fs/xfs/linux-2.6/xfs_buf.c

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