linux/fs/xfs/linux-2.6/xfs_buf.c
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   1/*
   2 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#include "xfs.h"
  19#include <linux/stddef.h>
  20#include <linux/errno.h>
  21#include <linux/slab.h>
  22#include <linux/pagemap.h>
  23#include <linux/init.h>
  24#include <linux/vmalloc.h>
  25#include <linux/bio.h>
  26#include <linux/sysctl.h>
  27#include <linux/proc_fs.h>
  28#include <linux/workqueue.h>
  29#include <linux/percpu.h>
  30#include <linux/blkdev.h>
  31#include <linux/hash.h>
  32#include <linux/kthread.h>
  33#include <linux/migrate.h>
  34#include <linux/backing-dev.h>
  35#include <linux/freezer.h>
  36
  37static kmem_zone_t *xfs_buf_zone;
  38STATIC int xfsbufd(void *);
  39STATIC int xfsbufd_wakeup(int, gfp_t);
  40STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
  41static struct shrinker xfs_buf_shake = {
  42        .shrink = xfsbufd_wakeup,
  43        .seeks = DEFAULT_SEEKS,
  44};
  45
  46static struct workqueue_struct *xfslogd_workqueue;
  47struct workqueue_struct *xfsdatad_workqueue;
  48
  49#ifdef XFS_BUF_TRACE
  50void
  51xfs_buf_trace(
  52        xfs_buf_t       *bp,
  53        char            *id,
  54        void            *data,
  55        void            *ra)
  56{
  57        ktrace_enter(xfs_buf_trace_buf,
  58                bp, id,
  59                (void *)(unsigned long)bp->b_flags,
  60                (void *)(unsigned long)bp->b_hold.counter,
  61                (void *)(unsigned long)bp->b_sema.count,
  62                (void *)current,
  63                data, ra,
  64                (void *)(unsigned long)((bp->b_file_offset>>32) & 0xffffffff),
  65                (void *)(unsigned long)(bp->b_file_offset & 0xffffffff),
  66                (void *)(unsigned long)bp->b_buffer_length,
  67                NULL, NULL, NULL, NULL, NULL);
  68}
  69ktrace_t *xfs_buf_trace_buf;
  70#define XFS_BUF_TRACE_SIZE      4096
  71#define XB_TRACE(bp, id, data)  \
  72        xfs_buf_trace(bp, id, (void *)data, (void *)__builtin_return_address(0))
  73#else
  74#define XB_TRACE(bp, id, data)  do { } while (0)
  75#endif
  76
  77#ifdef XFS_BUF_LOCK_TRACKING
  78# define XB_SET_OWNER(bp)       ((bp)->b_last_holder = current->pid)
  79# define XB_CLEAR_OWNER(bp)     ((bp)->b_last_holder = -1)
  80# define XB_GET_OWNER(bp)       ((bp)->b_last_holder)
  81#else
  82# define XB_SET_OWNER(bp)       do { } while (0)
  83# define XB_CLEAR_OWNER(bp)     do { } while (0)
  84# define XB_GET_OWNER(bp)       do { } while (0)
  85#endif
  86
  87#define xb_to_gfp(flags) \
  88        ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
  89          ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
  90
  91#define xb_to_km(flags) \
  92         (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
  93
  94#define xfs_buf_allocate(flags) \
  95        kmem_zone_alloc(xfs_buf_zone, xb_to_km(flags))
  96#define xfs_buf_deallocate(bp) \
  97        kmem_zone_free(xfs_buf_zone, (bp));
  98
  99/*
 100 *      Page Region interfaces.
 101 *
 102 *      For pages in filesystems where the blocksize is smaller than the
 103 *      pagesize, we use the page->private field (long) to hold a bitmap
 104 *      of uptodate regions within the page.
 105 *
 106 *      Each such region is "bytes per page / bits per long" bytes long.
