fs/xfs/linux-2.6/xfs_buf.c

   1 /*
   2  * Copyright (c) 2000-2004 Silicon Graphics, Inc.  All Rights Reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it would be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11  *
  12  * Further, this software is distributed without any warranty that it is
  13  * free of the rightful claim of any third person regarding infringement
  14  * or the like.  Any license provided herein, whether implied or
  15  * otherwise, applies only to this software file.  Patent licenses, if
  16  * any, provided herein do not apply to combinations of this program with
  17  * other software, or any other product whatsoever.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write the Free Software Foundation, Inc., 59
  21  * Temple Place - Suite 330, Boston MA 02111-1307, USA.
  22  *
  23  * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
  24  * Mountain View, CA  94043, or:
  25  *
  26  * http://www.sgi.com
  27  *
  28  * For further information regarding this notice, see:
  29  *
  30  * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
  31  */
  32
  33 /*
  34  *      The xfs_buf.c code provides an abstract buffer cache model on top
  35  *      of the Linux page cache.  Cached metadata blocks for a file system
  36  *      are hashed to the inode for the block device.  xfs_buf.c assembles
  37  *      buffers (xfs_buf_t) on demand to aggregate such cached pages for I/O.
  38  *
  39  *      Written by Steve Lord, Jim Mostek, Russell Cattelan
  40  *                  and Rajagopal Ananthanarayanan ("ananth") at SGI.
  41  *
  42  */
  43
  44 #include <linux/stddef.h>
  45 #include <linux/errno.h>
  46 #include <linux/slab.h>
  47 #include <linux/pagemap.h>
  48 #include <linux/init.h>
  49 #include <linux/vmalloc.h>
  50 #include <linux/bio.h>
  51 #include <linux/sysctl.h>
  52 #include <linux/proc_fs.h>
  53 #include <linux/workqueue.h>
  54 #include <linux/suspend.h>
  55 #include <linux/percpu.h>
  56
  57 #include "xfs_linux.h"
  58
  59 #ifndef GFP_READAHEAD
  60 #define GFP_READAHEAD   (__GFP_NOWARN|__GFP_NORETRY)
  61 #endif
  62
  63 /*
  64  * File wide globals
  65  */
  66
  67 STATIC kmem_cache_t *pagebuf_cache;
  68 STATIC kmem_shaker_t pagebuf_shake;
  69 STATIC int pagebuf_daemon_wakeup(int, unsigned int);
  70 STATIC void pagebuf_delwri_queue(xfs_buf_t *, int);
  71 STATIC struct workqueue_struct *pagebuf_logio_workqueue;
  72 STATIC struct workqueue_struct *pagebuf_dataio_workqueue;
  73
  74 /*
  75  * Pagebuf debugging
  76  */
  77
  78 #ifdef PAGEBUF_TRACE
  79 void
  80 pagebuf_trace(
  81         xfs_buf_t       *pb,
  82         char            *id,
  83         void            *data,
  84         void            *ra)
  85 {
  86         ktrace_enter(pagebuf_trace_buf,
  87                 pb, id,
  88                 (void *)(unsigned long)pb->pb_flags,
  89                 (void *)(unsigned long)pb->pb_hold.counter,
  90                 (void *)(unsigned long)pb->pb_sema.count.counter,
  91                 (void *)current,
  92                 data, ra,
  93                 (void *)(unsigned long)((pb->pb_file_offset>>32) & 0xffffffff),
  94                 (void *)(unsigned long)(pb->pb_file_offset & 0xffffffff),
  95                 (void *)(unsigned long)pb->pb_buffer_length,
  96                 NULL, NULL, NULL, NULL, NULL);
  97 }
  98 ktrace_t *pagebuf_trace_buf;
  99 #define PAGEBUF_TRACE_SIZE      4096
 100 #define PB_TRACE(pb, id, data)  \
 101         pagebuf_trace(pb, id, (void *)data, (void *)__builtin_return_address(0))
 102 #else
 103 #define PB_TRACE(pb, id, data)  do { } while (0)
 104 #endif
 105
 106 #ifdef PAGEBUF_LOCK_TRACKING
 107 # define PB_SET_OWNER(pb)       ((pb)->pb_last_holder = current->pid)
 108 # define PB_CLEAR_OWNER(pb)     ((pb)->pb_last_holder = -1)
 109 # define PB_GET_OWNER(pb)       ((pb)->pb_last_holder)
 110 #else
 111 # define PB_SET_OWNER(pb)       do { } while (0)
 112 # define PB_CLEAR_OWNER(pb)     do { } while (0)
 113 # define PB_GET_OWNER(pb)       do { } while (0)
 114 #endif
 115
 116 /*
 117  * Pagebuf allocation / freeing.
 118  */
 119
 120 #define pb_to_gfp(flags) \
 121         (((flags) & PBF_READ_AHEAD) ? GFP_READAHEAD : \
 122          ((flags) & PBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL)
 123
 124 #define pb_to_km(flags) \
 125          (((flags) & PBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
 126
 127
 128 #define pagebuf_allocate(flags) \
 129         kmem_zone_alloc(pagebuf_cache, pb_to_km(flags))
 130 #define pagebuf_deallocate(pb) \
 131         kmem_zone_free(pagebuf_cache, (pb));
 132
 133 /*
 134  * Pagebuf hashing
 135  */
 136
 137 #define NBITS   8
 138 #define NHASH   (1<<NBITS)
 139
 140 typedef struct {
 141         struct list_head        pb_hash;
 142         spinlock_t              pb_hash_lock;
 143 } pb_hash_t;
 144
 145 STATIC pb_hash_t        pbhash[NHASH];
 146 #define pb_hash(pb)     &pbhash[pb->pb_hash_index]
 147
 148 STATIC int
 149 _bhash(
 150         struct block_device *bdev,
 151         loff_t          base)
 152 {
 153         int             bit, hval;
 154
 155         base >>= 9;
 156         base ^= (unsigned long)bdev / L1_CACHE_BYTES;
 157         for (bit = hval = 0; base && bit < sizeof(base) * 8; bit += NBITS) {
 158                 hval ^= (int)base & (NHASH-1);
 159                 base >>= NBITS;
 160         }
 161         return hval;
 162 }
 163
 164 /*
 165  * Mapping of multi-page buffers into contiguous virtual space
 166  */
 167
 168 typedef struct a_list {
 169         void            *vm_addr;
 170         struct a_list   *next;
 171 } a_list_t;
 172
 173 STATIC a_list_t         *as_free_head;
 174 STATIC int              as_list_len;
 175 STATIC spinlock_t       as_lock = SPIN_LOCK_UNLOCKED;
 176
 177 /*
 178  * Try to batch vunmaps because they are costly.
 179  */
 180 STATIC void
 181 free_address(
 182         void            *addr)
 183 {
 184         a_list_t        *aentry;
 185
 186         aentry = kmalloc(sizeof(a_list_t), GFP_ATOMIC);
 187         if (aentry) {
 188                 spin_lock(&as_lock);
 189                 aentry->next = as_free_head;
 190                 aentry->vm_addr = addr;
 191                 as_free_head = aentry;
 192                 as_list_len++;
 193                 spin_unlock(&as_lock);
 194         } else {
 195                 vunmap(addr);
 196         }
 197 }
 198
 199 STATIC void
 200 purge_addresses(void)
 201 {
 202         a_list_t        *aentry, *old;
 203
 204         if (as_free_head == NULL)
 205                 return;
 206
 207         spin_lock(&as_lock);
 208         aentry = as_free_head;
 209         as_free_head = NULL;
 210         as_list_len = 0;
 211         spin_unlock(&as_lock);
 212
 213         while ((old = aentry) != NULL) {
 214                 vunmap(aentry->vm_addr);
 215                 aentry = aentry->next;
 216                 kfree(old);
 217         }
 218 }
 219
 220 /*
 221  *      Internal pagebuf object manipulation
 222  */
 223
 224 STATIC void
 225 _pagebuf_initialize(
 226         xfs_buf_t               *pb,
 227         xfs_buftarg_t           *target,
 228         loff_t                  range_base,
 229         size_t                  range_length,
 230         page_buf_flags_t        flags)
 231 {
 232         /*
 233          * We don't want certain flags to appear in pb->pb_flags.
