fs/xfs/linux-2.6/xfs_buf.c

   1 /*
   2  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include "xfs.h"
  19 #include <linux/stddef.h>
  20 #include <linux/errno.h>
  21 #include <linux/gfp.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/init.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/bio.h>
  26 #include <linux/sysctl.h>
  27 #include <linux/proc_fs.h>
  28 #include <linux/workqueue.h>
  29 #include <linux/percpu.h>
  30 #include <linux/blkdev.h>
  31 #include <linux/hash.h>
  32 #include <linux/kthread.h>
  33 #include <linux/migrate.h>
  34 #include <linux/backing-dev.h>
  35 #include <linux/freezer.h>
  36 #include <linux/list_sort.h>
  37
  38 #include "xfs_sb.h"
  39 #include "xfs_inum.h"
  40 #include "xfs_log.h"
  41 #include "xfs_ag.h"
  42 #include "xfs_dmapi.h"
  43 #include "xfs_mount.h"
  44 #include "xfs_trace.h"
  45
  46 static kmem_zone_t *xfs_buf_zone;
  47 STATIC int xfsbufd(void *);
  48 STATIC int xfsbufd_wakeup(int, gfp_t);
  49 STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
  50 static struct shrinker xfs_buf_shake = {
  51         .shrink = xfsbufd_wakeup,
  52         .seeks = DEFAULT_SEEKS,
  53 };
  54
  55 static struct workqueue_struct *xfslogd_workqueue;
  56 struct workqueue_struct *xfsdatad_workqueue;
  57 struct workqueue_struct *xfsconvertd_workqueue;
  58
  59 #ifdef XFS_BUF_LOCK_TRACKING
  60 # define XB_SET_OWNER(bp)       ((bp)->b_last_holder = current->pid)
  61 # define XB_CLEAR_OWNER(bp)     ((bp)->b_last_holder = -1)
  62 # define XB_GET_OWNER(bp)       ((bp)->b_last_holder)
  63 #else
  64 # define XB_SET_OWNER(bp)       do { } while (0)
  65 # define XB_CLEAR_OWNER(bp)     do { } while (0)
  66 # define XB_GET_OWNER(bp)       do { } while (0)
  67 #endif
  68
  69 #define xb_to_gfp(flags) \
  70         ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
  71           ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
  72
  73 #define xb_to_km(flags) \
  74          (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
  75
  76 #define xfs_buf_allocate(flags) \
  77         kmem_zone_alloc(xfs_buf_zone, xb_to_km(flags))
  78 #define xfs_buf_deallocate(bp) \
  79         kmem_zone_free(xfs_buf_zone, (bp));
  80
  81 static inline int
  82 xfs_buf_is_vmapped(
  83         struct xfs_buf  *bp)
  84 {
  85         /*
  86          * Return true if the buffer is vmapped.
  87          *
  88          * The XBF_MAPPED flag is set if the buffer should be mapped, but the
  89          * code is clever enough to know it doesn't have to map a single page,
  90          * so the check has to be both for XBF_MAPPED and bp->b_page_count > 1.
  91          */
  92         return (bp->b_flags & XBF_MAPPED) && bp->b_page_count > 1;
  93 }
  94
  95 static inline int
  96 xfs_buf_vmap_len(
  97         struct xfs_buf  *bp)
  98 {
  99         return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
 100 }
 101
 102 /*
 103  *      Page Region interfaces.
 104  *
 105  *      For pages in filesystems where the blocksize is smaller than the
 106  *      pagesize, we use the page->private field (long) to hold a bitmap
 107  *      of uptodate regions within the page.
 108  *
 109  *      Each such region is "bytes per page / bits per long" bytes long.
 110  *
 111  *      NBPPR == number-of-bytes-per-page-region
 112  *      BTOPR == bytes-to-page-region (rounded up)
 113  *      BTOPRT == bytes-to-page-region-truncated (rounded down)
 114  */
 115 #if (BITS_PER_LONG == 32)
 116 #define PRSHIFT         (PAGE_CACHE_SHIFT - 5)  /* (32 == 1<<5) */
 117 #elif (BITS_PER_LONG == 64)
 118 #define PRSHIFT         (PAGE_CACHE_SHIFT - 6)  /* (64 == 1<<6) */
 119 #else
 120 #error BITS_PER_LONG must be 32 or 64
 121 #endif
 122 #define NBPPR           (PAGE_CACHE_SIZE/BITS_PER_LONG)
 123 #define BTOPR(b)        (((unsigned int)(b) + (NBPPR - 1)) >> PRSHIFT)
 124 #define BTOPRT(b)       (((unsigned int)(b) >> PRSHIFT))
 125
 126 STATIC unsigned long
 127 page_region_mask(
 128         size_t          offset,
 129         size_t          length)
 130 {
 131         unsigned long   mask;
 132         int             first, final;
 133
 134         first = BTOPR(offset);
 135         final = BTOPRT(offset + length - 1);
 136         first = min(first, final);
 137
 138         mask = ~0UL;
 139         mask <<= BITS_PER_LONG - (final - first);
 140         mask >>= BITS_PER_LONG - (final);
 141
 142         ASSERT(offset + length <= PAGE_CACHE_SIZE);
 143         ASSERT((final - first) < BITS_PER_LONG && (final - first) >= 0);
 144
 145         return mask;
 146 }
 147
 148 STATIC void
 149 set_page_region(
 150         struct page     *page,
 151         size_t          offset,
 152         size_t          length)
 153 {
 154         set_page_private(page,
 155                 page_private(page) | page_region_mask(offset, length));
 156         if (page_private(page) == ~0UL)
 157                 SetPageUptodate(page);
 158 }
 159
 160 STATIC int
 161 test_page_region(
 162         struct page     *page,
 163         size_t          offset,
 164         size_t          length)
 165 {
 166         unsigned long   mask = page_region_mask(offset, length);
 167
 168         return (mask && (page_private(page) & mask) == mask);
 169 }
 170
 171 /*
 172  *      Internal xfs_buf_t object manipulation
 173  */
 174
 175 STATIC void
 176 _xfs_buf_initialize(
 177         xfs_buf_t               *bp,
 178         xfs_buftarg_t           *target,
 179         xfs_off_t               range_base,
 180         size_t                  range_length,
 181         xfs_buf_flags_t         flags)
 182 {
 183         /*
 184          * We don't want certain flags to appear in b_flags.
 185          */
 186         flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
 187
 188         memset(bp, 0, sizeof(xfs_buf_t));
 189         atomic_set(&bp->b_hold, 1);
 190         init_completion(&bp->b_iowait);
 191         INIT_LIST_HEAD(&bp->b_list);
 192         INIT_LIST_HEAD(&bp->b_hash_list);
 193         init_MUTEX_LOCKED(&bp->b_sema); /* held, no waiters */
 194         XB_SET_OWNER(bp);
 195         bp->b_target = target;
 196         bp->b_file_offset = range_base;
 197         /*
 198          * Set buffer_length and count_desired to the same value initially.
 199          * I/O routines should use count_desired, which will be the same in
 200          * most cases but may be reset (e.g. XFS recovery).
 201          */
 202         bp->b_buffer_length = bp->b_count_desired = range_length;
 203         bp->b_flags = flags;
 204         bp->b_bn = XFS_BUF_DADDR_NULL;
 205         atomic_set(&bp->b_pin_count, 0);
 206         init_waitqueue_head(&bp->b_waiters);
 207
 208         XFS_STATS_INC(xb_create);
 209
 210         trace_xfs_buf_init(bp, _RET_IP_);
 211 }
 212
 213 /*
 214  *      Allocate a page array capable of holding a specified number
 215  *      of pages, and point the page buf at it.
 216  */
 217 STATIC int
 218 _xfs_buf_get_pages(
 219         xfs_buf_t               *bp,
 220         int                     page_count,
 221         xfs_buf_flags_t         flags)
 222 {
 223         /* Make sure that we have a page list */
 224         if (bp->b_pages == NULL) {
 225                 bp->b_offset = xfs_buf_poff(bp->b_file_offset);
 226                 bp->b_page_count = page_count;
 227                 if (page_count <= XB_PAGES) {
 228                         bp->b_pages = bp->b_page_array;
 229                 } else {
 230                         bp->b_pages = kmem_alloc(sizeof(struct page *) *
 231                                         page_count, xb_to_km(flags));
 232                         if (bp->b_pages == NULL)
 233                                 return -ENOMEM;
 234                 }
 235                 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
 236         }
 237         return 0;
 238 }
 239
 240 /*
 241  *      Frees b_pages if it was allocated.
 242  */
 243 STATIC void
 244 _xfs_buf_free_pages(
 245         xfs_buf_t       *bp)
 246 {
 247         if (bp->b_pages != bp->b_page_array) {
 248                 kmem_free(bp->b_pages);
 249                 bp->b_pages = NULL;
 250         }
 251 }
 252
 253 /*
 254  *      Releases the specified buffer.
 255  *
 256  *      The modification state of any associated pages is left unchanged.
