the given memory buffer
 * are valid.
 */
STATIC void
xfs_validate_extents(
        xfs_ifork_t             *ifp,
        int                     nrecs,
        xfs_exntfmt_t           fmt)
{
        xfs_bmbt_irec_t         irec;
        xfs_bmbt_rec_host_t     rec;
        int                     i;

        for (i = 0; i < nrecs; i++) {
                xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
                rec.l0 = get_unaligned(&ep->l0);
                rec.l1 = get_unaligned(&ep->l1);
                xfs_bmbt_get_all(&rec, &irec);
                if (fmt == XFS_EXTFMT_NOSTATE)
                        ASSERT(irec.br_state == XFS_EXT_NORM);
        }
}
#else /* DEBUG */
#define xfs_validate_extents(ifp, nrecs, fmt)
#endif /* DEBUG */

/*
 * Check that none of the inode's in the buffer have a next
 * unlinked field of 0.
 */
#if defined(DEBUG)
void
xfs_inobp_check(
        xfs_mount_t     *mp,
        xfs_buf_t       *bp)
{
        int             i;
        int             j;
        xfs_dinode_t    *dip;

        j = mp->m_inode_cluster_size >> mp->m_sb.sb_inodelog;

        for (i = 0; i < j; i++) {
                dip = (xfs_dinode_t *)xfs_buf_offset(bp,
                                        i * mp->m_sb.sb_inodesize);
                if (!dip->di_next_unlinked)  {
                        xfs_fs_cmn_err(CE_ALERT, mp,
                                "Detected a bogus zero next_unlinked field in incore inode buffer 0x%p.  About to pop an ASSERT.",
                                bp);
                        ASSERT(dip->di_next_unlinked);
                }
        }
}
#endif

/*
 * Find the buffer associated with the given inode map
 * We do basic validation checks on the buffer once it has been
 * retrieved from disk.
 */
STATIC int
xfs_imap_to_bp(
        xfs_mount_t     *mp,
        xfs_trans_t     *tp,
        struct xfs_imap *imap,
        xfs_buf_t       **bpp,
        uint            buf_flags,
        uint            iget_flags)
{
        int             error;
        int             i;
        int             ni;
        xfs_buf_t       *bp;

        error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, imap->im_blkno,
                                   (int)imap->im_len, buf_flags, &bp);
        if (error) {
                if (error != EAGAIN) {
                        cmn_err(CE_WARN,
                                "xfs_imap_to_bp: xfs_trans_read_buf()returned "
                                "an error %d on %s.  Returning error.",
                                error, mp->m_fsname);
                } else {
                        ASSERT(buf_flags & XBF_TRYLOCK);
                }
                return error;
        }

        /*
         * Validate the magic number and version of every inode in the buffer
         * (if DEBUG kernel) or the first inode in the buffer, otherwise.
         */
#ifdef DEBUG
        ni = BBTOB(imap->im_len) >> mp->m_sb.sb_inodelog;
#else   /* usual case */
        ni = 1;
#endif

        for (i = 0; i < ni; i++) {
                int             di_ok;
                xfs_dinode_t    *dip;

                dip = (xfs_dinode_t *)xfs_buf_offset(bp,
                                        (i << mp->m_sb.sb_inodelog));
                di_ok = be16_to_cpu(dip->di_magic) == XFS_DINODE_MAGIC &&
                            XFS_DINODE_GOOD_VERSION(dip->di_version);
                if (unlikely(XFS_TEST_ERROR(!di_ok, mp,
                                                XFS_ERRTAG_ITOBP_INOTOBP,
                                                XFS_RANDOM_ITOBP_INOTOBP))) {
                        if (iget_flags & XFS_IGET_UNTRUSTED) {
                                xfs_trans_brelse(tp, bp);
                                return XFS_ERROR(EINVAL);
                        }
                        XFS_CORRUPTION_ERROR("xfs_imap_to_bp",
                                                XFS_ERRLEVEL_HIGH, mp, dip);
#ifdef DEBUG
                        cmn_err(CE_PANIC,
                                        "Device %s - bad inode magic/vsn "
                                        "daddr %lld #%d (magic=%x)",
                                XFS_BUFTARG_NAME(mp->m_ddev_targp),
                                (unsigned long long)imap->im_blkno, i,
                                be16_to_cpu(dip->di_magic));
#endif
                        xfs_trans_brelse(tp, bp);
                        return XFS_ERROR(EFSCORRUPTED);
                }
        }

        xfs_inobp_check(mp, bp);

        /*
         * Mark the buffer as an inode buffer now that it looks good
         */
        XFS_BUF_SET_VTYPE(bp, B_FS_INO);

        *bpp = bp;
        return 0;
}

/*
 * This routine is called to map an inode number within a file
 * system to the buffer containing the on-disk version of the
 * inode.  It returns a pointer to the buffer containing the
 * on-disk inode in the bpp parameter, and in the dip parameter
 * it returns a pointer to the on-disk inode within that buffer.
 *
 * If a non-zero error is returned, then the contents of bpp and
 * dipp are undefined.
 *
 * Use xfs_imap() to determine the size and location of the
 * buffer to read from disk.
 */
int
xfs_inotobp(
        xfs_mount_t     *mp,
        xfs_trans_t     *tp,
        xfs_ino_t       ino,
        xfs_dinode_t    **dipp,
        xfs_buf_t       **bpp,
        int             *offset,
        uint            imap_flags)
{
        struct xfs_imap imap;
        xfs_buf_t       *bp;
        int             error;

        imap.im_blkno = 0;
        error = xfs_imap(mp, tp, ino, &imap, imap_flags);
        if (error)
                return error;

        error = xfs_imap_to_bp(mp, tp, &imap, &bp, XBF_LOCK, imap_flags);
        if (error)
                return error;

        *dipp = (xfs_dinode_t *)xfs_buf_offset(bp, imap.im_boffset);
        *bpp = bp;
        *offset = imap.im_boffset;
        return 0;
}


/*
 * This routine is called to map an inode to the buffer containing
 * the on-disk version of the inode.  It returns a pointer to the
 * buffer containing the on-disk inode in the bpp parameter, and in
 * the dip parameter it returns a pointer to the on-disk inode within
 * that buffer.
 *
 * If a non-zero error is returned, then the contents of bpp and
 * dipp are undefined.
 *
 * The inode is expected to already been mapped to its buffer and read
 * in once, thus we can use the mapping information stored in the inode
 * rather than calling xfs_imap().  This allows us to avoid the overhead
 * of looking at the inode btree for small block file systems
 * (see xfs_imap()).
 */
int
xfs_itobp(
        xfs_mount_t     *mp,
        xfs_trans_t     *tp,
        xfs_inode_t     *ip,
        xfs_dinode_t    **dipp,
        xfs_buf_t       **bpp,
        uint            buf_flags)
{
        xfs_buf_t       *bp;
        int             error;

        ASSERT(ip->i_imap.im_blkno != 0);

        error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &bp, buf_flags, 0);
        if (error)
                return error;

        if (!bp) {
                ASSERT(buf_flags & XBF_TRYLOCK);
                ASSERT(tp == NULL);
                *bpp = NULL;
                return EAGAIN;
        }

        *dipp = (xfs_dinode_t *)xfs_buf_offset(bp, ip->i_imap.im_boffset);
        *bpp = bp;
        return 0;
}

/*
 * Move inode type and inode format specific information from the
 * on-disk inode to the in-core inode.  For fifos, devs, and sockets
 * this means set if_rdev to the proper value.  For files, directories,
 * and symlinks this means to bring in the in-line data or extent
 * pointers.  For a file in B-tree format, only the root is immediately
 * brought in-core.  The rest will be in-lined in if_extents when it
 * is first referenced (see xfs_iread_extents()).
 */
STATIC int
xfs_iformat(
        xfs_inode_t             *ip,
        xfs_dinode_t            *dip)
{
        xfs_attr_shortform_t    *atp;
        int                     size;
        int                     error;
        xfs_fsize_t             di_size;
        ip->i_df.if_ext_max =
                XFS_IFORK_DSIZE(ip) / (uint)sizeof(xfs_bmbt_rec_t);
        error = 0;

        if (unlikely(be32_to_cpu(dip->di_nextents) +
                     be16_to_cpu(dip->di_anextents) >
                     be64_to_cpu(dip->di_nblocks))) {
                xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                        "corrupt dinode %Lu, extent total = %d, nblocks = %Lu.",
                        (unsigned long long)ip->i_ino,
                        (int)(be32_to_cpu(dip->di_nextents) +
                              be16_to_cpu(dip->di_anextents)),
                        (unsigned long long)
                                be64_to_cpu(dip->di_nblocks));
                XFS_CORRUPTION_ERROR("xfs_iformat(1)", XFS_ERRLEVEL_LOW,
                                     ip->i_mount, dip);
                return XFS_ERROR(EFSCORRUPTED);
        }

        if (unlikely(dip->di_forkoff > ip->i_mount->m_sb.sb_inodesize)) {
                xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                        "corrupt dinode %Lu, forkoff = 0x%x.",
                        (unsigned long long)ip->i_ino,
                        dip->di_forkoff);
                XFS_CORRUPTION_ERROR("xfs_iformat(2)", XFS_ERRLEVEL_LOW,
                                     ip->i_mount, dip);
                return XFS_ERROR(EFSCORRUPTED);
        }

        if (unlikely((ip->i_d.di_flags & XFS_DIFLAG_REALTIME) &&
                     !ip->i_mount->m_rtdev_targp)) {
                xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                        "corrupt dinode %Lu, has realtime flag set.",
                        ip->i_ino);
                XFS_CORRUPTION_ERROR("xfs_iformat(realtime)",
                                     XFS_ERRLEVEL_LOW, ip->i_mount, dip);
                return XFS_ERROR(EFSCORRUPTED);
        }

        switch (ip->i_d.di_mode & S_IFMT) {
        case S_IFIFO:
        case S_IFCHR:
        case S_IFBLK:
        case S_IFSOCK:
                if (unlikely(dip->di_format != XFS_DINODE_FMT_DEV)) {
                        XFS_CORRUPTION_ERROR("xfs_iformat(3)", XFS_ERRLEVEL_LOW,
                                              ip->i_mount, dip);
                        return XFS_ERROR(EFSCORRUPTED);
                }
                ip->i_d.di_size = 0;
                ip->i_size = 0;
                ip->i_df.if_u2.if_rdev = xfs_dinode_get_rdev(dip);
                break;

        case S_IFREG:
        case S_IFLNK:
        case S_IFDIR:
                switch (dip->di_format) {
                case XFS_DINODE_FMT_LOCAL:
                        /*
                         * no local regular files yet
                         */
                        if (unlikely((be16_to_cpu(dip->di_mode) & S_IFMT) == S_IFREG)) {
                                xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                                        "corrupt inode %Lu "
                                        "(local format for regular file).",
                                        (unsigned long long) ip->i_ino);
                                XFS_CORRUPTION_ERROR("xfs_iformat(4)",
                                                     XFS_ERRLEVEL_LOW,
                                                     ip->i_mount, dip);
                                return XFS_ERROR(EFSCORRUPTED);
                        }

                        di_size = be64_to_cpu(dip->di_size);
                        if (unlikely(di_size > XFS_DFORK_DSIZE(dip, ip->i_mount))) {
                                xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                                        "corrupt inode %Lu "
                                        "(bad size %Ld for local inode).",
                                        (unsigned long long) ip->i_ino,
                                        (long long) di_size);
                                XFS_CORRUPTION_ERROR("xfs_iformat(5)",
                                                     XFS_ERRLEVEL_LOW,
                                                     ip->i_mount, dip);
                                return XFS_ERROR(EFSCORRUPTED);
                        }

                        size = (int)di_size;
                        error = xfs_iformat_local(ip, dip, XFS_DATA_FORK, size);
                        break;
                case XFS_DINODE_FMT_EXTENTS:
                        error = xfs_iformat_extents(ip, dip, XFS_DATA_FORK);
                        break;
                case XFS_DINODE_FMT_BTREE:
                        error = xfs_iformat_btree(ip, dip, XFS_DATA_FORK);
                        break;
                default:
                        XFS_ERROR_REPORT("xfs_iformat(6)", XFS_ERRLEVEL_LOW,
                                         ip->i_mount);
                        return XFS_ERROR(EFSCORRUPTED);
                }
                break;

        default:
                XFS_ERROR_REPORT("xfs_iformat(7)", XFS_ERRLEVEL_LOW, ip->i_mount);
                return XFS_ERROR(EFSCORRUPTED);
        }
        if (error) {
                return error;
        }
        if (!XFS_DFORK_Q(dip))
                return 0;
        ASSERT(ip->i_afp == NULL);
        ip->i_afp = kmem_zone_zalloc(xfs_ifork_zone, KM_SLEEP | KM_NOFS);
        ip->i_afp->if_ext_max =
                XFS_IFORK_ASIZE(ip) / (uint)sizeof(xfs_bmbt_rec_t);
        switch (dip->di_aformat) {
        case XFS_DINODE_FMT_LOCAL:
                atp = (xfs_attr_shortform_t *)XFS_DFORK_APTR(dip);
                size = be16_to_cpu(atp->hdr.totsize);

                if (unlikely(size < sizeof(struct xfs_attr_sf_hdr))) {
                        xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                                "corrupt inode %Lu "
                                "(bad attr fork size %Ld).",
                                (unsigned long long) ip->i_ino,
                                (long long) size);
                        XFS_CORRUPTION_ERROR("xfs_iformat(8)",
                                             XFS_ERRLEVEL_LOW,
                                             ip->i_mount, dip);
                        return XFS_ERROR(EFSCORRUPTED);
                }

                error = xfs_iformat_local(ip, dip, XFS_ATTR_FORK, size);
                break;
        case XFS_DINODE_FMT_EXTENTS:
                error = xfs_iformat_extents(ip, dip, XFS_ATTR_FORK);
                break;
        case XFS_DINODE_FMT_BTREE:
                error = xfs_iformat_btree(ip, dip, XFS_ATTR_FORK);
                break;
        default:
                error = XFS_ERROR(EFSCORRUPTED);
                break;
        }
        if (error) {
                kmem_zone_free(xfs_ifork_zone, ip->i_afp);
                ip->i_afp = NULL;
                xfs_idestroy_fork(ip, XFS_DATA_FORK);
        }
        return error;
}

/*
 * The file is in-lined in the on-disk inode.
 * If it fits into if_inline_data, then copy
 * it there, otherwise allocate a buffer for it
 * and copy the data there.  Either way, set
 * if_data to point at the data.
 * If we allocate a buffer for the data, make
 * sure that its size is a multiple of 4 and
 * record the real size in i_real_bytes.
 */
STATIC int
xfs_iformat_local(
        xfs_inode_t     *ip,
        xfs_dinode_t    *dip,
        int             whichfork,
        int             size)
{
        xfs_ifork_t     *ifp;
        int             real_size;

        /*
         * If the size is unreasonable, then something
         * is wrong and we just bail out rather than crash in
         * kmem_alloc() or memcpy() below.
         */
        if (unlikely(size > XFS_DFORK_SIZE(dip, ip->i_mount, whichfork))) {
                xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                        "corrupt inode %Lu "
                        "(bad size %d for local fork, size = %d).",
                        (unsigned long long) ip->i_ino, size,
                        XFS_DFORK_SIZE(dip, ip->i_mount, whichfork));
                XFS_CORRUPTION_ERROR("xfs_iformat_local", XFS_ERRLEVEL_LOW,
                                     ip->i_mount, dip);
                return XFS_ERROR(EFSCORRUPTED);
        }
        ifp = XFS_IFORK_PTR(ip, whichfork);
        real_size = 0;
        if (size == 0)
                ifp->if_u1.if_data = NULL;
        else if (size <= sizeof(ifp->if_u2.if_inline_data))
                ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
        else {
                real_size = roundup(size, 4);
                ifp->if_u1.if_data = kmem_alloc(real_size, KM_SLEEP | KM_NOFS);
        }
        ifp->if_bytes = size;
        ifp->if_real_bytes = real_size;
        if (size)
                memcpy(ifp->if_u1.if_data, XFS_DFORK_PTR(dip, whichfork), size);
        ifp->if_flags &= ~XFS_IFEXTENTS;
        ifp->if_flags |= XFS_IFINLINE;
        return 0;
}

/*
 * The file consists of a set of extents all
 * of which fit into the on-disk inode.
 * If there are few enough extents to fit into
 * the if_inline_ext, then copy them there.
 * Otherwise allocate a buffer for them and copy
 * them into it.  Either way, set if_extents
 * to point at the extents.
 */
STATIC int
xfs_iformat_extents(
        xfs_inode_t     *ip,
        xfs_dinode_t    *dip,
        int             whichfork)
{
        xfs_bmbt_rec_t  *dp;
        xfs_ifork_t     *ifp;
        int             nex;
        int             size;
        int             i;

        ifp = XFS_IFORK_PTR(ip, whichfork);
        nex = XFS_DFORK_NEXTENTS(dip, whichfork);
        size = nex * (uint)sizeof(xfs_bmbt_rec_t);

        /*
         * If the number of extents is unreasonable, then something
         * is wrong and we just bail out rather than crash in
         * kmem_alloc() or memcpy() below.
         */
        if (unlikely(size < 0 || size > XFS_DFORK_SIZE(dip, ip->i_mount, whichfork))) {
                xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                        "corrupt inode %Lu ((a)extents = %d).",
                        (unsigned long long) ip->i_ino, nex);
                XFS_CORRUPTION_ERROR("xfs_iformat_extents(1)", XFS_ERRLEVEL_LOW,
                                     ip->i_mount, dip);
                return XFS_ERROR(EFSCORRUPTED);
        }

        ifp->if_real_bytes = 0;
        if (nex == 0)
                ifp->if_u1.if_extents = NULL;
        else if (nex <= XFS_INLINE_EXTS)
                ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
        else
                xfs_iext_add(ifp, 0, nex);

        ifp->if_bytes = size;
        if (size) {
                dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
                xfs_validate_extents(ifp, nex, XFS_EXTFMT_INODE(ip));
                for (i = 0; i < nex; i++, dp++) {
                        xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
                        ep->l0 = get_unaligned_be64(&dp->l0);
                        ep->l1 = get_unaligned_be64(&dp->l1);
                }
                XFS_BMAP_TRACE_EXLIST(ip, nex, whichfork);
                if (whichfork != XFS_DATA_FORK ||
                        XFS_EXTFMT_INODE(ip) == XFS_EXTFMT_NOSTATE)
                                if (unlikely(xfs_check_nostate_extents(
                                    ifp, 0, nex))) {
                                        XFS_ERROR_REPORT("xfs_iformat_extents(2)",
                                                         XFS_ERRLEVEL_LOW,
                                                         ip->i_mount);
                                        return XFS_ERROR(EFSCORRUPTED);
                                }
        }
        ifp->if_flags |= XFS_IFEXTENTS;
        return 0;
}