 234          */
 235         flags &= ~(PBF_LOCK|PBF_MAPPED|PBF_DONT_BLOCK|PBF_READ_AHEAD);
 236
 237         memset(pb, 0, sizeof(xfs_buf_t));
 238         atomic_set(&pb->pb_hold, 1);
 239         init_MUTEX_LOCKED(&pb->pb_iodonesema);
 240         INIT_LIST_HEAD(&pb->pb_list);
 241         INIT_LIST_HEAD(&pb->pb_hash_list);
 242         init_MUTEX_LOCKED(&pb->pb_sema); /* held, no waiters */
 243         PB_SET_OWNER(pb);
 244         pb->pb_target = target;
 245         pb->pb_file_offset = range_base;
 246         /*
 247          * Set buffer_length and count_desired to the same value initially.
 248          * I/O routines should use count_desired, which will be the same in
 249          * most cases but may be reset (e.g. XFS recovery).
 250          */
 251         pb->pb_buffer_length = pb->pb_count_desired = range_length;
 252         pb->pb_flags = flags | PBF_NONE;
 253         pb->pb_bn = XFS_BUF_DADDR_NULL;
 254         atomic_set(&pb->pb_pin_count, 0);
 255         init_waitqueue_head(&pb->pb_waiters);
 256
 257         XFS_STATS_INC(pb_create);
 258         PB_TRACE(pb, "initialize", target);
 259 }
 260
 261 /*
 262  * Allocate a page array capable of holding a specified number
 263  * of pages, and point the page buf at it.
 264  */
 265 STATIC int
 266 _pagebuf_get_pages(
 267         xfs_buf_t               *pb,
 268         int                     page_count,
 269         page_buf_flags_t        flags)
 270 {
 271         /* Make sure that we have a page list */
 272         if (pb->pb_pages == NULL) {
 273                 pb->pb_offset = page_buf_poff(pb->pb_file_offset);
 274                 pb->pb_page_count = page_count;
 275                 if (page_count <= PB_PAGES) {
 276                         pb->pb_pages = pb->pb_page_array;
 277                 } else {
 278                         pb->pb_pages = kmem_alloc(sizeof(struct page *) *
 279                                         page_count, pb_to_km(flags));
 280                         if (pb->pb_pages == NULL)
 281                                 return -ENOMEM;
 282                 }
 283                 memset(pb->pb_pages, 0, sizeof(struct page *) * page_count);
 284         }
 285         return 0;
 286 }
 287
 288 /*
 289  *      Frees pb_pages if it was malloced.
 290  */
 291 STATIC void
 292 _pagebuf_free_pages(
 293         xfs_buf_t       *bp)
 294 {
 295         if (bp->pb_pages != bp->pb_page_array) {
 296                 kmem_free(bp->pb_pages,
 297                           bp->pb_page_count * sizeof(struct page *));
 298         }
 299 }
 300
 301 /*
 302  *      Releases the specified buffer.
 303  *
 304  *      The modification state of any associated pages is left unchanged.
 305  *      The buffer most not be on any hash - use pagebuf_rele instead for
 306  *      hashed and refcounted buffers
 307  */
 308 void
 309 pagebuf_free(
 310         xfs_buf_t               *bp)
 311 {
 312         PB_TRACE(bp, "free", 0);
 313
 314         ASSERT(list_empty(&bp->pb_hash_list));
 315
 316         if (bp->pb_flags & _PBF_PAGE_CACHE) {
 317                 uint            i;
 318
 319                 if ((bp->pb_flags & PBF_MAPPED) && (bp->pb_page_count > 1))
 320                         free_address(bp->pb_addr - bp->pb_offset);
 321
 322                 for (i = 0; i < bp->pb_page_count; i++)
 323                         page_cache_release(bp->pb_pages[i]);
 324                 _pagebuf_free_pages(bp);
 325         } else if (bp->pb_flags & _PBF_KMEM_ALLOC) {
 326                  /*
 327                   * XXX(hch): bp->pb_count_desired might be incorrect (see
 328                   * pagebuf_associate_memory for details), but fortunately
 329                   * the Linux version of kmem_free ignores the len argument..
 330                   */
 331                 kmem_free(bp->pb_addr, bp->pb_count_desired);
 332                 _pagebuf_free_pages(bp);
 333         }
 334
 335         pagebuf_deallocate(bp);
 336 }
 337
 338 /*
 339  *      Finds all pages for buffer in question and builds it's page list.
 340  */
 341 STATIC int
 342 _pagebuf_lookup_pages(
 343         xfs_buf_t               *bp,
 344         uint                    flags)
 345 {
 346         struct address_space    *mapping = bp->pb_target->pbr_mapping;
 347         unsigned int            sectorshift = bp->pb_target->pbr_sshift;
 348         size_t                  blocksize = bp->pb_target->pbr_bsize;
 349         size_t                  size = bp->pb_count_desired;
 350         size_t                  nbytes, offset;
 351         int                     gfp_mask = pb_to_gfp(flags);
 352         unsigned short          page_count, i;
 353         pgoff_t                 first;
 354         loff_t                  end;
 355         int                     error;
 356
 357         end = bp->pb_file_offset + bp->pb_buffer_length;
 358         page_count = page_buf_btoc(end) - page_buf_btoct(bp->pb_file_offset);
 359
 360         error = _pagebuf_get_pages(bp, page_count, flags);
 361         if (unlikely(error))
 362                 return error;
 363         bp->pb_flags |= _PBF_PAGE_CACHE;
 364
 365         offset = bp->pb_offset;
 366         first = bp->pb_file_offset >> PAGE_CACHE_SHIFT;
 367
 368         for (i = 0; i < bp->pb_page_count; i++) {
 369                 struct page     *page;
 370                 uint            retries = 0;
 371
 372               retry:
 373                 page = find_or_create_page(mapping, first + i, gfp_mask);
 374                 if (unlikely(page == NULL)) {
 375                         if (flags & PBF_READ_AHEAD) {
 376                                 bp->pb_page_count = i;
 377                                 for (i = 0; i < bp->pb_page_count; i++)
 378                                         unlock_page(bp->pb_pages[i]);
 379                                 return -ENOMEM;
 380                         }
 381
 382                         /*
 383                          * This could deadlock.
 384                          *
 385                          * But until all the XFS lowlevel code is revamped to
 386                          * handle buffer allocation failures we can't do much.
 387                          */
 388                         if (!(++retries % 100))
 389                                 printk(KERN_ERR
 390                                         "possible deadlock in %s (mode:0x%x)\n",
 391                                         __FUNCTION__, gfp_mask);
 392
 393                         XFS_STATS_INC(pb_page_retries);
 394                         pagebuf_daemon_wakeup(0, gfp_mask);
 395                         set_current_state(TASK_UNINTERRUPTIBLE);
 396                         schedule_timeout(10);
 397                         goto retry;
 398                 }
 399
 400                 XFS_STATS_INC(pb_page_found);
 401
 402                 nbytes = min_t(size_t, size, PAGE_CACHE_SIZE - offset);
 403                 size -= nbytes;
 404
 405                 if (!PageUptodate(page)) {
 406                         page_count--;
 407                         if (blocksize == PAGE_CACHE_SIZE) {
 408                                 if (flags & PBF_READ)
 409                                         bp->pb_locked = 1;
 410                         } else if (!PagePrivate(page)) {
 411                                 unsigned long   j, range;
 412
 413                                 /*
 414                                  * In this case page->private holds a bitmap
 415                                  * of uptodate sectors within the page
 416                                  */
 417                                 ASSERT(blocksize < PAGE_CACHE_SIZE);
 418                                 range = (offset + nbytes) >> sectorshift;
 419                                 for (j = offset >> sectorshift; j < range; j++)
 420                                         if (!test_bit(j, &page->private))
 421                                                 break;
 422                                 if (j == range)
 423                                         page_count++;
 424                         }
 425                 }
 426
 427                 bp->pb_pages[i] = page;
 428                 offset = 0;
 429         }
 430
 431         if (!bp->pb_locked) {
 432                 for (i = 0; i < bp->pb_page_count; i++)
 433                         unlock_page(bp->pb_pages[i]);
 434         }
 435
 436         if (page_count) {
 437                 /* if we have any uptodate pages, mark that in the buffer */
 438                 bp->pb_flags &= ~PBF_NONE;
 439
 440                 /* if some pages aren't uptodate, mark that in the buffer */
 441                 if (page_count != bp->pb_page_count)
 442                         bp->pb_flags |= PBF_PARTIAL;
 443         }
 444
 445         PB_TRACE(bp, "lookup_pages", (long)page_count);
 446         return error;
 447 }
 448
 449 /*
 450  *      Map buffer into kernel address-space if nessecary.
