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/slab.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
  37 #include "xfs_sb.h"
  38 #include "xfs_inum.h"
  39 #include "xfs_ag.h"
  40 #include "xfs_dmapi.h"
  41 #include "xfs_mount.h"
  42
  43 static kmem_zone_t *xfs_buf_zone;
  44 STATIC int xfsbufd(void *);
  45 STATIC int xfsbufd_wakeup(int, gfp_t);
  46 STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
  47 static struct shrinker xfs_buf_shake = {
  48         .shrink = xfsbufd_wakeup,
  49         .seeks = DEFAULT_SEEKS,
  50 };
  51
  52 static struct workqueue_struct *xfslogd_workqueue;
  53 struct workqueue_struct *xfsdatad_workqueue;
  54 struct workqueue_struct *xfsconvertd_workqueue;
  55
  56 #ifdef XFS_BUF_TRACE
  57 void
  58 xfs_buf_trace(
  59         xfs_buf_t       *bp,
  60         char            *id,
  61         void            *data,
  62         void            *ra)
  63 {
  64         ktrace_enter(xfs_buf_trace_buf,
  65                 bp, id,
  66                 (void *)(unsigned long)bp->b_flags,
  67                 (void *)(unsigned long)bp->b_hold.counter,
  68                 (void *)(unsigned long)bp->b_sema.count,
  69                 (void *)current,
  70                 data, ra,
  71                 (void *)(unsigned long)((bp->b_file_offset>>32) & 0xffffffff),
  72                 (void *)(unsigned long)(bp->b_file_offset & 0xffffffff),
  73                 (void *)(unsigned long)bp->b_buffer_length,
  74                 NULL, NULL, NULL, NULL, NULL);
  75 }
  76 ktrace_t *xfs_buf_trace_buf;
  77 #define XFS_BUF_TRACE_SIZE      4096
  78 #define XB_TRACE(bp, id, data)  \
  79         xfs_buf_trace(bp, id, (void *)data, (void *)__builtin_return_address(0))
  80 #else
  81 #define XB_TRACE(bp, id, data)  do { } while (0)
  82 #endif
  83
  84 #ifdef XFS_BUF_LOCK_TRACKING
  85 # define XB_SET_OWNER(bp)       ((bp)->b_last_holder = current->pid)
  86 # define XB_CLEAR_OWNER(bp)     ((bp)->b_last_holder = -1)
  87 # define XB_GET_OWNER(bp)       ((bp)->b_last_holder)
  88 #else
  89 # define XB_SET_OWNER(bp)       do { } while (0)
  90 # define XB_CLEAR_OWNER(bp)     do { } while (0)
  91 # define XB_GET_OWNER(bp)       do { } while (0)
  92 #endif
  93
  94 #define xb_to_gfp(flags) \
  95         ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
  96           ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
  97
  98 #define xb_to_km(flags) \
  99          (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
 100
 101 #define xfs_buf_allocate(flags) \
 102         kmem_zone_alloc(xfs_buf_zone, xb_to_km(flags))
 103 #define xfs_buf_deallocate(bp) \
 104         kmem_zone_free(xfs_buf_zone, (bp));
 105
 106 /*
 107  *      Page Region interfaces.
 108  *
 109  *      For pages in filesystems where the blocksize is smaller than the
 110  *      pagesize, we use the page->private field (long) to hold a bitmap
 111  *      of uptodate regions within the page.
 112  *
 113  *      Each such region is "bytes per page / bits per long" bytes long.
 114  *
 115  *      NBPPR == number-of-bytes-per-page-region
 116  *      BTOPR == bytes-to-page-region (rounded up)
 117  *      BTOPRT == bytes-to-page-region-truncated (rounded down)
 118  */
 119 #if (BITS_PER_LONG == 32)
 120 #define PRSHIFT         (PAGE_CACHE_SHIFT - 5)  /* (32 == 1<<5) */
 121 #elif (BITS_PER_LONG == 64)
 122 #define PRSHIFT         (PAGE_CACHE_SHIFT - 6)  /* (64 == 1<<6) */
 123 #else
 124 #error BITS_PER_LONG must be 32 or 64
 125 #endif
 126 #define NBPPR           (PAGE_CACHE_SIZE/BITS_PER_LONG)
 127 #define BTOPR(b)        (((unsigned int)(b) + (NBPPR - 1)) >> PRSHIFT)
 128 #define BTOPRT(b)       (((unsigned int)(b) >> PRSHIFT))
 129
 130 STATIC unsigned long
 131 page_region_mask(
 132         size_t          offset,
 133         size_t          length)
 134 {
 135         unsigned long   mask;
 136         int             first, final;
 137
 138         first = BTOPR(offset);
 139         final = BTOPRT(offset + length - 1);
 140         first = min(first, final);
 141
 142         mask = ~0UL;
 143         mask <<= BITS_PER_LONG - (final - first);
 144         mask >>= BITS_PER_LONG - (final);
 145
 146         ASSERT(offset + length <= PAGE_CACHE_SIZE);
 147         ASSERT((final - first) < BITS_PER_LONG && (final - first) >= 0);
 148
 149         return mask;
 150 }
 151
 152 STATIC_INLINE void
 153 set_page_region(
 154         struct page     *page,
 155         size_t          offset,
 156         size_t          length)
 157 {
 158         set_page_private(page,
 159                 page_private(page) | page_region_mask(offset, length));
 160         if (page_private(page) == ~0UL)
 161                 SetPageUptodate(page);
 162 }
 163
 164 STATIC_INLINE int
 165 test_page_region(
 166         struct page     *page,
 167         size_t          offset,
 168         size_t          length)
 169 {
 170         unsigned long   mask = page_region_mask(offset, length);
 171
 172         return (mask && (page_private(page) & mask) == mask);
 173 }
 174
 175 /*
 176  *      Mapping of multi-page buffers into contiguous virtual space
 177  */
 178
 179 typedef struct a_list {
 180         void            *vm_addr;
 181         struct a_list   *next;
 182 } a_list_t;
 183
 184 static a_list_t         *as_free_head;
 185 static int              as_list_len;
 186 static DEFINE_SPINLOCK(as_lock);
 187
 188 /*
 189  *      Try to batch vunmaps because they are costly.
 190  */
 191 STATIC void
 192 free_address(
 193         void            *addr)
 194 {
 195         a_list_t        *aentry;
 196
 197 #ifdef CONFIG_XEN
 198         /*
 199          * Xen needs to be able to make sure it can get an exclusive
 200          * RO mapping of pages it wants to turn into a pagetable.  If
 201          * a newly allocated page is also still being vmap()ed by xfs,
 202          * it will cause pagetable construction to fail.  This is a
 203          * quick workaround to always eagerly unmap pages so that Xen
 204          * is happy.
 205          */
 206         vunmap(addr);
 207         return;
 208 #endif
 209
 210         aentry = kmalloc(sizeof(a_list_t), GFP_NOWAIT);
 211         if (likely(aentry)) {
 212                 spin_lock(&as_lock);
 213                 aentry->next = as_free_head;
 214                 aentry->vm_addr = addr;
 215                 as_free_head = aentry;
 216                 as_list_len++;
 217                 spin_unlock(&as_lock);
 218         } else {
 219                 vunmap(addr);
 220         }
 221 }
 222
 223 STATIC void
 224 purge_addresses(void)
 225 {
 226         a_list_t        *aentry, *old;
 227
 228         if (as_free_head == NULL)
 229                 return;
 230
 231         spin_lock(&as_lock);
 232         aentry = as_free_head;
 233         as_free_head = NULL;
 234         as_list_len = 0;
 235         spin_unlock(&as_lock);
 236
 237         while ((old = aentry) != NULL) {
 238                 vunmap(aentry->vm_addr);
 239                 aentry = aentry->next;
 240                 kfree(old);
 241         }
 242 }
 243
 244 /*
 245  *      Internal xfs_buf_t object manipulation
 246  */
 247
 248 STATIC void
 249 _xfs_buf_initialize(
 250         xfs_buf_t               *bp,
 251         xfs_buftarg_t           *target,
 252         xfs_off_t               range_base,
 253         size_t                  range_length,
 254         xfs_buf_flags_t         flags)
 255 {
 256         /*
 257          * We don't want certain flags to appear in b_flags.