 257  *      The buffer most not be on any hash - use xfs_buf_rele instead for
 258  *      hashed and refcounted buffers
 259  */
 260 void
 261 xfs_buf_free(
 262         xfs_buf_t               *bp)
 263 {
 264         trace_xfs_buf_free(bp, _RET_IP_);
 265
 266         ASSERT(list_empty(&bp->b_hash_list));
 267
 268         if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) {
 269                 uint            i;
 270
 271                 if (xfs_buf_is_vmapped(bp))
 272                         vm_unmap_ram(bp->b_addr - bp->b_offset,
 273                                         bp->b_page_count);
 274
 275                 for (i = 0; i < bp->b_page_count; i++) {
 276                         struct page     *page = bp->b_pages[i];
 277
 278                         if (bp->b_flags & _XBF_PAGE_CACHE)
 279                                 ASSERT(!PagePrivate(page));
 280                         page_cache_release(page);
 281                 }
 282         }
 283         _xfs_buf_free_pages(bp);
 284         xfs_buf_deallocate(bp);
 285 }
 286
 287 /*
 288  *      Finds all pages for buffer in question and builds it's page list.
 289  */
 290 STATIC int
 291 _xfs_buf_lookup_pages(
 292         xfs_buf_t               *bp,
 293         uint                    flags)
 294 {
 295         struct address_space    *mapping = bp->b_target->bt_mapping;
 296         size_t                  blocksize = bp->b_target->bt_bsize;
 297         size_t                  size = bp->b_count_desired;
 298         size_t                  nbytes, offset;
 299         gfp_t                   gfp_mask = xb_to_gfp(flags);
 300         unsigned short          page_count, i;
 301         pgoff_t                 first;
 302         xfs_off_t               end;
 303         int                     error;
 304
 305         end = bp->b_file_offset + bp->b_buffer_length;
 306         page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
 307
 308         error = _xfs_buf_get_pages(bp, page_count, flags);
 309         if (unlikely(error))
 310                 return error;
 311         bp->b_flags |= _XBF_PAGE_CACHE;
 312
 313         offset = bp->b_offset;
 314         first = bp->b_file_offset >> PAGE_CACHE_SHIFT;
 315
 316         for (i = 0; i < bp->b_page_count; i++) {
 317                 struct page     *page;
 318                 uint            retries = 0;
 319
 320               retry:
 321                 page = find_or_create_page(mapping, first + i, gfp_mask);
 322                 if (unlikely(page == NULL)) {
 323                         if (flags & XBF_READ_AHEAD) {
 324                                 bp->b_page_count = i;
 325                                 for (i = 0; i < bp->b_page_count; i++)
 326                                         unlock_page(bp->b_pages[i]);
 327                                 return -ENOMEM;
 328                         }
 329
 330                         /*
 331                          * This could deadlock.
 332                          *
 333                          * But until all the XFS lowlevel code is revamped to
 334                          * handle buffer allocation failures we can't do much.
 335                          */
 336                         if (!(++retries % 100))
 337                                 printk(KERN_ERR
 338                                         "XFS: possible memory allocation "
 339                                         "deadlock in %s (mode:0x%x)\n",
 340                                         __func__, gfp_mask);
 341
 342                         XFS_STATS_INC(xb_page_retries);
 343                         xfsbufd_wakeup(0, gfp_mask);
 344                         congestion_wait(BLK_RW_ASYNC, HZ/50);
 345                         goto retry;
 346                 }
 347
 348                 XFS_STATS_INC(xb_page_found);
 349
 350                 nbytes = min_t(size_t, size, PAGE_CACHE_SIZE - offset);
 351                 size -= nbytes;
 352
 353                 ASSERT(!PagePrivate(page));
 354                 if (!PageUptodate(page)) {
 355                         page_count--;
 356                         if (blocksize >= PAGE_CACHE_SIZE) {
 357                                 if (flags & XBF_READ)
 358                                         bp->b_flags |= _XBF_PAGE_LOCKED;
 359                         } else if (!PagePrivate(page)) {
 360                                 if (test_page_region(page, offset, nbytes))
 361                                         page_count++;
 362                         }
 363                 }
 364
 365                 bp->b_pages[i] = page;
 366                 offset = 0;
 367         }
 368
 369         if (!(bp->b_flags & _XBF_PAGE_LOCKED)) {
 370                 for (i = 0; i < bp->b_page_count; i++)
 371                         unlock_page(bp->b_pages[i]);
 372         }
 373
 374         if (page_count == bp->b_page_count)
 375                 bp->b_flags |= XBF_DONE;
 376
 377         return error;
 378 }
 379
 380 /*
 381  *      Map buffer into kernel address-space if nessecary.
 382  */
 383 STATIC int
 384 _xfs_buf_map_pages(
 385         xfs_buf_t               *bp,
 386         uint                    flags)
 387 {
 388         /* A single page buffer is always mappable */
 389         if (bp->b_page_count == 1) {
 390                 bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
 391                 bp->b_flags |= XBF_MAPPED;
 392         } else if (flags & XBF_MAPPED) {
 393                 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
 394                                         -1, PAGE_KERNEL);
 395                 if (unlikely(bp->b_addr == NULL))
 396                         return -ENOMEM;
 397                 bp->b_addr += bp->b_offset;
 398                 bp->b_flags |= XBF_MAPPED;
 399         }
 400
 401         return 0;
 402 }
 403
 404 /*
 405  *      Finding and Reading Buffers
 406  */
 407
 408 /*
 409  *      Look up, and creates if absent, a lockable buffer for
 410  *      a given range of an inode.  The buffer is returned
 411  *      locked.  If other overlapping buffers exist, they are
 412  *      released before the new buffer is created and locked,
 413  *      which may imply that this call will block until those buffers
 414  *      are unlocked.  No I/O is implied by this call.
 415  */
 416 xfs_buf_t *
 417 _xfs_buf_find(
 418         xfs_buftarg_t           *btp,   /* block device target          */
 419         xfs_off_t               ioff,   /* starting offset of range     */
 420         size_t                  isize,  /* length of range              */
 421         xfs_buf_flags_t         flags,
 422         xfs_buf_t               *new_bp)
 423 {
 424         xfs_off_t               range_base;
 425         size_t                  range_length;
 426         xfs_bufhash_t           *hash;
 427         xfs_buf_t               *bp, *n;
 428
 429         range_base = (ioff << BBSHIFT);
 430         range_length = (isize << BBSHIFT);
 431
 432         /* Check for IOs smaller than the sector size / not sector aligned */
 433         ASSERT(!(range_length < (1 << btp->bt_sshift)));
 434         ASSERT(!(range_base & (xfs_off_t)btp->bt_smask));
 435
 436         hash = &btp->bt_hash[hash_long((unsigned long)ioff, btp->bt_hashshift)];
 437
 438         spin_lock(&hash->bh_lock);
 439
 440         list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
 441                 ASSERT(btp == bp->b_target);
 442                 if (bp->b_file_offset == range_base &&
 443                     bp->b_buffer_length == range_length) {
 444                         /*
 445                          * If we look at something, bring it to the
 446                          * front of the list for next time.
 447                          */
 448                         atomic_inc(&bp->b_hold);
 449                         list_move(&bp->b_hash_list, &hash->bh_list);
 450                         goto found;
 451                 }
 452         }
 453
 454         /* No match found */
 455         if (new_bp) {
 456                 _xfs_buf_initialize(new_bp, btp, range_base,
 457                                 range_length, flags);
 458                 new_bp->b_hash = hash;
 459                 list_add(&new_bp->b_hash_list, &hash->bh_list);
 460         } else {
 461                 XFS_STATS_INC(xb_miss_locked);
 462         }
 463
 464         spin_unlock(&hash->bh_lock);
 465         return new_bp;
 466
 467 found:
 468         spin_unlock(&hash->bh_lock);
 469
 470         /* Attempt to get the semaphore without sleeping,
 471          * if this does not work then we need to drop the
 472          * spinlock and do a hard attempt on the semaphore.
 473          */
 474         if (down_trylock(&bp->b_sema)) {
 475                 if (!(flags & XBF_TRYLOCK)) {
 476                         /* wait for buffer ownership */
 477                         xfs_buf_lock(bp);
 478                         XFS_STATS_INC(xb_get_locked_waited);
 479                 } else {
 480                         /* We asked for a trylock and failed, no need
 481                          * to look at file offset and length here, we
 482                          * know that this buffer at least overlaps our
 483                          * buffer and is locked, therefore our buffer
 484                          * either does not exist, or is this buffer.
 485                          */
 486                         xfs_buf_rele(bp);
 487                         XFS_STATS_INC(xb_busy_locked);
 488                         return NULL;
 489                 }
 490         } else {
 491                 /* trylock worked */
 492                 XB_SET_OWNER(bp);
 493         }
 494
 495         if (bp->b_flags & XBF_STALE) {
 496                 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
 497                 bp->b_flags &= XBF_MAPPED;
 498         }
 499
 500         trace_xfs_buf_find(bp, flags, _RET_IP_);
 501         XFS_STATS_INC(xb_get_locked);
 502         return bp;
 503 }
 504
 505 /*
 506  *      Assembles a buffer covering the specified range.