/*
 * The file has too many extents to fit into
 * the inode, so they are in B-tree format.
 * Allocate a buffer for the root of the B-tree
 * and copy the root into it.  The i_extents
 * field will remain NULL until all of the
 * extents are read in (when they are needed).
 */
STATIC int
xfs_iformat_btree(
        xfs_inode_t             *ip,
        xfs_dinode_t            *dip,
        int                     whichfork)
{
        xfs_bmdr_block_t        *dfp;
        xfs_ifork_t             *ifp;
        /* REFERENCED */
        int                     nrecs;
        int                     size;

        ifp = XFS_IFORK_PTR(ip, whichfork);
        dfp = (xfs_bmdr_block_t *)XFS_DFORK_PTR(dip, whichfork);
        size = XFS_BMAP_BROOT_SPACE(dfp);
        nrecs = be16_to_cpu(dfp->bb_numrecs);

        /*
         * blow out if -- fork has less extents than can fit in
         * fork (fork shouldn't be a btree format), root btree
         * block has more records than can fit into the fork,
         * or the number of extents is greater than the number of
         * blocks.
         */
        if (unlikely(XFS_IFORK_NEXTENTS(ip, whichfork) <= ifp->if_ext_max
            || XFS_BMDR_SPACE_CALC(nrecs) >
                        XFS_DFORK_SIZE(dip, ip->i_mount, whichfork)
            || XFS_IFORK_NEXTENTS(ip, whichfork) > ip->i_d.di_nblocks)) {
                xfs_fs_repair_cmn_err(CE_WARN, ip->i_mount,
                        "corrupt inode %Lu (btree).",
                        (unsigned long long) ip->i_ino);
                XFS_ERROR_REPORT("xfs_iformat_btree", XFS_ERRLEVEL_LOW,
                                 ip->i_mount);
                return XFS_ERROR(EFSCORRUPTED);
        }

        ifp->if_broot_bytes = size;
        ifp->if_broot = kmem_alloc(size, KM_SLEEP | KM_NOFS);
        ASSERT(ifp->if_broot != NULL);
        /*
         * Copy and convert from the on-disk structure
         * to the in-memory structure.
         */
        xfs_bmdr_to_bmbt(ip->i_mount, dfp,
                         XFS_DFORK_SIZE(dip, ip->i_mount, whichfork),
                         ifp->if_broot, size);
        ifp->if_flags &= ~XFS_IFEXTENTS;
        ifp->if_flags |= XFS_IFBROOT;

        return 0;
}

STATIC void
xfs_dinode_from_disk(
        xfs_icdinode_t          *to,
        xfs_dinode_t            *from)
{
        to->di_magic = be16_to_cpu(from->di_magic);
        to->di_mode = be16_to_cpu(from->di_mode);
        to->di_version = from ->di_version;
        to->di_format = from->di_format;
        to->di_onlink = be16_to_cpu(from->di_onlink);
        to->di_uid = be32_to_cpu(from->di_uid);
        to->di_gid = be32_to_cpu(from->di_gid);
        to->di_nlink = be32_to_cpu(from->di_nlink);
        to->di_projid_lo = be16_to_cpu(from->di_projid_lo);
        to->di_projid_hi = be16_to_cpu(from->di_projid_hi);
        memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
        to->di_flushiter = be16_to_cpu(from->di_flushiter);
        to->di_atime.t_sec = be32_to_cpu(from->di_atime.t_sec);
        to->di_atime.t_nsec = be32_to_cpu(from->di_atime.t_nsec);
        to->di_mtime.t_sec = be32_to_cpu(from->di_mtime.t_sec);
        to->di_mtime.t_nsec = be32_to_cpu(from->di_mtime.t_nsec);
        to->di_ctime.t_sec = be32_to_cpu(from->di_ctime.t_sec);
        to->di_ctime.t_nsec = be32_to_cpu(from->di_ctime.t_nsec);
        to->di_size = be64_to_cpu(from->di_size);
        to->di_nblocks = be64_to_cpu(from->di_nblocks);
        to->di_extsize = be32_to_cpu(from->di_extsize);
        to->di_nextents = be32_to_cpu(from->di_nextents);
        to->di_anextents = be16_to_cpu(from->di_anextents);
        to->di_forkoff = from->di_forkoff;
        to->di_aformat  = from->di_aformat;
        to->di_dmevmask = be32_to_cpu(from->di_dmevmask);
        to->di_dmstate  = be16_to_cpu(from->di_dmstate);
        to->di_flags    = be16_to_cpu(from->di_flags);
        to->di_gen      = be32_to_cpu(from->di_gen);
}

void
xfs_dinode_to_disk(
        xfs_dinode_t            *to,
        xfs_icdinode_t          *from)
{
        to->di_magic = cpu_to_be16(from->di_magic);
        to->di_mode = cpu_to_be16(from->di_mode);
        to->di_version = from ->di_version;
        to->di_format = from->di_format;
        to->di_onlink = cpu_to_be16(from->di_onlink);
        to->di_uid = cpu_to_be32(from->di_uid);
        to->di_gid = cpu_to_be32(from->di_gid);
        to->di_nlink = cpu_to_be32(from->di_nlink);
        to->di_projid_lo = cpu_to_be16(from->di_projid_lo);
        to->di_projid_hi = cpu_to_be16(from->di_projid_hi);
        memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
        to->di_flushiter = cpu_to_be16(from->di_flushiter);
        to->di_atime.t_sec = cpu_to_be32(from->di_atime.t_sec);
        to->di_atime.t_nsec = cpu_to_be32(from->di_atime.t_nsec);
        to->di_mtime.t_sec = cpu_to_be32(from->di_mtime.t_sec);
        to->di_mtime.t_nsec = cpu_to_be32(from->di_mtime.t_nsec);
        to->di_ctime.t_sec = cpu_to_be32(from->di_ctime.t_sec);
        to->di_ctime.t_nsec = cpu_to_be32(from->di_ctime.t_nsec);
        to->di_size = cpu_to_be64(from->di_size);
        to->di_nblocks = cpu_to_be64(from->di_nblocks);
        to->di_extsize = cpu_to_be32(from->di_extsize);
        to->di_nextents = cpu_to_be32(from->di_nextents);
        to->di_anextents = cpu_to_be16(from->di_anextents);
        to->di_forkoff = from->di_forkoff;
        to->di_aformat = from->di_aformat;
        to->di_dmevmask = cpu_to_be32(from->di_dmevmask);
        to->di_dmstate = cpu_to_be16(from->di_dmstate);
        to->di_flags = cpu_to_be16(from->di_flags);
        to->di_gen = cpu_to_be32(from->di_gen);
}

STATIC uint
_xfs_dic2xflags(
        __uint16_t              di_flags)
{
        uint                    flags = 0;

        if (di_flags & XFS_DIFLAG_ANY) {
                if (di_flags & XFS_DIFLAG_REALTIME)
                        flags |= XFS_XFLAG_REALTIME;
                if (di_flags & XFS_DIFLAG_PREALLOC)
                        flags |= XFS_XFLAG_PREALLOC;
                if (di_flags & XFS_DIFLAG_IMMUTABLE)
                        flags |= XFS_XFLAG_IMMUTABLE;
                if (di_flags & XFS_DIFLAG_APPEND)
                        flags |= XFS_XFLAG_APPEND;
                if (di_flags & XFS_DIFLAG_SYNC)
                        flags |= XFS_XFLAG_SYNC;
                if (di_flags & XFS_DIFLAG_NOATIME)
                        flags |= XFS_XFLAG_NOATIME;
                if (di_flags & XFS_DIFLAG_NODUMP)
                        flags |= XFS_XFLAG_NODUMP;
                if (di_flags & XFS_DIFLAG_RTINHERIT)
                        flags |= XFS_XFLAG_RTINHERIT;
                if (di_flags & XFS_DIFLAG_PROJINHERIT)
                        flags |= XFS_XFLAG_PROJINHERIT;
                if (di_flags & XFS_DIFLAG_NOSYMLINKS)
                        flags |= XFS_XFLAG_NOSYMLINKS;
                if (di_flags & XFS_DIFLAG_EXTSIZE)
                        flags |= XFS_XFLAG_EXTSIZE;
                if (di_flags & XFS_DIFLAG_EXTSZINHERIT)
                        flags |= XFS_XFLAG_EXTSZINHERIT;
                if (di_flags & XFS_DIFLAG_NODEFRAG)
                        flags |= XFS_XFLAG_NODEFRAG;
                if (di_flags & XFS_DIFLAG_FILESTREAM)
                        flags |= XFS_XFLAG_FILESTREAM;
        }

        return flags;
}

uint
xfs_ip2xflags(
        xfs_inode_t             *ip)
{
        xfs_icdinode_t          *dic = &ip->i_d;

        return _xfs_dic2xflags(dic->di_flags) |
                                (XFS_IFORK_Q(ip) ? XFS_XFLAG_HASATTR : 0);
}

uint
xfs_dic2xflags(
        xfs_dinode_t            *dip)
{
        return _xfs_dic2xflags(be16_to_cpu(dip->di_flags)) |
                                (XFS_DFORK_Q(dip) ? XFS_XFLAG_HASATTR : 0);
}

/*
 * Read the disk inode attributes into the in-core inode structure.
 */
int
xfs_iread(
        xfs_mount_t     *mp,
        xfs_trans_t     *tp,
        xfs_inode_t     *ip,
        uint            iget_flags)
{
        xfs_buf_t       *bp;
        xfs_dinode_t    *dip;
        int             error;

        /*
         * Fill in the location information in the in-core inode.
         */
        error = xfs_imap(mp, tp, ip->i_ino, &ip->i_imap, iget_flags);
        if (error)
                return error;

        /*
         * Get pointers to the on-disk inode and the buffer containing it.
         */
        error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &bp,
                               XBF_LOCK, iget_flags);
        if (error)
                return error;
        dip = (xfs_dinode_t *)xfs_buf_offset(bp, ip->i_imap.im_boffset);

        /*
         * If we got something that isn't an inode it means someone
         * (nfs or dmi) has a stale handle.
         */
        if (be16_to_cpu(dip->di_magic) != XFS_DINODE_MAGIC) {
#ifdef DEBUG
                xfs_fs_cmn_err(CE_ALERT, mp, "xfs_iread: "
                                "dip->di_magic (0x%x) != "
                                "XFS_DINODE_MAGIC (0x%x)",
                                be16_to_cpu(dip->di_magic),
                                XFS_DINODE_MAGIC);
#endif /* DEBUG */
                error = XFS_ERROR(EINVAL);
                goto out_brelse;
        }

        /*
         * If the on-disk inode is already linked to a directory
         * entry, copy all of the inode into the in-core inode.
         * xfs_iformat() handles copying in the inode format
         * specific information.
         * Otherwise, just get the truly permanent information.
         */
        if (dip->di_mode) {
                xfs_dinode_from_disk(&ip->i_d, dip);
                error = xfs_iformat(ip, dip);
                if (error)  {
#ifdef DEBUG
                        xfs_fs_cmn_err(CE_ALERT, mp, "xfs_iread: "
                                        "xfs_iformat() returned error %d",
                                        error);
#endif /* DEBUG */
                        goto out_brelse;
                }
        } else {
                ip->i_d.di_magic = be16_to_cpu(dip->di_magic);
                ip->i_d.di_version = dip->di_version;
                ip->i_d.di_gen = be32_to_cpu(dip->di_gen);
                ip->i_d.di_flushiter = be16_to_cpu(dip->di_flushiter);
                /*
                 * Make sure to pull in the mode here as well in
                 * case the inode is released without being used.
                 * This ensures that xfs_inactive() will see that
                 * the inode is already free and not try to mess
                 * with the uninitialized part of it.
                 */
                ip->i_d.di_mode = 0;
                /*
                 * Initialize the per-fork minima and maxima for a new
                 * inode here.  xfs_iformat will do it for old inodes.
                 */
                ip->i_df.if_ext_max =
                        XFS_IFORK_DSIZE(ip) / (uint)sizeof(xfs_bmbt_rec_t);
        }

        /*
         * The inode format changed when we moved the link count and
         * made it 32 bits long.  If this is an old format inode,
         * convert it in memory to look like a new one.  If it gets
         * flushed to disk we will convert back before flushing or
         * logging it.  We zero out the new projid field and the old link
         * count field.  We'll handle clearing the pad field (the remains
         * of the old uuid field) when we actually convert the inode to
         * the new format. We don't change the version number so that we
         * can distinguish this from a real new format inode.
         */
        if (ip->i_d.di_version == 1) {
                ip->i_d.di_nlink = ip->i_d.di_onlink;
                ip->i_d.di_onlink = 0;
                xfs_set_projid(ip, 0);
        }

        ip->i_delayed_blks = 0;
        ip->i_size = ip->i_d.di_size;

        /*
         * Mark the buffer containing the inode as something to keep
         * around for a while.  This helps to keep recently accessed
         * meta-data in-core longer.
         */
        xfs_buf_set_ref(bp, XFS_INO_REF);

        /*
         * Use xfs_trans_brelse() to release the buffer containing the
         * on-disk inode, because it was acquired with xfs_trans_read_buf()
         * in xfs_itobp() above.  If tp is NULL, this is just a normal
         * brelse().  If we're within a transaction, then xfs_trans_brelse()
         * will only release the buffer if it is not dirty within the
         * transaction.  It will be OK to release the buffer in this case,
         * because inodes on disk are never destroyed and we will be
         * locking the new in-core inode before putting it in the hash
         * table where other processes can find it.  Thus we don't have
         * to worry about the inode being changed just because we released
         * the buffer.
         */
 out_brelse:
        xfs_trans_brelse(tp, bp);
        return error;
}

/*
 * Read in extents from a btree-format inode.
 * Allocate and fill in if_extents.  Real work is done in xfs_bmap.c.
 */
int
xfs_iread_extents(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip,
        int             whichfork)
{
        int             error;
        xfs_ifork_t     *ifp;
        xfs_extnum_t    nextents;

        if (unlikely(XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE)) {
                XFS_ERROR_REPORT("xfs_iread_extents", XFS_ERRLEVEL_LOW,
                                 ip->i_mount);
                return XFS_ERROR(EFSCORRUPTED);
        }
        nextents = XFS_IFORK_NEXTENTS(ip, whichfork);
        ifp = XFS_IFORK_PTR(ip, whichfork);

        /*
         * We know that the size is valid (it's checked in iformat_btree)
         */
        ifp->if_lastex = NULLEXTNUM;
        ifp->if_bytes = ifp->if_real_bytes = 0;
        ifp->if_flags |= XFS_IFEXTENTS;
        xfs_iext_add(ifp, 0, nextents);
        error = xfs_bmap_read_extents(tp, ip, whichfork);
        if (error) {
                xfs_iext_destroy(ifp);
                ifp->if_flags &= ~XFS_IFEXTENTS;
                return error;
        }
        xfs_validate_extents(ifp, nextents, XFS_EXTFMT_INODE(ip));
        return 0;
}

/*
 * Allocate an inode on disk and return a copy of its in-core version.
 * The in-core inode is locked exclusively.  Set mode, nlink, and rdev
 * appropriately within the inode.  The uid and gid for the inode are
 * set according to the contents of the given cred structure.
 *
 * Use xfs_dialloc() to allocate the on-disk inode. If xfs_dialloc()
 * has a free inode available, call xfs_iget()
 * to obtain the in-core version of the allocated inode.  Finally,
 * fill in the inode and log its initial contents.  In this case,
 * ialloc_context would be set to NULL and call_again set to false.
 *
 * If xfs_dialloc() does not have an available inode,
 * it will replenish its supply by doing an allocation. Since we can
 * only do one allocation within a transaction without deadlocks, we
 * must commit the current transaction before returning the inode itself.
 * In this case, therefore, we will set call_again to true and return.
 * The caller should then commit the current transaction, start a new
 * transaction, and call xfs_ialloc() again to actually get the inode.
 *
 * To ensure that some other process does not grab the inode that
 * was allocated during the first call to xfs_ialloc(), this routine
 * also returns the [locked] bp pointing to the head of the freelist
 * as ialloc_context.  The caller should hold this buffer across
 * the commit and pass it back into this routine on the second call.
 *
 * If we are allocating quota inodes, we do not have a parent inode
 * to attach to or associate with (i.e. pip == NULL) because they
 * are not linked into the directory structure - they are attached
 * directly to the superblock - and so have no parent.
 */
int
xfs_ialloc(
        xfs_trans_t     *tp,
        xfs_inode_t     *pip,
        mode_t          mode,
        xfs_nlink_t     nlink,
        xfs_dev_t       rdev,
        prid_t          prid,
        int             okalloc,
        xfs_buf_t       **ialloc_context,
        boolean_t       *call_again,
        xfs_inode_t     **ipp)
{
        xfs_ino_t       ino;
        xfs_inode_t     *ip;
        uint            flags;
        int             error;
        timespec_t      tv;
        int             filestreams = 0;

        /*
         * Call the space management code to pick
         * the on-disk inode to be allocated.
         */
        error = xfs_dialloc(tp, pip ? pip->i_ino : 0, mode, okalloc,
                            ialloc_context, call_again, &ino);
        if (error)
                return error;
        if (*call_again || ino == NULLFSINO) {
                *ipp = NULL;
                return 0;
        }
        ASSERT(*ialloc_context == NULL);

        /*
         * Get the in-core inode with the lock held exclusively.
         * This is because we're setting fields here we need
         * to prevent others from looking at until we're done.
         */
        error = xfs_iget(tp->t_mountp, tp, ino, XFS_IGET_CREATE,
                         XFS_ILOCK_EXCL, &ip);
        if (error)
                return error;
        ASSERT(ip != NULL);

        ip->i_d.di_mode = (__uint16_t)mode;
        ip->i_d.di_onlink = 0;
        ip->i_d.di_nlink = nlink;
        ASSERT(ip->i_d.di_nlink == nlink);
        ip->i_d.di_uid = current_fsuid();
        ip->i_d.di_gid = current_fsgid();
        xfs_set_projid(ip, prid);
        memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));

        /*
         * If the superblock version is up to where we support new format
         * inodes and this is currently an old format inode, then change
         * the inode version number now.  This way we only do the conversion
         * here rather than here and in the flush/logging code.
         */
        if (xfs_sb_version_hasnlink(&tp->t_mountp->m_sb) &&
            ip->i_d.di_version == 1) {
                ip->i_d.di_version = 2;
                /*
                 * We've already zeroed the old link count, the projid field,
                 * and the pad field.
                 */
        }