 258          */
 259         flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
 260
 261         memset(bp, 0, sizeof(xfs_buf_t));
 262         atomic_set(&bp->b_hold, 1);
 263         init_completion(&bp->b_iowait);
 264         INIT_LIST_HEAD(&bp->b_list);
 265         INIT_LIST_HEAD(&bp->b_hash_list);
 266         init_MUTEX_LOCKED(&bp->b_sema); /* held, no waiters */
 267         XB_SET_OWNER(bp);
 268         bp->b_target = target;
 269         bp->b_file_offset = range_base;
 270         /*
 271          * Set buffer_length and count_desired to the same value initially.
 272          * I/O routines should use count_desired, which will be the same in
 273          * most cases but may be reset (e.g. XFS recovery).
 274          */
 275         bp->b_buffer_length = bp->b_count_desired = range_length;
 276         bp->b_flags = flags;
 277         bp->b_bn = XFS_BUF_DADDR_NULL;
 278         atomic_set(&bp->b_pin_count, 0);
 279         init_waitqueue_head(&bp->b_waiters);
 280
 281         XFS_STATS_INC(xb_create);
 282         XB_TRACE(bp, "initialize", target);
 283 }
 284
 285 /*
 286  *      Allocate a page array capable of holding a specified number
 287  *      of pages, and point the page buf at it.
 288  */
 289 STATIC int
 290 _xfs_buf_get_pages(
 291         xfs_buf_t               *bp,
 292         int                     page_count,
 293         xfs_buf_flags_t         flags)
 294 {
 295         /* Make sure that we have a page list */
 296         if (bp->b_pages == NULL) {
 297                 bp->b_offset = xfs_buf_poff(bp->b_file_offset);
 298                 bp->b_page_count = page_count;
 299                 if (page_count <= XB_PAGES) {
 300                         bp->b_pages = bp->b_page_array;
 301                 } else {
 302                         bp->b_pages = kmem_alloc(sizeof(struct page *) *
 303                                         page_count, xb_to_km(flags));
 304                         if (bp->b_pages == NULL)
 305                                 return -ENOMEM;
 306                 }
 307                 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
 308         }
 309         return 0;
 310 }
 311
 312 /*
 313  *      Frees b_pages if it was allocated.
 314  */
 315 STATIC void
 316 _xfs_buf_free_pages(
 317         xfs_buf_t       *bp)
 318 {
 319         if (bp->b_pages != bp->b_page_array) {
 320                 kmem_free(bp->b_pages);
 321         }
 322 }
 323
 324 /*
 325  *      Releases the specified buffer.
 326  *
 327  *      The modification state of any associated pages is left unchanged.
 328  *      The buffer most not be on any hash - use xfs_buf_rele instead for
 329  *      hashed and refcounted buffers
 330  */
 331 void
 332 xfs_buf_free(
 333         xfs_buf_t               *bp)
 334 {
 335         XB_TRACE(bp, "free", 0);
 336
 337         ASSERT(list_empty(&bp->b_hash_list));
 338
 339         if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) {
 340                 uint            i;
 341
 342                 if ((bp->b_flags & XBF_MAPPED) && (bp->b_page_count > 1))
 343                         free_address(bp->b_addr - bp->b_offset);
 344
 345                 for (i = 0; i < bp->b_page_count; i++) {
 346                         struct page     *page = bp->b_pages[i];
 347
 348                         if (bp->b_flags & _XBF_PAGE_CACHE)
 349                                 ASSERT(!PagePrivate(page));
 350                         page_cache_release(page);
 351                 }
 352                 _xfs_buf_free_pages(bp);
 353         }
 354
 355         xfs_buf_deallocate(bp);
 356 }
 357
 358 /*
 359  *      Finds all pages for buffer in question and builds it's page list.
 360  */
 361 STATIC int
 362 _xfs_buf_lookup_pages(
 363         xfs_buf_t               *bp,
 364         uint                    flags)
 365 {
 366         struct address_space    *mapping = bp->b_target->bt_mapping;
 367         size_t                  blocksize = bp->b_target->bt_bsize;
 368         size_t                  size = bp->b_count_desired;
 369         size_t                  nbytes, offset;
 370         gfp_t                   gfp_mask = xb_to_gfp(flags);
 371         unsigned short          page_count, i;
 372         pgoff_t                 first;
 373         xfs_off_t               end;
 374         int                     error;
 375
 376         end = bp->b_file_offset + bp->b_buffer_length;
 377         page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
 378
 379         error = _xfs_buf_get_pages(bp, page_count, flags);
 380         if (unlikely(error))
 381                 return error;
 382         bp->b_flags |= _XBF_PAGE_CACHE;
 383
 384         offset = bp->b_offset;
 385         first = bp->b_file_offset >> PAGE_CACHE_SHIFT;
 386
 387         for (i = 0; i < bp->b_page_count; i++) {
 388                 struct page     *page;
 389                 uint            retries = 0;
 390
 391               retry:
 392                 page = find_or_create_page(mapping, first + i, gfp_mask);
 393                 if (unlikely(page == NULL)) {
 394                         if (flags & XBF_READ_AHEAD) {
 395                                 bp->b_page_count = i;
 396                                 for (i = 0; i < bp->b_page_count; i++)
 397                                         unlock_page(bp->b_pages[i]);
 398                                 return -ENOMEM;
 399                         }
 400
 401                         /*
 402                          * This could deadlock.
 403                          *
 404                          * But until all the XFS lowlevel code is revamped to
 405                          * handle buffer allocation failures we can't do much.
 406                          */
 407                         if (!(++retries % 100))
 408                                 printk(KERN_ERR
 409                                         "XFS: possible memory allocation "
 410                                         "deadlock in %s (mode:0x%x)\n",
 411                                         __func__, gfp_mask);
 412
 413                         XFS_STATS_INC(xb_page_retries);
 414                         xfsbufd_wakeup(0, gfp_mask);
 415                         congestion_wait(WRITE, HZ/50);
 416                         goto retry;
 417                 }
 418
 419                 XFS_STATS_INC(xb_page_found);
 420
 421                 nbytes = min_t(size_t, size, PAGE_CACHE_SIZE - offset);
 422                 size -= nbytes;
 423
 424                 ASSERT(!PagePrivate(page));
 425                 if (!PageUptodate(page)) {
 426                         page_count--;
 427                         if (blocksize >= PAGE_CACHE_SIZE) {
 428                                 if (flags & XBF_READ)
 429                                         bp->b_flags |= _XBF_PAGE_LOCKED;
 430                         } else if (!PagePrivate(page)) {
 431                                 if (test_page_region(page, offset, nbytes))
 432                                         page_count++;
 433                         }
 434                 }
 435
 436                 bp->b_pages[i] = page;
 437                 offset = 0;
 438         }
 439
 440         if (!(bp->b_flags & _XBF_PAGE_LOCKED)) {
 441                 for (i = 0; i < bp->b_page_count; i++)
 442                         unlock_page(bp->b_pages[i]);
 443         }
 444
 445         if (page_count == bp->b_page_count)
 446                 bp->b_flags |= XBF_DONE;
 447
 448         XB_TRACE(bp, "lookup_pages", (long)page_count);
 449         return error;
 450 }
 451
 452 /*
 453  *      Map buffer into kernel address-space if nessecary.
 454  */
 455 STATIC int
 456 _xfs_buf_map_pages(
 457         xfs_buf_t               *bp,
 458         uint                    flags)
 459 {
 460         /* A single page buffer is always mappable */
 461         if (bp->b_page_count == 1) {
 462                 bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
 463                 bp->b_flags |= XBF_MAPPED;
 464         } else if (flags & XBF_MAPPED) {
 465                 if (as_list_len > 64)
 466                         purge_addresses();
 467                 bp->b_addr = vmap(bp->b_pages, bp->b_page_count,
 468                                         VM_MAP, PAGE_KERNEL);
 469                 if (unlikely(bp->b_addr == NULL))
 470                         return -ENOMEM;
 471                 bp->b_addr += bp->b_offset;
 472                 bp->b_flags |= XBF_MAPPED;
 473         }
 474
 475         return 0;
 476 }
 477
 478 /*
 479  *      Finding and Reading Buffers
 480  */
 481
 482 /*
 483  *      Look up, and creates if absent, a lockable buffer for
 484  *      a given range of an inode.  The buffer is returned
 485  *      locked.  If other overlapping buffers exist, they are
 486  *      released before the new buffer is created and locked,
 487  *      which may imply that this call will block until those buffers
 488  *      are unlocked.  No I/O is implied by this call.