 107 *
 108 *      NBPPR == number-of-bytes-per-page-region
 109 *      BTOPR == bytes-to-page-region (rounded up)
 110 *      BTOPRT == bytes-to-page-region-truncated (rounded down)
 111 */
 112#if (BITS_PER_LONG == 32)
 113#define PRSHIFT         (PAGE_CACHE_SHIFT - 5)  /* (32 == 1<<5) */
 114#elif (BITS_PER_LONG == 64)
 115#define PRSHIFT         (PAGE_CACHE_SHIFT - 6)  /* (64 == 1<<6) */
 116#else
 117#error BITS_PER_LONG must be 32 or 64
 118#endif
 119#define NBPPR           (PAGE_CACHE_SIZE/BITS_PER_LONG)
 120#define BTOPR(b)        (((unsigned int)(b) + (NBPPR - 1)) >> PRSHIFT)
 121#define BTOPRT(b)       (((unsigned int)(b) >> PRSHIFT))
 122
 123STATIC unsigned long
 124page_region_mask(
 125        size_t          offset,
 126        size_t          length)
 127{
 128        unsigned long   mask;
 129        int             first, final;
 130
 131        first = BTOPR(offset);
 132        final = BTOPRT(offset + length - 1);
 133        first = min(first, final);
 134
 135        mask = ~0UL;
 136        mask <<= BITS_PER_LONG - (final - first);
 137        mask >>= BITS_PER_LONG - (final);
 138
 139        ASSERT(offset + length <= PAGE_CACHE_SIZE);
 140        ASSERT((final - first) < BITS_PER_LONG && (final - first) >= 0);
 141
 142        return mask;
 143}
 144
 145STATIC_INLINE void
 146set_page_region(
 147        struct page     *page,
 148        size_t          offset,
 149        size_t          length)
 150{
 151        set_page_private(page,
 152                page_private(page) | page_region_mask(offset, length));
 153        if (page_private(page) == ~0UL)
 154                SetPageUptodate(page);
 155}
 156
 157STATIC_INLINE int
 158test_page_region(
 159        struct page     *page,
 160        size_t          offset,
 161        size_t          length)
 162{
 163        unsigned long   mask = page_region_mask(offset, length);
 164
 165        return (mask && (page_private(page) & mask) == mask);
 166}
 167
 168/*
 169 *      Mapping of multi-page buffers into contiguous virtual space
 170 */
 171
 172typedef struct a_list {
 173        void            *vm_addr;
 174        struct a_list   *next;
 175} a_list_t;
 176
 177static a_list_t         *as_free_head;
 178static int              as_list_len;
 179static DEFINE_SPINLOCK(as_lock);
 180
 181/*
 182 *      Try to batch vunmaps because they are costly.
 183 */
 184STATIC void
 185free_address(
 186        void            *addr)
 187{
 188        a_list_t        *aentry;
 189
 190#ifdef CONFIG_XEN
 191        /*
 192         * Xen needs to be able to make sure it can get an exclusive
 193         * RO mapping of pages it wants to turn into a pagetable.  If
 194         * a newly allocated page is also still being vmap()ed by xfs,
 195         * it will cause pagetable construction to fail.  This is a
 196         * quick workaround to always eagerly unmap pages so that Xen
 197         * is happy.
 198         */
 199        vunmap(addr);
 200        return;
 201#endif
 202
 203        aentry = kmalloc(sizeof(a_list_t), GFP_NOWAIT);
 204        if (likely(aentry)) {
 205                spin_lock(&as_lock);
 206                aentry->next = as_free_head;
 207                aentry->vm_addr = addr;
 208                as_free_head = aentry;
 209                as_list_len++;
 210                spin_unlock(&as_lock);
 211        } else {
 212                vunmap(addr);
 213        }
 214}
 215
 216STATIC void
 217purge_addresses(void)
 218{
 219        a_list_t        *aentry, *old;
 220
 221        if (as_free_head == NULL)
 222                return;
 223
 224        spin_lock(&as_lock);
 225        aentry = as_free_head;
 226        as_free_head = NULL;
 227        as_list_len = 0;
 228        spin_unlock(&as_lock);
 229
 230        while ((old = aentry) != NULL) {
 231                vunmap(aentry->vm_addr);
 232                aentry = aentry->next;
 233                kfree(old);
 234        }
 235}
 236
 237/*
 238 *      Internal xfs_buf_t object manipulation
 239 */
 240
 241STATIC void
 242_xfs_buf_initialize(
 243        xfs_buf_t               *bp,
 244        xfs_buftarg_t           *target,
 245        xfs_off_t               range_base,
 246        size_t                  range_length,
 247        xfs_buf_flags_t         flags)
 248{
 249        /*
 250         * We don't want certain flags to appear in b_flags.
 251         */
 252        flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
 253
 254        memset(bp, 0, sizeof(xfs_buf_t));
 255        atomic_set(&bp->b_hold, 1);
 256        init_completion(&bp->b_iowait);
 257        INIT_LIST_HEAD(&bp->b_list);
 258        INIT_LIST_HEAD(&bp->b_hash_list);
 259        init_MUTEX_LOCKED(&bp->b_sema); /* held, no waiters */
 260        XB_SET_OWNER(bp);
 261        bp->b_target = target;
 262        bp->b_file_offset = range_base;
 263        /*
 264         * Set buffer_length and count_desired to the same value initially.
 265         * I/O routines should use count_desired, which will be the same in
 266         * most cases but may be reset (e.g. XFS recovery).
 267         */
 268        bp->b_buffer_length = bp->b_count_desired = range_length;
 269        bp->b_flags = flags;
 270        bp->b_bn = XFS_BUF_DADDR_NULL;
 271        atomic_set(&bp->b_pin_count, 0);
 272        init_waitqueue_head(&bp->b_waiters);
 273
 274        XFS_STATS_INC(xb_create);
 275        XB_TRACE(bp, "initialize", target);
 276}
 277
 278/*
 279 *      Allocate a page array capable of holding a specified number
 280 *      of pages, and point the page buf at it.