        /*
         * Project ids won't be stored on disk if we are using a version 1 inode.
         */
        if ((prid != 0) && (ip->i_d.di_version == 1))
                xfs_bump_ino_vers2(tp, ip);

        if (pip && XFS_INHERIT_GID(pip)) {
                ip->i_d.di_gid = pip->i_d.di_gid;
                if ((pip->i_d.di_mode & S_ISGID) && (mode & S_IFMT) == S_IFDIR) {
                        ip->i_d.di_mode |= S_ISGID;
                }
        }

        /*
         * If the group ID of the new file does not match the effective group
         * ID or one of the supplementary group IDs, the S_ISGID bit is cleared
         * (and only if the irix_sgid_inherit compatibility variable is set).
         */
        if ((irix_sgid_inherit) &&
            (ip->i_d.di_mode & S_ISGID) &&
            (!in_group_p((gid_t)ip->i_d.di_gid))) {
                ip->i_d.di_mode &= ~S_ISGID;
        }

        ip->i_d.di_size = 0;
        ip->i_size = 0;
        ip->i_d.di_nextents = 0;
        ASSERT(ip->i_d.di_nblocks == 0);

        nanotime(&tv);
        ip->i_d.di_mtime.t_sec = (__int32_t)tv.tv_sec;
        ip->i_d.di_mtime.t_nsec = (__int32_t)tv.tv_nsec;
        ip->i_d.di_atime = ip->i_d.di_mtime;
        ip->i_d.di_ctime = ip->i_d.di_mtime;

        /*
         * di_gen will have been taken care of in xfs_iread.
         */
        ip->i_d.di_extsize = 0;
        ip->i_d.di_dmevmask = 0;
        ip->i_d.di_dmstate = 0;
        ip->i_d.di_flags = 0;
        flags = XFS_ILOG_CORE;
        switch (mode & S_IFMT) {
        case S_IFIFO:
        case S_IFCHR:
        case S_IFBLK:
        case S_IFSOCK:
                ip->i_d.di_format = XFS_DINODE_FMT_DEV;
                ip->i_df.if_u2.if_rdev = rdev;
                ip->i_df.if_flags = 0;
                flags |= XFS_ILOG_DEV;
                break;
        case S_IFREG:
                /*
                 * we can't set up filestreams until after the VFS inode
                 * is set up properly.
                 */
                if (pip && xfs_inode_is_filestream(pip))
                        filestreams = 1;
                /* fall through */
        case S_IFDIR:
                if (pip && (pip->i_d.di_flags & XFS_DIFLAG_ANY)) {
                        uint    di_flags = 0;

                        if ((mode & S_IFMT) == S_IFDIR) {
                                if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
                                        di_flags |= XFS_DIFLAG_RTINHERIT;
                                if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
                                        di_flags |= XFS_DIFLAG_EXTSZINHERIT;
                                        ip->i_d.di_extsize = pip->i_d.di_extsize;
                                }
                        } else if ((mode & S_IFMT) == S_IFREG) {
                                if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
                                        di_flags |= XFS_DIFLAG_REALTIME;
                                if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
                                        di_flags |= XFS_DIFLAG_EXTSIZE;
                                        ip->i_d.di_extsize = pip->i_d.di_extsize;
                                }
                        }
                        if ((pip->i_d.di_flags & XFS_DIFLAG_NOATIME) &&
                            xfs_inherit_noatime)
                                di_flags |= XFS_DIFLAG_NOATIME;
                        if ((pip->i_d.di_flags & XFS_DIFLAG_NODUMP) &&
                            xfs_inherit_nodump)
                                di_flags |= XFS_DIFLAG_NODUMP;
                        if ((pip->i_d.di_flags & XFS_DIFLAG_SYNC) &&
                            xfs_inherit_sync)
                                di_flags |= XFS_DIFLAG_SYNC;
                        if ((pip->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) &&
                            xfs_inherit_nosymlinks)
                                di_flags |= XFS_DIFLAG_NOSYMLINKS;
                        if (pip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
                                di_flags |= XFS_DIFLAG_PROJINHERIT;
                        if ((pip->i_d.di_flags & XFS_DIFLAG_NODEFRAG) &&
                            xfs_inherit_nodefrag)
                                di_flags |= XFS_DIFLAG_NODEFRAG;
                        if (pip->i_d.di_flags & XFS_DIFLAG_FILESTREAM)
                                di_flags |= XFS_DIFLAG_FILESTREAM;
                        ip->i_d.di_flags |= di_flags;
                }
                /* FALLTHROUGH */
        case S_IFLNK:
                ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
                ip->i_df.if_flags = XFS_IFEXTENTS;
                ip->i_df.if_bytes = ip->i_df.if_real_bytes = 0;
                ip->i_df.if_u1.if_extents = NULL;
                break;
        default:
                ASSERT(0);
        }
        /*
         * Attribute fork settings for new inode.
         */
        ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
        ip->i_d.di_anextents = 0;

        /*
         * Log the new values stuffed into the inode.
         */
        xfs_trans_ijoin_ref(tp, ip, XFS_ILOCK_EXCL);
        xfs_trans_log_inode(tp, ip, flags);

        /* now that we have an i_mode we can setup inode ops and unlock */
        xfs_setup_inode(ip);

        /* now we have set up the vfs inode we can associate the filestream */
        if (filestreams) {
                error = xfs_filestream_associate(pip, ip);
                if (error < 0)
                        return -error;
                if (!error)
                        xfs_iflags_set(ip, XFS_IFILESTREAM);
        }

        *ipp = ip;
        return 0;
}

/*
 * Check to make sure that there are no blocks allocated to the
 * file beyond the size of the file.  We don't check this for
 * files with fixed size extents or real time extents, but we
 * at least do it for regular files.
 */
#ifdef DEBUG
void
xfs_isize_check(
        xfs_mount_t     *mp,
        xfs_inode_t     *ip,
        xfs_fsize_t     isize)
{
        xfs_fileoff_t   map_first;
        int             nimaps;
        xfs_bmbt_irec_t imaps[2];

        if ((ip->i_d.di_mode & S_IFMT) != S_IFREG)
                return;

        if (XFS_IS_REALTIME_INODE(ip))
                return;

        if (ip->i_d.di_flags & XFS_DIFLAG_EXTSIZE)
                return;

        nimaps = 2;
        map_first = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
        /*
         * The filesystem could be shutting down, so bmapi may return
         * an error.
         */
        if (xfs_bmapi(NULL, ip, map_first,
                         (XFS_B_TO_FSB(mp,
                                       (xfs_ufsize_t)XFS_MAXIOFFSET(mp)) -
                          map_first),
                         XFS_BMAPI_ENTIRE, NULL, 0, imaps, &nimaps,
                         NULL))
            return;
        ASSERT(nimaps == 1);
        ASSERT(imaps[0].br_startblock == HOLESTARTBLOCK);
}
#endif  /* DEBUG */

/*
 * Calculate the last possible buffered byte in a file.  This must
 * include data that was buffered beyond the EOF by the write code.
 * This also needs to deal with overflowing the xfs_fsize_t type
 * which can happen for sizes near the limit.
 *
 * We also need to take into account any blocks beyond the EOF.  It
 * may be the case that they were buffered by a write which failed.
 * In that case the pages will still be in memory, but the inode size
 * will never have been updated.
 */
STATIC xfs_fsize_t
xfs_file_last_byte(
        xfs_inode_t     *ip)
{
        xfs_mount_t     *mp;
        xfs_fsize_t     last_byte;
        xfs_fileoff_t   last_block;
        xfs_fileoff_t   size_last_block;
        int             error;

        ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED));

        mp = ip->i_mount;
        /*
         * Only check for blocks beyond the EOF if the extents have
         * been read in.  This eliminates the need for the inode lock,
         * and it also saves us from looking when it really isn't
         * necessary.
         */
        if (ip->i_df.if_flags & XFS_IFEXTENTS) {
                xfs_ilock(ip, XFS_ILOCK_SHARED);
                error = xfs_bmap_last_offset(NULL, ip, &last_block,
                        XFS_DATA_FORK);
                xfs_iunlock(ip, XFS_ILOCK_SHARED);
                if (error) {
                        last_block = 0;
                }
        } else {
                last_block = 0;
        }
        size_last_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)ip->i_size);
        last_block = XFS_FILEOFF_MAX(last_block, size_last_block);

        last_byte = XFS_FSB_TO_B(mp, last_block);
        if (last_byte < 0) {
                return XFS_MAXIOFFSET(mp);
        }
        last_byte += (1 << mp->m_writeio_log);
        if (last_byte < 0) {
                return XFS_MAXIOFFSET(mp);
        }
        return last_byte;
}

/*
 * Start the truncation of the file to new_size.  The new size
 * must be smaller than the current size.  This routine will
 * clear the buffer and page caches of file data in the removed
 * range, and xfs_itruncate_finish() will remove the underlying
 * disk blocks.
 *
 * The inode must have its I/O lock locked EXCLUSIVELY, and it
 * must NOT have the inode lock held at all.  This is because we're
 * calling into the buffer/page cache code and we can't hold the
 * inode lock when we do so.
 *
 * We need to wait for any direct I/Os in flight to complete before we
 * proceed with the truncate. This is needed to prevent the extents
 * being read or written by the direct I/Os from being removed while the
 * I/O is in flight as there is no other method of synchronising
 * direct I/O with the truncate operation.  Also, because we hold
 * the IOLOCK in exclusive mode, we prevent new direct I/Os from being
 * started until the truncate completes and drops the lock. Essentially,
 * the xfs_ioend_wait() call forms an I/O barrier that provides strict
 * ordering between direct I/Os and the truncate operation.
 *
 * The flags parameter can have either the value XFS_ITRUNC_DEFINITE
 * or XFS_ITRUNC_MAYBE.  The XFS_ITRUNC_MAYBE value should be used
 * in the case that the caller is locking things out of order and
 * may not be able to call xfs_itruncate_finish() with the inode lock
 * held without dropping the I/O lock.  If the caller must drop the
 * I/O lock before calling xfs_itruncate_finish(), then xfs_itruncate_start()
 * must be called again with all the same restrictions as the initial
 * call.
 */
int
xfs_itruncate_start(
        xfs_inode_t     *ip,
        uint            flags,
        xfs_fsize_t     new_size)
{
        xfs_fsize_t     last_byte;
        xfs_off_t       toss_start;
        xfs_mount_t     *mp;
        int             error = 0;

        ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
        ASSERT((new_size == 0) || (new_size <= ip->i_size));
        ASSERT((flags == XFS_ITRUNC_DEFINITE) ||
               (flags == XFS_ITRUNC_MAYBE));

        mp = ip->i_mount;

        /* wait for the completion of any pending DIOs */
        if (new_size == 0 || new_size < ip->i_size)
                xfs_ioend_wait(ip);

        /*
         * Call toss_pages or flushinval_pages to get rid of pages
         * overlapping the region being removed.  We have to use
         * the less efficient flushinval_pages in the case that the
         * caller may not be able to finish the truncate without
         * dropping the inode's I/O lock.  Make sure
         * to catch any pages brought in by buffers overlapping
         * the EOF by searching out beyond the isize by our
         * block size. We round new_size up to a block boundary
         * so that we don't toss things on the same block as
         * new_size but before it.
         *
         * Before calling toss_page or flushinval_pages, make sure to
         * call remapf() over the same region if the file is mapped.
         * This frees up mapped file references to the pages in the
         * given range and for the flushinval_pages case it ensures
         * that we get the latest mapped changes flushed out.
         */
        toss_start = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
        toss_start = XFS_FSB_TO_B(mp, toss_start);
        if (toss_start < 0) {
                /*
                 * The place to start tossing is beyond our maximum
                 * file size, so there is no way that the data extended
                 * out there.
                 */
                return 0;
        }
        last_byte = xfs_file_last_byte(ip);
        trace_xfs_itruncate_start(ip, flags, new_size, toss_start, last_byte);
        if (last_byte > toss_start) {
                if (flags & XFS_ITRUNC_DEFINITE) {
                        xfs_tosspages(ip, toss_start,
                                        -1, FI_REMAPF_LOCKED);
                } else {
                        error = xfs_flushinval_pages(ip, toss_start,
                                        -1, FI_REMAPF_LOCKED);
                }
        }

#ifdef DEBUG
        if (new_size == 0) {
                ASSERT(VN_CACHED(VFS_I(ip)) == 0);
        }
#endif
        return error;
}

/*
 * Shrink the file to the given new_size.  The new size must be smaller than
 * the current size.  This will free up the underlying blocks in the removed
 * range after a call to xfs_itruncate_start() or xfs_atruncate_start().
 *
 * The transaction passed to this routine must have made a permanent log
 * reservation of at least XFS_ITRUNCATE_LOG_RES.  This routine may commit the
 * given transaction and start new ones, so make sure everything involved in
 * the transaction is tidy before calling here.  Some transaction will be
 * returned to the caller to be committed.  The incoming transaction must
 * already include the inode, and both inode locks must be held exclusively.
 * The inode must also be "held" within the transaction.  On return the inode
 * will be "held" within the returned transaction.  This routine does NOT
 * require any disk space to be reserved for it within the transaction.
 *
 * The fork parameter must be either xfs_attr_fork or xfs_data_fork, and it
 * indicates the fork which is to be truncated.  For the attribute fork we only
 * support truncation to size 0.
 *
 * We use the sync parameter to indicate whether or not the first transaction
 * we perform might have to be synchronous.  For the attr fork, it needs to be
 * so if the unlink of the inode is not yet known to be permanent in the log.
 * This keeps us from freeing and reusing the blocks of the attribute fork
 * before the unlink of the inode becomes permanent.
 *
 * For the data fork, we normally have to run synchronously if we're being
 * called out of the inactive path or we're being called out of the create path
 * where we're truncating an existing file.  Either way, the truncate needs to
 * be sync so blocks don't reappear in the file with altered data in case of a
 * crash.  wsync filesystems can run the first case async because anything that
 * shrinks the inode has to run sync so by the time we're called here from
 * inactive, the inode size is permanently set to 0.
 *
 * Calls from the truncate path always need to be sync unless we're in a wsync
 * filesystem and the file has already been unlinked.
 *
 * The caller is responsible for correctly setting the sync parameter.  It gets
 * too hard for us to guess here which path we're being called out of just
 * based on inode state.
 *
 * If we get an error, we must return with the inode locked and linked into the
 * current transaction. This keeps things simple for the higher level code,
 * because it always knows that the inode is locked and held in the transaction
 * that returns to it whether errors occur or not.  We don't mark the inode
 * dirty on error so that transactions can be easily aborted if possible.
 */
int
xfs_itruncate_finish(
        xfs_trans_t     **tp,
        xfs_inode_t     *ip,
        xfs_fsize_t     new_size,
        int             fork,
        int             sync)
{
        xfs_fsblock_t   first_block;
        xfs_fileoff_t   first_unmap_block;
        xfs_fileoff_t   last_block;
        xfs_filblks_t   unmap_len=0;
        xfs_mount_t     *mp;
        xfs_trans_t     *ntp;
        int             done;
        int             committed;
        xfs_bmap_free_t free_list;
        int             error;

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
        ASSERT((new_size == 0) || (new_size <= ip->i_size));
        ASSERT(*tp != NULL);
        ASSERT((*tp)->t_flags & XFS_TRANS_PERM_LOG_RES);
        ASSERT(ip->i_transp == *tp);
        ASSERT(ip->i_itemp != NULL);
        ASSERT(ip->i_itemp->ili_lock_flags == 0);


        ntp = *tp;
        mp = (ntp)->t_mountp;
        ASSERT(! XFS_NOT_DQATTACHED(mp, ip));

        /*
         * We only support truncating the entire attribute fork.
         */
        if (fork == XFS_ATTR_FORK) {
                new_size = 0LL;
        }
        first_unmap_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
        trace_xfs_itruncate_finish_start(ip, new_size);

        /*
         * The first thing we do is set the size to new_size permanently
         * on disk.  This way we don't have to worry about anyone ever
         * being able to look at the data being freed even in the face
         * of a crash.  What we're getting around here is the case where
         * we free a block, it is allocated to another file, it is written
         * to, and then we crash.  If the new data gets written to the
         * file but the log buffers containing the free and reallocation
         * don't, then we'd end up with garbage in the blocks being freed.
         * As long as we make the new_size permanent before actually
         * freeing any blocks it doesn't matter if they get writtten to.
         *
         * The callers must signal into us whether or not the size
         * setting here must be synchronous.  There are a few cases
         * where it doesn't have to be synchronous.  Those cases
         * occur if the file is unlinked and we know the unlink is
         * permanent or if the blocks being truncated are guaranteed
         * to be beyond the inode eof (regardless of the link count)
         * and the eof value is permanent.  Both of these cases occur
         * only on wsync-mounted filesystems.  In those cases, we're
         * guaranteed that no user will ever see the data in the blocks
         * that are being truncated so the truncate can run async.
         * In the free beyond eof case, the file may wind up with
         * more blocks allocated to it than it needs if we crash
         * and that won't get fixed until the next time the file
         * is re-opened and closed but that's ok as that shouldn't
         * be too many blocks.
         *
         * However, we can't just make all wsync xactions run async
         * because there's one call out of the create path that needs
         * to run sync where it's truncating an existing file to size
         * 0 whose size is > 0.
         *
         * It's probably possible to come up with a test in this
         * routine that would correctly distinguish all the above
         * cases from the values of the function parameters and the
         * inode state but for sanity's sake, I've decided to let the
         * layers above just tell us.  It's simpler to correctly figure
         * out in the layer above exactly under what conditions we
         * can run async and I think it's easier for others read and
         * follow the logic in case something has to be changed.
         * cscope is your friend -- rcc.
         *
         * The attribute fork is much simpler.
         *
         * For the attribute fork we allow the caller to tell us whether
         * the unlink of the inode that led to this call is yet permanent
         * in the on disk log.  If it is not and we will be freeing extents
         * in this inode then we make the first transaction synchronous
         * to make sure that the unlink is permanent by the time we free
         * the blocks.
         */
        if (fork == XFS_DATA_FORK) {
                if (ip->i_d.di_nextents > 0) {
                        /*
                         * If we are not changing the file size then do
                         * not update the on-disk file size - we may be
                         * called from xfs_inactive_free_eofblocks().  If we
                         * update the on-disk file size and then the system
                         * crashes before the contents of the file are
                         * flushed to disk then the files may be full of
                         * holes (ie NULL files bug).
                         */
                        if (ip->i_size != new_size) {
                                ip->i_d.di_size = new_size;
                                ip->i_size = new_size;
                                xfs_trans_log_inode(ntp, ip, XFS_ILOG_CORE);
                        }
                }
        } else if (sync) {
                ASSERT(!(mp->m_flags & XFS_MOUNT_WSYNC));
                if (ip->i_d.di_anextents > 0)
                        xfs_trans_set_sync(ntp);
        }
        ASSERT(fork == XFS_DATA_FORK ||
                (fork == XFS_ATTR_FORK &&
                        ((sync && !(mp->m_flags & XFS_MOUNT_WSYNC)) ||
                         (sync == 0 && (mp->m_flags & XFS_MOUNT_WSYNC)))));