 489  */
 490 xfs_buf_t *
 491 _xfs_buf_find(
 492         xfs_buftarg_t           *btp,   /* block device target          */
 493         xfs_off_t               ioff,   /* starting offset of range     */
 494         size_t                  isize,  /* length of range              */
 495         xfs_buf_flags_t         flags,
 496         xfs_buf_t               *new_bp)
 497 {
 498         xfs_off_t               range_base;
 499         size_t                  range_length;
 500         xfs_bufhash_t           *hash;
 501         xfs_buf_t               *bp, *n;
 502
 503         range_base = (ioff << BBSHIFT);
 504         range_length = (isize << BBSHIFT);
 505
 506         /* Check for IOs smaller than the sector size / not sector aligned */
 507         ASSERT(!(range_length < (1 << btp->bt_sshift)));
 508         ASSERT(!(range_base & (xfs_off_t)btp->bt_smask));
 509
 510         hash = &btp->bt_hash[hash_long((unsigned long)ioff, btp->bt_hashshift)];
 511
 512         spin_lock(&hash->bh_lock);
 513
 514         list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
 515                 ASSERT(btp == bp->b_target);
 516                 if (bp->b_file_offset == range_base &&
 517                     bp->b_buffer_length == range_length) {
 518                         /*
 519                          * If we look at something, bring it to the
 520                          * front of the list for next time.
 521                          */
 522                         atomic_inc(&bp->b_hold);
 523                         list_move(&bp->b_hash_list, &hash->bh_list);
 524                         goto found;
 525                 }
 526         }
 527
 528         /* No match found */
 529         if (new_bp) {
 530                 _xfs_buf_initialize(new_bp, btp, range_base,
 531                                 range_length, flags);
 532                 new_bp->b_hash = hash;
 533                 list_add(&new_bp->b_hash_list, &hash->bh_list);
 534         } else {
 535                 XFS_STATS_INC(xb_miss_locked);
 536         }
 537
 538         spin_unlock(&hash->bh_lock);
 539         return new_bp;
 540
 541 found:
 542         spin_unlock(&hash->bh_lock);
 543
 544         /* Attempt to get the semaphore without sleeping,
 545          * if this does not work then we need to drop the
 546          * spinlock and do a hard attempt on the semaphore.
 547          */
 548         if (down_trylock(&bp->b_sema)) {
 549                 if (!(flags & XBF_TRYLOCK)) {
 550                         /* wait for buffer ownership */
 551                         XB_TRACE(bp, "get_lock", 0);
 552                         xfs_buf_lock(bp);
 553                         XFS_STATS_INC(xb_get_locked_waited);
 554                 } else {
 555                         /* We asked for a trylock and failed, no need
 556                          * to look at file offset and length here, we
 557                          * know that this buffer at least overlaps our
 558                          * buffer and is locked, therefore our buffer
 559                          * either does not exist, or is this buffer.
 560                          */
 561                         xfs_buf_rele(bp);
 562                         XFS_STATS_INC(xb_busy_locked);
 563                         return NULL;
 564                 }
 565         } else {
 566                 /* trylock worked */
 567                 XB_SET_OWNER(bp);
 568         }
 569
 570         if (bp->b_flags & XBF_STALE) {
 571                 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
 572                 bp->b_flags &= XBF_MAPPED;
 573         }
 574         XB_TRACE(bp, "got_lock", 0);
 575         XFS_STATS_INC(xb_get_locked);
 576         return bp;
 577 }
 578
 579 /*
 580  *      Assembles a buffer covering the specified range.
 581  *      Storage in memory for all portions of the buffer will be allocated,
 582  *      although backing storage may not be.
 583  */
 584 xfs_buf_t *
 585 xfs_buf_get_flags(
 586         xfs_buftarg_t           *target,/* target for buffer            */
 587         xfs_off_t               ioff,   /* starting offset of range     */
 588         size_t                  isize,  /* length of range              */
 589         xfs_buf_flags_t         flags)
 590 {
 591         xfs_buf_t               *bp, *new_bp;
 592         int                     error = 0, i;
 593
 594         new_bp = xfs_buf_allocate(flags);
 595         if (unlikely(!new_bp))
 596                 return NULL;
 597
 598         bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
 599         if (bp == new_bp) {
 600                 error = _xfs_buf_lookup_pages(bp, flags);
 601                 if (error)
 602                         goto no_buffer;
 603         } else {
 604                 xfs_buf_deallocate(new_bp);
 605                 if (unlikely(bp == NULL))
 606                         return NULL;
 607         }
 608
 609         for (i = 0; i < bp->b_page_count; i++)
 610                 mark_page_accessed(bp->b_pages[i]);
 611
 612         if (!(bp->b_flags & XBF_MAPPED)) {
 613                 error = _xfs_buf_map_pages(bp, flags);
 614                 if (unlikely(error)) {
 615                         printk(KERN_WARNING "%s: failed to map pages\n",
 616                                         __func__);
 617                         goto no_buffer;
 618                 }
 619         }
 620
 621         XFS_STATS_INC(xb_get);
 622
 623         /*
 624          * Always fill in the block number now, the mapped cases can do
 625          * their own overlay of this later.
 626          */
 627         bp->b_bn = ioff;
 628         bp->b_count_desired = bp->b_buffer_length;
 629
 630         XB_TRACE(bp, "get", (unsigned long)flags);
 631         return bp;
 632
 633  no_buffer:
 634         if (flags & (XBF_LOCK | XBF_TRYLOCK))
 635                 xfs_buf_unlock(bp);
 636         xfs_buf_rele(bp);
 637         return NULL;
 638 }
 639
 640 STATIC int
 641 _xfs_buf_read(
 642         xfs_buf_t               *bp,
 643         xfs_buf_flags_t         flags)
 644 {
 645         int                     status;
 646
 647         XB_TRACE(bp, "_xfs_buf_read", (unsigned long)flags);
 648
 649         ASSERT(!(flags & (XBF_DELWRI|XBF_WRITE)));
 650         ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
 651
 652         bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_DELWRI | \
 653                         XBF_READ_AHEAD | _XBF_RUN_QUEUES);
 654         bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | \
 655                         XBF_READ_AHEAD | _XBF_RUN_QUEUES);
 656
 657         status = xfs_buf_iorequest(bp);
 658         if (!status && !(flags & XBF_ASYNC))
 659                 status = xfs_buf_iowait(bp);
 660         return status;
 661 }
 662
 663 xfs_buf_t *
 664 xfs_buf_read_flags(
 665         xfs_buftarg_t           *target,
 666         xfs_off_t               ioff,
 667         size_t                  isize,
 668         xfs_buf_flags_t         flags)
 669 {
 670         xfs_buf_t               *bp;
 671
 672         flags |= XBF_READ;
 673
 674         bp = xfs_buf_get_flags(target, ioff, isize, flags);
 675         if (bp) {
 676                 if (!XFS_BUF_ISDONE(bp)) {
 677                         XB_TRACE(bp, "read", (unsigned long)flags);
 678                         XFS_STATS_INC(xb_get_read);
 679                         _xfs_buf_read(bp, flags);
 680                 } else if (flags & XBF_ASYNC) {
 681                         XB_TRACE(bp, "read_async", (unsigned long)flags);
 682                         /*
 683                          * Read ahead call which is already satisfied,
 684                          * drop the buffer
 685                          */
 686                         goto no_buffer;
 687                 } else {
 688                         XB_TRACE(bp, "read_done", (unsigned long)flags);
 689                         /* We do not want read in the flags */
 690                         bp->b_flags &= ~XBF_READ;
 691                 }
 692         }
 693
 694         return bp;
 695
 696  no_buffer:
 697         if (flags & (XBF_LOCK | XBF_TRYLOCK))
 698                 xfs_buf_unlock(bp);
 699         xfs_buf_rele(bp);
 700         return NULL;
 701 }
 702
 703 /*
 704  *      If we are not low on memory then do the readahead in a deadlock
 705  *      safe manner.