 451  */
 452 STATIC int
 453 _pagebuf_map_pages(
 454         xfs_buf_t               *bp,
 455         uint                    flags)
 456 {
 457         /* A single page buffer is always mappable */
 458         if (bp->pb_page_count == 1) {
 459                 bp->pb_addr = page_address(bp->pb_pages[0]) + bp->pb_offset;
 460                 bp->pb_flags |= PBF_MAPPED;
 461         } else if (flags & PBF_MAPPED) {
 462                 if (as_list_len > 64)
 463                         purge_addresses();
 464                 bp->pb_addr = vmap(bp->pb_pages, bp->pb_page_count,
 465                                 VM_MAP, PAGE_KERNEL);
 466                 if (unlikely(bp->pb_addr == NULL))
 467                         return -ENOMEM;
 468                 bp->pb_addr += bp->pb_offset;
 469                 bp->pb_flags |= PBF_MAPPED;
 470         }
 471
 472         return 0;
 473 }
 474
 475 /*
 476  *      Finding and Reading Buffers
 477  */
 478
 479 /*
 480  *      _pagebuf_find
 481  *
 482  *      Looks up, and creates if absent, a lockable buffer for
 483  *      a given range of an inode.  The buffer is returned
 484  *      locked.  If other overlapping buffers exist, they are
 485  *      released before the new buffer is created and locked,
 486  *      which may imply that this call will block until those buffers
 487  *      are unlocked.  No I/O is implied by this call.
 488  */
 489 STATIC xfs_buf_t *
 490 _pagebuf_find(                          /* find buffer for block        */
 491         xfs_buftarg_t           *target,/* target for block             */
 492         loff_t                  ioff,   /* starting offset of range     */
 493         size_t                  isize,  /* length of range              */
 494         page_buf_flags_t        flags,  /* PBF_TRYLOCK                  */
 495         xfs_buf_t               *new_pb)/* newly allocated buffer       */
 496 {
 497         loff_t                  range_base;
 498         size_t                  range_length;
 499         int                     hval;
 500         pb_hash_t               *h;
 501         xfs_buf_t               *pb, *n;
 502         int                     not_locked;
 503
 504         range_base = (ioff << BBSHIFT);
 505         range_length = (isize << BBSHIFT);
 506
 507         /* Ensure we never do IOs smaller than the sector size */
 508         BUG_ON(range_length < (1 << target->pbr_sshift));
 509
 510         /* Ensure we never do IOs that are not sector aligned */
 511         BUG_ON(range_base & (loff_t)target->pbr_smask);
 512
 513         hval = _bhash(target->pbr_bdev, range_base);
 514         h = &pbhash[hval];
 515
 516         spin_lock(&h->pb_hash_lock);
 517         list_for_each_entry_safe(pb, n, &h->pb_hash, pb_hash_list) {
 518                 if (pb->pb_target == target &&
 519                     pb->pb_file_offset == range_base &&
 520                     pb->pb_buffer_length == range_length) {
 521                         /* If we look at something bring it to the
 522                          * front of the list for next time
 523                          */
 524                         atomic_inc(&pb->pb_hold);
 525                         list_move(&pb->pb_hash_list, &h->pb_hash);
 526                         goto found;
 527                 }
 528         }
 529
 530         /* No match found */
 531         if (new_pb) {
 532                 _pagebuf_initialize(new_pb, target, range_base,
 533                                 range_length, flags);
 534                 new_pb->pb_hash_index = hval;
 535                 list_add(&new_pb->pb_hash_list, &h->pb_hash);
 536         } else {
 537                 XFS_STATS_INC(pb_miss_locked);
 538         }
 539
 540         spin_unlock(&h->pb_hash_lock);
 541         return (new_pb);
 542
 543 found:
 544         spin_unlock(&h->pb_hash_lock);
 545
 546         /* Attempt to get the semaphore without sleeping,
 547          * if this does not work then we need to drop the
 548          * spinlock and do a hard attempt on the semaphore.
 549          */
 550         not_locked = down_trylock(&pb->pb_sema);
 551         if (not_locked) {
 552                 if (!(flags & PBF_TRYLOCK)) {
 553                         /* wait for buffer ownership */
 554                         PB_TRACE(pb, "get_lock", 0);
 555                         pagebuf_lock(pb);
 556                         XFS_STATS_INC(pb_get_locked_waited);
 557                 } else {
 558                         /* We asked for a trylock and failed, no need
 559                          * to look at file offset and length here, we
 560                          * know that this pagebuf at least overlaps our
 561                          * pagebuf and is locked, therefore our buffer
 562                          * either does not exist, or is this buffer
 563                          */
 564
 565                         pagebuf_rele(pb);
 566                         XFS_STATS_INC(pb_busy_locked);
 567                         return (NULL);
 568                 }
 569         } else {
 570                 /* trylock worked */
 571                 PB_SET_OWNER(pb);
 572         }
 573
 574         if (pb->pb_flags & PBF_STALE)
 575                 pb->pb_flags &= PBF_MAPPED;
 576         PB_TRACE(pb, "got_lock", 0);
 577         XFS_STATS_INC(pb_get_locked);
 578         return (pb);
 579 }
 580
 581
 582 /*
 583  *      pagebuf_find
 584  *
 585  *      pagebuf_find returns a buffer matching the specified range of
 586  *      data for the specified target, if any of the relevant blocks
 587  *      are in memory.  The buffer may have unallocated holes, if
 588  *      some, but not all, of the blocks are in memory.  Even where
 589  *      pages are present in the buffer, not all of every page may be
 590  *      valid.
 591  */
 592 xfs_buf_t *
 593 pagebuf_find(                           /* find buffer for block        */
 594                                         /* if the block is in memory    */
 595         xfs_buftarg_t           *target,/* target for block             */
 596         loff_t                  ioff,   /* starting offset of range     */
 597         size_t                  isize,  /* length of range              */
 598         page_buf_flags_t        flags)  /* PBF_TRYLOCK                  */
 599 {
 600         return _pagebuf_find(target, ioff, isize, flags, NULL);
 601 }
 602
 603 /*
 604  *      pagebuf_get
 605  *
 606  *      pagebuf_get assembles a buffer covering the specified range.
 607  *      Some or all of the blocks in the range may be valid.  Storage
 608  *      in memory for all portions of the buffer will be allocated,
 609  *      although backing storage may not be.  If PBF_READ is set in
 610  *      flags, pagebuf_iostart is called also.
 611  */
 612 xfs_buf_t *
 613 pagebuf_get(                            /* allocate a buffer            */
 614         xfs_buftarg_t           *target,/* target for buffer            */
 615         loff_t                  ioff,   /* starting offset of range     */
 616         size_t                  isize,  /* length of range              */
 617         page_buf_flags_t        flags)  /* PBF_TRYLOCK                  */
 618 {
 619         xfs_buf_t               *pb, *new_pb;
 620         int                     error = 0, i;
 621
 622         new_pb = pagebuf_allocate(flags);
 623         if (unlikely(!new_pb))
 624                 return NULL;
 625
 626         pb = _pagebuf_find(target, ioff, isize, flags, new_pb);
 627         if (pb == new_pb) {
 628                 error = _pagebuf_lookup_pages(pb, flags);
 629                 if (unlikely(error)) {
 630                         printk(KERN_WARNING
 631                                "pagebuf_get: failed to lookup pages\n");
 632                         goto no_buffer;
 633                 }
 634         } else {
 635                 pagebuf_deallocate(new_pb);
 636                 if (unlikely(pb == NULL))
 637                         return NULL;
 638         }
 639
 640         for (i = 0; i < pb->pb_page_count; i++)
 641                 mark_page_accessed(pb->pb_pages[i]);
 642
 643         if (!(pb->pb_flags & PBF_MAPPED)) {
 644                 error = _pagebuf_map_pages(pb, flags);
 645                 if (unlikely(error)) {
 646                         printk(KERN_WARNING
 647                                "pagebuf_get: failed to map pages\n");
 648                         goto no_buffer;
 649                 }
 650         }
 651
 652         XFS_STATS_INC(pb_get);
 653
 654         /*
 655          * Always fill in the block number now, the mapped cases can do
 656          * their own overlay of this later.
