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