        /*
         * Since it is possible for space to become allocated beyond
         * the end of the file (in a crash where the space is allocated
         * but the inode size is not yet updated), simply remove any
         * blocks which show up between the new EOF and the maximum
         * possible file size.  If the first block to be removed is
         * beyond the maximum file size (ie it is the same as last_block),
         * then there is nothing to do.
         */
        last_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
        ASSERT(first_unmap_block <= last_block);
        done = 0;
        if (last_block == first_unmap_block) {
                done = 1;
        } else {
                unmap_len = last_block - first_unmap_block + 1;
        }
        while (!done) {
                /*
                 * Free up up to XFS_ITRUNC_MAX_EXTENTS.  xfs_bunmapi()
                 * will tell us whether it freed the entire range or
                 * not.  If this is a synchronous mount (wsync),
                 * then we can tell bunmapi to keep all the
                 * transactions asynchronous since the unlink
                 * transaction that made this inode inactive has
                 * already hit the disk.  There's no danger of
                 * the freed blocks being reused, there being a
                 * crash, and the reused blocks suddenly reappearing
                 * in this file with garbage in them once recovery
                 * runs.
                 */
                xfs_bmap_init(&free_list, &first_block);
                error = xfs_bunmapi(ntp, ip,
                                    first_unmap_block, unmap_len,
                                    xfs_bmapi_aflag(fork),
                                    XFS_ITRUNC_MAX_EXTENTS,
                                    &first_block, &free_list,
                                    &done);
                if (error) {
                        /*
                         * If the bunmapi call encounters an error,
                         * return to the caller where the transaction
                         * can be properly aborted.  We just need to
                         * make sure we're not holding any resources
                         * that we were not when we came in.
                         */
                        xfs_bmap_cancel(&free_list);
                        return error;
                }

                /*
                 * Duplicate the transaction that has the permanent
                 * reservation and commit the old transaction.
                 */
                error = xfs_bmap_finish(tp, &free_list, &committed);
                ntp = *tp;
                if (committed)
                        xfs_trans_ijoin(ntp, ip);

                if (error) {
                        /*
                         * If the bmap finish call encounters an error, return
                         * to the caller where the transaction can be properly
                         * aborted.  We just need to make sure we're not
                         * holding any resources that we were not when we came
                         * in.
                         *
                         * Aborting from this point might lose some blocks in
                         * the file system, but oh well.
                         */
                        xfs_bmap_cancel(&free_list);
                        return error;
                }

                if (committed) {
                        /*
                         * Mark the inode dirty so it will be logged and
                         * moved forward in the log as part of every commit.
                         */
                        xfs_trans_log_inode(ntp, ip, XFS_ILOG_CORE);
                }

                ntp = xfs_trans_dup(ntp);
                error = xfs_trans_commit(*tp, 0);
                *tp = ntp;

                xfs_trans_ijoin(ntp, ip);

                if (error)
                        return error;
                /*
                 * transaction commit worked ok so we can drop the extra ticket
                 * reference that we gained in xfs_trans_dup()
                 */
                xfs_log_ticket_put(ntp->t_ticket);
                error = xfs_trans_reserve(ntp, 0,
                                        XFS_ITRUNCATE_LOG_RES(mp), 0,
                                        XFS_TRANS_PERM_LOG_RES,
                                        XFS_ITRUNCATE_LOG_COUNT);
                if (error)
                        return error;
        }
        /*
         * Only update the size in the case of the data fork, but
         * always re-log the inode so that our permanent transaction
         * can keep on rolling it forward in the log.
         */
        if (fork == XFS_DATA_FORK) {
                xfs_isize_check(mp, ip, new_size);
                /*
                 * If we are not changing the file size then do
                 * not update the on-disk file size - we may be
                 * called from xfs_inactive_free_eofblocks().  If we
                 * update the on-disk file size and then the system
                 * crashes before the contents of the file are
                 * flushed to disk then the files may be full of
                 * holes (ie NULL files bug).
                 */
                if (ip->i_size != new_size) {
                        ip->i_d.di_size = new_size;
                        ip->i_size = new_size;
                }
        }
        xfs_trans_log_inode(ntp, ip, XFS_ILOG_CORE);
        ASSERT((new_size != 0) ||
               (fork == XFS_ATTR_FORK) ||
               (ip->i_delayed_blks == 0));
        ASSERT((new_size != 0) ||
               (fork == XFS_ATTR_FORK) ||
               (ip->i_d.di_nextents == 0));
        trace_xfs_itruncate_finish_end(ip, new_size);
        return 0;
}

/*
 * This is called when the inode's link count goes to 0.
 * We place the on-disk inode on a list in the AGI.  It
 * will be pulled from this list when the inode is freed.
 */
int
xfs_iunlink(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip)
{
        xfs_mount_t     *mp;
        xfs_agi_t       *agi;
        xfs_dinode_t    *dip;
        xfs_buf_t       *agibp;
        xfs_buf_t       *ibp;
        xfs_agino_t     agino;
        short           bucket_index;
        int             offset;
        int             error;

        ASSERT(ip->i_d.di_nlink == 0);
        ASSERT(ip->i_d.di_mode != 0);
        ASSERT(ip->i_transp == tp);

        mp = tp->t_mountp;

        /*
         * Get the agi buffer first.  It ensures lock ordering
         * on the list.
         */
        error = xfs_read_agi(mp, tp, XFS_INO_TO_AGNO(mp, ip->i_ino), &agibp);
        if (error)
                return error;
        agi = XFS_BUF_TO_AGI(agibp);

        /*
         * Get the index into the agi hash table for the
         * list this inode will go on.
         */
        agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
        ASSERT(agino != 0);
        bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
        ASSERT(agi->agi_unlinked[bucket_index]);
        ASSERT(be32_to_cpu(agi->agi_unlinked[bucket_index]) != agino);

        if (be32_to_cpu(agi->agi_unlinked[bucket_index]) != NULLAGINO) {
                /*
                 * There is already another inode in the bucket we need
                 * to add ourselves to.  Add us at the front of the list.
                 * Here we put the head pointer into our next pointer,
                 * and then we fall through to point the head at us.
                 */
                error = xfs_itobp(mp, tp, ip, &dip, &ibp, XBF_LOCK);
                if (error)
                        return error;

                ASSERT(be32_to_cpu(dip->di_next_unlinked) == NULLAGINO);
                /* both on-disk, don't endian flip twice */
                dip->di_next_unlinked = agi->agi_unlinked[bucket_index];
                offset = ip->i_imap.im_boffset +
                        offsetof(xfs_dinode_t, di_next_unlinked);
                xfs_trans_inode_buf(tp, ibp);
                xfs_trans_log_buf(tp, ibp, offset,
                                  (offset + sizeof(xfs_agino_t) - 1));
                xfs_inobp_check(mp, ibp);
        }

        /*
         * Point the bucket head pointer at the inode being inserted.
         */
        ASSERT(agino != 0);
        agi->agi_unlinked[bucket_index] = cpu_to_be32(agino);
        offset = offsetof(xfs_agi_t, agi_unlinked) +
                (sizeof(xfs_agino_t) * bucket_index);
        xfs_trans_log_buf(tp, agibp, offset,
                          (offset + sizeof(xfs_agino_t) - 1));
        return 0;
}

/*
 * Pull the on-disk inode from the AGI unlinked list.
 */
STATIC int
xfs_iunlink_remove(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip)
{
        xfs_ino_t       next_ino;
        xfs_mount_t     *mp;
        xfs_agi_t       *agi;
        xfs_dinode_t    *dip;
        xfs_buf_t       *agibp;
        xfs_buf_t       *ibp;
        xfs_agnumber_t  agno;
        xfs_agino_t     agino;
        xfs_agino_t     next_agino;
        xfs_buf_t       *last_ibp;
        xfs_dinode_t    *last_dip = NULL;
        short           bucket_index;
        int             offset, last_offset = 0;
        int             error;

        mp = tp->t_mountp;
        agno = XFS_INO_TO_AGNO(mp, ip->i_ino);

        /*
         * Get the agi buffer first.  It ensures lock ordering
         * on the list.
         */
        error = xfs_read_agi(mp, tp, agno, &agibp);
        if (error)
                return error;

        agi = XFS_BUF_TO_AGI(agibp);

        /*
         * Get the index into the agi hash table for the
         * list this inode will go on.
         */
        agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
        ASSERT(agino != 0);
        bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
        ASSERT(be32_to_cpu(agi->agi_unlinked[bucket_index]) != NULLAGINO);
        ASSERT(agi->agi_unlinked[bucket_index]);

        if (be32_to_cpu(agi->agi_unlinked[bucket_index]) == agino) {
                /*
                 * We're at the head of the list.  Get the inode's
                 * on-disk buffer to see if there is anyone after us
                 * on the list.  Only modify our next pointer if it
                 * is not already NULLAGINO.  This saves us the overhead
                 * of dealing with the buffer when there is no need to
                 * change it.
                 */
                error = xfs_itobp(mp, tp, ip, &dip, &ibp, XBF_LOCK);
                if (error) {
                        cmn_err(CE_WARN,
                                "xfs_iunlink_remove: xfs_itobp()  returned an error %d on %s.  Returning error.",
                                error, mp->m_fsname);
                        return error;
                }
                next_agino = be32_to_cpu(dip->di_next_unlinked);
                ASSERT(next_agino != 0);
                if (next_agino != NULLAGINO) {
                        dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
                        offset = ip->i_imap.im_boffset +
                                offsetof(xfs_dinode_t, di_next_unlinked);
                        xfs_trans_inode_buf(tp, ibp);
                        xfs_trans_log_buf(tp, ibp, offset,
                                          (offset + sizeof(xfs_agino_t) - 1));
                        xfs_inobp_check(mp, ibp);
                } else {
                        xfs_trans_brelse(tp, ibp);
                }
                /*
                 * Point the bucket head pointer at the next inode.
                 */
                ASSERT(next_agino != 0);
                ASSERT(next_agino != agino);
                agi->agi_unlinked[bucket_index] = cpu_to_be32(next_agino);
                offset = offsetof(xfs_agi_t, agi_unlinked) +
                        (sizeof(xfs_agino_t) * bucket_index);
                xfs_trans_log_buf(tp, agibp, offset,
                                  (offset + sizeof(xfs_agino_t) - 1));
        } else {
                /*
                 * We need to search the list for the inode being freed.
                 */
                next_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
                last_ibp = NULL;
                while (next_agino != agino) {
                        /*
                         * If the last inode wasn't the one pointing to
                         * us, then release its buffer since we're not
                         * going to do anything with it.
                         */
                        if (last_ibp != NULL) {
                                xfs_trans_brelse(tp, last_ibp);
                        }
                        next_ino = XFS_AGINO_TO_INO(mp, agno, next_agino);
                        error = xfs_inotobp(mp, tp, next_ino, &last_dip,
                                            &last_ibp, &last_offset, 0);
                        if (error) {
                                cmn_err(CE_WARN,
                        "xfs_iunlink_remove: xfs_inotobp()  returned an error %d on %s.  Returning error.",
                                        error, mp->m_fsname);
                                return error;
                        }
                        next_agino = be32_to_cpu(last_dip->di_next_unlinked);
                        ASSERT(next_agino != NULLAGINO);
                        ASSERT(next_agino != 0);
                }
                /*
                 * Now last_ibp points to the buffer previous to us on
                 * the unlinked list.  Pull us from the list.
                 */
                error = xfs_itobp(mp, tp, ip, &dip, &ibp, XBF_LOCK);
                if (error) {
                        cmn_err(CE_WARN,
                                "xfs_iunlink_remove: xfs_itobp()  returned an error %d on %s.  Returning error.",
                                error, mp->m_fsname);
                        return error;
                }
                next_agino = be32_to_cpu(dip->di_next_unlinked);
                ASSERT(next_agino != 0);
                ASSERT(next_agino != agino);
                if (next_agino != NULLAGINO) {
                        dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
                        offset = ip->i_imap.im_boffset +
                                offsetof(xfs_dinode_t, di_next_unlinked);
                        xfs_trans_inode_buf(tp, ibp);
                        xfs_trans_log_buf(tp, ibp, offset,
                                          (offset + sizeof(xfs_agino_t) - 1));
                        xfs_inobp_check(mp, ibp);
                } else {
                        xfs_trans_brelse(tp, ibp);
                }
                /*
                 * Point the previous inode on the list to the next inode.
                 */
                last_dip->di_next_unlinked = cpu_to_be32(next_agino);
                ASSERT(next_agino != 0);
                offset = last_offset + offsetof(xfs_dinode_t, di_next_unlinked);
                xfs_trans_inode_buf(tp, last_ibp);
                xfs_trans_log_buf(tp, last_ibp, offset,
                                  (offset + sizeof(xfs_agino_t) - 1));
                xfs_inobp_check(mp, last_ibp);
        }
        return 0;
}

/*
 * A big issue when freeing the inode cluster is is that we _cannot_ skip any
 * inodes that are in memory - they all must be marked stale and attached to
 * the cluster buffer.
 */
STATIC void
xfs_ifree_cluster(
        xfs_inode_t     *free_ip,
        xfs_trans_t     *tp,
        xfs_ino_t       inum)
{
        xfs_mount_t             *mp = free_ip->i_mount;
        int                     blks_per_cluster;
        int                     nbufs;
        int                     ninodes;
        int                     i, j;
        xfs_daddr_t             blkno;
        xfs_buf_t               *bp;
        xfs_inode_t             *ip;
        xfs_inode_log_item_t    *iip;
        xfs_log_item_t          *lip;
        struct xfs_perag        *pag;

        pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, inum));
        if (mp->m_sb.sb_blocksize >= XFS_INODE_CLUSTER_SIZE(mp)) {
                blks_per_cluster = 1;
                ninodes = mp->m_sb.sb_inopblock;
                nbufs = XFS_IALLOC_BLOCKS(mp);
        } else {
                blks_per_cluster = XFS_INODE_CLUSTER_SIZE(mp) /
                                        mp->m_sb.sb_blocksize;
                ninodes = blks_per_cluster * mp->m_sb.sb_inopblock;
                nbufs = XFS_IALLOC_BLOCKS(mp) / blks_per_cluster;
        }

        for (j = 0; j < nbufs; j++, inum += ninodes) {
                blkno = XFS_AGB_TO_DADDR(mp, XFS_INO_TO_AGNO(mp, inum),
                                         XFS_INO_TO_AGBNO(mp, inum));

                /*
                 * We obtain and lock the backing buffer first in the process
                 * here, as we have to ensure that any dirty inode that we
                 * can't get the flush lock on is attached to the buffer.
                 * If we scan the in-memory inodes first, then buffer IO can
                 * complete before we get a lock on it, and hence we may fail
                 * to mark all the active inodes on the buffer stale.
                 */
                bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, blkno,
                                        mp->m_bsize * blks_per_cluster,
                                        XBF_LOCK);

                /*
                 * Walk the inodes already attached to the buffer and mark them
                 * stale. These will all have the flush locks held, so an
                 * in-memory inode walk can't lock them. By marking them all
                 * stale first, we will not attempt to lock them in the loop
                 * below as the XFS_ISTALE flag will be set.
                 */
                lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
                while (lip) {
                        if (lip->li_type == XFS_LI_INODE) {
                                iip = (xfs_inode_log_item_t *)lip;
                                ASSERT(iip->ili_logged == 1);
                                lip->li_cb = xfs_istale_done;
                                xfs_trans_ail_copy_lsn(mp->m_ail,
                                                        &iip->ili_flush_lsn,
                                                        &iip->ili_item.li_lsn);
                                xfs_iflags_set(iip->ili_inode, XFS_ISTALE);
                        }
                        lip = lip->li_bio_list;
                }


                /*
                 * For each inode in memory attempt to add it to the inode
                 * buffer and set it up for being staled on buffer IO
                 * completion.  This is safe as we've locked out tail pushing
                 * and flushing by locking the buffer.
                 *
                 * We have already marked every inode that was part of a
                 * transaction stale above, which means there is no point in
                 * even trying to lock them.
                 */
                for (i = 0; i < ninodes; i++) {
retry:
                        rcu_read_lock();
                        ip = radix_tree_lookup(&pag->pag_ici_root,
                                        XFS_INO_TO_AGINO(mp, (inum + i)));

                        /* Inode not in memory, nothing to do */
                        if (!ip) {
                                rcu_read_unlock();
                                continue;
                        }

                        /*
                         * because this is an RCU protected lookup, we could
                         * find a recently freed or even reallocated inode
                         * during the lookup. We need to check under the
                         * i_flags_lock for a valid inode here. Skip it if it
                         * is not valid, the wrong inode or stale.
                         */
                        spin_lock(&ip->i_flags_lock);
                        if (ip->i_ino != inum + i ||
                            __xfs_iflags_test(ip, XFS_ISTALE)) {
                                spin_unlock(&ip->i_flags_lock);
                                rcu_read_unlock();
                                continue;
                        }
                        spin_unlock(&ip->i_flags_lock);

                        /*
                         * Don't try to lock/unlock the current inode, but we
                         * _cannot_ skip the other inodes that we did not find
                         * in the list attached to the buffer and are not
                         * already marked stale. If we can't lock it, back off
                         * and retry.
                         */
                        if (ip != free_ip &&
                            !xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
                                rcu_read_unlock();
                                delay(1);
                                goto retry;
                        }
                        rcu_read_unlock();

                        xfs_iflock(ip);
                        xfs_iflags_set(ip, XFS_ISTALE);

                        /*
                         * we don't need to attach clean inodes or those only
                         * with unlogged changes (which we throw away, anyway).
                         */
                        iip = ip->i_itemp;
                        if (!iip || xfs_inode_clean(ip)) {
                                ASSERT(ip != free_ip);
                                ip->i_update_core = 0;
                                xfs_ifunlock(ip);
                                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                                continue;
                        }

                        iip->ili_last_fields = iip->ili_format.ilf_fields;
                        iip->ili_format.ilf_fields = 0;
                        iip->ili_logged = 1;
                        xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
                                                &iip->ili_item.li_lsn);