 657          */
 658         pb->pb_bn = ioff;
 659         pb->pb_count_desired = pb->pb_buffer_length;
 660
 661         if (flags & PBF_READ) {
 662                 if (PBF_NOT_DONE(pb)) {
 663                         PB_TRACE(pb, "get_read", (unsigned long)flags);
 664                         XFS_STATS_INC(pb_get_read);
 665                         pagebuf_iostart(pb, flags);
 666                 } else if (flags & PBF_ASYNC) {
 667                         PB_TRACE(pb, "get_read_async", (unsigned long)flags);
 668                         /*
 669                          * Read ahead call which is already satisfied,
 670                          * drop the buffer
 671                          */
 672                         goto no_buffer;
 673                 } else {
 674                         PB_TRACE(pb, "get_read_done", (unsigned long)flags);
 675                         /* We do not want read in the flags */
 676                         pb->pb_flags &= ~PBF_READ;
 677                 }
 678         } else {
 679                 PB_TRACE(pb, "get_write", (unsigned long)flags);
 680         }
 681
 682         return pb;
 683
 684 no_buffer:
 685         if (flags & (PBF_LOCK | PBF_TRYLOCK))
 686                 pagebuf_unlock(pb);
 687         pagebuf_rele(pb);
 688         return NULL;
 689 }
 690
 691 /*
 692  * Create a skeletal pagebuf (no pages associated with it).
 693  */
 694 xfs_buf_t *
 695 pagebuf_lookup(
 696         xfs_buftarg_t           *target,
 697         loff_t                  ioff,
 698         size_t                  isize,
 699         page_buf_flags_t        flags)
 700 {
 701         xfs_buf_t               *pb;
 702
 703         pb = pagebuf_allocate(flags);
 704         if (pb) {
 705                 _pagebuf_initialize(pb, target, ioff, isize, flags);
 706         }
 707         return pb;
 708 }
 709
 710 /*
 711  * If we are not low on memory then do the readahead in a deadlock
 712  * safe manner.
 713  */
 714 void
 715 pagebuf_readahead(
 716         xfs_buftarg_t           *target,
 717         loff_t                  ioff,
 718         size_t                  isize,
 719         page_buf_flags_t        flags)
 720 {
 721         struct backing_dev_info *bdi;
 722
 723         bdi = target->pbr_mapping->backing_dev_info;
 724         if (bdi_read_congested(bdi))
 725                 return;
 726         if (bdi_write_congested(bdi))
 727                 return;
 728
 729         flags |= (PBF_TRYLOCK|PBF_READ|PBF_ASYNC|PBF_READ_AHEAD);
 730         pagebuf_get(target, ioff, isize, flags);
 731 }
 732
 733 xfs_buf_t *
 734 pagebuf_get_empty(
 735         size_t                  len,
 736         xfs_buftarg_t           *target)
 737 {
 738         xfs_buf_t               *pb;
 739
 740         pb = pagebuf_allocate(0);
 741         if (pb)
 742                 _pagebuf_initialize(pb, target, 0, len, 0);
 743         return pb;
 744 }
 745
 746 static inline struct page *
 747 mem_to_page(
 748         void                    *addr)
 749 {
 750         if (((unsigned long)addr < VMALLOC_START) ||
 751             ((unsigned long)addr >= VMALLOC_END)) {
 752                 return virt_to_page(addr);
 753         } else {
 754                 return vmalloc_to_page(addr);
 755         }
 756 }
 757
 758 int
 759 pagebuf_associate_memory(
 760         xfs_buf_t               *pb,
 761         void                    *mem,
 762         size_t                  len)
 763 {
 764         int                     rval;
 765         int                     i = 0;
 766         size_t                  ptr;
 767         size_t                  end, end_cur;
 768         off_t                   offset;
 769         int                     page_count;
 770
 771         page_count = PAGE_CACHE_ALIGN(len) >> PAGE_CACHE_SHIFT;
 772         offset = (off_t) mem - ((off_t)mem & PAGE_CACHE_MASK);
 773         if (offset && (len > PAGE_CACHE_SIZE))
 774                 page_count++;
 775
 776         /* Free any previous set of page pointers */
 777         if (pb->pb_pages)
 778                 _pagebuf_free_pages(pb);
 779
 780         pb->pb_pages = NULL;
 781         pb->pb_addr = mem;
 782
 783         rval = _pagebuf_get_pages(pb, page_count, 0);
 784         if (rval)
 785                 return rval;
 786
 787         pb->pb_offset = offset;
 788         ptr = (size_t) mem & PAGE_CACHE_MASK;
 789         end = PAGE_CACHE_ALIGN((size_t) mem + len);
 790         end_cur = end;
 791         /* set up first page */
 792         pb->pb_pages[0] = mem_to_page(mem);
 793
 794         ptr += PAGE_CACHE_SIZE;
 795         pb->pb_page_count = ++i;
 796         while (ptr < end) {
 797                 pb->pb_pages[i] = mem_to_page((void *)ptr);
 798                 pb->pb_page_count = ++i;
 799                 ptr += PAGE_CACHE_SIZE;
 800         }
 801         pb->pb_locked = 0;
 802
 803         pb->pb_count_desired = pb->pb_buffer_length = len;
 804         pb->pb_flags |= PBF_MAPPED;
 805
 806         return 0;
 807 }
 808
 809 xfs_buf_t *
 810 pagebuf_get_no_daddr(
 811         size_t                  len,
 812         xfs_buftarg_t           *target)
 813 {
 814         size_t                  malloc_len = len;
 815         xfs_buf_t               *bp;
 816         void                    *data;
 817         int                     error;
 818
 819         bp = pagebuf_allocate(0);
 820         if (unlikely(bp == NULL))
 821                 goto fail;
 822         _pagebuf_initialize(bp, target, 0, len, PBF_FORCEIO);
 823
 824  try_again:
 825         data = kmem_alloc(malloc_len, KM_SLEEP | KM_MAYFAIL);
 826         if (unlikely(data == NULL))
 827                 goto fail_free_buf;
 828
 829         /* check whether alignment matches.. */
 830         if ((__psunsigned_t)data !=
 831             ((__psunsigned_t)data & ~target->pbr_smask)) {
 832                 /* .. else double the size and try again */
 833                 kmem_free(data, malloc_len);
 834                 malloc_len <<= 1;
 835                 goto try_again;
 836         }
 837
 838         error = pagebuf_associate_memory(bp, data, len);
 839         if (error)
 840                 goto fail_free_mem;
 841         bp->pb_flags |= _PBF_KMEM_ALLOC;
 842
 843         pagebuf_unlock(bp);
 844
 845         PB_TRACE(bp, "no_daddr", data);
 846         return bp;
 847  fail_free_mem:
 848         kmem_free(data, malloc_len);
 849  fail_free_buf:
 850         pagebuf_free(bp);
 851  fail:
 852         return NULL;
 853 }
 854
 855 /*
 856  *      pagebuf_hold
 857  *
 858  *      Increment reference count on buffer, to hold the buffer concurrently
 859  *      with another thread which may release (free) the buffer asynchronously.
 860  *
 861  *      Must hold the buffer already to call this function.
 862  */
 863 void
 864 pagebuf_hold(
 865         xfs_buf_t               *pb)
 866 {
 867         atomic_inc(&pb->pb_hold);
 868         PB_TRACE(pb, "hold", 0);
 869 }
 870
 871 /*
 872  *      pagebuf_rele
 873  *
 874  *      pagebuf_rele releases a hold on the specified buffer.  If the
 875  *      the hold count is 1, pagebuf_rele calls pagebuf_free.
 876  */
 877 void
 878 pagebuf_rele(
 879         xfs_buf_t               *pb)
 880 {
 881         pb_hash_t               *hash = pb_hash(pb);
 882
 883         PB_TRACE(pb, "rele", pb->pb_relse);
 884
 885         if (atomic_dec_and_lock(&pb->pb_hold, &hash->pb_hash_lock)) {
 886                 int             do_free = 1;
 887
 888                 if (pb->pb_relse) {
 889                         atomic_inc(&pb->pb_hold);
 890                         spin_unlock(&hash->pb_hash_lock);
 891                         (*(pb->pb_relse)) (pb);
 892                         spin_lock(&hash->pb_hash_lock);
 893                         do_free = 0;
 894                 }
 895
 896                 if (pb->pb_flags & PBF_DELWRI) {
 897                         pb->pb_flags |= PBF_ASYNC;
 898                         atomic_inc(&pb->pb_hold);
 899                         pagebuf_delwri_queue(pb, 0);
 900                         do_free = 0;
 901                 } else if (pb->pb_flags & PBF_FS_MANAGED) {
 902                         do_free = 0;
 903                 }
 904
 905                 if (do_free) {
 906                         list_del_init(&pb->pb_hash_list);
 907                         spin_unlock(&hash->pb_hash_lock);
 908                         pagebuf_free(pb);
 909                 } else {
 910                         spin_unlock(&hash->pb_hash_lock);
 911                 }
 912         }
 913 }
 914
 915
 916 /*
 917  *      Mutual exclusion on buffers.  Locking model:
 918  *
 919  *      Buffers associated with inodes for which buffer locking
 920  *      is not enabled are not protected by semaphores, and are
 921  *      assumed to be exclusively owned by the caller.  There is a
 922  *      spinlock in the buffer, used by the caller when concurrent
 923  *      access is possible.
