xfs: limit xfs_imap_to_bmap to a single mapping

We only call xfs_iomap for single mappings anyway, so remove all
code dealing with multiple mappings from xfs_imap_to_bmap and add
asserts that we never get results that we do not expect.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 0b65039..2d9bce7 100644 (file)
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -55,49 +55,41 @@
 #define XFS_STRAT_WRITE_IMAPS  2
 #define XFS_WRITE_IMAPS                XFS_BMAP_MAX_NMAP
 
-STATIC int
+STATIC void
 xfs_imap_to_bmap(
        xfs_inode_t     *ip,
        xfs_off_t       offset,
        xfs_bmbt_irec_t *imap,
        xfs_iomap_t     *iomapp,
        int             imaps,                  /* Number of imap entries */
-       int             iomaps,                 /* Number of iomap entries */
        int             flags)
 {
        xfs_mount_t     *mp = ip->i_mount;
-       int             pbm;
        xfs_fsblock_t   start_block;
 
+       iomapp->iomap_offset = XFS_FSB_TO_B(mp, imap->br_startoff);
+       iomapp->iomap_delta = offset - iomapp->iomap_offset;
+       iomapp->iomap_bsize = XFS_FSB_TO_B(mp, imap->br_blockcount);
+       iomapp->iomap_flags = flags;
 
-       for (pbm = 0; imaps && pbm < iomaps; imaps--, iomapp++, imap++, pbm++) {
-               iomapp->iomap_offset = XFS_FSB_TO_B(mp, imap->br_startoff);
-               iomapp->iomap_delta = offset - iomapp->iomap_offset;
-               iomapp->iomap_bsize = XFS_FSB_TO_B(mp, imap->br_blockcount);
-               iomapp->iomap_flags = flags;
-
-               if (XFS_IS_REALTIME_INODE(ip)) {
-                       iomapp->iomap_flags |= IOMAP_REALTIME;
-                       iomapp->iomap_target = mp->m_rtdev_targp;
-               } else {
-                       iomapp->iomap_target = mp->m_ddev_targp;
-               }
-               start_block = imap->br_startblock;
-               if (start_block == HOLESTARTBLOCK) {
-                       iomapp->iomap_bn = IOMAP_DADDR_NULL;
-                       iomapp->iomap_flags |= IOMAP_HOLE;
-               } else if (start_block == DELAYSTARTBLOCK) {
-                       iomapp->iomap_bn = IOMAP_DADDR_NULL;
-                       iomapp->iomap_flags |= IOMAP_DELAY;
-               } else {
-                       iomapp->iomap_bn = xfs_fsb_to_db(ip, start_block);
-                       if (ISUNWRITTEN(imap))
-                               iomapp->iomap_flags |= IOMAP_UNWRITTEN;
-               }
-
-               offset += iomapp->iomap_bsize - iomapp->iomap_delta;
+       if (XFS_IS_REALTIME_INODE(ip)) {
+               iomapp->iomap_flags |= IOMAP_REALTIME;
+               iomapp->iomap_target = mp->m_rtdev_targp;
+       } else {
+               iomapp->iomap_target = mp->m_ddev_targp;
+       }
+       start_block = imap->br_startblock;
+       if (start_block == HOLESTARTBLOCK) {
+               iomapp->iomap_bn = IOMAP_DADDR_NULL;
+               iomapp->iomap_flags |= IOMAP_HOLE;
+       } else if (start_block == DELAYSTARTBLOCK) {
+               iomapp->iomap_bn = IOMAP_DADDR_NULL;
+               iomapp->iomap_flags |= IOMAP_DELAY;
+       } else {
+               iomapp->iomap_bn = xfs_fsb_to_db(ip, start_block);
+               if (ISUNWRITTEN(imap))
+                       iomapp->iomap_flags |= IOMAP_UNWRITTEN;
        }
-       return pbm;     /* Return the number filled */
 }
 
 int
@@ -119,6 +111,7 @@ xfs_iomap(
        int             iomap_flags = 0;
 
        ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
+       ASSERT(niomaps && *niomaps == 1);
 
        if (XFS_FORCED_SHUTDOWN(mp))
                return XFS_ERROR(EIO);
@@ -203,12 +196,11 @@ xfs_iomap(
                break;
        }
 
-       if (nimaps) {
-               *niomaps = xfs_imap_to_bmap(ip, offset, &imap,
-                                           iomapp, nimaps, *niomaps, iomap_flags);
-       } else if (niomaps) {
-               *niomaps = 0;
-       }
+       ASSERT(nimaps <= 1);
+
+       if (nimaps)
+               xfs_imap_to_bmap(ip, offset, &imap, iomapp, nimaps, iomap_flags);
+       *niomaps = nimaps;
 
 out:
        if (lockmode)