                        xfs_buf_attach_iodone(bp, xfs_istale_done,
                                                  &iip->ili_item);

                        if (ip != free_ip)
                                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                }

                xfs_trans_stale_inode_buf(tp, bp);
                xfs_trans_binval(tp, bp);
        }

        xfs_perag_put(pag);
}

/*
 * This is called to return an inode to the inode free list.
 * The inode should already be truncated to 0 length and have
 * no pages associated with it.  This routine also assumes that
 * the inode is already a part of the transaction.
 *
 * The on-disk copy of the inode will have been added to the list
 * of unlinked inodes in the AGI. We need to remove the inode from
 * that list atomically with respect to freeing it here.
 */
int
xfs_ifree(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip,
        xfs_bmap_free_t *flist)
{
        int                     error;
        int                     delete;
        xfs_ino_t               first_ino;
        xfs_dinode_t            *dip;
        xfs_buf_t               *ibp;

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
        ASSERT(ip->i_transp == tp);
        ASSERT(ip->i_d.di_nlink == 0);
        ASSERT(ip->i_d.di_nextents == 0);
        ASSERT(ip->i_d.di_anextents == 0);
        ASSERT((ip->i_d.di_size == 0 && ip->i_size == 0) ||
               ((ip->i_d.di_mode & S_IFMT) != S_IFREG));
        ASSERT(ip->i_d.di_nblocks == 0);

        /*
         * Pull the on-disk inode from the AGI unlinked list.
         */
        error = xfs_iunlink_remove(tp, ip);
        if (error != 0) {
                return error;
        }

        error = xfs_difree(tp, ip->i_ino, flist, &delete, &first_ino);
        if (error != 0) {
                return error;
        }
        ip->i_d.di_mode = 0;            /* mark incore inode as free */
        ip->i_d.di_flags = 0;
        ip->i_d.di_dmevmask = 0;
        ip->i_d.di_forkoff = 0;         /* mark the attr fork not in use */
        ip->i_df.if_ext_max =
                XFS_IFORK_DSIZE(ip) / (uint)sizeof(xfs_bmbt_rec_t);
        ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
        ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
        /*
         * Bump the generation count so no one will be confused
         * by reincarnations of this inode.
         */
        ip->i_d.di_gen++;

        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        error = xfs_itobp(ip->i_mount, tp, ip, &dip, &ibp, XBF_LOCK);
        if (error)
                return error;

        /*
        * Clear the on-disk di_mode. This is to prevent xfs_bulkstat
        * from picking up this inode when it is reclaimed (its incore state
        * initialzed but not flushed to disk yet). The in-core di_mode is
        * already cleared  and a corresponding transaction logged.
        * The hack here just synchronizes the in-core to on-disk
        * di_mode value in advance before the actual inode sync to disk.
        * This is OK because the inode is already unlinked and would never
        * change its di_mode again for this inode generation.
        * This is a temporary hack that would require a proper fix
        * in the future.
        */
        dip->di_mode = 0;

        if (delete) {
                xfs_ifree_cluster(ip, tp, first_ino);
        }

        return 0;
}

/*
 * Reallocate the space for if_broot based on the number of records
 * being added or deleted as indicated in rec_diff.  Move the records
 * and pointers in if_broot to fit the new size.  When shrinking this
 * will eliminate holes between the records and pointers created by
 * the caller.  When growing this will create holes to be filled in
 * by the caller.
 *
 * The caller must not request to add more records than would fit in
 * the on-disk inode root.  If the if_broot is currently NULL, then
 * if we adding records one will be allocated.  The caller must also
 * not request that the number of records go below zero, although
 * it can go to zero.
 *
 * ip -- the inode whose if_broot area is changing
 * ext_diff -- the change in the number of records, positive or negative,
 *       requested for the if_broot array.
 */
void
xfs_iroot_realloc(
        xfs_inode_t             *ip,
        int                     rec_diff,
        int                     whichfork)
{
        struct xfs_mount        *mp = ip->i_mount;
        int                     cur_max;
        xfs_ifork_t             *ifp;
        struct xfs_btree_block  *new_broot;
        int                     new_max;
        size_t                  new_size;
        char                    *np;
        char                    *op;

        /*
         * Handle the degenerate case quietly.
         */
        if (rec_diff == 0) {
                return;
        }

        ifp = XFS_IFORK_PTR(ip, whichfork);
        if (rec_diff > 0) {
                /*
                 * If there wasn't any memory allocated before, just
                 * allocate it now and get out.
                 */
                if (ifp->if_broot_bytes == 0) {
                        new_size = (size_t)XFS_BMAP_BROOT_SPACE_CALC(rec_diff);
                        ifp->if_broot = kmem_alloc(new_size, KM_SLEEP | KM_NOFS);
                        ifp->if_broot_bytes = (int)new_size;
                        return;
                }

                /*
                 * If there is already an existing if_broot, then we need
                 * to realloc() it and shift the pointers to their new
                 * location.  The records don't change location because
                 * they are kept butted up against the btree block header.
                 */
                cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
                new_max = cur_max + rec_diff;
                new_size = (size_t)XFS_BMAP_BROOT_SPACE_CALC(new_max);
                ifp->if_broot = kmem_realloc(ifp->if_broot, new_size,
                                (size_t)XFS_BMAP_BROOT_SPACE_CALC(cur_max), /* old size */
                                KM_SLEEP | KM_NOFS);
                op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
                                                     ifp->if_broot_bytes);
                np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
                                                     (int)new_size);
                ifp->if_broot_bytes = (int)new_size;
                ASSERT(ifp->if_broot_bytes <=
                        XFS_IFORK_SIZE(ip, whichfork) + XFS_BROOT_SIZE_ADJ);
                memmove(np, op, cur_max * (uint)sizeof(xfs_dfsbno_t));
                return;
        }

        /*
         * rec_diff is less than 0.  In this case, we are shrinking the
         * if_broot buffer.  It must already exist.  If we go to zero
         * records, just get rid of the root and clear the status bit.
         */
        ASSERT((ifp->if_broot != NULL) && (ifp->if_broot_bytes > 0));
        cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
        new_max = cur_max + rec_diff;
        ASSERT(new_max >= 0);
        if (new_max > 0)
                new_size = (size_t)XFS_BMAP_BROOT_SPACE_CALC(new_max);
        else
                new_size = 0;
        if (new_size > 0) {
                new_broot = kmem_alloc(new_size, KM_SLEEP | KM_NOFS);
                /*
                 * First copy over the btree block header.
                 */
                memcpy(new_broot, ifp->if_broot, XFS_BTREE_LBLOCK_LEN);
        } else {
                new_broot = NULL;
                ifp->if_flags &= ~XFS_IFBROOT;
        }

        /*
         * Only copy the records and pointers if there are any.
         */
        if (new_max > 0) {
                /*
                 * First copy the records.
                 */
                op = (char *)XFS_BMBT_REC_ADDR(mp, ifp->if_broot, 1);
                np = (char *)XFS_BMBT_REC_ADDR(mp, new_broot, 1);
                memcpy(np, op, new_max * (uint)sizeof(xfs_bmbt_rec_t));

                /*
                 * Then copy the pointers.
                 */
                op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
                                                     ifp->if_broot_bytes);
                np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, new_broot, 1,
                                                     (int)new_size);
                memcpy(np, op, new_max * (uint)sizeof(xfs_dfsbno_t));
        }
        kmem_free(ifp->if_broot);
        ifp->if_broot = new_broot;
        ifp->if_broot_bytes = (int)new_size;
        ASSERT(ifp->if_broot_bytes <=
                XFS_IFORK_SIZE(ip, whichfork) + XFS_BROOT_SIZE_ADJ);
        return;
}


/*
 * This is called when the amount of space needed for if_data
 * is increased or decreased.  The change in size is indicated by
 * the number of bytes that need to be added or deleted in the
 * byte_diff parameter.
 *
 * If the amount of space needed has decreased below the size of the
 * inline buffer, then switch to using the inline buffer.  Otherwise,
 * use kmem_realloc() or kmem_alloc() to adjust the size of the buffer
 * to what is needed.
 *
 * ip -- the inode whose if_data area is changing
 * byte_diff -- the change in the number of bytes, positive or negative,
 *       requested for the if_data array.
 */
void
xfs_idata_realloc(
        xfs_inode_t     *ip,
        int             byte_diff,
        int             whichfork)
{
        xfs_ifork_t     *ifp;
        int             new_size;
        int             real_size;

        if (byte_diff == 0) {
                return;
        }

        ifp = XFS_IFORK_PTR(ip, whichfork);
        new_size = (int)ifp->if_bytes + byte_diff;
        ASSERT(new_size >= 0);

        if (new_size == 0) {
                if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
                        kmem_free(ifp->if_u1.if_data);
                }
                ifp->if_u1.if_data = NULL;
                real_size = 0;
        } else if (new_size <= sizeof(ifp->if_u2.if_inline_data)) {
                /*
                 * If the valid extents/data can fit in if_inline_ext/data,
                 * copy them from the malloc'd vector and free it.
                 */
                if (ifp->if_u1.if_data == NULL) {
                        ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
                } else if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
                        ASSERT(ifp->if_real_bytes != 0);
                        memcpy(ifp->if_u2.if_inline_data, ifp->if_u1.if_data,
                              new_size);
                        kmem_free(ifp->if_u1.if_data);
                        ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
                }
                real_size = 0;
        } else {
                /*
                 * Stuck with malloc/realloc.
                 * For inline data, the underlying buffer must be
                 * a multiple of 4 bytes in size so that it can be
                 * logged and stay on word boundaries.  We enforce
                 * that here.
                 */
                real_size = roundup(new_size, 4);
                if (ifp->if_u1.if_data == NULL) {
                        ASSERT(ifp->if_real_bytes == 0);
                        ifp->if_u1.if_data = kmem_alloc(real_size,
                                                        KM_SLEEP | KM_NOFS);
                } else if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
                        /*
                         * Only do the realloc if the underlying size
                         * is really changing.
                         */
                        if (ifp->if_real_bytes != real_size) {
                                ifp->if_u1.if_data =
                                        kmem_realloc(ifp->if_u1.if_data,
                                                        real_size,
                                                        ifp->if_real_bytes,
                                                        KM_SLEEP | KM_NOFS);
                        }
                } else {
                        ASSERT(ifp->if_real_bytes == 0);
                        ifp->if_u1.if_data = kmem_alloc(real_size,
                                                        KM_SLEEP | KM_NOFS);
                        memcpy(ifp->if_u1.if_data, ifp->if_u2.if_inline_data,
                                ifp->if_bytes);
                }
        }
        ifp->if_real_bytes = real_size;
        ifp->if_bytes = new_size;
        ASSERT(ifp->if_bytes <= XFS_IFORK_SIZE(ip, whichfork));
}

void
xfs_idestroy_fork(
        xfs_inode_t     *ip,
        int             whichfork)
{
        xfs_ifork_t     *ifp;

        ifp = XFS_IFORK_PTR(ip, whichfork);
        if (ifp->if_broot != NULL) {
                kmem_free(ifp->if_broot);
                ifp->if_broot = NULL;
        }

        /*
         * If the format is local, then we can't have an extents
         * array so just look for an inline data array.  If we're
         * not local then we may or may not have an extents list,
         * so check and free it up if we do.
         */
        if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL) {
                if ((ifp->if_u1.if_data != ifp->if_u2.if_inline_data) &&
                    (ifp->if_u1.if_data != NULL)) {
                        ASSERT(ifp->if_real_bytes != 0);
                        kmem_free(ifp->if_u1.if_data);
                        ifp->if_u1.if_data = NULL;
                        ifp->if_real_bytes = 0;
                }
        } else if ((ifp->if_flags & XFS_IFEXTENTS) &&
                   ((ifp->if_flags & XFS_IFEXTIREC) ||
                    ((ifp->if_u1.if_extents != NULL) &&
                     (ifp->if_u1.if_extents != ifp->if_u2.if_inline_ext)))) {
                ASSERT(ifp->if_real_bytes != 0);
                xfs_iext_destroy(ifp);
        }
        ASSERT(ifp->if_u1.if_extents == NULL ||
               ifp->if_u1.if_extents == ifp->if_u2.if_inline_ext);
        ASSERT(ifp->if_real_bytes == 0);
        if (whichfork == XFS_ATTR_FORK) {
                kmem_zone_free(xfs_ifork_zone, ip->i_afp);
                ip->i_afp = NULL;
        }
}

/*
 * This is called to unpin an inode.  The caller must have the inode locked
 * in at least shared mode so that the buffer cannot be subsequently pinned
 * once someone is waiting for it to be unpinned.
 */
static void
xfs_iunpin_nowait(
        struct xfs_inode        *ip)
{
        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));

        trace_xfs_inode_unpin_nowait(ip, _RET_IP_);

        /* Give the log a push to start the unpinning I/O */
        xfs_log_force_lsn(ip->i_mount, ip->i_itemp->ili_last_lsn, 0);

}

void
xfs_iunpin_wait(
        struct xfs_inode        *ip)
{
        if (xfs_ipincount(ip)) {
                xfs_iunpin_nowait(ip);
                wait_event(ip->i_ipin_wait, (xfs_ipincount(ip) == 0));
        }
}

/*
 * xfs_iextents_copy()
 *
 * This is called to copy the REAL extents (as opposed to the delayed
 * allocation extents) from the inode into the given buffer.  It
 * returns the number of bytes copied into the buffer.
 *
 * If there are no delayed allocation extents, then we can just
 * memcpy() the extents into the buffer.  Otherwise, we need to
 * examine each extent in turn and skip those which are delayed.
 */
int
xfs_iextents_copy(
        xfs_inode_t             *ip,
        xfs_bmbt_rec_t          *dp,
        int                     whichfork)
{
        int                     copied;
        int                     i;
        xfs_ifork_t             *ifp;
        int                     nrecs;
        xfs_fsblock_t           start_block;

        ifp = XFS_IFORK_PTR(ip, whichfork);
        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
        ASSERT(ifp->if_bytes > 0);

        nrecs = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
        XFS_BMAP_TRACE_EXLIST(ip, nrecs, whichfork);
        ASSERT(nrecs > 0);

        /*
         * There are some delayed allocation extents in the
         * inode, so copy the extents one at a time and skip
         * the delayed ones.  There must be at least one
         * non-delayed extent.
         */
        copied = 0;
        for (i = 0; i < nrecs; i++) {
                xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
                start_block = xfs_bmbt_get_startblock(ep);
                if (isnullstartblock(start_block)) {
                        /*
                         * It's a delayed allocation extent, so skip it.
                         */
                        continue;
                }

                /* Translate to on disk format */
                put_unaligned(cpu_to_be64(ep->l0), &dp->l0);
                put_unaligned(cpu_to_be64(ep->l1), &dp->l1);
                dp++;
                copied++;
        }
        ASSERT(copied != 0);
        xfs_validate_extents(ifp, copied, XFS_EXTFMT_INODE(ip));

        return (copied * (uint)sizeof(xfs_bmbt_rec_t));
}

/*
 * Each of the following cases stores data into the same region
 * of the on-disk inode, so only one of them can be valid at
 * any given time. While it is possible to have conflicting formats
 * and log flags, e.g. having XFS_ILOG_?DATA set when the fork is
 * in EXTENTS format, this can only happen when the fork has
 * changed formats after being modified but before being flushed.
 * In these cases, the format always takes precedence, because the
 * format indicates the current state of the fork.
 */
/*ARGSUSED*/
STATIC void
xfs_iflush_fork(
        xfs_inode_t             *ip,
        xfs_dinode_t            *dip,
        xfs_inode_log_item_t    *iip,
        int                     whichfork,
        xfs_buf_t               *bp)
{
        char                    *cp;
        xfs_ifork_t             *ifp;
        xfs_mount_t             *mp;
#ifdef XFS_TRANS_DEBUG
        int                     first;
#endif
        static const short      brootflag[2] =
                { XFS_ILOG_DBROOT, XFS_ILOG_ABROOT };
        static const short      dataflag[2] =
                { XFS_ILOG_DDATA, XFS_ILOG_ADATA };
        static const short      extflag[2] =
                { XFS_ILOG_DEXT, XFS_ILOG_AEXT };

        if (!iip)
                return;
        ifp = XFS_IFORK_PTR(ip, whichfork);
        /*
         * This can happen if we gave up in iformat in an error path,
         * for the attribute fork.
         */
        if (!ifp) {
                ASSERT(whichfork == XFS_ATTR_FORK);
                return;
        }
        cp = XFS_DFORK_PTR(dip, whichfork);
        mp = ip->i_mount;
        switch (XFS_IFORK_FORMAT(ip, whichfork)) {
        case XFS_DINODE_FMT_LOCAL:
                if ((iip->ili_format.ilf_fields & dataflag[whichfork]) &&
                    (ifp->if_bytes > 0)) {
                        ASSERT(ifp->if_u1.if_data != NULL);
                        ASSERT(ifp->if_bytes <= XFS_IFORK_SIZE(ip, whichfork));
                        memcpy(cp, ifp->if_u1.if_data, ifp->if_bytes);
                }
                break;

        case XFS_DINODE_FMT_EXTENTS:
                ASSERT((ifp->if_flags & XFS_IFEXTENTS) ||
                       !(iip->ili_format.ilf_fields & extflag[whichfork]));
                ASSERT((xfs_iext_get_ext(ifp, 0) != NULL) ||
                        (ifp->if_bytes == 0));
                ASSERT((xfs_iext_get_ext(ifp, 0) == NULL) ||
                        (ifp->if_bytes > 0));
                if ((iip->ili_format.ilf_fields & extflag[whichfork]) &&
                    (ifp->if_bytes > 0)) {
                        ASSERT(XFS_IFORK_NEXTENTS(ip, whichfork) > 0);
                        (void)xfs_iextents_copy(ip, (xfs_bmbt_rec_t *)cp,
                                whichfork);
                }
                break;

        case XFS_DINODE_FMT_BTREE:
                if ((iip->ili_format.ilf_fields & brootflag[whichfork]) &&
                    (ifp->if_broot_bytes > 0)) {
                        ASSERT(ifp->if_broot != NULL);
                        ASSERT(ifp->if_broot_bytes <=
                               (XFS_IFORK_SIZE(ip, whichfork) +
                                XFS_BROOT_SIZE_ADJ));
                        xfs_bmbt_to_bmdr(mp, ifp->if_broot, ifp->if_broot_bytes,
                                (xfs_bmdr_block_t *)cp,
                                XFS_DFORK_SIZE(dip, mp, whichfork));
                }
                break;

        case XFS_DINODE_FMT_DEV:
                if (iip->ili_format.ilf_fields & XFS_ILOG_DEV) {
                        ASSERT(whichfork == XFS_DATA_FORK);
                        xfs_dinode_put_rdev(dip, ip->i_df.if_u2.if_rdev);
                }
                break;

        case XFS_DINODE_FMT_UUID:
                if (iip->ili_format.ilf_fields & XFS_ILOG_UUID) {
                        ASSERT(whichfork == XFS_DATA_FORK);
                        memcpy(XFS_DFORK_DPTR(dip),
                               &ip->i_df.if_u2.if_uuid,
                               sizeof(uuid_t));
                }
                break;

        default:
                ASSERT(0);
                break;
        }
}

STATIC int
xfs_iflush_cluster(
        xfs_inode_t     *ip,
        xfs_buf_t       *bp)
{
        xfs_mount_t             *mp = ip->i_mount;
        struct xfs_perag        *pag;
        unsigned long           first_index, mask;
        unsigned long           inodes_per_cluster;
        int                     ilist_size;
        xfs_inode_t             **ilist;
        xfs_inode_t             *iq;
        int                     nr_found;
        int                     clcount = 0;
        int                     bufwasdelwri;
        int                     i;

        pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));

        inodes_per_cluster = XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_inodelog;
        ilist_size = inodes_per_cluster * sizeof(xfs_inode_t *);
        ilist = kmem_alloc(ilist_size, KM_MAYFAIL|KM_NOFS);
        if (!ilist)
                goto out_put;

        mask = ~(((XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_inodelog)) - 1);
        first_index = XFS_INO_TO_AGINO(mp, ip->i_ino) & mask;
        rcu_read_lock();
        /* really need a gang lookup range call here */
        nr_found = radix_tree_gang_lookup(&pag->pag_ici_root, (void**)ilist,
                                        first_index, inodes_per_cluster);
        if (nr_found == 0)
                goto out_free;

        for (i = 0; i < nr_found; i++) {
                iq = ilist[i];
                if (iq == ip)
                        continue;