 924  */
 925
 926 /*
 927  *      pagebuf_cond_lock
 928  *
 929  *      pagebuf_cond_lock locks a buffer object, if it is not already locked.
 930  *      Note that this in no way
 931  *      locks the underlying pages, so it is only useful for synchronizing
 932  *      concurrent use of page buffer objects, not for synchronizing independent
 933  *      access to the underlying pages.
 934  */
 935 int
 936 pagebuf_cond_lock(                      /* lock buffer, if not locked   */
 937                                         /* returns -EBUSY if locked)    */
 938         xfs_buf_t               *pb)
 939 {
 940         int                     locked;
 941
 942         locked = down_trylock(&pb->pb_sema) == 0;
 943         if (locked) {
 944                 PB_SET_OWNER(pb);
 945         }
 946         PB_TRACE(pb, "cond_lock", (long)locked);
 947         return(locked ? 0 : -EBUSY);
 948 }
 949
 950 /*
 951  *      pagebuf_lock_value
 952  *
 953  *      Return lock value for a pagebuf
 954  */
 955 int
 956 pagebuf_lock_value(
 957         xfs_buf_t               *pb)
 958 {
 959         return(atomic_read(&pb->pb_sema.count));
 960 }
 961
 962 /*
 963  *      pagebuf_lock
 964  *
 965  *      pagebuf_lock locks a buffer object.  Note that this in no way
 966  *      locks the underlying pages, so it is only useful for synchronizing
 967  *      concurrent use of page buffer objects, not for synchronizing independent
 968  *      access to the underlying pages.
 969  */
 970 int
 971 pagebuf_lock(
 972         xfs_buf_t               *pb)
 973 {
 974         PB_TRACE(pb, "lock", 0);
 975         if (atomic_read(&pb->pb_io_remaining))
 976                 blk_run_address_space(pb->pb_target->pbr_mapping);
 977         down(&pb->pb_sema);
 978         PB_SET_OWNER(pb);
 979         PB_TRACE(pb, "locked", 0);
 980         return 0;
 981 }
 982
 983 /*
 984  *      pagebuf_unlock
 985  *
 986  *      pagebuf_unlock releases the lock on the buffer object created by
 987  *      pagebuf_lock or pagebuf_cond_lock (not any
 988  *      pinning of underlying pages created by pagebuf_pin).
 989  */
 990 void
 991 pagebuf_unlock(                         /* unlock buffer                */
 992         xfs_buf_t               *pb)    /* buffer to unlock             */
 993 {
 994         PB_CLEAR_OWNER(pb);
 995         up(&pb->pb_sema);
 996         PB_TRACE(pb, "unlock", 0);
 997 }
 998
 999
1000 /*
1001  *      Pinning Buffer Storage in Memory
1002  */
1003
1004 /*
1005  *      pagebuf_pin
1006  *
1007  *      pagebuf_pin locks all of the memory represented by a buffer in
1008  *      memory.  Multiple calls to pagebuf_pin and pagebuf_unpin, for
1009  *      the same or different buffers affecting a given page, will
1010  *      properly count the number of outstanding "pin" requests.  The
1011  *      buffer may be released after the pagebuf_pin and a different
1012  *      buffer used when calling pagebuf_unpin, if desired.
1013  *      pagebuf_pin should be used by the file system when it wants be
1014  *      assured that no attempt will be made to force the affected
1015  *      memory to disk.  It does not assure that a given logical page
1016  *      will not be moved to a different physical page.
1017  */
1018 void
1019 pagebuf_pin(
1020         xfs_buf_t               *pb)
1021 {
1022         atomic_inc(&pb->pb_pin_count);
1023         PB_TRACE(pb, "pin", (long)pb->pb_pin_count.counter);
1024 }
1025
1026 /*
1027  *      pagebuf_unpin
1028  *
1029  *      pagebuf_unpin reverses the locking of memory performed by
1030  *      pagebuf_pin.  Note that both functions affected the logical
1031  *      pages associated with the buffer, not the buffer itself.
1032  */
1033 void
1034 pagebuf_unpin(
1035         xfs_buf_t               *pb)
1036 {
1037         if (atomic_dec_and_test(&pb->pb_pin_count)) {
1038                 wake_up_all(&pb->pb_waiters);
1039         }
1040         PB_TRACE(pb, "unpin", (long)pb->pb_pin_count.counter);
1041 }
1042
1043 int
1044 pagebuf_ispin(
1045         xfs_buf_t               *pb)
1046 {
1047         return atomic_read(&pb->pb_pin_count);
1048 }
1049
1050 /*
1051  *      pagebuf_wait_unpin
1052  *
1053  *      pagebuf_wait_unpin waits until all of the memory associated
1054  *      with the buffer is not longer locked in memory.  It returns
1055  *      immediately if none of the affected pages are locked.
1056  */
1057 static inline void
1058 _pagebuf_wait_unpin(
1059         xfs_buf_t               *pb)
1060 {
1061         DECLARE_WAITQUEUE       (wait, current);
1062
1063         if (atomic_read(&pb->pb_pin_count) == 0)
1064                 return;
1065
1066         add_wait_queue(&pb->pb_waiters, &wait);
1067         for (;;) {
1068                 set_current_state(TASK_UNINTERRUPTIBLE);
1069                 if (atomic_read(&pb->pb_pin_count) == 0)
1070                         break;
1071                 if (atomic_read(&pb->pb_io_remaining))
1072                         blk_run_address_space(pb->pb_target->pbr_mapping);
1073                 schedule();
1074         }
1075         remove_wait_queue(&pb->pb_waiters, &wait);
1076         set_current_state(TASK_RUNNING);
1077 }
1078
1079 /*
1080  *      Buffer Utility Routines
1081  */
1082
1083 /*
1084  *      pagebuf_iodone
1085  *
1086  *      pagebuf_iodone marks a buffer for which I/O is in progress
1087  *      done with respect to that I/O.  The pb_iodone routine, if
1088  *      present, will be called as a side-effect.
1089  */
1090 void
1091 pagebuf_iodone_work(
1092         void                    *v)
1093 {
1094         xfs_buf_t               *bp = (xfs_buf_t *)v;
1095
1096         if (bp->pb_iodone)
1097                 (*(bp->pb_iodone))(bp);
1098         else if (bp->pb_flags & PBF_ASYNC)
1099                 xfs_buf_relse(bp);
1100 }
1101
1102 void
1103 pagebuf_iodone(
1104         xfs_buf_t               *pb,
1105         int                     dataio,
1106         int                     schedule)
1107 {
1108         pb->pb_flags &= ~(PBF_READ | PBF_WRITE);
1109         if (pb->pb_error == 0) {
1110                 pb->pb_flags &= ~(PBF_PARTIAL | PBF_NONE);
1111         }
1112
1113         PB_TRACE(pb, "iodone", pb->pb_iodone);
1114
1115         if ((pb->pb_iodone) || (pb->pb_flags & PBF_ASYNC)) {
1116                 if (schedule) {
1117                         INIT_WORK(&pb->pb_iodone_work, pagebuf_iodone_work, pb);
1118                         queue_work(dataio ? pagebuf_dataio_workqueue :
1119                                 pagebuf_logio_workqueue, &pb->pb_iodone_work);
1120                 } else {
1121                         pagebuf_iodone_work(pb);
1122                 }
1123         } else {
1124                 up(&pb->pb_iodonesema);
1125         }
1126 }
1127
1128 /*
1129  *      pagebuf_ioerror
1130  *
1131  *      pagebuf_ioerror sets the error code for a buffer.
1132  */
1133 void
1134 pagebuf_ioerror(                        /* mark/clear buffer error flag */
1135         xfs_buf_t               *pb,    /* buffer to mark               */
1136         int                     error)  /* error to store (0 if none)   */
1137 {
1138         ASSERT(error >= 0 && error <= 0xffff);
1139         pb->pb_error = (unsigned short)error;
1140         PB_TRACE(pb, "ioerror", (unsigned long)error);
1141 }
1142
1143 /*
1144  *      pagebuf_iostart
1145  *
1146  *      pagebuf_iostart initiates I/O on a buffer, based on the flags supplied.
1147  *      If necessary, it will arrange for any disk space allocation required,
1148  *      and it will break up the request if the block mappings require it.