 706  */
 707 void
 708 xfs_buf_readahead(
 709         xfs_buftarg_t           *target,
 710         xfs_off_t               ioff,
 711         size_t                  isize,
 712         xfs_buf_flags_t         flags)
 713 {
 714         struct backing_dev_info *bdi;
 715
 716         bdi = target->bt_mapping->backing_dev_info;
 717         if (bdi_read_congested(bdi))
 718                 return;
 719
 720         flags |= (XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD);
 721         xfs_buf_read_flags(target, ioff, isize, flags);
 722 }
 723
 724 xfs_buf_t *
 725 xfs_buf_get_empty(
 726         size_t                  len,
 727         xfs_buftarg_t           *target)
 728 {
 729         xfs_buf_t               *bp;
 730
 731         bp = xfs_buf_allocate(0);
 732         if (bp)
 733                 _xfs_buf_initialize(bp, target, 0, len, 0);
 734         return bp;
 735 }
 736
 737 static inline struct page *
 738 mem_to_page(
 739         void                    *addr)
 740 {
 741         if ((!is_vmalloc_addr(addr))) {
 742                 return virt_to_page(addr);
 743         } else {
 744                 return vmalloc_to_page(addr);
 745         }
 746 }
 747
 748 int
 749 xfs_buf_associate_memory(
 750         xfs_buf_t               *bp,
 751         void                    *mem,
 752         size_t                  len)
 753 {
 754         int                     rval;
 755         int                     i = 0;
 756         unsigned long           pageaddr;
 757         unsigned long           offset;
 758         size_t                  buflen;
 759         int                     page_count;
 760
 761         pageaddr = (unsigned long)mem & PAGE_CACHE_MASK;
 762         offset = (unsigned long)mem - pageaddr;
 763         buflen = PAGE_CACHE_ALIGN(len + offset);
 764         page_count = buflen >> PAGE_CACHE_SHIFT;
 765
 766         /* Free any previous set of page pointers */
 767         if (bp->b_pages)
 768                 _xfs_buf_free_pages(bp);
 769
 770         bp->b_pages = NULL;
 771         bp->b_addr = mem;
 772
 773         rval = _xfs_buf_get_pages(bp, page_count, 0);
 774         if (rval)
 775                 return rval;
 776
 777         bp->b_offset = offset;
 778
 779         for (i = 0; i < bp->b_page_count; i++) {
 780                 bp->b_pages[i] = mem_to_page((void *)pageaddr);
 781                 pageaddr += PAGE_CACHE_SIZE;
 782         }
 783
 784         bp->b_count_desired = len;
 785         bp->b_buffer_length = buflen;
 786         bp->b_flags |= XBF_MAPPED;
 787         bp->b_flags &= ~_XBF_PAGE_LOCKED;
 788
 789         return 0;
 790 }
 791
 792 xfs_buf_t *
 793 xfs_buf_get_noaddr(
 794         size_t                  len,
 795         xfs_buftarg_t           *target)
 796 {
 797         unsigned long           page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
 798         int                     error, i;
 799         xfs_buf_t               *bp;
 800
 801         bp = xfs_buf_allocate(0);
 802         if (unlikely(bp == NULL))
 803                 goto fail;
 804         _xfs_buf_initialize(bp, target, 0, len, 0);
 805
 806         error = _xfs_buf_get_pages(bp, page_count, 0);
 807         if (error)
 808                 goto fail_free_buf;
 809
 810         for (i = 0; i < page_count; i++) {
 811                 bp->b_pages[i] = alloc_page(GFP_KERNEL);
 812                 if (!bp->b_pages[i])
 813                         goto fail_free_mem;
 814         }
 815         bp->b_flags |= _XBF_PAGES;
 816
 817         error = _xfs_buf_map_pages(bp, XBF_MAPPED);
 818         if (unlikely(error)) {
 819                 printk(KERN_WARNING "%s: failed to map pages\n",
 820                                 __func__);
 821                 goto fail_free_mem;
 822         }
 823
 824         xfs_buf_unlock(bp);
 825
 826         XB_TRACE(bp, "no_daddr", len);
 827         return bp;
 828
 829  fail_free_mem:
 830         while (--i >= 0)
 831                 __free_page(bp->b_pages[i]);
 832         _xfs_buf_free_pages(bp);
 833  fail_free_buf:
 834         xfs_buf_deallocate(bp);
 835  fail:
 836         return NULL;
 837 }
 838
 839 /*
 840  *      Increment reference count on buffer, to hold the buffer concurrently
 841  *      with another thread which may release (free) the buffer asynchronously.
 842  *      Must hold the buffer already to call this function.
 843  */
 844 void
 845 xfs_buf_hold(
 846         xfs_buf_t               *bp)
 847 {
 848         atomic_inc(&bp->b_hold);
 849         XB_TRACE(bp, "hold", 0);
 850 }
 851
 852 /*
 853  *      Releases a hold on the specified buffer.  If the
 854  *      the hold count is 1, calls xfs_buf_free.
 855  */
 856 void
 857 xfs_buf_rele(
 858         xfs_buf_t               *bp)
 859 {
 860         xfs_bufhash_t           *hash = bp->b_hash;
 861
 862         XB_TRACE(bp, "rele", bp->b_relse);
 863
 864         if (unlikely(!hash)) {
 865                 ASSERT(!bp->b_relse);
 866                 if (atomic_dec_and_test(&bp->b_hold))
 867                         xfs_buf_free(bp);
 868                 return;
 869         }
 870
 871         ASSERT(atomic_read(&bp->b_hold) > 0);
 872         if (atomic_dec_and_lock(&bp->b_hold, &hash->bh_lock)) {
 873                 if (bp->b_relse) {
 874                         atomic_inc(&bp->b_hold);
 875                         spin_unlock(&hash->bh_lock);
 876                         (*(bp->b_relse)) (bp);
 877                 } else if (bp->b_flags & XBF_FS_MANAGED) {
 878                         spin_unlock(&hash->bh_lock);
 879                 } else {
 880                         ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
 881                         list_del_init(&bp->b_hash_list);
 882                         spin_unlock(&hash->bh_lock);
 883                         xfs_buf_free(bp);
 884                 }
 885         }
 886 }
 887
 888
 889 /*
 890  *      Mutual exclusion on buffers.  Locking model:
 891  *
 892  *      Buffers associated with inodes for which buffer locking
 893  *      is not enabled are not protected by semaphores, and are
 894  *      assumed to be exclusively owned by the caller.  There is a
 895  *      spinlock in the buffer, used by the caller when concurrent
 896  *      access is possible.
 897  */
 898
 899 /*
 900  *      Locks a buffer object, if it is not already locked.
 901  *      Note that this in no way locks the underlying pages, so it is only
 902  *      useful for synchronizing concurrent use of buffer objects, not for
 903  *      synchronizing independent access to the underlying pages.
 904  */
 905 int
 906 xfs_buf_cond_lock(
 907         xfs_buf_t               *bp)
 908 {
 909         int                     locked;
 910
 911         locked = down_trylock(&bp->b_sema) == 0;
 912         if (locked) {
 913                 XB_SET_OWNER(bp);
 914         }
 915         XB_TRACE(bp, "cond_lock", (long)locked);
 916         return locked ? 0 : -EBUSY;
 917 }
 918
 919 #if defined(DEBUG) || defined(XFS_BLI_TRACE)
 920 int
 921 xfs_buf_lock_value(
 922         xfs_buf_t               *bp)
 923 {
 924         return bp->b_sema.count;
 925 }
 926 #endif
 927
 928 /*
 929  *      Locks a buffer object.
 930  *      Note that this in no way locks the underlying pages, so it is only
 931  *      useful for synchronizing concurrent use of buffer objects, not for
 932  *      synchronizing independent access to the underlying pages.
 933  */
 934 void
 935 xfs_buf_lock(
 936         xfs_buf_t               *bp)
 937 {
 938         XB_TRACE(bp, "lock", 0);
 939         if (atomic_read(&bp->b_io_remaining))
 940                 blk_run_address_space(bp->b_target->bt_mapping);
 941         down(&bp->b_sema);
 942         XB_SET_OWNER(bp);
 943         XB_TRACE(bp, "locked", 0);
 944 }
 945
 946 /*
 947  *      Releases the lock on the buffer object.
 948  *      If the buffer is marked delwri but is not queued, do so before we
 949  *      unlock the buffer as we need to set flags correctly.  We also need to
 950  *      take a reference for the delwri queue because the unlocker is going to
 951  *      drop their's and they don't know we just queued it.