                /*
                 * because this is an RCU protected lookup, we could find a
                 * recently freed or even reallocated inode during the lookup.
                 * We need to check under the i_flags_lock for a valid inode
                 * here. Skip it if it is not valid or the wrong inode.
                 */
                spin_lock(&ip->i_flags_lock);
                if (!ip->i_ino ||
                    (XFS_INO_TO_AGINO(mp, iq->i_ino) & mask) != first_index) {
                        spin_unlock(&ip->i_flags_lock);
                        continue;
                }
                spin_unlock(&ip->i_flags_lock);

                /*
                 * Do an un-protected check to see if the inode is dirty and
                 * is a candidate for flushing.  These checks will be repeated
                 * later after the appropriate locks are acquired.
                 */
                if (xfs_inode_clean(iq) && xfs_ipincount(iq) == 0)
                        continue;

                /*
                 * Try to get locks.  If any are unavailable or it is pinned,
                 * then this inode cannot be flushed and is skipped.
                 */

                if (!xfs_ilock_nowait(iq, XFS_ILOCK_SHARED))
                        continue;
                if (!xfs_iflock_nowait(iq)) {
                        xfs_iunlock(iq, XFS_ILOCK_SHARED);
                        continue;
                }
                if (xfs_ipincount(iq)) {
                        xfs_ifunlock(iq);
                        xfs_iunlock(iq, XFS_ILOCK_SHARED);
                        continue;
                }

                /*
                 * arriving here means that this inode can be flushed.  First
                 * re-check that it's dirty before flushing.
                 */
                if (!xfs_inode_clean(iq)) {
                        int     error;
                        error = xfs_iflush_int(iq, bp);
                        if (error) {
                                xfs_iunlock(iq, XFS_ILOCK_SHARED);
                                goto cluster_corrupt_out;
                        }
                        clcount++;
                } else {
                        xfs_ifunlock(iq);
                }
                xfs_iunlock(iq, XFS_ILOCK_SHARED);
        }

        if (clcount) {
                XFS_STATS_INC(xs_icluster_flushcnt);
                XFS_STATS_ADD(xs_icluster_flushinode, clcount);
        }

out_free:
        rcu_read_unlock();
        kmem_free(ilist);
out_put:
        xfs_perag_put(pag);
        return 0;


cluster_corrupt_out:
        /*
         * Corruption detected in the clustering loop.  Invalidate the
         * inode buffer and shut down the filesystem.
         */
        rcu_read_unlock();
        /*
         * Clean up the buffer.  If it was B_DELWRI, just release it --
         * brelse can handle it with no problems.  If not, shut down the
         * filesystem before releasing the buffer.
         */
        bufwasdelwri = XFS_BUF_ISDELAYWRITE(bp);
        if (bufwasdelwri)
                xfs_buf_relse(bp);

        xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);

        if (!bufwasdelwri) {
                /*
                 * Just like incore_relse: if we have b_iodone functions,
                 * mark the buffer as an error and call them.  Otherwise
                 * mark it as stale and brelse.
                 */
                if (XFS_BUF_IODONE_FUNC(bp)) {
                        XFS_BUF_UNDONE(bp);
                        XFS_BUF_STALE(bp);
                        XFS_BUF_ERROR(bp,EIO);
                        xfs_buf_ioend(bp, 0);
                } else {
                        XFS_BUF_STALE(bp);
                        xfs_buf_relse(bp);
                }
        }

        /*
         * Unlocks the flush lock
         */
        xfs_iflush_abort(iq);
        kmem_free(ilist);
        xfs_perag_put(pag);
        return XFS_ERROR(EFSCORRUPTED);
}

/*
 * xfs_iflush() will write a modified inode's changes out to the
 * inode's on disk home.  The caller must have the inode lock held
 * in at least shared mode and the inode flush completion must be
 * active as well.  The inode lock will still be held upon return from
 * the call and the caller is free to unlock it.
 * The inode flush will be completed when the inode reaches the disk.
 * The flags indicate how the inode's buffer should be written out.
 */
int
xfs_iflush(
        xfs_inode_t             *ip,
        uint                    flags)
{
        xfs_inode_log_item_t    *iip;
        xfs_buf_t               *bp;
        xfs_dinode_t            *dip;
        xfs_mount_t             *mp;
        int                     error;

        XFS_STATS_INC(xs_iflush_count);

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
        ASSERT(!completion_done(&ip->i_flush));
        ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
               ip->i_d.di_nextents > ip->i_df.if_ext_max);

        iip = ip->i_itemp;
        mp = ip->i_mount;

        /*
         * We can't flush the inode until it is unpinned, so wait for it if we
         * are allowed to block.  We know noone new can pin it, because we are
         * holding the inode lock shared and you need to hold it exclusively to
         * pin the inode.
         *
         * If we are not allowed to block, force the log out asynchronously so
         * that when we come back the inode will be unpinned. If other inodes
         * in the same cluster are dirty, they will probably write the inode
         * out for us if they occur after the log force completes.
         */
        if (!(flags & SYNC_WAIT) && xfs_ipincount(ip)) {
                xfs_iunpin_nowait(ip);
                xfs_ifunlock(ip);
                return EAGAIN;
        }
        xfs_iunpin_wait(ip);

        /*
         * For stale inodes we cannot rely on the backing buffer remaining
         * stale in cache for the remaining life of the stale inode and so
         * xfs_itobp() below may give us a buffer that no longer contains
         * inodes below. We have to check this after ensuring the inode is
         * unpinned so that it is safe to reclaim the stale inode after the
         * flush call.
         */
        if (xfs_iflags_test(ip, XFS_ISTALE)) {
                xfs_ifunlock(ip);
                return 0;
        }

        /*
         * This may have been unpinned because the filesystem is shutting
         * down forcibly. If that's the case we must not write this inode
         * to disk, because the log record didn't make it to disk!
         */
        if (XFS_FORCED_SHUTDOWN(mp)) {
                ip->i_update_core = 0;
                if (iip)
                        iip->ili_format.ilf_fields = 0;
                xfs_ifunlock(ip);
                return XFS_ERROR(EIO);
        }

        /*
         * Get the buffer containing the on-disk inode.
         */
        error = xfs_itobp(mp, NULL, ip, &dip, &bp,
                                (flags & SYNC_WAIT) ? XBF_LOCK : XBF_TRYLOCK);
        if (error || !bp) {
                xfs_ifunlock(ip);
                return error;
        }

        /*
         * First flush out the inode that xfs_iflush was called with.
         */
        error = xfs_iflush_int(ip, bp);
        if (error)
                goto corrupt_out;

        /*
         * If the buffer is pinned then push on the log now so we won't
         * get stuck waiting in the write for too long.
         */
        if (XFS_BUF_ISPINNED(bp))
                xfs_log_force(mp, 0);

        /*
         * inode clustering:
         * see if other inodes can be gathered into this write
         */
        error = xfs_iflush_cluster(ip, bp);
        if (error)
                goto cluster_corrupt_out;

        if (flags & SYNC_WAIT)
                error = xfs_bwrite(mp, bp);
        else
                xfs_bdwrite(mp, bp);
        return error;

corrupt_out:
        xfs_buf_relse(bp);
        xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
cluster_corrupt_out:
        /*
         * Unlocks the flush lock
         */
        xfs_iflush_abort(ip);
        return XFS_ERROR(EFSCORRUPTED);
}


STATIC int
xfs_iflush_int(
        xfs_inode_t             *ip,
        xfs_buf_t               *bp)
{
        xfs_inode_log_item_t    *iip;
        xfs_dinode_t            *dip;
        xfs_mount_t             *mp;
#ifdef XFS_TRANS_DEBUG
        int                     first;
#endif

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
        ASSERT(!completion_done(&ip->i_flush));
        ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
               ip->i_d.di_nextents > ip->i_df.if_ext_max);

        iip = ip->i_itemp;
        mp = ip->i_mount;

        /* set *dip = inode's place in the buffer */
        dip = (xfs_dinode_t *)xfs_buf_offset(bp, ip->i_imap.im_boffset);

        /*
         * Clear i_update_core before copying out the data.
         * This is for coordination with our timestamp updates
         * that don't hold the inode lock. They will always
         * update the timestamps BEFORE setting i_update_core,
         * so if we clear i_update_core after they set it we
         * are guaranteed to see their updates to the timestamps.
         * I believe that this depends on strongly ordered memory
         * semantics, but we have that.  We use the SYNCHRONIZE
         * macro to make sure that the compiler does not reorder
         * the i_update_core access below the data copy below.
         */
        ip->i_update_core = 0;
        SYNCHRONIZE();

        /*
         * Make sure to get the latest timestamps from the Linux inode.
         */
        xfs_synchronize_times(ip);

        if (XFS_TEST_ERROR(be16_to_cpu(dip->di_magic) != XFS_DINODE_MAGIC,
                               mp, XFS_ERRTAG_IFLUSH_1, XFS_RANDOM_IFLUSH_1)) {
                xfs_cmn_err(XFS_PTAG_IFLUSH, CE_ALERT, mp,
                    "xfs_iflush: Bad inode %Lu magic number 0x%x, ptr 0x%p",
                        ip->i_ino, be16_to_cpu(dip->di_magic), dip);
                goto corrupt_out;
        }
        if (XFS_TEST_ERROR(ip->i_d.di_magic != XFS_DINODE_MAGIC,
                                mp, XFS_ERRTAG_IFLUSH_2, XFS_RANDOM_IFLUSH_2)) {
                xfs_cmn_err(XFS_PTAG_IFLUSH, CE_ALERT, mp,
                        "xfs_iflush: Bad inode %Lu, ptr 0x%p, magic number 0x%x",
                        ip->i_ino, ip, ip->i_d.di_magic);
                goto corrupt_out;
        }
        if ((ip->i_d.di_mode & S_IFMT) == S_IFREG) {
                if (XFS_TEST_ERROR(
                    (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
                    (ip->i_d.di_format != XFS_DINODE_FMT_BTREE),
                    mp, XFS_ERRTAG_IFLUSH_3, XFS_RANDOM_IFLUSH_3)) {
                        xfs_cmn_err(XFS_PTAG_IFLUSH, CE_ALERT, mp,
                                "xfs_iflush: Bad regular inode %Lu, ptr 0x%p",
                                ip->i_ino, ip);
                        goto corrupt_out;
                }
        } else if ((ip->i_d.di_mode & S_IFMT) == S_IFDIR) {
                if (XFS_TEST_ERROR(
                    (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
                    (ip->i_d.di_format != XFS_DINODE_FMT_BTREE) &&
                    (ip->i_d.di_format != XFS_DINODE_FMT_LOCAL),
                    mp, XFS_ERRTAG_IFLUSH_4, XFS_RANDOM_IFLUSH_4)) {
                        xfs_cmn_err(XFS_PTAG_IFLUSH, CE_ALERT, mp,
                                "xfs_iflush: Bad directory inode %Lu, ptr 0x%p",
                                ip->i_ino, ip);
                        goto corrupt_out;
                }
        }
        if (XFS_TEST_ERROR(ip->i_d.di_nextents + ip->i_d.di_anextents >
                                ip->i_d.di_nblocks, mp, XFS_ERRTAG_IFLUSH_5,
                                XFS_RANDOM_IFLUSH_5)) {
                xfs_cmn_err(XFS_PTAG_IFLUSH, CE_ALERT, mp,
                        "xfs_iflush: detected corrupt incore inode %Lu, total extents = %d, nblocks = %Ld, ptr 0x%p",
                        ip->i_ino,
                        ip->i_d.di_nextents + ip->i_d.di_anextents,
                        ip->i_d.di_nblocks,
                        ip);
                goto corrupt_out;
        }
        if (XFS_TEST_ERROR(ip->i_d.di_forkoff > mp->m_sb.sb_inodesize,
                                mp, XFS_ERRTAG_IFLUSH_6, XFS_RANDOM_IFLUSH_6)) {
                xfs_cmn_err(XFS_PTAG_IFLUSH, CE_ALERT, mp,
                        "xfs_iflush: bad inode %Lu, forkoff 0x%x, ptr 0x%p",
                        ip->i_ino, ip->i_d.di_forkoff, ip);
                goto corrupt_out;
        }
        /*
         * bump the flush iteration count, used to detect flushes which
         * postdate a log record during recovery.
         */

        ip->i_d.di_flushiter++;

        /*
         * Copy the dirty parts of the inode into the on-disk
         * inode.  We always copy out the core of the inode,
         * because if the inode is dirty at all the core must
         * be.
         */
        xfs_dinode_to_disk(dip, &ip->i_d);

        /* Wrap, we never let the log put out DI_MAX_FLUSH */
        if (ip->i_d.di_flushiter == DI_MAX_FLUSH)
                ip->i_d.di_flushiter = 0;

        /*
         * If this is really an old format inode and the superblock version
         * has not been updated to support only new format inodes, then
         * convert back to the old inode format.  If the superblock version
         * has been updated, then make the conversion permanent.
         */
        ASSERT(ip->i_d.di_version == 1 || xfs_sb_version_hasnlink(&mp->m_sb));
        if (ip->i_d.di_version == 1) {
                if (!xfs_sb_version_hasnlink(&mp->m_sb)) {
                        /*
                         * Convert it back.
                         */
                        ASSERT(ip->i_d.di_nlink <= XFS_MAXLINK_1);
                        dip->di_onlink = cpu_to_be16(ip->i_d.di_nlink);
                } else {
                        /*
                         * The superblock version has already been bumped,
                         * so just make the conversion to the new inode
                         * format permanent.
                         */
                        ip->i_d.di_version = 2;
                        dip->di_version = 2;
                        ip->i_d.di_onlink = 0;
                        dip->di_onlink = 0;
                        memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
                        memset(&(dip->di_pad[0]), 0,
                              sizeof(dip->di_pad));
                        ASSERT(xfs_get_projid(ip) == 0);
                }
        }

        xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK, bp);
        if (XFS_IFORK_Q(ip))
                xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK, bp);
        xfs_inobp_check(mp, bp);

        /*
         * We've recorded everything logged in the inode, so we'd
         * like to clear the ilf_fields bits so we don't log and
         * flush things unnecessarily.  However, we can't stop
         * logging all this information until the data we've copied
         * into the disk buffer is written to disk.  If we did we might
         * overwrite the copy of the inode in the log with all the
         * data after re-logging only part of it, and in the face of
         * a crash we wouldn't have all the data we need to recover.
         *
         * What we do is move the bits to the ili_last_fields field.
         * When logging the inode, these bits are moved back to the
         * ilf_fields field.  In the xfs_iflush_done() routine we
         * clear ili_last_fields, since we know that the information
         * those bits represent is permanently on disk.  As long as
         * the flush completes before the inode is logged again, then
         * both ilf_fields and ili_last_fields will be cleared.
         *
         * We can play with the ilf_fields bits here, because the inode
         * lock must be held exclusively in order to set bits there
         * and the flush lock protects the ili_last_fields bits.
         * Set ili_logged so the flush done
         * routine can tell whether or not to look in the AIL.
         * Also, store the current LSN of the inode so that we can tell
         * whether the item has moved in the AIL from xfs_iflush_done().
         * In order to read the lsn we need the AIL lock, because
         * it is a 64 bit value that cannot be read atomically.
         */
        if (iip != NULL && iip->ili_format.ilf_fields != 0) {
                iip->ili_last_fields = iip->ili_format.ilf_fields;
                iip->ili_format.ilf_fields = 0;
                iip->ili_logged = 1;

                xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
                                        &iip->ili_item.li_lsn);

                /*
                 * Attach the function xfs_iflush_done to the inode's
                 * buffer.  This will remove the inode from the AIL
                 * and unlock the inode's flush lock when the inode is
                 * completely written to disk.
                 */
                xfs_buf_attach_iodone(bp, xfs_iflush_done, &iip->ili_item);

                ASSERT(XFS_BUF_FSPRIVATE(bp, void *) != NULL);
                ASSERT(XFS_BUF_IODONE_FUNC(bp) != NULL);
        } else {
                /*
                 * We're flushing an inode which is not in the AIL and has
                 * not been logged but has i_update_core set.  For this
                 * case we can use a B_DELWRI flush and immediately drop
                 * the inode flush lock because we can avoid the whole
                 * AIL state thing.  It's OK to drop the flush lock now,
                 * because we've already locked the buffer and to do anything
                 * you really need both.
                 */
                if (iip != NULL) {
                        ASSERT(iip->ili_logged == 0);
                        ASSERT(iip->ili_last_fields == 0);
                        ASSERT((iip->ili_item.li_flags & XFS_LI_IN_AIL) == 0);
                }
                xfs_ifunlock(ip);
        }

        return 0;

corrupt_out:
        return XFS_ERROR(EFSCORRUPTED);
}

/*
 * Return a pointer to the extent record at file index idx.
 */
xfs_bmbt_rec_host_t *
xfs_iext_get_ext(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_extnum_t    idx)            /* index of target extent */
{
        ASSERT(idx >= 0);
        if ((ifp->if_flags & XFS_IFEXTIREC) && (idx == 0)) {
                return ifp->if_u1.if_ext_irec->er_extbuf;
        } else if (ifp->if_flags & XFS_IFEXTIREC) {
                xfs_ext_irec_t  *erp;           /* irec pointer */
                int             erp_idx = 0;    /* irec index */
                xfs_extnum_t    page_idx = idx; /* ext index in target list */

                erp = xfs_iext_idx_to_irec(ifp, &page_idx, &erp_idx, 0);
                return &erp->er_extbuf[page_idx];
        } else if (ifp->if_bytes) {
                return &ifp->if_u1.if_extents[idx];
        } else {
                return NULL;
        }
}