1149  *      The pb_iodone routine in the buffer supplied will only be called
1150  *      when all of the subsidiary I/O requests, if any, have been completed.
1151  *      pagebuf_iostart calls the pagebuf_ioinitiate routine or
1152  *      pagebuf_iorequest, if the former routine is not defined, to start
1153  *      the I/O on a given low-level request.
1154  */
1155 int
1156 pagebuf_iostart(                        /* start I/O on a buffer          */
1157         xfs_buf_t               *pb,    /* buffer to start                */
1158         page_buf_flags_t        flags)  /* PBF_LOCK, PBF_ASYNC, PBF_READ, */
1159                                         /* PBF_WRITE, PBF_DELWRI,         */
1160                                         /* PBF_DONT_BLOCK                 */
1161 {
1162         int                     status = 0;
1163
1164         PB_TRACE(pb, "iostart", (unsigned long)flags);
1165
1166         if (flags & PBF_DELWRI) {
1167                 pb->pb_flags &= ~(PBF_READ | PBF_WRITE | PBF_ASYNC);
1168                 pb->pb_flags |= flags & (PBF_DELWRI | PBF_ASYNC);
1169                 pagebuf_delwri_queue(pb, 1);
1170                 return status;
1171         }
1172
1173         pb->pb_flags &= ~(PBF_READ | PBF_WRITE | PBF_ASYNC | PBF_DELWRI | \
1174                         PBF_READ_AHEAD | _PBF_RUN_QUEUES);
1175         pb->pb_flags |= flags & (PBF_READ | PBF_WRITE | PBF_ASYNC | \
1176                         PBF_READ_AHEAD | _PBF_RUN_QUEUES);
1177
1178         BUG_ON(pb->pb_bn == XFS_BUF_DADDR_NULL);
1179
1180         /* For writes allow an alternate strategy routine to precede
1181          * the actual I/O request (which may not be issued at all in
1182          * a shutdown situation, for example).
1183          */
1184         status = (flags & PBF_WRITE) ?
1185                 pagebuf_iostrategy(pb) : pagebuf_iorequest(pb);
1186
1187         /* Wait for I/O if we are not an async request.
1188          * Note: async I/O request completion will release the buffer,
1189          * and that can already be done by this point.  So using the
1190          * buffer pointer from here on, after async I/O, is invalid.
1191          */
1192         if (!status && !(flags & PBF_ASYNC))
1193                 status = pagebuf_iowait(pb);
1194
1195         return status;
1196 }
1197
1198 /*
1199  * Helper routine for pagebuf_iorequest
1200  */
1201
1202 STATIC __inline__ int
1203 _pagebuf_iolocked(
1204         xfs_buf_t               *pb)
1205 {
1206         ASSERT(pb->pb_flags & (PBF_READ|PBF_WRITE));
1207         if (pb->pb_flags & PBF_READ)
1208                 return pb->pb_locked;
1209         return 0;
1210 }
1211
1212 STATIC __inline__ void
1213 _pagebuf_iodone(
1214         xfs_buf_t               *pb,
1215         int                     schedule)
1216 {
1217         if (atomic_dec_and_test(&pb->pb_io_remaining) == 1) {
1218                 pb->pb_locked = 0;
1219                 pagebuf_iodone(pb, (pb->pb_flags & PBF_FS_DATAIOD), schedule);
1220         }
1221 }
1222
1223 STATIC int
1224 bio_end_io_pagebuf(
1225         struct bio              *bio,
1226         unsigned int            bytes_done,
1227         int                     error)
1228 {
1229         xfs_buf_t               *pb = (xfs_buf_t *)bio->bi_private;
1230         unsigned int            i, blocksize = pb->pb_target->pbr_bsize;
1231         unsigned int            sectorshift = pb->pb_target->pbr_sshift;
1232         struct bio_vec          *bvec = bio->bi_io_vec;
1233
1234         if (bio->bi_size)
1235                 return 1;
1236
1237         if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1238                 pb->pb_error = EIO;
1239
1240         for (i = 0; i < bio->bi_vcnt; i++, bvec++) {
1241                 struct page     *page = bvec->bv_page;
1242
1243                 if (pb->pb_error) {
1244                         SetPageError(page);
1245                 } else if (blocksize == PAGE_CACHE_SIZE) {
1246                         SetPageUptodate(page);
1247                 } else if (!PagePrivate(page) &&
1248                                 (pb->pb_flags & _PBF_PAGE_CACHE)) {
1249                         unsigned long   j, range;
1250
1251                         ASSERT(blocksize < PAGE_CACHE_SIZE);
1252                         range = (bvec->bv_offset + bvec->bv_len) >> sectorshift;
1253                         for (j = bvec->bv_offset >> sectorshift; j < range; j++)
1254                                 set_bit(j, &page->private);
1255                         if (page->private == (unsigned long)(PAGE_CACHE_SIZE-1))
1256                                 SetPageUptodate(page);
1257                 }
1258
1259                 if (_pagebuf_iolocked(pb)) {
1260                         unlock_page(page);
1261                 }
1262         }
1263
1264         _pagebuf_iodone(pb, 1);
1265         bio_put(bio);
1266         return 0;
1267 }
1268
1269 void
1270 _pagebuf_ioapply(
1271         xfs_buf_t               *pb)
1272 {
1273         int                     i, map_i, total_nr_pages, nr_pages;
1274         struct bio              *bio;
1275         int                     offset = pb->pb_offset;
1276         int                     size = pb->pb_count_desired;
1277         sector_t                sector = pb->pb_bn;
1278         unsigned int            blocksize = pb->pb_target->pbr_bsize;
1279         int                     locking = _pagebuf_iolocked(pb);
1280
1281         total_nr_pages = pb->pb_page_count;
1282         map_i = 0;
1283
1284         /* Special code path for reading a sub page size pagebuf in --
1285          * we populate up the whole page, and hence the other metadata
1286          * in the same page.  This optimization is only valid when the
1287          * filesystem block size and the page size are equal.
1288          */
1289         if ((pb->pb_buffer_length < PAGE_CACHE_SIZE) &&
1290             (pb->pb_flags & PBF_READ) && locking &&
1291             (blocksize == PAGE_CACHE_SIZE)) {
1292                 bio = bio_alloc(GFP_NOIO, 1);
1293
1294                 bio->bi_bdev = pb->pb_target->pbr_bdev;
1295                 bio->bi_sector = sector - (offset >> BBSHIFT);
1296                 bio->bi_end_io = bio_end_io_pagebuf;
1297                 bio->bi_private = pb;
1298
1299                 bio_add_page(bio, pb->pb_pages[0], PAGE_CACHE_SIZE, 0);
1300                 size = 0;
1301
1302                 atomic_inc(&pb->pb_io_remaining);
1303
1304                 goto submit_io;
1305         }
1306
1307         /* Lock down the pages which we need to for the request */
1308         if (locking && (pb->pb_flags & PBF_WRITE) && (pb->pb_locked == 0)) {
1309                 for (i = 0; size; i++) {
1310                         int             nbytes = PAGE_CACHE_SIZE - offset;
1311                         struct page     *page = pb->pb_pages[i];
1312
1313                         if (nbytes > size)
1314                                 nbytes = size;
1315
1316                         lock_page(page);
1317
1318                         size -= nbytes;
1319                         offset = 0;
1320                 }
1321                 offset = pb->pb_offset;
1322                 size = pb->pb_count_desired;
1323         }
1324
1325 next_chunk:
1326         atomic_inc(&pb->pb_io_remaining);
1327         nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1328         if (nr_pages > total_nr_pages)
1329                 nr_pages = total_nr_pages;
1330
1331         bio = bio_alloc(GFP_NOIO, nr_pages);
1332         bio->bi_bdev = pb->pb_target->pbr_bdev;
1333         bio->bi_sector = sector;
1334         bio->bi_end_io = bio_end_io_pagebuf;
1335         bio->bi_private = pb;
1336
1337         for (; size && nr_pages; nr_pages--, map_i++) {
1338                 int     nbytes = PAGE_CACHE_SIZE - offset;
1339
1340                 if (nbytes > size)
1341                         nbytes = size;
1342
1343                 if (bio_add_page(bio, pb->pb_pages[map_i],
1344                                         nbytes, offset) < nbytes)
1345                         break;
1346
1347                 offset = 0;
1348                 sector += nbytes >> BBSHIFT;
1349                 size -= nbytes;
1350                 total_nr_pages--;
1351         }
1352
1353 submit_io:
1354         if (likely(bio->bi_size)) {
1355                 submit_bio((pb->pb_flags & PBF_READ) ? READ : WRITE, bio);
1356                 if (size)
1357                         goto next_chunk;
1358         } else {
1359                 bio_put(bio);
1360                 pagebuf_ioerror(pb, EIO);
1361         }
1362
1363         if (pb->pb_flags & _PBF_RUN_QUEUES) {
1364                 pb->pb_flags &= ~_PBF_RUN_QUEUES;
1365                 if (atomic_read(&pb->pb_io_remaining) > 1)
1366                         blk_run_address_space(pb->pb_target->pbr_mapping);
1367         }
1368 }
1369
1370 /*
1371  *      pagebuf_iorequest -- the core I/O request routine.