 952  */
 953 void
 954 xfs_buf_unlock(
 955         xfs_buf_t               *bp)
 956 {
 957         if ((bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)) == XBF_DELWRI) {
 958                 atomic_inc(&bp->b_hold);
 959                 bp->b_flags |= XBF_ASYNC;
 960                 xfs_buf_delwri_queue(bp, 0);
 961         }
 962
 963         XB_CLEAR_OWNER(bp);
 964         up(&bp->b_sema);
 965         XB_TRACE(bp, "unlock", 0);
 966 }
 967
 968
 969 /*
 970  *      Pinning Buffer Storage in Memory
 971  *      Ensure that no attempt to force a buffer to disk will succeed.
 972  */
 973 void
 974 xfs_buf_pin(
 975         xfs_buf_t               *bp)
 976 {
 977         atomic_inc(&bp->b_pin_count);
 978         XB_TRACE(bp, "pin", (long)bp->b_pin_count.counter);
 979 }
 980
 981 void
 982 xfs_buf_unpin(
 983         xfs_buf_t               *bp)
 984 {
 985         if (atomic_dec_and_test(&bp->b_pin_count))
 986                 wake_up_all(&bp->b_waiters);
 987         XB_TRACE(bp, "unpin", (long)bp->b_pin_count.counter);
 988 }
 989
 990 int
 991 xfs_buf_ispin(
 992         xfs_buf_t               *bp)
 993 {
 994         return atomic_read(&bp->b_pin_count);
 995 }
 996
 997 STATIC void
 998 xfs_buf_wait_unpin(
 999         xfs_buf_t               *bp)
1000 {
1001         DECLARE_WAITQUEUE       (wait, current);
1002
1003         if (atomic_read(&bp->b_pin_count) == 0)
1004                 return;
1005
1006         add_wait_queue(&bp->b_waiters, &wait);
1007         for (;;) {
1008                 set_current_state(TASK_UNINTERRUPTIBLE);
1009                 if (atomic_read(&bp->b_pin_count) == 0)
1010                         break;
1011                 if (atomic_read(&bp->b_io_remaining))
1012                         blk_run_address_space(bp->b_target->bt_mapping);
1013                 schedule();
1014         }
1015         remove_wait_queue(&bp->b_waiters, &wait);
1016         set_current_state(TASK_RUNNING);
1017 }
1018
1019 /*
1020  *      Buffer Utility Routines
1021  */
1022
1023 STATIC void
1024 xfs_buf_iodone_work(
1025         struct work_struct      *work)
1026 {
1027         xfs_buf_t               *bp =
1028                 container_of(work, xfs_buf_t, b_iodone_work);
1029
1030         /*
1031          * We can get an EOPNOTSUPP to ordered writes.  Here we clear the
1032          * ordered flag and reissue them.  Because we can't tell the higher
1033          * layers directly that they should not issue ordered I/O anymore, they
1034          * need to check if the _XFS_BARRIER_FAILED flag was set during I/O completion.
1035          */
1036         if ((bp->b_error == EOPNOTSUPP) &&
1037             (bp->b_flags & (XBF_ORDERED|XBF_ASYNC)) == (XBF_ORDERED|XBF_ASYNC)) {
1038                 XB_TRACE(bp, "ordered_retry", bp->b_iodone);
1039                 bp->b_flags &= ~XBF_ORDERED;
1040                 bp->b_flags |= _XFS_BARRIER_FAILED;
1041                 xfs_buf_iorequest(bp);
1042         } else if (bp->b_iodone)
1043                 (*(bp->b_iodone))(bp);
1044         else if (bp->b_flags & XBF_ASYNC)
1045                 xfs_buf_relse(bp);
1046 }
1047
1048 void
1049 xfs_buf_ioend(
1050         xfs_buf_t               *bp,
1051         int                     schedule)
1052 {
1053         bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
1054         if (bp->b_error == 0)
1055                 bp->b_flags |= XBF_DONE;
1056
1057         XB_TRACE(bp, "iodone", bp->b_iodone);
1058
1059         if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
1060                 if (schedule) {
1061                         INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
1062                         queue_work(xfslogd_workqueue, &bp->b_iodone_work);
1063                 } else {
1064                         xfs_buf_iodone_work(&bp->b_iodone_work);
1065                 }
1066         } else {
1067                 complete(&bp->b_iowait);
1068         }
1069 }
1070
1071 void
1072 xfs_buf_ioerror(
1073         xfs_buf_t               *bp,
1074         int                     error)
1075 {
1076         ASSERT(error >= 0 && error <= 0xffff);
1077         bp->b_error = (unsigned short)error;
1078         XB_TRACE(bp, "ioerror", (unsigned long)error);
1079 }
1080
1081 int
1082 xfs_bawrite(
1083         void                    *mp,
1084         struct xfs_buf          *bp)
1085 {
1086         XB_TRACE(bp, "bawrite", 0);
1087
1088         ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
1089
1090         xfs_buf_delwri_dequeue(bp);
1091
1092         bp->b_flags &= ~(XBF_READ | XBF_DELWRI | XBF_READ_AHEAD);
1093         bp->b_flags |= (XBF_WRITE | XBF_ASYNC | _XBF_RUN_QUEUES);
1094
1095         bp->b_mount = mp;
1096         bp->b_strat = xfs_bdstrat_cb;
1097         return xfs_bdstrat_cb(bp);
1098 }
1099
1100 void
1101 xfs_bdwrite(
1102         void                    *mp,
1103         struct xfs_buf          *bp)
1104 {
1105         XB_TRACE(bp, "bdwrite", 0);
1106
1107         bp->b_strat = xfs_bdstrat_cb;
1108         bp->b_mount = mp;
1109
1110         bp->b_flags &= ~XBF_READ;
1111         bp->b_flags |= (XBF_DELWRI | XBF_ASYNC);
1112
1113         xfs_buf_delwri_queue(bp, 1);
1114 }
1115
1116 STATIC_INLINE void
1117 _xfs_buf_ioend(
1118         xfs_buf_t               *bp,
1119         int                     schedule)
1120 {
1121         if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1122                 bp->b_flags &= ~_XBF_PAGE_LOCKED;
1123                 xfs_buf_ioend(bp, schedule);
1124         }
1125 }
1126
1127 STATIC void
1128 xfs_buf_bio_end_io(
1129         struct bio              *bio,
1130         int                     error)
1131 {
1132         xfs_buf_t               *bp = (xfs_buf_t *)bio->bi_private;
1133         unsigned int            blocksize = bp->b_target->bt_bsize;
1134         struct bio_vec          *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1135
1136         xfs_buf_ioerror(bp, -error);
1137
1138         do {
1139                 struct page     *page = bvec->bv_page;
1140
1141                 ASSERT(!PagePrivate(page));
1142                 if (unlikely(bp->b_error)) {
1143                         if (bp->b_flags & XBF_READ)
1144                                 ClearPageUptodate(page);
1145                 } else if (blocksize >= PAGE_CACHE_SIZE) {
1146                         SetPageUptodate(page);
1147                 } else if (!PagePrivate(page) &&
1148                                 (bp->b_flags & _XBF_PAGE_CACHE)) {
1149                         set_page_region(page, bvec->bv_offset, bvec->bv_len);
1150                 }
1151
1152                 if (--bvec >= bio->bi_io_vec)
1153                         prefetchw(&bvec->bv_page->flags);
1154
1155                 if (bp->b_flags & _XBF_PAGE_LOCKED)
1156                         unlock_page(page);
1157         } while (bvec >= bio->bi_io_vec);
1158
1159         _xfs_buf_ioend(bp, 1);
1160         bio_put(bio);
1161 }
1162
1163 STATIC void
1164 _xfs_buf_ioapply(
1165         xfs_buf_t               *bp)
1166 {
1167         int                     rw, map_i, total_nr_pages, nr_pages;
1168         struct bio              *bio;
1169         int                     offset = bp->b_offset;
1170         int                     size = bp->b_count_desired;
1171         sector_t                sector = bp->b_bn;
1172         unsigned int            blocksize = bp->b_target->bt_bsize;
1173
1174         total_nr_pages = bp->b_page_count;
1175         map_i = 0;
1176
1177         if (bp->b_flags & XBF_ORDERED) {
1178                 ASSERT(!(bp->b_flags & XBF_READ));
1179                 rw = WRITE_BARRIER;
1180         } else if (bp->b_flags & _XBF_RUN_QUEUES) {
1181                 ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
1182                 bp->b_flags &= ~_XBF_RUN_QUEUES;
1183                 rw = (bp->b_flags & XBF_WRITE) ? WRITE_SYNC : READ_SYNC;
1184         } else {
1185                 rw = (bp->b_flags & XBF_WRITE) ? WRITE :
1186                      (bp->b_flags & XBF_READ_AHEAD) ? READA : READ;
1187         }
1188
1189         /* Special code path for reading a sub page size buffer in --
1190          * we populate up the whole page, and hence the other metadata
1191          * in the same page.  This optimization is only valid when the
1192          * filesystem block size is not smaller than the page size.