 507  *      Storage in memory for all portions of the buffer will be allocated,
 508  *      although backing storage may not be.
 509  */
 510 xfs_buf_t *
 511 xfs_buf_get(
 512         xfs_buftarg_t           *target,/* target for buffer            */
 513         xfs_off_t               ioff,   /* starting offset of range     */
 514         size_t                  isize,  /* length of range              */
 515         xfs_buf_flags_t         flags)
 516 {
 517         xfs_buf_t               *bp, *new_bp;
 518         int                     error = 0, i;
 519
 520         new_bp = xfs_buf_allocate(flags);
 521         if (unlikely(!new_bp))
 522                 return NULL;
 523
 524         bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
 525         if (bp == new_bp) {
 526                 error = _xfs_buf_lookup_pages(bp, flags);
 527                 if (error)
 528                         goto no_buffer;
 529         } else {
 530                 xfs_buf_deallocate(new_bp);
 531                 if (unlikely(bp == NULL))
 532                         return NULL;
 533         }
 534
 535         for (i = 0; i < bp->b_page_count; i++)
 536                 mark_page_accessed(bp->b_pages[i]);
 537
 538         if (!(bp->b_flags & XBF_MAPPED)) {
 539                 error = _xfs_buf_map_pages(bp, flags);
 540                 if (unlikely(error)) {
 541                         printk(KERN_WARNING "%s: failed to map pages\n",
 542                                         __func__);
 543                         goto no_buffer;
 544                 }
 545         }
 546
 547         XFS_STATS_INC(xb_get);
 548
 549         /*
 550          * Always fill in the block number now, the mapped cases can do
 551          * their own overlay of this later.
 552          */
 553         bp->b_bn = ioff;
 554         bp->b_count_desired = bp->b_buffer_length;
 555
 556         trace_xfs_buf_get(bp, flags, _RET_IP_);
 557         return bp;
 558
 559  no_buffer:
 560         if (flags & (XBF_LOCK | XBF_TRYLOCK))
 561                 xfs_buf_unlock(bp);
 562         xfs_buf_rele(bp);
 563         return NULL;
 564 }
 565
 566 STATIC int
 567 _xfs_buf_read(
 568         xfs_buf_t               *bp,
 569         xfs_buf_flags_t         flags)
 570 {
 571         int                     status;
 572
 573         ASSERT(!(flags & (XBF_DELWRI|XBF_WRITE)));
 574         ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
 575
 576         bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_DELWRI | \
 577                         XBF_READ_AHEAD | _XBF_RUN_QUEUES);
 578         bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | \
 579                         XBF_READ_AHEAD | _XBF_RUN_QUEUES);
 580
 581         status = xfs_buf_iorequest(bp);
 582         if (!status && !(flags & XBF_ASYNC))
 583                 status = xfs_buf_iowait(bp);
 584         return status;
 585 }
 586
 587 xfs_buf_t *
 588 xfs_buf_read(
 589         xfs_buftarg_t           *target,
 590         xfs_off_t               ioff,
 591         size_t                  isize,
 592         xfs_buf_flags_t         flags)
 593 {
 594         xfs_buf_t               *bp;
 595
 596         flags |= XBF_READ;
 597
 598         bp = xfs_buf_get(target, ioff, isize, flags);
 599         if (bp) {
 600                 trace_xfs_buf_read(bp, flags, _RET_IP_);
 601
 602                 if (!XFS_BUF_ISDONE(bp)) {
 603                         XFS_STATS_INC(xb_get_read);
 604                         _xfs_buf_read(bp, flags);
 605                 } else if (flags & XBF_ASYNC) {
 606                         /*
 607                          * Read ahead call which is already satisfied,
 608                          * drop the buffer
 609                          */
 610                         goto no_buffer;
 611                 } else {
 612                         /* We do not want read in the flags */
 613                         bp->b_flags &= ~XBF_READ;
 614                 }
 615         }
 616
 617         return bp;
 618
 619  no_buffer:
 620         if (flags & (XBF_LOCK | XBF_TRYLOCK))
 621                 xfs_buf_unlock(bp);
 622         xfs_buf_rele(bp);
 623         return NULL;
 624 }
 625
 626 /*
 627  *      If we are not low on memory then do the readahead in a deadlock
 628  *      safe manner.
 629  */
 630 void
 631 xfs_buf_readahead(
 632         xfs_buftarg_t           *target,
 633         xfs_off_t               ioff,
 634         size_t                  isize,
 635         xfs_buf_flags_t         flags)
 636 {
 637         struct backing_dev_info *bdi;
 638
 639         bdi = target->bt_mapping->backing_dev_info;
 640         if (bdi_read_congested(bdi))
 641                 return;
 642
 643         flags |= (XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD);
 644         xfs_buf_read(target, ioff, isize, flags);
 645 }
 646
 647 xfs_buf_t *
 648 xfs_buf_get_empty(
 649         size_t                  len,
 650         xfs_buftarg_t           *target)
 651 {
 652         xfs_buf_t               *bp;
 653
 654         bp = xfs_buf_allocate(0);
 655         if (bp)
 656                 _xfs_buf_initialize(bp, target, 0, len, 0);
 657         return bp;
 658 }
 659
 660 static inline struct page *
 661 mem_to_page(
 662         void                    *addr)
 663 {
 664         if ((!is_vmalloc_addr(addr))) {
 665                 return virt_to_page(addr);
 666         } else {
 667                 return vmalloc_to_page(addr);
 668         }
 669 }
 670
 671 int
 672 xfs_buf_associate_memory(
 673         xfs_buf_t               *bp,
 674         void                    *mem,
 675         size_t                  len)
 676 {
 677         int                     rval;
 678         int                     i = 0;
 679         unsigned long           pageaddr;
 680         unsigned long           offset;
 681         size_t                  buflen;
 682         int                     page_count;
 683
 684         pageaddr = (unsigned long)mem & PAGE_CACHE_MASK;
 685         offset = (unsigned long)mem - pageaddr;
 686         buflen = PAGE_CACHE_ALIGN(len + offset);
 687         page_count = buflen >> PAGE_CACHE_SHIFT;
 688
 689         /* Free any previous set of page pointers */
 690         if (bp->b_pages)
 691                 _xfs_buf_free_pages(bp);
 692
 693         bp->b_pages = NULL;
 694         bp->b_addr = mem;
 695
 696         rval = _xfs_buf_get_pages(bp, page_count, XBF_DONT_BLOCK);
 697         if (rval)
 698                 return rval;
 699
 700         bp->b_offset = offset;
 701
 702         for (i = 0; i < bp->b_page_count; i++) {
 703                 bp->b_pages[i] = mem_to_page((void *)pageaddr);
 704                 pageaddr += PAGE_CACHE_SIZE;
 705         }
 706
 707         bp->b_count_desired = len;
 708         bp->b_buffer_length = buflen;
 709         bp->b_flags |= XBF_MAPPED;
 710         bp->b_flags &= ~_XBF_PAGE_LOCKED;
 711
 712         return 0;
 713 }
 714
 715 xfs_buf_t *
 716 xfs_buf_get_noaddr(
 717         size_t                  len,
 718         xfs_buftarg_t           *target)
 719 {
 720         unsigned long           page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
 721         int                     error, i;
 722         xfs_buf_t               *bp;
 723
 724         bp = xfs_buf_allocate(0);
 725         if (unlikely(bp == NULL))
 726                 goto fail;
 727         _xfs_buf_initialize(bp, target, 0, len, 0);
 728
 729         error = _xfs_buf_get_pages(bp, page_count, 0);
 730         if (error)
 731                 goto fail_free_buf;
 732
 733         for (i = 0; i < page_count; i++) {
 734                 bp->b_pages[i] = alloc_page(GFP_KERNEL);
 735                 if (!bp->b_pages[i])
 736                         goto fail_free_mem;
 737         }
 738         bp->b_flags |= _XBF_PAGES;
 739
 740         error = _xfs_buf_map_pages(bp, XBF_MAPPED);
 741         if (unlikely(error)) {
 742                 printk(KERN_WARNING "%s: failed to map pages\n",
 743                                 __func__);
 744                 goto fail_free_mem;
 745         }
 746
 747         xfs_buf_unlock(bp);
 748
 749         trace_xfs_buf_get_noaddr(bp, _RET_IP_);
 750         return bp;
 751
 752  fail_free_mem:
 753         while (--i >= 0)
 754                 __free_page(bp->b_pages[i]);
 755         _xfs_buf_free_pages(bp);
 756  fail_free_buf:
 757         xfs_buf_deallocate(bp);
 758  fail:
 759         return NULL;
 760 }
 761
 762 /*
 763  *      Increment reference count on buffer, to hold the buffer concurrently
 764  *      with another thread which may release (free) the buffer asynchronously.
 765  *      Must hold the buffer already to call this function.