1372  */
1373 int
1374 pagebuf_iorequest(                      /* start real I/O               */
1375         xfs_buf_t               *pb)    /* buffer to convey to device   */
1376 {
1377         PB_TRACE(pb, "iorequest", 0);
1378
1379         if (pb->pb_flags & PBF_DELWRI) {
1380                 pagebuf_delwri_queue(pb, 1);
1381                 return 0;
1382         }
1383
1384         if (pb->pb_flags & PBF_WRITE) {
1385                 _pagebuf_wait_unpin(pb);
1386         }
1387
1388         pagebuf_hold(pb);
1389
1390         /* Set the count to 1 initially, this will stop an I/O
1391          * completion callout which happens before we have started
1392          * all the I/O from calling pagebuf_iodone too early.
1393          */
1394         atomic_set(&pb->pb_io_remaining, 1);
1395         _pagebuf_ioapply(pb);
1396         _pagebuf_iodone(pb, 0);
1397
1398         pagebuf_rele(pb);
1399         return 0;
1400 }
1401
1402 /*
1403  *      pagebuf_iowait
1404  *
1405  *      pagebuf_iowait waits for I/O to complete on the buffer supplied.
1406  *      It returns immediately if no I/O is pending.  In any case, it returns
1407  *      the error code, if any, or 0 if there is no error.
1408  */
1409 int
1410 pagebuf_iowait(
1411         xfs_buf_t               *pb)
1412 {
1413         PB_TRACE(pb, "iowait", 0);
1414         if (atomic_read(&pb->pb_io_remaining))
1415                 blk_run_address_space(pb->pb_target->pbr_mapping);
1416         down(&pb->pb_iodonesema);
1417         PB_TRACE(pb, "iowaited", (long)pb->pb_error);
1418         return pb->pb_error;
1419 }
1420
1421 caddr_t
1422 pagebuf_offset(
1423         xfs_buf_t               *pb,
1424         size_t                  offset)
1425 {
1426         struct page             *page;
1427
1428         offset += pb->pb_offset;
1429
1430         page = pb->pb_pages[offset >> PAGE_CACHE_SHIFT];
1431         return (caddr_t) page_address(page) + (offset & (PAGE_CACHE_SIZE - 1));
1432 }
1433
1434 /*
1435  *      pagebuf_iomove
1436  *
1437  *      Move data into or out of a buffer.
1438  */
1439 void
1440 pagebuf_iomove(
1441         xfs_buf_t               *pb,    /* buffer to process            */
1442         size_t                  boff,   /* starting buffer offset       */
1443         size_t                  bsize,  /* length to copy               */
1444         caddr_t                 data,   /* data address                 */
1445         page_buf_rw_t           mode)   /* read/write flag              */
1446 {
1447         size_t                  bend, cpoff, csize;
1448         struct page             *page;
1449
1450         bend = boff + bsize;
1451         while (boff < bend) {
1452                 page = pb->pb_pages[page_buf_btoct(boff + pb->pb_offset)];
1453                 cpoff = page_buf_poff(boff + pb->pb_offset);
1454                 csize = min_t(size_t,
1455                               PAGE_CACHE_SIZE-cpoff, pb->pb_count_desired-boff);
1456
1457                 ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE));
1458
1459                 switch (mode) {
1460                 case PBRW_ZERO:
1461                         memset(page_address(page) + cpoff, 0, csize);
1462                         break;
1463                 case PBRW_READ:
1464                         memcpy(data, page_address(page) + cpoff, csize);
1465                         break;
1466                 case PBRW_WRITE:
1467                         memcpy(page_address(page) + cpoff, data, csize);
1468                 }
1469
1470                 boff += csize;
1471                 data += csize;
1472         }
1473 }
1474
1475 /*
1476  *      Handling of buftargs.
1477  */
1478
1479 void
1480 xfs_free_buftarg(
1481         xfs_buftarg_t           *btp,
1482         int                     external)
1483 {
1484         xfs_flush_buftarg(btp, 1);
1485         if (external)
1486                 xfs_blkdev_put(btp->pbr_bdev);
1487         kmem_free(btp, sizeof(*btp));
1488 }
1489
1490 void
1491 xfs_incore_relse(
1492         xfs_buftarg_t           *btp,
1493         int                     delwri_only,
1494         int                     wait)
1495 {
1496         invalidate_bdev(btp->pbr_bdev, 1);
1497         truncate_inode_pages(btp->pbr_mapping, 0LL);
1498 }
1499
1500 void
1501 xfs_setsize_buftarg(
1502         xfs_buftarg_t           *btp,
1503         unsigned int            blocksize,
1504         unsigned int            sectorsize)
1505 {
1506         btp->pbr_bsize = blocksize;
1507         btp->pbr_sshift = ffs(sectorsize) - 1;
1508         btp->pbr_smask = sectorsize - 1;
1509
1510         if (set_blocksize(btp->pbr_bdev, sectorsize)) {
1511                 printk(KERN_WARNING
1512                         "XFS: Cannot set_blocksize to %u on device %s\n",
1513                         sectorsize, XFS_BUFTARG_NAME(btp));
1514         }
1515 }
1516
1517 xfs_buftarg_t *
1518 xfs_alloc_buftarg(
1519         struct block_device     *bdev)
1520 {
1521         xfs_buftarg_t           *btp;
1522
1523         btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
1524
1525         btp->pbr_dev =  bdev->bd_dev;
1526         btp->pbr_bdev = bdev;
1527         btp->pbr_mapping = bdev->bd_inode->i_mapping;
1528         xfs_setsize_buftarg(btp, PAGE_CACHE_SIZE, bdev_hardsect_size(bdev));
1529
1530         return btp;
1531 }
1532
1533
1534 /*
1535  * Pagebuf delayed write buffer handling
1536  */
1537
1538 STATIC LIST_HEAD(pbd_delwrite_queue);
1539 STATIC spinlock_t pbd_delwrite_lock = SPIN_LOCK_UNLOCKED;
1540
1541 STATIC void
1542 pagebuf_delwri_queue(
1543         xfs_buf_t               *pb,
1544         int                     unlock)
1545 {
1546         PB_TRACE(pb, "delwri_q", (long)unlock);
1547         ASSERT(pb->pb_flags & PBF_DELWRI);
1548
1549         spin_lock(&pbd_delwrite_lock);
1550         /* If already in the queue, dequeue and place at tail */
1551         if (!list_empty(&pb->pb_list)) {
1552                 if (unlock) {
1553                         atomic_dec(&pb->pb_hold);
1554                 }
1555                 list_del(&pb->pb_list);
1556         }
1557
1558         list_add_tail(&pb->pb_list, &pbd_delwrite_queue);
1559         pb->pb_queuetime = jiffies;
1560         spin_unlock(&pbd_delwrite_lock);
1561
1562         if (unlock)
1563                 pagebuf_unlock(pb);
1564 }
1565
1566 void
1567 pagebuf_delwri_dequeue(
1568         xfs_buf_t               *pb)
1569 {
1570         int                     dequeued = 0;
1571
1572         spin_lock(&pbd_delwrite_lock);
1573         if ((pb->pb_flags & PBF_DELWRI) && !list_empty(&pb->pb_list)) {
1574                 list_del_init(&pb->pb_list);
1575                 dequeued = 1;
1576         }
1577         pb->pb_flags &= ~PBF_DELWRI;
1578         spin_unlock(&pbd_delwrite_lock);
1579
1580         if (dequeued)
1581                 pagebuf_rele(pb);
1582
1583         PB_TRACE(pb, "delwri_dq", (long)dequeued);
1584 }
1585
1586 STATIC void
1587 pagebuf_runall_queues(
1588         struct workqueue_struct *queue)
1589 {
1590         flush_workqueue(queue);
1591 }
1592
1593 /* Defines for pagebuf daemon */
1594 STATIC DECLARE_COMPLETION(pagebuf_daemon_done);
1595 STATIC struct task_struct *pagebuf_daemon_task;
1596 STATIC int pagebuf_daemon_active;
1597 STATIC int force_flush;
1598
1599
1600 STATIC int
1601 pagebuf_daemon_wakeup(
1602         int                     priority,
1603         unsigned int            mask)
1604 {
1605         force_flush = 1;
1606         barrier();
1607         wake_up_process(pagebuf_daemon_task);
1608         return 0;
1609 }
1610
1611 STATIC int