1193          */
1194         if ((bp->b_buffer_length < PAGE_CACHE_SIZE) &&
1195             ((bp->b_flags & (XBF_READ|_XBF_PAGE_LOCKED)) ==
1196               (XBF_READ|_XBF_PAGE_LOCKED)) &&
1197             (blocksize >= PAGE_CACHE_SIZE)) {
1198                 bio = bio_alloc(GFP_NOIO, 1);
1199
1200                 bio->bi_bdev = bp->b_target->bt_bdev;
1201                 bio->bi_sector = sector - (offset >> BBSHIFT);
1202                 bio->bi_end_io = xfs_buf_bio_end_io;
1203                 bio->bi_private = bp;
1204
1205                 bio_add_page(bio, bp->b_pages[0], PAGE_CACHE_SIZE, 0);
1206                 size = 0;
1207
1208                 atomic_inc(&bp->b_io_remaining);
1209
1210                 goto submit_io;
1211         }
1212
1213 next_chunk:
1214         atomic_inc(&bp->b_io_remaining);
1215         nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1216         if (nr_pages > total_nr_pages)
1217                 nr_pages = total_nr_pages;
1218
1219         bio = bio_alloc(GFP_NOIO, nr_pages);
1220         bio->bi_bdev = bp->b_target->bt_bdev;
1221         bio->bi_sector = sector;
1222         bio->bi_end_io = xfs_buf_bio_end_io;
1223         bio->bi_private = bp;
1224
1225         for (; size && nr_pages; nr_pages--, map_i++) {
1226                 int     rbytes, nbytes = PAGE_CACHE_SIZE - offset;
1227
1228                 if (nbytes > size)
1229                         nbytes = size;
1230
1231                 rbytes = bio_add_page(bio, bp->b_pages[map_i], nbytes, offset);
1232                 if (rbytes < nbytes)
1233                         break;
1234
1235                 offset = 0;
1236                 sector += nbytes >> BBSHIFT;
1237                 size -= nbytes;
1238                 total_nr_pages--;
1239         }
1240
1241 submit_io:
1242         if (likely(bio->bi_size)) {
1243                 submit_bio(rw, bio);
1244                 if (size)
1245                         goto next_chunk;
1246         } else {
1247                 bio_put(bio);
1248                 xfs_buf_ioerror(bp, EIO);
1249         }
1250 }
1251
1252 int
1253 xfs_buf_iorequest(
1254         xfs_buf_t               *bp)
1255 {
1256         XB_TRACE(bp, "iorequest", 0);
1257
1258         if (bp->b_flags & XBF_DELWRI) {
1259                 xfs_buf_delwri_queue(bp, 1);
1260                 return 0;
1261         }
1262
1263         if (bp->b_flags & XBF_WRITE) {
1264                 xfs_buf_wait_unpin(bp);
1265         }
1266
1267         xfs_buf_hold(bp);
1268
1269         /* Set the count to 1 initially, this will stop an I/O
1270          * completion callout which happens before we have started
1271          * all the I/O from calling xfs_buf_ioend too early.
1272          */
1273         atomic_set(&bp->b_io_remaining, 1);
1274         _xfs_buf_ioapply(bp);
1275         _xfs_buf_ioend(bp, 0);
1276
1277         xfs_buf_rele(bp);
1278         return 0;
1279 }
1280
1281 /*
1282  *      Waits for I/O to complete on the buffer supplied.
1283  *      It returns immediately if no I/O is pending.
1284  *      It returns the I/O error code, if any, or 0 if there was no error.
1285  */
1286 int
1287 xfs_buf_iowait(
1288         xfs_buf_t               *bp)
1289 {
1290         XB_TRACE(bp, "iowait", 0);
1291         if (atomic_read(&bp->b_io_remaining))
1292                 blk_run_address_space(bp->b_target->bt_mapping);
1293         wait_for_completion(&bp->b_iowait);
1294         XB_TRACE(bp, "iowaited", (long)bp->b_error);
1295         return bp->b_error;
1296 }
1297
1298 xfs_caddr_t
1299 xfs_buf_offset(
1300         xfs_buf_t               *bp,
1301         size_t                  offset)
1302 {
1303         struct page             *page;
1304
1305         if (bp->b_flags & XBF_MAPPED)
1306                 return XFS_BUF_PTR(bp) + offset;
1307
1308         offset += bp->b_offset;
1309         page = bp->b_pages[offset >> PAGE_CACHE_SHIFT];
1310         return (xfs_caddr_t)page_address(page) + (offset & (PAGE_CACHE_SIZE-1));
1311 }
1312
1313 /*
1314  *      Move data into or out of a buffer.
1315  */
1316 void
1317 xfs_buf_iomove(
1318         xfs_buf_t               *bp,    /* buffer to process            */
1319         size_t                  boff,   /* starting buffer offset       */
1320         size_t                  bsize,  /* length to copy               */
1321         caddr_t                 data,   /* data address                 */
1322         xfs_buf_rw_t            mode)   /* read/write/zero flag         */
1323 {
1324         size_t                  bend, cpoff, csize;
1325         struct page             *page;
1326
1327         bend = boff + bsize;
1328         while (boff < bend) {
1329                 page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
1330                 cpoff = xfs_buf_poff(boff + bp->b_offset);
1331                 csize = min_t(size_t,
1332                               PAGE_CACHE_SIZE-cpoff, bp->b_count_desired-boff);
1333
1334                 ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE));
1335
1336                 switch (mode) {
1337                 case XBRW_ZERO:
1338                         memset(page_address(page) + cpoff, 0, csize);
1339                         break;
1340                 case XBRW_READ:
1341                         memcpy(data, page_address(page) + cpoff, csize);
1342                         break;
1343                 case XBRW_WRITE:
1344                         memcpy(page_address(page) + cpoff, data, csize);
1345                 }
1346
1347                 boff += csize;
1348                 data += csize;
1349         }
1350 }
1351
1352 /*
1353  *      Handling of buffer targets (buftargs).
1354  */
1355
1356 /*
1357  *      Wait for any bufs with callbacks that have been submitted but
1358  *      have not yet returned... walk the hash list for the target.
1359  */
1360 void
1361 xfs_wait_buftarg(
1362         xfs_buftarg_t   *btp)
1363 {
1364         xfs_buf_t       *bp, *n;
1365         xfs_bufhash_t   *hash;
1366         uint            i;
1367
1368         for (i = 0; i < (1 << btp->bt_hashshift); i++) {
1369                 hash = &btp->bt_hash[i];
1370 again:
1371                 spin_lock(&hash->bh_lock);
1372                 list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
1373                         ASSERT(btp == bp->b_target);
1374                         if (!(bp->b_flags & XBF_FS_MANAGED)) {
1375                                 spin_unlock(&hash->bh_lock);
1376                                 /*
1377                                  * Catch superblock reference count leaks
1378                                  * immediately
1379                                  */
1380                                 BUG_ON(bp->b_bn == 0);
1381                                 delay(100);
1382                                 goto again;
1383                         }
1384                 }
1385                 spin_unlock(&hash->bh_lock);
1386         }
1387 }
1388
1389 /*
1390  *      Allocate buffer hash table for a given target.
1391  *      For devices containing metadata (i.e. not the log/realtime devices)
1392  *      we need to allocate a much larger hash table.