 766  */
 767 void
 768 xfs_buf_hold(
 769         xfs_buf_t               *bp)
 770 {
 771         trace_xfs_buf_hold(bp, _RET_IP_);
 772         atomic_inc(&bp->b_hold);
 773 }
 774
 775 /*
 776  *      Releases a hold on the specified buffer.  If the
 777  *      the hold count is 1, calls xfs_buf_free.
 778  */
 779 void
 780 xfs_buf_rele(
 781         xfs_buf_t               *bp)
 782 {
 783         xfs_bufhash_t           *hash = bp->b_hash;
 784
 785         trace_xfs_buf_rele(bp, _RET_IP_);
 786
 787         if (unlikely(!hash)) {
 788                 ASSERT(!bp->b_relse);
 789                 if (atomic_dec_and_test(&bp->b_hold))
 790                         xfs_buf_free(bp);
 791                 return;
 792         }
 793
 794         ASSERT(atomic_read(&bp->b_hold) > 0);
 795         if (atomic_dec_and_lock(&bp->b_hold, &hash->bh_lock)) {
 796                 if (bp->b_relse) {
 797                         atomic_inc(&bp->b_hold);
 798                         spin_unlock(&hash->bh_lock);
 799                         (*(bp->b_relse)) (bp);
 800                 } else if (bp->b_flags & XBF_FS_MANAGED) {
 801                         spin_unlock(&hash->bh_lock);
 802                 } else {
 803                         ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
 804                         list_del_init(&bp->b_hash_list);
 805                         spin_unlock(&hash->bh_lock);
 806                         xfs_buf_free(bp);
 807                 }
 808         }
 809 }
 810
 811
 812 /*
 813  *      Mutual exclusion on buffers.  Locking model:
 814  *
 815  *      Buffers associated with inodes for which buffer locking
 816  *      is not enabled are not protected by semaphores, and are
 817  *      assumed to be exclusively owned by the caller.  There is a
 818  *      spinlock in the buffer, used by the caller when concurrent
 819  *      access is possible.
 820  */
 821
 822 /*
 823  *      Locks a buffer object, if it is not already locked.
 824  *      Note that this in no way locks the underlying pages, so it is only
 825  *      useful for synchronizing concurrent use of buffer objects, not for
 826  *      synchronizing independent access to the underlying pages.
 827  */
 828 int
 829 xfs_buf_cond_lock(
 830         xfs_buf_t               *bp)
 831 {
 832         int                     locked;
 833
 834         locked = down_trylock(&bp->b_sema) == 0;
 835         if (locked)
 836                 XB_SET_OWNER(bp);
 837
 838         trace_xfs_buf_cond_lock(bp, _RET_IP_);
 839         return locked ? 0 : -EBUSY;
 840 }
 841
 842 int
 843 xfs_buf_lock_value(
 844         xfs_buf_t               *bp)
 845 {
 846         return bp->b_sema.count;
 847 }
 848
 849 /*
 850  *      Locks a buffer object.
 851  *      Note that this in no way locks the underlying pages, so it is only
 852  *      useful for synchronizing concurrent use of buffer objects, not for
 853  *      synchronizing independent access to the underlying pages.
 854  *
 855  *      If we come across a stale, pinned, locked buffer, we know that we
 856  *      are being asked to lock a buffer that has been reallocated. Because
 857  *      it is pinned, we know that the log has not been pushed to disk and
 858  *      hence it will still be locked. Rather than sleeping until someone
 859  *      else pushes the log, push it ourselves before trying to get the lock.
 860  */
 861 void
 862 xfs_buf_lock(
 863         xfs_buf_t               *bp)
 864 {
 865         trace_xfs_buf_lock(bp, _RET_IP_);
 866
 867         if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
 868                 xfs_log_force(bp->b_mount, 0);
 869         if (atomic_read(&bp->b_io_remaining))
 870                 blk_run_address_space(bp->b_target->bt_mapping);
 871         down(&bp->b_sema);
 872         XB_SET_OWNER(bp);
 873
 874         trace_xfs_buf_lock_done(bp, _RET_IP_);
 875 }
 876
 877 /*
 878  *      Releases the lock on the buffer object.
 879  *      If the buffer is marked delwri but is not queued, do so before we
 880  *      unlock the buffer as we need to set flags correctly.  We also need to
 881  *      take a reference for the delwri queue because the unlocker is going to
 882  *      drop their's and they don't know we just queued it.
 883  */
 884 void
 885 xfs_buf_unlock(
 886         xfs_buf_t               *bp)
 887 {
 888         if ((bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)) == XBF_DELWRI) {
 889                 atomic_inc(&bp->b_hold);
 890                 bp->b_flags |= XBF_ASYNC;
 891                 xfs_buf_delwri_queue(bp, 0);
 892         }
 893
 894         XB_CLEAR_OWNER(bp);
 895         up(&bp->b_sema);
 896
 897         trace_xfs_buf_unlock(bp, _RET_IP_);
 898 }
 899
 900
 901 /*
 902  *      Pinning Buffer Storage in Memory
 903  *      Ensure that no attempt to force a buffer to disk will succeed.
 904  */
 905 void
 906 xfs_buf_pin(
 907         xfs_buf_t               *bp)
 908 {
 909         trace_xfs_buf_pin(bp, _RET_IP_);
 910         atomic_inc(&bp->b_pin_count);
 911 }
 912
 913 void
 914 xfs_buf_unpin(
 915         xfs_buf_t               *bp)
 916 {
 917         trace_xfs_buf_unpin(bp, _RET_IP_);
 918
 919         if (atomic_dec_and_test(&bp->b_pin_count))
 920                 wake_up_all(&bp->b_waiters);
 921 }
 922
 923 int
 924 xfs_buf_ispin(
 925         xfs_buf_t               *bp)
 926 {
 927         return atomic_read(&bp->b_pin_count);
 928 }
 929
 930 STATIC void
 931 xfs_buf_wait_unpin(
 932         xfs_buf_t               *bp)
 933 {
 934         DECLARE_WAITQUEUE       (wait, current);
 935
 936         if (atomic_read(&bp->b_pin_count) == 0)
 937                 return;
 938
 939         add_wait_queue(&bp->b_waiters, &wait);
 940         for (;;) {
 941                 set_current_state(TASK_UNINTERRUPTIBLE);
 942                 if (atomic_read(&bp->b_pin_count) == 0)
 943                         break;
 944                 if (atomic_read(&bp->b_io_remaining))
 945                         blk_run_address_space(bp->b_target->bt_mapping);
 946                 schedule();
 947         }
 948         remove_wait_queue(&bp->b_waiters, &wait);
 949         set_current_state(TASK_RUNNING);
 950 }
 951
 952 /*
 953  *      Buffer Utility Routines
 954  */
 955
 956 STATIC void
 957 xfs_buf_iodone_work(
 958         struct work_struct      *work)
 959 {
 960         xfs_buf_t               *bp =
 961                 container_of(work, xfs_buf_t, b_iodone_work);
 962
 963         /*
 964          * We can get an EOPNOTSUPP to ordered writes.  Here we clear the
 965          * ordered flag and reissue them.  Because we can't tell the higher
 966          * layers directly that they should not issue ordered I/O anymore, they
 967          * need to check if the _XFS_BARRIER_FAILED flag was set during I/O completion.
 968          */
 969         if ((bp->b_error == EOPNOTSUPP) &&
 970             (bp->b_flags & (XBF_ORDERED|XBF_ASYNC)) == (XBF_ORDERED|XBF_ASYNC)) {
 971                 trace_xfs_buf_ordered_retry(bp, _RET_IP_);
 972                 bp->b_flags &= ~XBF_ORDERED;
 973                 bp->b_flags |= _XFS_BARRIER_FAILED;
 974                 xfs_buf_iorequest(bp);
 975         } else if (bp->b_iodone)
 976                 (*(bp->b_iodone))(bp);
 977         else if (bp->b_flags & XBF_ASYNC)
 978                 xfs_buf_relse(bp);
 979 }
 980
 981 void
 982 xfs_buf_ioend(
 983         xfs_buf_t               *bp,
 984         int                     schedule)
 985 {
 986         trace_xfs_buf_iodone(bp, _RET_IP_);
 987
 988         bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
 989         if (bp->b_error == 0)
 990                 bp->b_flags |= XBF_DONE;
 991
 992         if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
 993                 if (schedule) {
 994                         INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
 995                         queue_work(xfslogd_workqueue, &bp->b_iodone_work);
 996                 } else {
 997                         xfs_buf_iodone_work(&bp->b_iodone_work);
 998                 }
 999         } else {
1000                 complete(&bp->b_iowait);
1001         }
1002 }
1003
1004 void
1005 xfs_buf_ioerror(
1006         xfs_buf_t               *bp,
1007         int                     error)
1008 {
1009         ASSERT(error >= 0 && error <= 0xffff);
1010         bp->b_error = (unsigned short)error;
1011         trace_xfs_buf_ioerror(bp, error, _RET_IP_);
1012 }
1013
1014 int
1015 xfs_bwrite(
1016         struct xfs_mount        *mp,
1017         struct xfs_buf          *bp)
1018 {
1019         int                     error;
1020
1021         bp->b_strat = xfs_bdstrat_cb;
1022         bp->b_mount = mp;
1023         bp->b_flags |= XBF_WRITE;
1024         bp->b_flags &= ~(XBF_ASYNC | XBF_READ);
1025
1026         xfs_buf_delwri_dequeue(bp);
1027         xfs_buf_iostrategy(bp);
1028
1029         error = xfs_buf_iowait(bp);
1030         if (error)
1031                 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1032         xfs_buf_relse(bp);
1033         return error;
1034 }
1035
1036 void
1037 xfs_bdwrite(
1038         void                    *mp,
1039         struct xfs_buf          *bp)
1040 {
1041         trace_xfs_buf_bdwrite(bp, _RET_IP_);
1042
1043         bp->b_strat = xfs_bdstrat_cb;
1044         bp->b_mount = mp;
1045
1046         bp->b_flags &= ~XBF_READ;
1047         bp->b_flags |= (XBF_DELWRI | XBF_ASYNC);
1048
1049         xfs_buf_delwri_queue(bp, 1);
1050 }
1051
1052 /*
1053  * Called when we want to stop a buffer from getting written or read.