1612 pagebuf_daemon(
1613         void                    *data)
1614 {
1615         struct list_head        tmp;
1616         unsigned long           age;
1617         xfs_buftarg_t           *target;
1618         xfs_buf_t               *pb, *n;
1619
1620         /*  Set up the thread  */
1621         daemonize("xfsbufd");
1622         current->flags |= PF_MEMALLOC;
1623
1624         pagebuf_daemon_task = current;
1625         pagebuf_daemon_active = 1;
1626         barrier();
1627
1628         INIT_LIST_HEAD(&tmp);
1629         do {
1630                 /* swsusp */
1631                 if (current->flags & PF_FREEZE)
1632                         refrigerator(PF_FREEZE);
1633
1634                 set_current_state(TASK_INTERRUPTIBLE);
1635                 schedule_timeout((xfs_buf_timer_centisecs * HZ) / 100);
1636
1637                 age = (xfs_buf_age_centisecs * HZ) / 100;
1638                 spin_lock(&pbd_delwrite_lock);
1639                 list_for_each_entry_safe(pb, n, &pbd_delwrite_queue, pb_list) {
1640                         PB_TRACE(pb, "walkq1", (long)pagebuf_ispin(pb));
1641                         ASSERT(pb->pb_flags & PBF_DELWRI);
1642
1643                         if (!pagebuf_ispin(pb) && !pagebuf_cond_lock(pb)) {
1644                                 if (!force_flush &&
1645                                     time_before(jiffies,
1646                                                 pb->pb_queuetime + age)) {
1647                                         pagebuf_unlock(pb);
1648                                         break;
1649                                 }
1650
1651                                 pb->pb_flags &= ~PBF_DELWRI;
1652                                 pb->pb_flags |= PBF_WRITE;
1653                                 list_move(&pb->pb_list, &tmp);
1654                         }
1655                 }
1656                 spin_unlock(&pbd_delwrite_lock);
1657
1658                 while (!list_empty(&tmp)) {
1659                         pb = list_entry(tmp.next, xfs_buf_t, pb_list);
1660                         target = pb->pb_target;
1661
1662                         list_del_init(&pb->pb_list);
1663                         pagebuf_iostrategy(pb);
1664
1665                         blk_run_address_space(target->pbr_mapping);
1666                 }
1667
1668                 if (as_list_len > 0)
1669                         purge_addresses();
1670
1671                 force_flush = 0;
1672         } while (pagebuf_daemon_active);
1673
1674         complete_and_exit(&pagebuf_daemon_done, 0);
1675 }
1676
1677 /*
1678  * Go through all incore buffers, and release buffers if they belong to
1679  * the given device. This is used in filesystem error handling to
1680  * preserve the consistency of its metadata.
1681  */
1682 int
1683 xfs_flush_buftarg(
1684         xfs_buftarg_t           *target,
1685         int                     wait)
1686 {
1687         struct list_head        tmp;
1688         xfs_buf_t               *pb, *n;
1689         int                     pincount = 0;
1690
1691         pagebuf_runall_queues(pagebuf_dataio_workqueue);
1692         pagebuf_runall_queues(pagebuf_logio_workqueue);
1693
1694         INIT_LIST_HEAD(&tmp);
1695         spin_lock(&pbd_delwrite_lock);
1696         list_for_each_entry_safe(pb, n, &pbd_delwrite_queue, pb_list) {
1697
1698                 if (pb->pb_target != target)
1699                         continue;
1700
1701                 ASSERT(pb->pb_flags & PBF_DELWRI);
1702                 PB_TRACE(pb, "walkq2", (long)pagebuf_ispin(pb));
1703                 if (pagebuf_ispin(pb)) {
1704                         pincount++;
1705                         continue;
1706                 }
1707
1708                 pb->pb_flags &= ~PBF_DELWRI;
1709                 pb->pb_flags |= PBF_WRITE;
1710                 list_move(&pb->pb_list, &tmp);
1711         }
1712         spin_unlock(&pbd_delwrite_lock);
1713
1714         /*
1715          * Dropped the delayed write list lock, now walk the temporary list
1716          */
1717         list_for_each_entry_safe(pb, n, &tmp, pb_list) {
1718                 if (wait)
1719                         pb->pb_flags &= ~PBF_ASYNC;
1720                 else
1721                         list_del_init(&pb->pb_list);
1722
1723                 pagebuf_lock(pb);
1724                 pagebuf_iostrategy(pb);
1725         }
1726
1727         /*
1728          * Remaining list items must be flushed before returning
1729          */
1730         while (!list_empty(&tmp)) {
1731                 pb = list_entry(tmp.next, xfs_buf_t, pb_list);
1732
1733                 list_del_init(&pb->pb_list);
1734                 xfs_iowait(pb);
1735                 xfs_buf_relse(pb);
1736         }
1737
1738         if (wait)
1739                 blk_run_address_space(target->pbr_mapping);
1740
1741         return pincount;
1742 }
1743
1744 STATIC int
1745 pagebuf_daemon_start(void)
1746 {
1747         int             rval;
1748
1749         pagebuf_logio_workqueue = create_workqueue("xfslogd");
1750         if (!pagebuf_logio_workqueue)
1751                 return -ENOMEM;
1752
1753         pagebuf_dataio_workqueue = create_workqueue("xfsdatad");
1754         if (!pagebuf_dataio_workqueue) {
1755                 destroy_workqueue(pagebuf_logio_workqueue);
1756                 return -ENOMEM;
1757         }
1758
1759         rval = kernel_thread(pagebuf_daemon, NULL, CLONE_FS|CLONE_FILES);
1760         if (rval < 0) {
1761                 destroy_workqueue(pagebuf_logio_workqueue);
1762                 destroy_workqueue(pagebuf_dataio_workqueue);
1763         }
1764
1765         return rval;
1766 }
1767
1768 /*
1769  * pagebuf_daemon_stop
1770  *
1771  * Note: do not mark as __exit, it is called from pagebuf_terminate.
1772  */
1773 STATIC void
1774 pagebuf_daemon_stop(void)
1775 {
1776         pagebuf_daemon_active = 0;
1777         barrier();
1778         wait_for_completion(&pagebuf_daemon_done);
1779
1780         destroy_workqueue(pagebuf_logio_workqueue);
1781         destroy_workqueue(pagebuf_dataio_workqueue);
1782 }
1783
1784 /*
1785  *      Initialization and Termination
1786  */
1787
1788 int __init
1789 pagebuf_init(void)
1790 {
1791         int                     i;
1792
1793         pagebuf_cache = kmem_cache_create("xfs_buf_t", sizeof(xfs_buf_t), 0,
1794                         SLAB_HWCACHE_ALIGN, NULL, NULL);
1795         if (pagebuf_cache == NULL) {
1796                 printk("XFS: couldn't init xfs_buf_t cache\n");
1797                 pagebuf_terminate();
1798                 return -ENOMEM;
1799         }
1800
1801 #ifdef PAGEBUF_TRACE
1802         pagebuf_trace_buf = ktrace_alloc(PAGEBUF_TRACE_SIZE, KM_SLEEP);
1803 #endif
1804
1805         pagebuf_daemon_start();
1806
1807         pagebuf_shake = kmem_shake_register(pagebuf_daemon_wakeup);
1808         if (pagebuf_shake == NULL) {
1809                 pagebuf_terminate();
1810                 return -ENOMEM;
1811         }
1812
1813         for (i = 0; i < NHASH; i++) {
1814                 spin_lock_init(&pbhash[i].pb_hash_lock);
1815                 INIT_LIST_HEAD(&pbhash[i].pb_hash);
1816         }
1817
1818         return 0;
1819 }
1820
1821
1822 /*
1823  *      pagebuf_terminate.
1824  *
1825  *      Note: do not mark as __exit, this is also called from the __init code.
1826  */
1827 void
1828 pagebuf_terminate(void)
1829 {
1830         pagebuf_daemon_stop();
1831
1832 #ifdef PAGEBUF_TRACE
1833         ktrace_free(pagebuf_trace_buf);
1834 #endif
1835
1836         kmem_zone_destroy(pagebuf_cache);
1837         kmem_shake_deregister(pagebuf_shake);
1838 }