1393  */
1394 STATIC void
1395 xfs_alloc_bufhash(
1396         xfs_buftarg_t           *btp,
1397         int                     external)
1398 {
1399         unsigned int            i;
1400
1401         btp->bt_hashshift = external ? 3 : 8;   /* 8 or 256 buckets */
1402         btp->bt_hashmask = (1 << btp->bt_hashshift) - 1;
1403         btp->bt_hash = kmem_zalloc((1 << btp->bt_hashshift) *
1404                                         sizeof(xfs_bufhash_t), KM_SLEEP | KM_LARGE);
1405         for (i = 0; i < (1 << btp->bt_hashshift); i++) {
1406                 spin_lock_init(&btp->bt_hash[i].bh_lock);
1407                 INIT_LIST_HEAD(&btp->bt_hash[i].bh_list);
1408         }
1409 }
1410
1411 STATIC void
1412 xfs_free_bufhash(
1413         xfs_buftarg_t           *btp)
1414 {
1415         kmem_free(btp->bt_hash);
1416         btp->bt_hash = NULL;
1417 }
1418
1419 /*
1420  *      buftarg list for delwrite queue processing
1421  */
1422 static LIST_HEAD(xfs_buftarg_list);
1423 static DEFINE_SPINLOCK(xfs_buftarg_lock);
1424
1425 STATIC void
1426 xfs_register_buftarg(
1427         xfs_buftarg_t           *btp)
1428 {
1429         spin_lock(&xfs_buftarg_lock);
1430         list_add(&btp->bt_list, &xfs_buftarg_list);
1431         spin_unlock(&xfs_buftarg_lock);
1432 }
1433
1434 STATIC void
1435 xfs_unregister_buftarg(
1436         xfs_buftarg_t           *btp)
1437 {
1438         spin_lock(&xfs_buftarg_lock);
1439         list_del(&btp->bt_list);
1440         spin_unlock(&xfs_buftarg_lock);
1441 }
1442
1443 void
1444 xfs_free_buftarg(
1445         struct xfs_mount        *mp,
1446         struct xfs_buftarg      *btp)
1447 {
1448         xfs_flush_buftarg(btp, 1);
1449         if (mp->m_flags & XFS_MOUNT_BARRIER)
1450                 xfs_blkdev_issue_flush(btp);
1451         xfs_free_bufhash(btp);
1452         iput(btp->bt_mapping->host);
1453
1454         /* Unregister the buftarg first so that we don't get a
1455          * wakeup finding a non-existent task
1456          */
1457         xfs_unregister_buftarg(btp);
1458         kthread_stop(btp->bt_task);
1459
1460         kmem_free(btp);
1461 }
1462
1463 STATIC int
1464 xfs_setsize_buftarg_flags(
1465         xfs_buftarg_t           *btp,
1466         unsigned int            blocksize,
1467         unsigned int            sectorsize,
1468         int                     verbose)
1469 {
1470         btp->bt_bsize = blocksize;
1471         btp->bt_sshift = ffs(sectorsize) - 1;
1472         btp->bt_smask = sectorsize - 1;
1473
1474         if (set_blocksize(btp->bt_bdev, sectorsize)) {
1475                 printk(KERN_WARNING
1476                         "XFS: Cannot set_blocksize to %u on device %s\n",
1477                         sectorsize, XFS_BUFTARG_NAME(btp));
1478                 return EINVAL;
1479         }
1480
1481         if (verbose &&
1482             (PAGE_CACHE_SIZE / BITS_PER_LONG) > sectorsize) {
1483                 printk(KERN_WARNING
1484                         "XFS: %u byte sectors in use on device %s.  "
1485                         "This is suboptimal; %u or greater is ideal.\n",
1486                         sectorsize, XFS_BUFTARG_NAME(btp),
1487                         (unsigned int)PAGE_CACHE_SIZE / BITS_PER_LONG);
1488         }
1489
1490         return 0;
1491 }
1492
1493 /*
1494  *      When allocating the initial buffer target we have not yet
1495  *      read in the superblock, so don't know what sized sectors
1496  *      are being used is at this early stage.  Play safe.
1497  */
1498 STATIC int
1499 xfs_setsize_buftarg_early(
1500         xfs_buftarg_t           *btp,
1501         struct block_device     *bdev)
1502 {
1503         return xfs_setsize_buftarg_flags(btp,
1504                         PAGE_CACHE_SIZE, bdev_hardsect_size(bdev), 0);
1505 }
1506
1507 int
1508 xfs_setsize_buftarg(
1509         xfs_buftarg_t           *btp,
1510         unsigned int            blocksize,
1511         unsigned int            sectorsize)
1512 {
1513         return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
1514 }
1515
1516 STATIC int
1517 xfs_mapping_buftarg(
1518         xfs_buftarg_t           *btp,
1519         struct block_device     *bdev)
1520 {
1521         struct backing_dev_info *bdi;
1522         struct inode            *inode;
1523         struct address_space    *mapping;
1524         static const struct address_space_operations mapping_aops = {
1525                 .sync_page = block_sync_page,
1526                 .migratepage = fail_migrate_page,
1527         };
1528
1529         inode = new_inode(bdev->bd_inode->i_sb);
1530         if (!inode) {
1531                 printk(KERN_WARNING
1532                         "XFS: Cannot allocate mapping inode for device %s\n",
1533                         XFS_BUFTARG_NAME(btp));
1534                 return ENOMEM;
1535         }
1536         inode->i_mode = S_IFBLK;
1537         inode->i_bdev = bdev;
1538         inode->i_rdev = bdev->bd_dev;
1539         bdi = blk_get_backing_dev_info(bdev);
1540         if (!bdi)
1541                 bdi = &default_backing_dev_info;
1542         mapping = &inode->i_data;
1543         mapping->a_ops = &mapping_aops;
1544         mapping->backing_dev_info = bdi;
1545         mapping_set_gfp_mask(mapping, GFP_NOFS);
1546         btp->bt_mapping = mapping;
1547         return 0;
1548 }
1549
1550 STATIC int
1551 xfs_alloc_delwrite_queue(
1552         xfs_buftarg_t           *btp)
1553 {
1554         int     error = 0;
1555
1556         INIT_LIST_HEAD(&btp->bt_list);
1557         INIT_LIST_HEAD(&btp->bt_delwrite_queue);
1558         spin_lock_init(&btp->bt_delwrite_lock);
1559         btp->bt_flags = 0;
1560         btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd");
1561         if (IS_ERR(btp->bt_task)) {
1562                 error = PTR_ERR(btp->bt_task);
1563                 goto out_error;
1564         }
1565         xfs_register_buftarg(btp);
1566 out_error:
1567         return error;
1568 }
1569
1570 xfs_buftarg_t *
1571 xfs_alloc_buftarg(
1572         struct block_device     *bdev,
1573         int                     external)
1574 {
1575         xfs_buftarg_t           *btp;
1576
1577         btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
1578
1579         btp->bt_dev =  bdev->bd_dev;
1580         btp->bt_bdev = bdev;
1581         if (xfs_setsize_buftarg_early(btp, bdev))
1582                 goto error;
1583         if (xfs_mapping_buftarg(btp, bdev))
1584                 goto error;
1585         if (xfs_alloc_delwrite_queue(btp))
1586                 goto error;
1587         xfs_alloc_bufhash(btp, external);
1588         return btp;
1589
1590 error:
1591         kmem_free(btp);
1592         return NULL;
1593 }
1594
1595
1596 /*
1597  *      Delayed write buffer handling
1598  */
1599 STATIC void
1600 xfs_buf_delwri_queue(
1601         xfs_buf_t               *bp,
1602         int                     unlock)
1603 {
1604         struct list_head        *dwq = &bp->b_target->bt_delwrite_queue;
1605         spinlock_t              *dwlk = &bp->b_target->bt_delwrite_lock;
1606
1607         XB_TRACE(bp, "delwri_q", (long)unlock);
1608         ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));
1609
1610         spin_lock(dwlk);
1611         /* If already in the queue, dequeue and place at tail */
1612         if (!list_empty(&bp->b_list)) {
1613                 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1614                 if (unlock)
1615                         atomic_dec(&bp->b_hold);
1616                 list_del(&bp->b_list);
1617         }
1618
1619         bp->b_flags |= _XBF_DELWRI_Q;
1620         list_add_tail(&bp->b_list, dwq);
1621         bp->b_queuetime = jiffies;
1622         spin_unlock(dwlk);
1623
1624         if (unlock)
1625                 xfs_buf_unlock(bp);
1626 }
1627
1628 void
1629 xfs_buf_delwri_dequeue(
1630         xfs_buf_t               *bp)
1631 {
1632         spinlock_t              *dwlk = &bp->b_target->bt_delwrite_lock;
1633         int                     dequeued = 0;
1634
1635         spin_lock(dwlk);
1636         if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
1637                 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1638                 list_del_init(&bp->b_list);
1639                 dequeued = 1;
1640         }
1641         bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
1642         spin_unlock(dwlk);
1643
1644         if (dequeued)
1645                 xfs_buf_rele(bp);
1646
1647         XB_TRACE(bp, "delwri_dq", (long)dequeued);
1648 }
1649
1650 STATIC void
1651 xfs_buf_runall_queues(
1652         struct workqueue_struct *queue)
1653 {
1654         flush_workqueue(queue);
1655 }
1656
1657 STATIC int
1658 xfsbufd_wakeup(
1659         int                     priority,
1660         gfp_t                   mask)
1661 {
1662         xfs_buftarg_t           *btp;
1663
1664         spin_lock(&xfs_buftarg_lock);
1665         list_for_each_entry(btp, &xfs_buftarg_list, bt_list) {
1666                 if (test_bit(XBT_FORCE_SLEEP, &btp->bt_flags))
1667                         continue;
1668                 set_bit(XBT_FORCE_FLUSH, &btp->bt_flags);
1669                 wake_up_process(btp->bt_task);
1670         }
1671         spin_unlock(&xfs_buftarg_lock);
1672         return 0;
1673 }
1674
1675 /*
1676  * Move as many buffers as specified to the supplied list
1677  * idicating if we skipped any buffers to prevent deadlocks.