1054  * We attach the EIO error, muck with its flags, and call biodone
1055  * so that the proper iodone callbacks get called.
1056  */
1057 STATIC int
1058 xfs_bioerror(
1059         xfs_buf_t *bp)
1060 {
1061 #ifdef XFSERRORDEBUG
1062         ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone);
1063 #endif
1064
1065         /*
1066          * No need to wait until the buffer is unpinned, we aren't flushing it.
1067          */
1068         XFS_BUF_ERROR(bp, EIO);
1069
1070         /*
1071          * We're calling biodone, so delete XBF_DONE flag.
1072          */
1073         XFS_BUF_UNREAD(bp);
1074         XFS_BUF_UNDELAYWRITE(bp);
1075         XFS_BUF_UNDONE(bp);
1076         XFS_BUF_STALE(bp);
1077
1078         XFS_BUF_CLR_BDSTRAT_FUNC(bp);
1079         xfs_biodone(bp);
1080
1081         return EIO;
1082 }
1083
1084 /*
1085  * Same as xfs_bioerror, except that we are releasing the buffer
1086  * here ourselves, and avoiding the biodone call.
1087  * This is meant for userdata errors; metadata bufs come with
1088  * iodone functions attached, so that we can track down errors.
1089  */
1090 STATIC int
1091 xfs_bioerror_relse(
1092         struct xfs_buf  *bp)
1093 {
1094         int64_t         fl = XFS_BUF_BFLAGS(bp);
1095         /*
1096          * No need to wait until the buffer is unpinned.
1097          * We aren't flushing it.
1098          *
1099          * chunkhold expects B_DONE to be set, whether
1100          * we actually finish the I/O or not. We don't want to
1101          * change that interface.
1102          */
1103         XFS_BUF_UNREAD(bp);
1104         XFS_BUF_UNDELAYWRITE(bp);
1105         XFS_BUF_DONE(bp);
1106         XFS_BUF_STALE(bp);
1107         XFS_BUF_CLR_IODONE_FUNC(bp);
1108         XFS_BUF_CLR_BDSTRAT_FUNC(bp);
1109         if (!(fl & XBF_ASYNC)) {
1110                 /*
1111                  * Mark b_error and B_ERROR _both_.
1112                  * Lot's of chunkcache code assumes that.
1113                  * There's no reason to mark error for
1114                  * ASYNC buffers.
1115                  */
1116                 XFS_BUF_ERROR(bp, EIO);
1117                 XFS_BUF_FINISH_IOWAIT(bp);
1118         } else {
1119                 xfs_buf_relse(bp);
1120         }
1121
1122         return EIO;
1123 }
1124
1125
1126 /*
1127  * All xfs metadata buffers except log state machine buffers
1128  * get this attached as their b_bdstrat callback function.
1129  * This is so that we can catch a buffer
1130  * after prematurely unpinning it to forcibly shutdown the filesystem.
1131  */
1132 int
1133 xfs_bdstrat_cb(
1134         struct xfs_buf  *bp)
1135 {
1136         if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
1137                 trace_xfs_bdstrat_shut(bp, _RET_IP_);
1138                 /*
1139                  * Metadata write that didn't get logged but
1140                  * written delayed anyway. These aren't associated
1141                  * with a transaction, and can be ignored.
1142                  */
1143                 if (!bp->b_iodone && !XFS_BUF_ISREAD(bp))
1144                         return xfs_bioerror_relse(bp);
1145                 else
1146                         return xfs_bioerror(bp);
1147         }
1148
1149         xfs_buf_iorequest(bp);
1150         return 0;
1151 }
1152
1153 /*
1154  * Wrapper around bdstrat so that we can stop data from going to disk in case
1155  * we are shutting down the filesystem.  Typically user data goes thru this
1156  * path; one of the exceptions is the superblock.
1157  */
1158 void
1159 xfsbdstrat(
1160         struct xfs_mount        *mp,
1161         struct xfs_buf          *bp)
1162 {
1163         if (XFS_FORCED_SHUTDOWN(mp)) {
1164                 trace_xfs_bdstrat_shut(bp, _RET_IP_);
1165                 xfs_bioerror_relse(bp);
1166                 return;
1167         }
1168
1169         xfs_buf_iorequest(bp);
1170 }
1171
1172 STATIC void
1173 _xfs_buf_ioend(
1174         xfs_buf_t               *bp,
1175         int                     schedule)
1176 {
1177         if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1178                 bp->b_flags &= ~_XBF_PAGE_LOCKED;
1179                 xfs_buf_ioend(bp, schedule);
1180         }
1181 }
1182
1183 STATIC void
1184 xfs_buf_bio_end_io(
1185         struct bio              *bio,
1186         int                     error)
1187 {
1188         xfs_buf_t               *bp = (xfs_buf_t *)bio->bi_private;
1189         unsigned int            blocksize = bp->b_target->bt_bsize;
1190         struct bio_vec          *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1191
1192         xfs_buf_ioerror(bp, -error);
1193
1194         if (!error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1195                 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1196
1197         do {
1198                 struct page     *page = bvec->bv_page;
1199
1200                 ASSERT(!PagePrivate(page));
1201                 if (unlikely(bp->b_error)) {
1202                         if (bp->b_flags & XBF_READ)
1203                                 ClearPageUptodate(page);
1204                 } else if (blocksize >= PAGE_CACHE_SIZE) {
1205                         SetPageUptodate(page);
1206                 } else if (!PagePrivate(page) &&
1207                                 (bp->b_flags & _XBF_PAGE_CACHE)) {
1208                         set_page_region(page, bvec->bv_offset, bvec->bv_len);
1209                 }
1210
1211                 if (--bvec >= bio->bi_io_vec)
1212                         prefetchw(&bvec->bv_page->flags);
1213
1214                 if (bp->b_flags & _XBF_PAGE_LOCKED)
1215                         unlock_page(page);
1216         } while (bvec >= bio->bi_io_vec);
1217
1218         _xfs_buf_ioend(bp, 1);
1219         bio_put(bio);
1220 }
1221
1222 STATIC void
1223 _xfs_buf_ioapply(
1224         xfs_buf_t               *bp)
1225 {
1226         int                     rw, map_i, total_nr_pages, nr_pages;
1227         struct bio              *bio;
1228         int                     offset = bp->b_offset;
1229         int                     size = bp->b_count_desired;
1230         sector_t                sector = bp->b_bn;
1231         unsigned int            blocksize = bp->b_target->bt_bsize;
1232
1233         total_nr_pages = bp->b_page_count;
1234         map_i = 0;
1235
1236         if (bp->b_flags & XBF_ORDERED) {
1237                 ASSERT(!(bp->b_flags & XBF_READ));
1238                 rw = WRITE_BARRIER;
1239         } else if (bp->b_flags & XBF_LOG_BUFFER) {
1240                 ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
1241                 bp->b_flags &= ~_XBF_RUN_QUEUES;
1242                 rw = (bp->b_flags & XBF_WRITE) ? WRITE_SYNC : READ_SYNC;
1243         } else if (bp->b_flags & _XBF_RUN_QUEUES) {
1244                 ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
1245                 bp->b_flags &= ~_XBF_RUN_QUEUES;
1246                 rw = (bp->b_flags & XBF_WRITE) ? WRITE_META : READ_META;
1247         } else {
1248                 rw = (bp->b_flags & XBF_WRITE) ? WRITE :
1249                      (bp->b_flags & XBF_READ_AHEAD) ? READA : READ;
1250         }
1251
1252         /* Special code path for reading a sub page size buffer in --
1253          * we populate up the whole page, and hence the other metadata
1254          * in the same page.  This optimization is only valid when the
1255          * filesystem block size is not smaller than the page size.