/*
 * Insert new item(s) into the extent records for incore inode
 * fork 'ifp'.  'count' new items are inserted at index 'idx'.
 */
void
xfs_iext_insert(
        xfs_inode_t     *ip,            /* incore inode pointer */
        xfs_extnum_t    idx,            /* starting index of new items */
        xfs_extnum_t    count,          /* number of inserted items */
        xfs_bmbt_irec_t *new,           /* items to insert */
        int             state)          /* type of extent conversion */
{
        xfs_ifork_t     *ifp = (state & BMAP_ATTRFORK) ? ip->i_afp : &ip->i_df;
        xfs_extnum_t    i;              /* extent record index */

        trace_xfs_iext_insert(ip, idx, new, state, _RET_IP_);

        ASSERT(ifp->if_flags & XFS_IFEXTENTS);
        xfs_iext_add(ifp, idx, count);
        for (i = idx; i < idx + count; i++, new++)
                xfs_bmbt_set_all(xfs_iext_get_ext(ifp, i), new);
}

/*
 * This is called when the amount of space required for incore file
 * extents needs to be increased. The ext_diff parameter stores the
 * number of new extents being added and the idx parameter contains
 * the extent index where the new extents will be added. If the new
 * extents are being appended, then we just need to (re)allocate and
 * initialize the space. Otherwise, if the new extents are being
 * inserted into the middle of the existing entries, a bit more work
 * is required to make room for the new extents to be inserted. The
 * caller is responsible for filling in the new extent entries upon
 * return.
 */
void
xfs_iext_add(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_extnum_t    idx,            /* index to begin adding exts */
        int             ext_diff)       /* number of extents to add */
{
        int             byte_diff;      /* new bytes being added */
        int             new_size;       /* size of extents after adding */
        xfs_extnum_t    nextents;       /* number of extents in file */

        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
        ASSERT((idx >= 0) && (idx <= nextents));
        byte_diff = ext_diff * sizeof(xfs_bmbt_rec_t);
        new_size = ifp->if_bytes + byte_diff;
        /*
         * If the new number of extents (nextents + ext_diff)
         * fits inside the inode, then continue to use the inline
         * extent buffer.
         */
        if (nextents + ext_diff <= XFS_INLINE_EXTS) {
                if (idx < nextents) {
                        memmove(&ifp->if_u2.if_inline_ext[idx + ext_diff],
                                &ifp->if_u2.if_inline_ext[idx],
                                (nextents - idx) * sizeof(xfs_bmbt_rec_t));
                        memset(&ifp->if_u2.if_inline_ext[idx], 0, byte_diff);
                }
                ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
                ifp->if_real_bytes = 0;
                ifp->if_lastex = nextents + ext_diff;
        }
        /*
         * Otherwise use a linear (direct) extent list.
         * If the extents are currently inside the inode,
         * xfs_iext_realloc_direct will switch us from
         * inline to direct extent allocation mode.
         */
        else if (nextents + ext_diff <= XFS_LINEAR_EXTS) {
                xfs_iext_realloc_direct(ifp, new_size);
                if (idx < nextents) {
                        memmove(&ifp->if_u1.if_extents[idx + ext_diff],
                                &ifp->if_u1.if_extents[idx],
                                (nextents - idx) * sizeof(xfs_bmbt_rec_t));
                        memset(&ifp->if_u1.if_extents[idx], 0, byte_diff);
                }
        }
        /* Indirection array */
        else {
                xfs_ext_irec_t  *erp;
                int             erp_idx = 0;
                int             page_idx = idx;

                ASSERT(nextents + ext_diff > XFS_LINEAR_EXTS);
                if (ifp->if_flags & XFS_IFEXTIREC) {
                        erp = xfs_iext_idx_to_irec(ifp, &page_idx, &erp_idx, 1);
                } else {
                        xfs_iext_irec_init(ifp);
                        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
                        erp = ifp->if_u1.if_ext_irec;
                }
                /* Extents fit in target extent page */
                if (erp && erp->er_extcount + ext_diff <= XFS_LINEAR_EXTS) {
                        if (page_idx < erp->er_extcount) {
                                memmove(&erp->er_extbuf[page_idx + ext_diff],
                                        &erp->er_extbuf[page_idx],
                                        (erp->er_extcount - page_idx) *
                                        sizeof(xfs_bmbt_rec_t));
                                memset(&erp->er_extbuf[page_idx], 0, byte_diff);
                        }
                        erp->er_extcount += ext_diff;
                        xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
                }
                /* Insert a new extent page */
                else if (erp) {
                        xfs_iext_add_indirect_multi(ifp,
                                erp_idx, page_idx, ext_diff);
                }
                /*
                 * If extent(s) are being appended to the last page in
                 * the indirection array and the new extent(s) don't fit
                 * in the page, then erp is NULL and erp_idx is set to
                 * the next index needed in the indirection array.
                 */
                else {
                        int     count = ext_diff;

                        while (count) {
                                erp = xfs_iext_irec_new(ifp, erp_idx);
                                erp->er_extcount = count;
                                count -= MIN(count, (int)XFS_LINEAR_EXTS);
                                if (count) {
                                        erp_idx++;
                                }
                        }
                }
        }
        ifp->if_bytes = new_size;
}

/*
 * This is called when incore extents are being added to the indirection
 * array and the new extents do not fit in the target extent list. The
 * erp_idx parameter contains the irec index for the target extent list
 * in the indirection array, and the idx parameter contains the extent
 * index within the list. The number of extents being added is stored
 * in the count parameter.
 *
 *    |-------|   |-------|
 *    |       |   |       |    idx - number of extents before idx
 *    |  idx  |   | count |
 *    |       |   |       |    count - number of extents being inserted at idx
 *    |-------|   |-------|
 *    | count |   | nex2  |    nex2 - number of extents after idx + count
 *    |-------|   |-------|
 */
void
xfs_iext_add_indirect_multi(
        xfs_ifork_t     *ifp,                   /* inode fork pointer */
        int             erp_idx,                /* target extent irec index */
        xfs_extnum_t    idx,                    /* index within target list */
        int             count)                  /* new extents being added */
{
        int             byte_diff;              /* new bytes being added */
        xfs_ext_irec_t  *erp;                   /* pointer to irec entry */
        xfs_extnum_t    ext_diff;               /* number of extents to add */
        xfs_extnum_t    ext_cnt;                /* new extents still needed */
        xfs_extnum_t    nex2;                   /* extents after idx + count */
        xfs_bmbt_rec_t  *nex2_ep = NULL;        /* temp list for nex2 extents */
        int             nlists;                 /* number of irec's (lists) */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        erp = &ifp->if_u1.if_ext_irec[erp_idx];
        nex2 = erp->er_extcount - idx;
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;

        /*
         * Save second part of target extent list
         * (all extents past */
        if (nex2) {
                byte_diff = nex2 * sizeof(xfs_bmbt_rec_t);
                nex2_ep = (xfs_bmbt_rec_t *) kmem_alloc(byte_diff, KM_NOFS);
                memmove(nex2_ep, &erp->er_extbuf[idx], byte_diff);
                erp->er_extcount -= nex2;
                xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, -nex2);
                memset(&erp->er_extbuf[idx], 0, byte_diff);
        }

        /*
         * Add the new extents to the end of the target
         * list, then allocate new irec record(s) and
         * extent buffer(s) as needed to store the rest
         * of the new extents.
         */
        ext_cnt = count;
        ext_diff = MIN(ext_cnt, (int)XFS_LINEAR_EXTS - erp->er_extcount);
        if (ext_diff) {
                erp->er_extcount += ext_diff;
                xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
                ext_cnt -= ext_diff;
        }
        while (ext_cnt) {
                erp_idx++;
                erp = xfs_iext_irec_new(ifp, erp_idx);
                ext_diff = MIN(ext_cnt, (int)XFS_LINEAR_EXTS);
                erp->er_extcount = ext_diff;
                xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
                ext_cnt -= ext_diff;
        }

        /* Add nex2 extents back to indirection array */
        if (nex2) {
                xfs_extnum_t    ext_avail;
                int             i;

                byte_diff = nex2 * sizeof(xfs_bmbt_rec_t);
                ext_avail = XFS_LINEAR_EXTS - erp->er_extcount;
                i = 0;
                /*
                 * If nex2 extents fit in the current page, append
                 * nex2_ep after the new extents.
                 */
                if (nex2 <= ext_avail) {
                        i = erp->er_extcount;
                }
                /*
                 * Otherwise, check if space is available in the
                 * next page.
                 */
                else if ((erp_idx < nlists - 1) &&
                         (nex2 <= (ext_avail = XFS_LINEAR_EXTS -
                          ifp->if_u1.if_ext_irec[erp_idx+1].er_extcount))) {
                        erp_idx++;
                        erp++;
                        /* Create a hole for nex2 extents */
                        memmove(&erp->er_extbuf[nex2], erp->er_extbuf,
                                erp->er_extcount * sizeof(xfs_bmbt_rec_t));
                }
                /*
                 * Final choice, create a new extent page for
                 * nex2 extents.
                 */
                else {
                        erp_idx++;
                        erp = xfs_iext_irec_new(ifp, erp_idx);
                }
                memmove(&erp->er_extbuf[i], nex2_ep, byte_diff);
                kmem_free(nex2_ep);
                erp->er_extcount += nex2;
                xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, nex2);
        }
}

/*
 * This is called when the amount of space required for incore file
 * extents needs to be decreased. The ext_diff parameter stores the
 * number of extents to be removed and the idx parameter contains
 * the extent index where the extents will be removed from.
 *
 * If the amount of space needed has decreased below the linear
 * limit, XFS_IEXT_BUFSZ, then switch to using the contiguous
 * extent array.  Otherwise, use kmem_realloc() to adjust the
 * size to what is needed.
 */
void
xfs_iext_remove(
        xfs_inode_t     *ip,            /* incore inode pointer */
        xfs_extnum_t    idx,            /* index to begin removing exts */
        int             ext_diff,       /* number of extents to remove */
        int             state)          /* type of extent conversion */
{
        xfs_ifork_t     *ifp = (state & BMAP_ATTRFORK) ? ip->i_afp : &ip->i_df;
        xfs_extnum_t    nextents;       /* number of extents in file */
        int             new_size;       /* size of extents after removal */

        trace_xfs_iext_remove(ip, idx, state, _RET_IP_);

        ASSERT(ext_diff > 0);
        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
        new_size = (nextents - ext_diff) * sizeof(xfs_bmbt_rec_t);

        if (new_size == 0) {
                xfs_iext_destroy(ifp);
        } else if (ifp->if_flags & XFS_IFEXTIREC) {
                xfs_iext_remove_indirect(ifp, idx, ext_diff);
        } else if (ifp->if_real_bytes) {
                xfs_iext_remove_direct(ifp, idx, ext_diff);
        } else {
                xfs_iext_remove_inline(ifp, idx, ext_diff);
        }
        ifp->if_bytes = new_size;
}

/*
 * This removes ext_diff extents from the inline buffer, beginning
 * at extent index idx.
 */
void
xfs_iext_remove_inline(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_extnum_t    idx,            /* index to begin removing exts */
        int             ext_diff)       /* number of extents to remove */
{
        int             nextents;       /* number of extents in file */

        ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
        ASSERT(idx < XFS_INLINE_EXTS);
        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
        ASSERT(((nextents - ext_diff) > 0) &&
                (nextents - ext_diff) < XFS_INLINE_EXTS);

        if (idx + ext_diff < nextents) {
                memmove(&ifp->if_u2.if_inline_ext[idx],
                        &ifp->if_u2.if_inline_ext[idx + ext_diff],
                        (nextents - (idx + ext_diff)) *
                         sizeof(xfs_bmbt_rec_t));
                memset(&ifp->if_u2.if_inline_ext[nextents - ext_diff],
                        0, ext_diff * sizeof(xfs_bmbt_rec_t));
        } else {
                memset(&ifp->if_u2.if_inline_ext[idx], 0,
                        ext_diff * sizeof(xfs_bmbt_rec_t));
        }
}

/*
 * This removes ext_diff extents from a linear (direct) extent list,
 * beginning at extent index idx. If the extents are being removed
 * from the end of the list (ie. truncate) then we just need to re-
 * allocate the list to remove the extra space. Otherwise, if the
 * extents are being removed from the middle of the existing extent
 * entries, then we first need to move the extent records beginning
 * at idx + ext_diff up in the list to overwrite the records being
 * removed, then remove the extra space via kmem_realloc.
 */
void
xfs_iext_remove_direct(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_extnum_t    idx,            /* index to begin removing exts */
        int             ext_diff)       /* number of extents to remove */
{
        xfs_extnum_t    nextents;       /* number of extents in file */
        int             new_size;       /* size of extents after removal */

        ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
        new_size = ifp->if_bytes -
                (ext_diff * sizeof(xfs_bmbt_rec_t));
        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);

        if (new_size == 0) {
                xfs_iext_destroy(ifp);
                return;
        }
        /* Move extents up in the list (if needed) */
        if (idx + ext_diff < nextents) {
                memmove(&ifp->if_u1.if_extents[idx],
                        &ifp->if_u1.if_extents[idx + ext_diff],
                        (nextents - (idx + ext_diff)) *
                         sizeof(xfs_bmbt_rec_t));
        }
        memset(&ifp->if_u1.if_extents[nextents - ext_diff],
                0, ext_diff * sizeof(xfs_bmbt_rec_t));
        /*
         * Reallocate the direct extent list. If the extents
         * will fit inside the inode then xfs_iext_realloc_direct
         * will switch from direct to inline extent allocation
         * mode for us.
         */
        xfs_iext_realloc_direct(ifp, new_size);
        ifp->if_bytes = new_size;
}

/*
 * This is called when incore extents are being removed from the
 * indirection array and the extents being removed span multiple extent
 * buffers. The idx parameter contains the file extent index where we
 * want to begin removing extents, and the count parameter contains
 * how many extents need to be removed.
 *
 *    |-------|   |-------|
 *    | nex1  |   |       |    nex1 - number of extents before idx
 *    |-------|   | count |
 *    |       |   |       |    count - number of extents being removed at idx
 *    | count |   |-------|
 *    |       |   | nex2  |    nex2 - number of extents after idx + count
 *    |-------|   |-------|
 */
void
xfs_iext_remove_indirect(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_extnum_t    idx,            /* index to begin removing extents */
        int             count)          /* number of extents to remove */
{
        xfs_ext_irec_t  *erp;           /* indirection array pointer */
        int             erp_idx = 0;    /* indirection array index */
        xfs_extnum_t    ext_cnt;        /* extents left to remove */
        xfs_extnum_t    ext_diff;       /* extents to remove in current list */
        xfs_extnum_t    nex1;           /* number of extents before idx */
        xfs_extnum_t    nex2;           /* extents after idx + count */
        int             page_idx = idx; /* index in target extent list */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        erp = xfs_iext_idx_to_irec(ifp,  &page_idx, &erp_idx, 0);
        ASSERT(erp != NULL);
        nex1 = page_idx;
        ext_cnt = count;
        while (ext_cnt) {
                nex2 = MAX((erp->er_extcount - (nex1 + ext_cnt)), 0);
                ext_diff = MIN(ext_cnt, (erp->er_extcount - nex1));
                /*
                 * Check for deletion of entire list;
                 * xfs_iext_irec_remove() updates extent offsets.
                 */
                if (ext_diff == erp->er_extcount) {
                        xfs_iext_irec_remove(ifp, erp_idx);
                        ext_cnt -= ext_diff;
                        nex1 = 0;
                        if (ext_cnt) {
                                ASSERT(erp_idx < ifp->if_real_bytes /
                                        XFS_IEXT_BUFSZ);
                                erp = &ifp->if_u1.if_ext_irec[erp_idx];
                                nex1 = 0;
                                continue;
                        } else {
                                break;
                        }
                }
                /* Move extents up (if needed) */
                if (nex2) {
                        memmove(&erp->er_extbuf[nex1],
                                &erp->er_extbuf[nex1 + ext_diff],
                                nex2 * sizeof(xfs_bmbt_rec_t));
                }
                /* Zero out rest of page */
                memset(&erp->er_extbuf[nex1 + nex2], 0, (XFS_IEXT_BUFSZ -
                        ((nex1 + nex2) * sizeof(xfs_bmbt_rec_t))));
                /* Update remaining counters */
                erp->er_extcount -= ext_diff;
                xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, -ext_diff);
                ext_cnt -= ext_diff;
                nex1 = 0;
                erp_idx++;
                erp++;
        }
        ifp->if_bytes -= count * sizeof(xfs_bmbt_rec_t);
        xfs_iext_irec_compact(ifp);
}

/*
 * Create, destroy, or resize a linear (direct) block of extents.
 */
void
xfs_iext_realloc_direct(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        int             new_size)       /* new size of extents */
{
        int             rnew_size;      /* real new size of extents */

        rnew_size = new_size;

        ASSERT(!(ifp->if_flags & XFS_IFEXTIREC) ||
                ((new_size >= 0) && (new_size <= XFS_IEXT_BUFSZ) &&
                 (new_size != ifp->if_real_bytes)));