1678  */
1679 STATIC int
1680 xfs_buf_delwri_split(
1681         xfs_buftarg_t   *target,
1682         struct list_head *list,
1683         unsigned long   age)
1684 {
1685         xfs_buf_t       *bp, *n;
1686         struct list_head *dwq = &target->bt_delwrite_queue;
1687         spinlock_t      *dwlk = &target->bt_delwrite_lock;
1688         int             skipped = 0;
1689         int             force;
1690
1691         force = test_and_clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1692         INIT_LIST_HEAD(list);
1693         spin_lock(dwlk);
1694         list_for_each_entry_safe(bp, n, dwq, b_list) {
1695                 XB_TRACE(bp, "walkq1", (long)xfs_buf_ispin(bp));
1696                 ASSERT(bp->b_flags & XBF_DELWRI);
1697
1698                 if (!xfs_buf_ispin(bp) && !xfs_buf_cond_lock(bp)) {
1699                         if (!force &&
1700                             time_before(jiffies, bp->b_queuetime + age)) {
1701                                 xfs_buf_unlock(bp);
1702                                 break;
1703                         }
1704
1705                         bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q|
1706                                          _XBF_RUN_QUEUES);
1707                         bp->b_flags |= XBF_WRITE;
1708                         list_move_tail(&bp->b_list, list);
1709                 } else
1710                         skipped++;
1711         }
1712         spin_unlock(dwlk);
1713
1714         return skipped;
1715
1716 }
1717
1718 STATIC int
1719 xfsbufd(
1720         void            *data)
1721 {
1722         struct list_head tmp;
1723         xfs_buftarg_t   *target = (xfs_buftarg_t *)data;
1724         int             count;
1725         xfs_buf_t       *bp;
1726
1727         current->flags |= PF_MEMALLOC;
1728
1729         set_freezable();
1730
1731         do {
1732                 if (unlikely(freezing(current))) {
1733                         set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1734                         refrigerator();
1735                 } else {
1736                         clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1737                 }
1738
1739                 schedule_timeout_interruptible(
1740                         xfs_buf_timer_centisecs * msecs_to_jiffies(10));
1741
1742                 xfs_buf_delwri_split(target, &tmp,
1743                                 xfs_buf_age_centisecs * msecs_to_jiffies(10));
1744
1745                 count = 0;
1746                 while (!list_empty(&tmp)) {
1747                         bp = list_entry(tmp.next, xfs_buf_t, b_list);
1748                         ASSERT(target == bp->b_target);
1749
1750                         list_del_init(&bp->b_list);
1751                         xfs_buf_iostrategy(bp);
1752                         count++;
1753                 }
1754
1755                 if (as_list_len > 0)
1756                         purge_addresses();
1757                 if (count)
1758                         blk_run_address_space(target->bt_mapping);
1759
1760         } while (!kthread_should_stop());
1761
1762         return 0;
1763 }
1764
1765 /*
1766  *      Go through all incore buffers, and release buffers if they belong to
1767  *      the given device. This is used in filesystem error handling to
1768  *      preserve the consistency of its metadata.
1769  */
1770 int
1771 xfs_flush_buftarg(
1772         xfs_buftarg_t   *target,
1773         int             wait)
1774 {
1775         struct list_head tmp;
1776         xfs_buf_t       *bp, *n;
1777         int             pincount = 0;
1778
1779         xfs_buf_runall_queues(xfsconvertd_workqueue);
1780         xfs_buf_runall_queues(xfsdatad_workqueue);
1781         xfs_buf_runall_queues(xfslogd_workqueue);
1782
1783         set_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1784         pincount = xfs_buf_delwri_split(target, &tmp, 0);
1785
1786         /*
1787          * Dropped the delayed write list lock, now walk the temporary list
1788          */
1789         list_for_each_entry_safe(bp, n, &tmp, b_list) {
1790                 ASSERT(target == bp->b_target);
1791                 if (wait)
1792                         bp->b_flags &= ~XBF_ASYNC;
1793                 else
1794                         list_del_init(&bp->b_list);
1795
1796                 xfs_buf_iostrategy(bp);
1797         }
1798
1799         if (wait)
1800                 blk_run_address_space(target->bt_mapping);
1801
1802         /*
1803          * Remaining list items must be flushed before returning
1804          */
1805         while (!list_empty(&tmp)) {
1806                 bp = list_entry(tmp.next, xfs_buf_t, b_list);
1807
1808                 list_del_init(&bp->b_list);
1809                 xfs_iowait(bp);
1810                 xfs_buf_relse(bp);
1811         }
1812
1813         return pincount;
1814 }
1815
1816 int __init
1817 xfs_buf_init(void)
1818 {
1819 #ifdef XFS_BUF_TRACE
1820         xfs_buf_trace_buf = ktrace_alloc(XFS_BUF_TRACE_SIZE, KM_NOFS);
1821 #endif
1822
1823         xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
1824                                                 KM_ZONE_HWALIGN, NULL);
1825         if (!xfs_buf_zone)
1826                 goto out_free_trace_buf;
1827
1828         xfslogd_workqueue = create_workqueue("xfslogd");
1829         if (!xfslogd_workqueue)
1830                 goto out_free_buf_zone;
1831
1832         xfsdatad_workqueue = create_workqueue("xfsdatad");
1833         if (!xfsdatad_workqueue)
1834                 goto out_destroy_xfslogd_workqueue;
1835
1836         xfsconvertd_workqueue = create_workqueue("xfsconvertd");
1837         if (!xfsconvertd_workqueue)
1838                 goto out_destroy_xfsdatad_workqueue;
1839
1840         register_shrinker(&xfs_buf_shake);
1841         return 0;
1842
1843  out_destroy_xfsdatad_workqueue:
1844         destroy_workqueue(xfsdatad_workqueue);
1845  out_destroy_xfslogd_workqueue:
1846         destroy_workqueue(xfslogd_workqueue);
1847  out_free_buf_zone:
1848         kmem_zone_destroy(xfs_buf_zone);
1849  out_free_trace_buf:
1850 #ifdef XFS_BUF_TRACE
1851         ktrace_free(xfs_buf_trace_buf);
1852 #endif
1853         return -ENOMEM;
1854 }
1855
1856 void
1857 xfs_buf_terminate(void)
1858 {
1859         unregister_shrinker(&xfs_buf_shake);
1860         destroy_workqueue(xfsconvertd_workqueue);
1861         destroy_workqueue(xfsdatad_workqueue);
1862         destroy_workqueue(xfslogd_workqueue);
1863         kmem_zone_destroy(xfs_buf_zone);
1864 #ifdef XFS_BUF_TRACE
1865         ktrace_free(xfs_buf_trace_buf);
1866 #endif
1867 }
1868
1869 #ifdef CONFIG_KDB_MODULES
1870 struct list_head *
1871 xfs_get_buftarg_list(void)
1872 {
1873         return &xfs_buftarg_list;
1874 }
1875 #endif