1256          */
1257         if ((bp->b_buffer_length < PAGE_CACHE_SIZE) &&
1258             ((bp->b_flags & (XBF_READ|_XBF_PAGE_LOCKED)) ==
1259               (XBF_READ|_XBF_PAGE_LOCKED)) &&
1260             (blocksize >= PAGE_CACHE_SIZE)) {
1261                 bio = bio_alloc(GFP_NOIO, 1);
1262
1263                 bio->bi_bdev = bp->b_target->bt_bdev;
1264                 bio->bi_sector = sector - (offset >> BBSHIFT);
1265                 bio->bi_end_io = xfs_buf_bio_end_io;
1266                 bio->bi_private = bp;
1267
1268                 bio_add_page(bio, bp->b_pages[0], PAGE_CACHE_SIZE, 0);
1269                 size = 0;
1270
1271                 atomic_inc(&bp->b_io_remaining);
1272
1273                 goto submit_io;
1274         }
1275
1276 next_chunk:
1277         atomic_inc(&bp->b_io_remaining);
1278         nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1279         if (nr_pages > total_nr_pages)
1280                 nr_pages = total_nr_pages;
1281
1282         bio = bio_alloc(GFP_NOIO, nr_pages);
1283         bio->bi_bdev = bp->b_target->bt_bdev;
1284         bio->bi_sector = sector;
1285         bio->bi_end_io = xfs_buf_bio_end_io;
1286         bio->bi_private = bp;
1287
1288         for (; size && nr_pages; nr_pages--, map_i++) {
1289                 int     rbytes, nbytes = PAGE_CACHE_SIZE - offset;
1290
1291                 if (nbytes > size)
1292                         nbytes = size;
1293
1294                 rbytes = bio_add_page(bio, bp->b_pages[map_i], nbytes, offset);
1295                 if (rbytes < nbytes)
1296                         break;
1297
1298                 offset = 0;
1299                 sector += nbytes >> BBSHIFT;
1300                 size -= nbytes;
1301                 total_nr_pages--;
1302         }
1303
1304 submit_io:
1305         if (likely(bio->bi_size)) {
1306                 if (xfs_buf_is_vmapped(bp)) {
1307                         flush_kernel_vmap_range(bp->b_addr,
1308                                                 xfs_buf_vmap_len(bp));
1309                 }
1310                 submit_bio(rw, bio);
1311                 if (size)
1312                         goto next_chunk;
1313         } else {
1314                 bio_put(bio);
1315                 xfs_buf_ioerror(bp, EIO);
1316         }
1317 }
1318
1319 int
1320 xfs_buf_iorequest(
1321         xfs_buf_t               *bp)
1322 {
1323         trace_xfs_buf_iorequest(bp, _RET_IP_);
1324
1325         if (bp->b_flags & XBF_DELWRI) {
1326                 xfs_buf_delwri_queue(bp, 1);
1327                 return 0;
1328         }
1329
1330         if (bp->b_flags & XBF_WRITE) {
1331                 xfs_buf_wait_unpin(bp);
1332         }
1333
1334         xfs_buf_hold(bp);
1335
1336         /* Set the count to 1 initially, this will stop an I/O
1337          * completion callout which happens before we have started
1338          * all the I/O from calling xfs_buf_ioend too early.
1339          */
1340         atomic_set(&bp->b_io_remaining, 1);
1341         _xfs_buf_ioapply(bp);
1342         _xfs_buf_ioend(bp, 0);
1343
1344         xfs_buf_rele(bp);
1345         return 0;
1346 }
1347
1348 /*
1349  *      Waits for I/O to complete on the buffer supplied.
1350  *      It returns immediately if no I/O is pending.
1351  *      It returns the I/O error code, if any, or 0 if there was no error.
1352  */
1353 int
1354 xfs_buf_iowait(
1355         xfs_buf_t               *bp)
1356 {
1357         trace_xfs_buf_iowait(bp, _RET_IP_);
1358
1359         if (atomic_read(&bp->b_io_remaining))
1360                 blk_run_address_space(bp->b_target->bt_mapping);
1361         wait_for_completion(&bp->b_iowait);
1362
1363         trace_xfs_buf_iowait_done(bp, _RET_IP_);
1364         return bp->b_error;
1365 }
1366
1367 xfs_caddr_t
1368 xfs_buf_offset(
1369         xfs_buf_t               *bp,
1370         size_t                  offset)
1371 {
1372         struct page             *page;
1373
1374         if (bp->b_flags & XBF_MAPPED)
1375                 return XFS_BUF_PTR(bp) + offset;
1376
1377         offset += bp->b_offset;
1378         page = bp->b_pages[offset >> PAGE_CACHE_SHIFT];
1379         return (xfs_caddr_t)page_address(page) + (offset & (PAGE_CACHE_SIZE-1));
1380 }
1381
1382 /*
1383  *      Move data into or out of a buffer.
1384  */
1385 void
1386 xfs_buf_iomove(
1387         xfs_buf_t               *bp,    /* buffer to process            */
1388         size_t                  boff,   /* starting buffer offset       */
1389         size_t                  bsize,  /* length to copy               */
1390         void                    *data,  /* data address                 */
1391         xfs_buf_rw_t            mode)   /* read/write/zero flag         */
1392 {
1393         size_t                  bend, cpoff, csize;
1394         struct page             *page;
1395
1396         bend = boff + bsize;
1397         while (boff < bend) {
1398                 page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
1399                 cpoff = xfs_buf_poff(boff + bp->b_offset);
1400                 csize = min_t(size_t,
1401                               PAGE_CACHE_SIZE-cpoff, bp->b_count_desired-boff);
1402
1403                 ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE));
1404
1405                 switch (mode) {
1406                 case XBRW_ZERO:
1407                         memset(page_address(page) + cpoff, 0, csize);
1408                         break;
1409                 case XBRW_READ:
1410                         memcpy(data, page_address(page) + cpoff, csize);
1411                         break;
1412                 case XBRW_WRITE:
1413                         memcpy(page_address(page) + cpoff, data, csize);
1414                 }
1415
1416                 boff += csize;
1417                 data += csize;
1418         }
1419 }
1420
1421 /*
1422  *      Handling of buffer targets (buftargs).
1423  */
1424
1425 /*
1426  *      Wait for any bufs with callbacks that have been submitted but
1427  *      have not yet returned... walk the hash list for the target.
1428  */
1429 void
1430 xfs_wait_buftarg(
1431         xfs_buftarg_t   *btp)
1432 {
1433         xfs_buf_t       *bp, *n;
1434         xfs_bufhash_t   *hash;
1435         uint            i;
1436
1437         for (i = 0; i < (1 << btp->bt_hashshift); i++) {
1438                 hash = &btp->bt_hash[i];
1439 again:
1440                 spin_lock(&hash->bh_lock);
1441                 list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
1442                         ASSERT(btp == bp->b_target);
1443                         if (!(bp->b_flags & XBF_FS_MANAGED)) {
1444                                 spin_unlock(&hash->bh_lock);
1445                                 /*
1446                                  * Catch superblock reference count leaks
1447                                  * immediately
1448                                  */
1449                                 BUG_ON(bp->b_bn == 0);
1450                                 delay(100);
1451                                 goto again;
1452                         }
1453                 }
1454                 spin_unlock(&hash->bh_lock);
1455         }
1456 }
1457
1458 /*
1459  *      Allocate buffer hash table for a given target.
1460  *      For devices containing metadata (i.e. not the log/realtime devices)
1461  *      we need to allocate a much larger hash table.