        /* Free extent records */
        if (new_size == 0) {
                xfs_iext_destroy(ifp);
        }
        /* Resize direct extent list and zero any new bytes */
        else if (ifp->if_real_bytes) {
                /* Check if extents will fit inside the inode */
                if (new_size <= XFS_INLINE_EXTS * sizeof(xfs_bmbt_rec_t)) {
                        xfs_iext_direct_to_inline(ifp, new_size /
                                (uint)sizeof(xfs_bmbt_rec_t));
                        ifp->if_bytes = new_size;
                        return;
                }
                if (!is_power_of_2(new_size)){
                        rnew_size = roundup_pow_of_two(new_size);
                }
                if (rnew_size != ifp->if_real_bytes) {
                        ifp->if_u1.if_extents =
                                kmem_realloc(ifp->if_u1.if_extents,
                                                rnew_size,
                                                ifp->if_real_bytes, KM_NOFS);
                }
                if (rnew_size > ifp->if_real_bytes) {
                        memset(&ifp->if_u1.if_extents[ifp->if_bytes /
                                (uint)sizeof(xfs_bmbt_rec_t)], 0,
                                rnew_size - ifp->if_real_bytes);
                }
        }
        /*
         * Switch from the inline extent buffer to a direct
         * extent list. Be sure to include the inline extent
         * bytes in new_size.
         */
        else {
                new_size += ifp->if_bytes;
                if (!is_power_of_2(new_size)) {
                        rnew_size = roundup_pow_of_two(new_size);
                }
                xfs_iext_inline_to_direct(ifp, rnew_size);
        }
        ifp->if_real_bytes = rnew_size;
        ifp->if_bytes = new_size;
}

/*
 * Switch from linear (direct) extent records to inline buffer.
 */
void
xfs_iext_direct_to_inline(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_extnum_t    nextents)       /* number of extents in file */
{
        ASSERT(ifp->if_flags & XFS_IFEXTENTS);
        ASSERT(nextents <= XFS_INLINE_EXTS);
        /*
         * The inline buffer was zeroed when we switched
         * from inline to direct extent allocation mode,
         * so we don't need to clear it here.
         */
        memcpy(ifp->if_u2.if_inline_ext, ifp->if_u1.if_extents,
                nextents * sizeof(xfs_bmbt_rec_t));
        kmem_free(ifp->if_u1.if_extents);
        ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
        ifp->if_real_bytes = 0;
}

/*
 * Switch from inline buffer to linear (direct) extent records.
 * new_size should already be rounded up to the next power of 2
 * by the caller (when appropriate), so use new_size as it is.
 * However, since new_size may be rounded up, we can't update
 * if_bytes here. It is the caller's responsibility to update
 * if_bytes upon return.
 */
void
xfs_iext_inline_to_direct(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        int             new_size)       /* number of extents in file */
{
        ifp->if_u1.if_extents = kmem_alloc(new_size, KM_NOFS);
        memset(ifp->if_u1.if_extents, 0, new_size);
        if (ifp->if_bytes) {
                memcpy(ifp->if_u1.if_extents, ifp->if_u2.if_inline_ext,
                        ifp->if_bytes);
                memset(ifp->if_u2.if_inline_ext, 0, XFS_INLINE_EXTS *
                        sizeof(xfs_bmbt_rec_t));
        }
        ifp->if_real_bytes = new_size;
}

/*
 * Resize an extent indirection array to new_size bytes.
 */
STATIC void
xfs_iext_realloc_indirect(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        int             new_size)       /* new indirection array size */
{
        int             nlists;         /* number of irec's (ex lists) */
        int             size;           /* current indirection array size */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
        size = nlists * sizeof(xfs_ext_irec_t);
        ASSERT(ifp->if_real_bytes);
        ASSERT((new_size >= 0) && (new_size != size));
        if (new_size == 0) {
                xfs_iext_destroy(ifp);
        } else {
                ifp->if_u1.if_ext_irec = (xfs_ext_irec_t *)
                        kmem_realloc(ifp->if_u1.if_ext_irec,
                                new_size, size, KM_NOFS);
        }
}

/*
 * Switch from indirection array to linear (direct) extent allocations.
 */
STATIC void
xfs_iext_indirect_to_direct(
         xfs_ifork_t    *ifp)           /* inode fork pointer */
{
        xfs_bmbt_rec_host_t *ep;        /* extent record pointer */
        xfs_extnum_t    nextents;       /* number of extents in file */
        int             size;           /* size of file extents */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
        ASSERT(nextents <= XFS_LINEAR_EXTS);
        size = nextents * sizeof(xfs_bmbt_rec_t);

        xfs_iext_irec_compact_pages(ifp);
        ASSERT(ifp->if_real_bytes == XFS_IEXT_BUFSZ);

        ep = ifp->if_u1.if_ext_irec->er_extbuf;
        kmem_free(ifp->if_u1.if_ext_irec);
        ifp->if_flags &= ~XFS_IFEXTIREC;
        ifp->if_u1.if_extents = ep;
        ifp->if_bytes = size;
        if (nextents < XFS_LINEAR_EXTS) {
                xfs_iext_realloc_direct(ifp, size);
        }
}

/*
 * Free incore file extents.
 */
void
xfs_iext_destroy(
        xfs_ifork_t     *ifp)           /* inode fork pointer */
{
        if (ifp->if_flags & XFS_IFEXTIREC) {
                int     erp_idx;
                int     nlists;

                nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
                for (erp_idx = nlists - 1; erp_idx >= 0 ; erp_idx--) {
                        xfs_iext_irec_remove(ifp, erp_idx);
                }
                ifp->if_flags &= ~XFS_IFEXTIREC;
        } else if (ifp->if_real_bytes) {
                kmem_free(ifp->if_u1.if_extents);
        } else if (ifp->if_bytes) {
                memset(ifp->if_u2.if_inline_ext, 0, XFS_INLINE_EXTS *
                        sizeof(xfs_bmbt_rec_t));
        }
        ifp->if_u1.if_extents = NULL;
        ifp->if_real_bytes = 0;
        ifp->if_bytes = 0;
}

/*
 * Return a pointer to the extent record for file system block bno.
 */
xfs_bmbt_rec_host_t *                   /* pointer to found extent record */
xfs_iext_bno_to_ext(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_fileoff_t   bno,            /* block number to search for */
        xfs_extnum_t    *idxp)          /* index of target extent */
{
        xfs_bmbt_rec_host_t *base;      /* pointer to first extent */
        xfs_filblks_t   blockcount = 0; /* number of blocks in extent */
        xfs_bmbt_rec_host_t *ep = NULL; /* pointer to target extent */
        xfs_ext_irec_t  *erp = NULL;    /* indirection array pointer */
        int             high;           /* upper boundary in search */
        xfs_extnum_t    idx = 0;        /* index of target extent */
        int             low;            /* lower boundary in search */
        xfs_extnum_t    nextents;       /* number of file extents */
        xfs_fileoff_t   startoff = 0;   /* start offset of extent */

        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
        if (nextents == 0) {
                *idxp = 0;
                return NULL;
        }
        low = 0;
        if (ifp->if_flags & XFS_IFEXTIREC) {
                /* Find target extent list */
                int     erp_idx = 0;
                erp = xfs_iext_bno_to_irec(ifp, bno, &erp_idx);
                base = erp->er_extbuf;
                high = erp->er_extcount - 1;
        } else {
                base = ifp->if_u1.if_extents;
                high = nextents - 1;
        }
        /* Binary search extent records */
        while (low <= high) {
                idx = (low + high) >> 1;
                ep = base + idx;
                startoff = xfs_bmbt_get_startoff(ep);
                blockcount = xfs_bmbt_get_blockcount(ep);
                if (bno < startoff) {
                        high = idx - 1;
                } else if (bno >= startoff + blockcount) {
                        low = idx + 1;
                } else {
                        /* Convert back to file-based extent index */
                        if (ifp->if_flags & XFS_IFEXTIREC) {
                                idx += erp->er_extoff;
                        }
                        *idxp = idx;
                        return ep;
                }
        }
        /* Convert back to file-based extent index */
        if (ifp->if_flags & XFS_IFEXTIREC) {
                idx += erp->er_extoff;
        }
        if (bno >= startoff + blockcount) {
                if (++idx == nextents) {
                        ep = NULL;
                } else {
                        ep = xfs_iext_get_ext(ifp, idx);
                }
        }
        *idxp = idx;
        return ep;
}

/*
 * Return a pointer to the indirection array entry containing the
 * extent record for filesystem block bno. Store the index of the
 * target irec in *erp_idxp.
 */
xfs_ext_irec_t *                        /* pointer to found extent record */
xfs_iext_bno_to_irec(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_fileoff_t   bno,            /* block number to search for */
        int             *erp_idxp)      /* irec index of target ext list */
{
        xfs_ext_irec_t  *erp = NULL;    /* indirection array pointer */
        xfs_ext_irec_t  *erp_next;      /* next indirection array entry */
        int             erp_idx;        /* indirection array index */
        int             nlists;         /* number of extent irec's (lists) */
        int             high;           /* binary search upper limit */
        int             low;            /* binary search lower limit */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
        erp_idx = 0;
        low = 0;
        high = nlists - 1;
        while (low <= high) {
                erp_idx = (low + high) >> 1;
                erp = &ifp->if_u1.if_ext_irec[erp_idx];
                erp_next = erp_idx < nlists - 1 ? erp + 1 : NULL;
                if (bno < xfs_bmbt_get_startoff(erp->er_extbuf)) {
                        high = erp_idx - 1;
                } else if (erp_next && bno >=
                           xfs_bmbt_get_startoff(erp_next->er_extbuf)) {
                        low = erp_idx + 1;
                } else {
                        break;
                }
        }
        *erp_idxp = erp_idx;
        return erp;
}

/*
 * Return a pointer to the indirection array entry containing the
 * extent record at file extent index *idxp. Store the index of the
 * target irec in *erp_idxp and store the page index of the target
 * extent record in *idxp.
 */
xfs_ext_irec_t *
xfs_iext_idx_to_irec(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        xfs_extnum_t    *idxp,          /* extent index (file -> page) */
        int             *erp_idxp,      /* pointer to target irec */
        int             realloc)        /* new bytes were just added */
{
        xfs_ext_irec_t  *prev;          /* pointer to previous irec */
        xfs_ext_irec_t  *erp = NULL;    /* pointer to current irec */
        int             erp_idx;        /* indirection array index */
        int             nlists;         /* number of irec's (ex lists) */
        int             high;           /* binary search upper limit */
        int             low;            /* binary search lower limit */
        xfs_extnum_t    page_idx = *idxp; /* extent index in target list */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        ASSERT(page_idx >= 0 && page_idx <=
                ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t));
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
        erp_idx = 0;
        low = 0;
        high = nlists - 1;

        /* Binary search extent irec's */
        while (low <= high) {
                erp_idx = (low + high) >> 1;
                erp = &ifp->if_u1.if_ext_irec[erp_idx];
                prev = erp_idx > 0 ? erp - 1 : NULL;
                if (page_idx < erp->er_extoff || (page_idx == erp->er_extoff &&
                     realloc && prev && prev->er_extcount < XFS_LINEAR_EXTS)) {
                        high = erp_idx - 1;
                } else if (page_idx > erp->er_extoff + erp->er_extcount ||
                           (page_idx == erp->er_extoff + erp->er_extcount &&
                            !realloc)) {
                        low = erp_idx + 1;
                } else if (page_idx == erp->er_extoff + erp->er_extcount &&
                           erp->er_extcount == XFS_LINEAR_EXTS) {
                        ASSERT(realloc);
                        page_idx = 0;
                        erp_idx++;
                        erp = erp_idx < nlists ? erp + 1 : NULL;
                        break;
                } else {
                        page_idx -= erp->er_extoff;
                        break;
                }
        }
        *idxp = page_idx;
        *erp_idxp = erp_idx;
        return(erp);
}

/*
 * Allocate and initialize an indirection array once the space needed
 * for incore extents increases above XFS_IEXT_BUFSZ.
 */
void
xfs_iext_irec_init(
        xfs_ifork_t     *ifp)           /* inode fork pointer */
{
        xfs_ext_irec_t  *erp;           /* indirection array pointer */
        xfs_extnum_t    nextents;       /* number of extents in file */

        ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
        ASSERT(nextents <= XFS_LINEAR_EXTS);

        erp = kmem_alloc(sizeof(xfs_ext_irec_t), KM_NOFS);

        if (nextents == 0) {
                ifp->if_u1.if_extents = kmem_alloc(XFS_IEXT_BUFSZ, KM_NOFS);
        } else if (!ifp->if_real_bytes) {
                xfs_iext_inline_to_direct(ifp, XFS_IEXT_BUFSZ);
        } else if (ifp->if_real_bytes < XFS_IEXT_BUFSZ) {
                xfs_iext_realloc_direct(ifp, XFS_IEXT_BUFSZ);
        }
        erp->er_extbuf = ifp->if_u1.if_extents;
        erp->er_extcount = nextents;
        erp->er_extoff = 0;

        ifp->if_flags |= XFS_IFEXTIREC;
        ifp->if_real_bytes = XFS_IEXT_BUFSZ;
        ifp->if_bytes = nextents * sizeof(xfs_bmbt_rec_t);
        ifp->if_u1.if_ext_irec = erp;

        return;
}

/*
 * Allocate and initialize a new entry in the indirection array.
 */
xfs_ext_irec_t *
xfs_iext_irec_new(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        int             erp_idx)        /* index for new irec */
{
        xfs_ext_irec_t  *erp;           /* indirection array pointer */
        int             i;              /* loop counter */
        int             nlists;         /* number of irec's (ex lists) */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;

        /* Resize indirection array */
        xfs_iext_realloc_indirect(ifp, ++nlists *
                                  sizeof(xfs_ext_irec_t));
        /*
         * Move records down in the array so the
         * new page can use erp_idx.
         */
        erp = ifp->if_u1.if_ext_irec;
        for (i = nlists - 1; i > erp_idx; i--) {
                memmove(&erp[i], &erp[i-1], sizeof(xfs_ext_irec_t));
        }
        ASSERT(i == erp_idx);

        /* Initialize new extent record */
        erp = ifp->if_u1.if_ext_irec;
        erp[erp_idx].er_extbuf = kmem_alloc(XFS_IEXT_BUFSZ, KM_NOFS);
        ifp->if_real_bytes = nlists * XFS_IEXT_BUFSZ;
        memset(erp[erp_idx].er_extbuf, 0, XFS_IEXT_BUFSZ);
        erp[erp_idx].er_extcount = 0;
        erp[erp_idx].er_extoff = erp_idx > 0 ?
                erp[erp_idx-1].er_extoff + erp[erp_idx-1].er_extcount : 0;
        return (&erp[erp_idx]);
}

/*
 * Remove a record from the indirection array.
 */
void
xfs_iext_irec_remove(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        int             erp_idx)        /* irec index to remove */
{
        xfs_ext_irec_t  *erp;           /* indirection array pointer */
        int             i;              /* loop counter */
        int             nlists;         /* number of irec's (ex lists) */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
        erp = &ifp->if_u1.if_ext_irec[erp_idx];
        if (erp->er_extbuf) {
                xfs_iext_irec_update_extoffs(ifp, erp_idx + 1,
                        -erp->er_extcount);
                kmem_free(erp->er_extbuf);
        }
        /* Compact extent records */
        erp = ifp->if_u1.if_ext_irec;
        for (i = erp_idx; i < nlists - 1; i++) {
                memmove(&erp[i], &erp[i+1], sizeof(xfs_ext_irec_t));
        }
        /*
         * Manually free the last extent record from the indirection
         * array.  A call to xfs_iext_realloc_indirect() with a size
         * of zero would result in a call to xfs_iext_destroy() which
         * would in turn call this function again, creating a nasty
         * infinite loop.
         */
        if (--nlists) {
                xfs_iext_realloc_indirect(ifp,
                        nlists * sizeof(xfs_ext_irec_t));
        } else {
                kmem_free(ifp->if_u1.if_ext_irec);
        }
        ifp->if_real_bytes = nlists * XFS_IEXT_BUFSZ;
}

/*
 * This is called to clean up large amounts of unused memory allocated
 * by the indirection array.  Before compacting anything though, verify
 * that the indirection array is still needed and switch back to the
 * linear extent list (or even the inline buffer) if possible.  The
 * compaction policy is as follows:
 *
 *    Full Compaction: Extents fit into a single page (or inline buffer)
 * Partial Compaction: Extents occupy less than 50% of allocated space
 *      No Compaction: Extents occupy at least 50% of allocated space
 */
void
xfs_iext_irec_compact(
        xfs_ifork_t     *ifp)           /* inode fork pointer */
{
        xfs_extnum_t    nextents;       /* number of extents in file */
        int             nlists;         /* number of irec's (ex lists) */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);

        if (nextents == 0) {
                xfs_iext_destroy(ifp);
        } else if (nextents <= XFS_INLINE_EXTS) {
                xfs_iext_indirect_to_direct(ifp);
                xfs_iext_direct_to_inline(ifp, nextents);
        } else if (nextents <= XFS_LINEAR_EXTS) {
                xfs_iext_indirect_to_direct(ifp);
        } else if (nextents < (nlists * XFS_LINEAR_EXTS) >> 1) {
                xfs_iext_irec_compact_pages(ifp);
        }
}

/*
 * Combine extents from neighboring extent pages.
 */
void
xfs_iext_irec_compact_pages(
        xfs_ifork_t     *ifp)           /* inode fork pointer */
{
        xfs_ext_irec_t  *erp, *erp_next;/* pointers to irec entries */
        int             erp_idx = 0;    /* indirection array index */
        int             nlists;         /* number of irec's (ex lists) */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
        while (erp_idx < nlists - 1) {
                erp = &ifp->if_u1.if_ext_irec[erp_idx];
                erp_next = erp + 1;
                if (erp_next->er_extcount <=
                    (XFS_LINEAR_EXTS - erp->er_extcount)) {
                        memcpy(&erp->er_extbuf[erp->er_extcount],
                                erp_next->er_extbuf, erp_next->er_extcount *
                                sizeof(xfs_bmbt_rec_t));
                        erp->er_extcount += erp_next->er_extcount;
                        /*
                         * Free page before removing extent record
                         * so er_extoffs don't get modified in
                         * xfs_iext_irec_remove.
                         */
                        kmem_free(erp_next->er_extbuf);
                        erp_next->er_extbuf = NULL;
                        xfs_iext_irec_remove(ifp, erp_idx + 1);
                        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
                } else {
                        erp_idx++;
                }
        }
}

/*
 * This is called to update the er_extoff field in the indirection
 * array when extents have been added or removed from one of the
 * extent lists. erp_idx contains the irec index to begin updating
 * at and ext_diff contains the number of extents that were added
 * or removed.
 */
void
xfs_iext_irec_update_extoffs(
        xfs_ifork_t     *ifp,           /* inode fork pointer */
        int             erp_idx,        /* irec index to update */
        int             ext_diff)       /* number of new extents */
{
        int             i;              /* loop counter */
        int             nlists;         /* number of irec's (ex lists */

        ASSERT(ifp->if_flags & XFS_IFEXTIREC);
        nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
        for (i = erp_idx; i < nlists; i++) {
                ifp->if_u1.if_ext_irec[i].er_extoff += ext_diff;
        }
}