1462  */
1463 STATIC void
1464 xfs_alloc_bufhash(
1465         xfs_buftarg_t           *btp,
1466         int                     external)
1467 {
1468         unsigned int            i;
1469
1470         btp->bt_hashshift = external ? 3 : 8;   /* 8 or 256 buckets */
1471         btp->bt_hashmask = (1 << btp->bt_hashshift) - 1;
1472         btp->bt_hash = kmem_zalloc_large((1 << btp->bt_hashshift) *
1473                                          sizeof(xfs_bufhash_t));
1474         for (i = 0; i < (1 << btp->bt_hashshift); i++) {
1475                 spin_lock_init(&btp->bt_hash[i].bh_lock);
1476                 INIT_LIST_HEAD(&btp->bt_hash[i].bh_list);
1477         }
1478 }
1479
1480 STATIC void
1481 xfs_free_bufhash(
1482         xfs_buftarg_t           *btp)
1483 {
1484         kmem_free_large(btp->bt_hash);
1485         btp->bt_hash = NULL;
1486 }
1487
1488 /*
1489  *      buftarg list for delwrite queue processing
1490  */
1491 static LIST_HEAD(xfs_buftarg_list);
1492 static DEFINE_SPINLOCK(xfs_buftarg_lock);
1493
1494 STATIC void
1495 xfs_register_buftarg(
1496         xfs_buftarg_t           *btp)
1497 {
1498         spin_lock(&xfs_buftarg_lock);
1499         list_add(&btp->bt_list, &xfs_buftarg_list);
1500         spin_unlock(&xfs_buftarg_lock);
1501 }
1502
1503 STATIC void
1504 xfs_unregister_buftarg(
1505         xfs_buftarg_t           *btp)
1506 {
1507         spin_lock(&xfs_buftarg_lock);
1508         list_del(&btp->bt_list);
1509         spin_unlock(&xfs_buftarg_lock);
1510 }
1511
1512 void
1513 xfs_free_buftarg(
1514         struct xfs_mount        *mp,
1515         struct xfs_buftarg      *btp)
1516 {
1517         xfs_flush_buftarg(btp, 1);
1518         if (mp->m_flags & XFS_MOUNT_BARRIER)
1519                 xfs_blkdev_issue_flush(btp);
1520         xfs_free_bufhash(btp);
1521         iput(btp->bt_mapping->host);
1522
1523         /* Unregister the buftarg first so that we don't get a
1524          * wakeup finding a non-existent task
1525          */
1526         xfs_unregister_buftarg(btp);
1527         kthread_stop(btp->bt_task);
1528
1529         kmem_free(btp);
1530 }
1531
1532 STATIC int
1533 xfs_setsize_buftarg_flags(
1534         xfs_buftarg_t           *btp,
1535         unsigned int            blocksize,
1536         unsigned int            sectorsize,
1537         int                     verbose)
1538 {
1539         btp->bt_bsize = blocksize;
1540         btp->bt_sshift = ffs(sectorsize) - 1;
1541         btp->bt_smask = sectorsize - 1;
1542
1543         if (set_blocksize(btp->bt_bdev, sectorsize)) {
1544                 printk(KERN_WARNING
1545                         "XFS: Cannot set_blocksize to %u on device %s\n",
1546                         sectorsize, XFS_BUFTARG_NAME(btp));
1547                 return EINVAL;
1548         }
1549
1550         if (verbose &&
1551             (PAGE_CACHE_SIZE / BITS_PER_LONG) > sectorsize) {
1552                 printk(KERN_WARNING
1553                         "XFS: %u byte sectors in use on device %s.  "
1554                         "This is suboptimal; %u or greater is ideal.\n",
1555                         sectorsize, XFS_BUFTARG_NAME(btp),
1556                         (unsigned int)PAGE_CACHE_SIZE / BITS_PER_LONG);
1557         }
1558
1559         return 0;
1560 }
1561
1562 /*
1563  *      When allocating the initial buffer target we have not yet
1564  *      read in the superblock, so don't know what sized sectors
1565  *      are being used is at this early stage.  Play safe.
1566  */
1567 STATIC int
1568 xfs_setsize_buftarg_early(
1569         xfs_buftarg_t           *btp,
1570         struct block_device     *bdev)
1571 {
1572         return xfs_setsize_buftarg_flags(btp,
1573                         PAGE_CACHE_SIZE, bdev_logical_block_size(bdev), 0);
1574 }
1575
1576 int
1577 xfs_setsize_buftarg(
1578         xfs_buftarg_t           *btp,
1579         unsigned int            blocksize,
1580         unsigned int            sectorsize)
1581 {
1582         return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
1583 }
1584
1585 STATIC int
1586 xfs_mapping_buftarg(
1587         xfs_buftarg_t           *btp,
1588         struct block_device     *bdev)
1589 {
1590         struct backing_dev_info *bdi;
1591         struct inode            *inode;
1592         struct address_space    *mapping;
1593         static const struct address_space_operations mapping_aops = {
1594                 .sync_page = block_sync_page,
1595                 .migratepage = fail_migrate_page,
1596         };
1597
1598         inode = new_inode(bdev->bd_inode->i_sb);
1599         if (!inode) {
1600                 printk(KERN_WARNING
1601                         "XFS: Cannot allocate mapping inode for device %s\n",
1602                         XFS_BUFTARG_NAME(btp));
1603                 return ENOMEM;
1604         }
1605         inode->i_mode = S_IFBLK;
1606         inode->i_bdev = bdev;
1607         inode->i_rdev = bdev->bd_dev;
1608         bdi = blk_get_backing_dev_info(bdev);
1609         if (!bdi)
1610                 bdi = &default_backing_dev_info;
1611         mapping = &inode->i_data;
1612         mapping->a_ops = &mapping_aops;
1613         mapping->backing_dev_info = bdi;
1614         mapping_set_gfp_mask(mapping, GFP_NOFS);
1615         btp->bt_mapping = mapping;
1616         return 0;
1617 }
1618
1619 STATIC int
1620 xfs_alloc_delwrite_queue(
1621         xfs_buftarg_t           *btp,
1622         const char              *fsname)
1623 {
1624         int     error = 0;
1625
1626         INIT_LIST_HEAD(&btp->bt_list);
1627         INIT_LIST_HEAD(&btp->bt_delwrite_queue);
1628         spin_lock_init(&btp->bt_delwrite_lock);
1629         btp->bt_flags = 0;
1630         btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd/%s", fsname);
1631         if (IS_ERR(btp->bt_task)) {
1632                 error = PTR_ERR(btp->bt_task);
1633                 goto out_error;
1634         }
1635         xfs_register_buftarg(btp);
1636 out_error:
1637         return error;
1638 }
1639
1640 xfs_buftarg_t *
1641 xfs_alloc_buftarg(
1642         struct block_device     *bdev,
1643         int                     external,
1644         const char              *fsname)
1645 {
1646         xfs_buftarg_t           *btp;
1647
1648         btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
1649
1650         btp->bt_dev =  bdev->bd_dev;
1651         btp->bt_bdev = bdev;
1652         if (xfs_setsize_buftarg_early(btp, bdev))
1653                 goto error;
1654         if (xfs_mapping_buftarg(btp, bdev))
1655                 goto error;
1656         if (xfs_alloc_delwrite_queue(btp, fsname))
1657                 goto error;
1658         xfs_alloc_bufhash(btp, external);
1659         return btp;
1660
1661 error:
1662         kmem_free(btp);
1663         return NULL;
1664 }
1665
1666
1667 /*
1668  *      Delayed write buffer handling
1669  */
1670 STATIC void
1671 xfs_buf_delwri_queue(
1672         xfs_buf_t               *bp,
1673         int                     unlock)
1674 {
1675         struct list_head        *dwq = &bp->b_target->bt_delwrite_queue;
1676         spinlock_t              *dwlk = &bp->b_target->bt_delwrite_lock;
1677
1678         trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1679
1680         ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));
1681
1682         spin_lock(dwlk);
1683         /* If already in the queue, dequeue and place at tail */
1684         if (!list_empty(&bp->b_list)) {
1685                 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1686                 if (unlock)
1687                         atomic_dec(&bp->b_hold);
1688                 list_del(&bp->b_list);
1689         }
1690
1691         if (list_empty(dwq)) {
1692                 /* start xfsbufd as it is about to have something to do */
1693                 wake_up_process(bp->b_target->bt_task);
1694         }
1695
1696         bp->b_flags |= _XBF_DELWRI_Q;
1697         list_add_tail(&bp->b_list, dwq);
1698         bp->b_queuetime = jiffies;
1699         spin_unlock(dwlk);
1700
1701         if (unlock)
1702                 xfs_buf_unlock(bp);
1703 }
1704
1705 void
1706 xfs_buf_delwri_dequeue(
1707         xfs_buf_t               *bp)
1708 {
1709         spinlock_t              *dwlk = &bp->b_target->bt_delwrite_lock;
1710         int                     dequeued = 0;
1711
1712         spin_lock(dwlk);
1713         if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
1714                 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1715                 list_del_init(&bp->b_list);
1716                 dequeued = 1;
1717         }
1718         bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
1719         spin_unlock(dwlk);
1720
1721         if (dequeued)
1722                 xfs_buf_rele(bp);
1723
1724         trace_xfs_buf_delwri_dequeue(bp, _RET_IP_);
1725 }
1726
1727 /*
1728  * If a delwri buffer needs to be pushed before it has aged out, then promote
1729  * it to the head of the delwri queue so that it will be flushed on the next
1730  * xfsbufd run. We do this by resetting the queuetime of the buffer to be older
1731  * than the age currently needed to flush the buffer. Hence the next time the
1732  * xfsbufd sees it is guaranteed to be considered old enough to flush.
1733  */
1734 void
1735 xfs_buf_delwri_promote(
1736         struct xfs_buf  *bp)
1737 {
1738         struct xfs_buftarg *btp = bp->b_target;
1739         long            age = xfs_buf_age_centisecs * msecs_to_jiffies(10) + 1;
1740
1741         ASSERT(bp->b_flags & XBF_DELWRI);
1742         ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1743
1744         /*
1745          * Check the buffer age before locking the delayed write queue as we
1746          * don't need to promote buffers that are already past the flush age.
1747          */
1748         if (bp->b_queuetime < jiffies - age)
1749                 return;
1750         bp->b_queuetime = jiffies - age;
1751         spin_lock(&btp->bt_delwrite_lock);
1752         list_move(&bp->b_list, &btp->bt_delwrite_queue);
1753         spin_unlock(&btp->bt_delwrite_lock);
1754 }
1755
1756 STATIC void
1757 xfs_buf_runall_queues(
1758         struct workqueue_struct *queue)
1759 {
1760         flush_workqueue(queue);
1761 }
1762
1763 STATIC int
1764 xfsbufd_wakeup(
1765         int                     priority,
1766         gfp_t                   mask)
1767 {
1768         xfs_buftarg_t           *btp;
1769
1770         spin_lock(&xfs_buftarg_lock);
1771         list_for_each_entry(btp, &xfs_buftarg_list, bt_list) {
1772                 if (test_bit(XBT_FORCE_SLEEP, &btp->bt_flags))
1773                         continue;
1774                 if (list_empty(&btp->bt_delwrite_queue))
1775                         continue;
1776                 set_bit(XBT_FORCE_FLUSH, &btp->bt_flags);
1777                 wake_up_process(btp->bt_task);
1778         }
1779         spin_unlock(&xfs_buftarg_lock);
1780         return 0;
1781 }
1782
1783 /*
1784  * Move as many buffers as specified to the supplied list
1785  * idicating if we skipped any buffers to prevent deadlocks.
1786  */
1787 STATIC int
1788 xfs_buf_delwri_split(
1789         xfs_buftarg_t   *target,
1790         struct list_head *list,
1791         unsigned long   age)
1792 {
1793         xfs_buf_t       *bp, *n;
1794         struct list_head *dwq = &target->bt_delwrite_queue;
1795         spinlock_t      *dwlk = &target->bt_delwrite_lock;
1796         int             skipped = 0;
1797         int             force;
1798
1799         force = test_and_clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1800         INIT_LIST_HEAD(list);
1801         spin_lock(dwlk);
1802         list_for_each_entry_safe(bp, n, dwq, b_list) {
1803                 trace_xfs_buf_delwri_split(bp, _RET_IP_);
1804                 ASSERT(bp->b_flags & XBF_DELWRI);
1805
1806                 if (!xfs_buf_ispin(bp) && !xfs_buf_cond_lock(bp)) {
1807                         if (!force &&
1808                             time_before(jiffies, bp->b_queuetime + age)) {
1809                                 xfs_buf_unlock(bp);
1810                                 break;
1811                         }
1812
1813                         bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q|
1814                                          _XBF_RUN_QUEUES);
1815                         bp->b_flags |= XBF_WRITE;
1816                         list_move_tail(&bp->b_list, list);
1817                 } else
1818                         skipped++;
1819         }
1820         spin_unlock(dwlk);
1821
1822         return skipped;
1823
1824 }
1825
1826 /*
1827  * Compare function is more complex than it needs to be because
1828  * the return value is only 32 bits and we are doing comparisons
1829  * on 64 bit values
1830  */
1831 static int
1832 xfs_buf_cmp(
1833         void            *priv,
1834         struct list_head *a,
1835         struct list_head *b)
1836 {
1837         struct xfs_buf  *ap = container_of(a, struct xfs_buf, b_list);
1838         struct xfs_buf  *bp = container_of(b, struct xfs_buf, b_list);
1839         xfs_daddr_t             diff;
1840
1841         diff = ap->b_bn - bp->b_bn;
1842         if (diff < 0)
1843                 return -1;
1844         if (diff > 0)
1845                 return 1;
1846         return 0;
1847 }
1848
1849 void
1850 xfs_buf_delwri_sort(
1851         xfs_buftarg_t   *target,
1852         struct list_head *list)
1853 {
1854         list_sort(NULL, list, xfs_buf_cmp);
1855 }
1856
1857 STATIC int
1858 xfsbufd(
1859         void            *data)
1860 {
1861         xfs_buftarg_t   *target = (xfs_buftarg_t *)data;
1862
1863         current->flags |= PF_MEMALLOC;
1864
1865         set_freezable();
1866
1867         do {
1868                 long    age = xfs_buf_age_centisecs * msecs_to_jiffies(10);
1869                 long    tout = xfs_buf_timer_centisecs * msecs_to_jiffies(10);
1870                 int     count = 0;
1871                 struct list_head tmp;
1872
1873                 if (unlikely(freezing(current))) {
1874                         set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1875                         refrigerator();
1876                 } else {
1877                         clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1878                 }
1879
1880                 /* sleep for a long time if there is nothing to do. */
1881                 if (list_empty(&target->bt_delwrite_queue))
1882                         tout = MAX_SCHEDULE_TIMEOUT;
1883                 schedule_timeout_interruptible(tout);
1884
1885                 xfs_buf_delwri_split(target, &tmp, age);
1886                 list_sort(NULL, &tmp, xfs_buf_cmp);
1887                 while (!list_empty(&tmp)) {
1888                         struct xfs_buf *bp;
1889                         bp = list_first_entry(&tmp, struct xfs_buf, b_list);
1890                         list_del_init(&bp->b_list);
1891                         xfs_buf_iostrategy(bp);
1892                         count++;
1893                 }
1894                 if (count)
1895                         blk_run_address_space(target->bt_mapping);
1896
1897         } while (!kthread_should_stop());
1898
1899         return 0;
1900 }
1901
1902 /*
1903  *      Go through all incore buffers, and release buffers if they belong to
1904  *      the given device. This is used in filesystem error handling to
1905  *      preserve the consistency of its metadata.
1906  */
1907 int
1908 xfs_flush_buftarg(
1909         xfs_buftarg_t   *target,
1910         int             wait)
1911 {
1912         xfs_buf_t       *bp;
1913         int             pincount = 0;
1914         LIST_HEAD(tmp_list);
1915         LIST_HEAD(wait_list);
1916
1917         xfs_buf_runall_queues(xfsconvertd_workqueue);
1918         xfs_buf_runall_queues(xfsdatad_workqueue);
1919         xfs_buf_runall_queues(xfslogd_workqueue);
1920
1921         set_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1922         pincount = xfs_buf_delwri_split(target, &tmp_list, 0);
1923
1924         /*
1925          * Dropped the delayed write list lock, now walk the temporary list.
1926          * All I/O is issued async and then if we need to wait for completion
1927          * we do that after issuing all the IO.
1928          */
1929         list_sort(NULL, &tmp_list, xfs_buf_cmp);
1930         while (!list_empty(&tmp_list)) {
1931                 bp = list_first_entry(&tmp_list, struct xfs_buf, b_list);
1932                 ASSERT(target == bp->b_target);
1933                 list_del_init(&bp->b_list);
1934                 if (wait) {
1935                         bp->b_flags &= ~XBF_ASYNC;
1936                         list_add(&bp->b_list, &wait_list);
1937                 }
1938                 xfs_buf_iostrategy(bp);
1939         }
1940
1941         if (wait) {
1942                 /* Expedite and wait for IO to complete. */
1943                 blk_run_address_space(target->bt_mapping);
1944                 while (!list_empty(&wait_list)) {
1945                         bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
1946
1947                         list_del_init(&bp->b_list);
1948                         xfs_iowait(bp);
1949                         xfs_buf_relse(bp);
1950                 }
1951         }
1952
1953         return pincount;
1954 }
1955
1956 int __init
1957 xfs_buf_init(void)
1958 {
1959         xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
1960                                                 KM_ZONE_HWALIGN, NULL);
1961         if (!xfs_buf_zone)
1962                 goto out;
1963
1964         xfslogd_workqueue = create_workqueue("xfslogd");
1965         if (!xfslogd_workqueue)
1966                 goto out_free_buf_zone;
1967
1968         xfsdatad_workqueue = create_workqueue("xfsdatad");
1969         if (!xfsdatad_workqueue)
1970                 goto out_destroy_xfslogd_workqueue;
1971
1972         xfsconvertd_workqueue = create_workqueue("xfsconvertd");
1973         if (!xfsconvertd_workqueue)
1974                 goto out_destroy_xfsdatad_workqueue;
1975
1976         register_shrinker(&xfs_buf_shake);
1977         return 0;
1978
1979  out_destroy_xfsdatad_workqueue:
1980         destroy_workqueue(xfsdatad_workqueue);
1981  out_destroy_xfslogd_workqueue:
1982         destroy_workqueue(xfslogd_workqueue);
1983  out_free_buf_zone:
1984         kmem_zone_destroy(xfs_buf_zone);
1985  out:
1986         return -ENOMEM;
1987 }
1988
1989 void
1990 xfs_buf_terminate(void)
1991 {
1992         unregister_shrinker(&xfs_buf_shake);
1993         destroy_workqueue(xfsconvertd_workqueue);
1994         destroy_workqueue(xfsdatad_workqueue);
1995         destroy_workqueue(xfslogd_workqueue);
1996         kmem_zone_destroy(xfs_buf_zone);
1997 }
1998
1999 #ifdef CONFIG_KDB_MODULES
2000 struct list_head *
2001 xfs_get_buftarg_list(void)
2002 {
2003         return &xfs_buftarg_list;
2004 }
2005 #endif