 281 */
 282STATIC int
 283_xfs_buf_get_pages(
 284        xfs_buf_t               *bp,
 285        int                     page_count,
 286        xfs_buf_flags_t         flags)
 287{
 288        /* Make sure that we have a page list */
 289        if (bp->b_pages == NULL) {
 290                bp->b_offset = xfs_buf_poff(bp->b_file_offset);
 291                bp->b_page_count = page_count;
 292                if (page_count <= XB_PAGES) {
 293                        bp->b_pages = bp->b_page_array;
 294                } else {
 295                        bp->b_pages = kmem_alloc(sizeof(struct page *) *
 296                                        page_count, xb_to_km(flags));
 297                        if (bp->b_pages == NULL)
 298                                return -ENOMEM;
 299                }
 300                memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
 301        }
 302        return 0;
 303}
 304
 305/*
 306 *      Frees b_pages if it was allocated.
 307 */
 308STATIC void
 309_xfs_buf_free_pages(
 310        xfs_buf_t       *bp)
 311{
 312        if (bp->b_pages != bp->b_page_array) {
 313                kmem_free(bp->b_pages);
 314        }
 315}
 316
 317/*
 318 *      Releases the specified buffer.
 319 *
 320 *      The modification state of any associated pages is left unchanged.
 321 *      The buffer most not be on any hash - use xfs_buf_rele instead for
 322 *      hashed and refcounted buffers
 323 */
 324void
 325xfs_buf_free(
 326        xfs_buf_t               *bp)
 327{
 328        XB_TRACE(bp, "free", 0);
 329
 330        ASSERT(list_empty(&bp->b_hash_list));
 331
 332        if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) {
 333                uint            i;
 334
 335                if ((bp->b_flags & XBF_MAPPED) && (bp->b_page_count > 1))
 336                        free_address(bp->b_addr - bp->b_offset);
 337
 338                for (i = 0; i < bp->b_page_count; i++) {
 339                        struct page     *page = bp->b_pages[i];
 340
 341                        if (bp->b_flags & _XBF_PAGE_CACHE)
 342                                ASSERT(!PagePrivate(page));
 343                        page_cache_release(page);
 344                }
 345                _xfs_buf_free_pages(bp);
 346        }
 347
 348        xfs_buf_deallocate(bp);
 349}
 350
 351/*
 352 *      Finds all pages for buffer in question and builds it's page list.
 353 */
 354STATIC int
 355_xfs_buf_lookup_pages(
 356        xfs_buf_t               *bp,
 357        uint                    flags)
 358{
 359        struct address_space    *mapping = bp->b_target->bt_mapping;
 360        size_t                  blocksize = bp->b_target->bt_bsize;
 361        size_t                  size = bp->b_count_desired;
 362        size_t                  nbytes, offset;
 363        gfp_t                   gfp_mask = xb_to_gfp(flags);
 364        unsigned short          page_count, i;
 365        pgoff_t                 first;
 366        xfs_off_t               end;
 367        int                     error;
 368
 369        end = bp->b_file_offset + bp->b_buffer_length;
 370        page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
 371
 372        error = _xfs_buf_get_pages(bp, page_count, flags);
 373        if (unlikely(error))
 374                return error;
 375        bp->b_flags |= _XBF_PAGE_CACHE;
 376
 377        offset = bp->b_offset;
 378        first = bp->b_file_offset >> PAGE_CACHE_SHIFT;
 379
 380        for (i = 0; i < bp->b_page_count; i++) {
 381                struct page     *page;
 382                uint            retries = 0;
 383
 384              retry:
 385                page = find_or_create_page(mapping, first + i, gfp_mask);
 386                if (unlikely(page == NULL)) {
 387                        if (flags & XBF_READ_AHEAD) {
 388                                bp->b_page_count = i;
 389                                for (i = 0; i < bp->b_page_count; i++)
 390                                        unlock_page(bp->b_pages[i]);
 391                                return -ENOMEM;
 392                        }
 393
 394                        /*
 395                         * This could deadlock.
 396                         *
 397                         * But until all the XFS lowlevel code is revamped to
 398                         * handle buffer allocation failures we can't do much.
 399                         */
 400                        if (!(++retries % 100))
 401                                printk(KERN_ERR
 402                                        "XFS: possible memory allocation "
 403                                        "deadlock in %s (mode:0x%x)\n",
 404                                        __func__, gfp_mask);
 405
 406                        XFS_STATS_INC(xb_page_retries);
 407                        xfsbufd_wakeup(0, gfp_mask);
 408                        congestion_wait(WRITE, HZ/50);
 409                        goto retry;
 410                }
 411
 412                XFS_STATS_INC(xb_page_found);
 413
 414                nbytes = min_t(size_t, size, PAGE_CACHE_SIZE - offset);
 415                size -= nbytes;
 416
 417                ASSERT(!PagePrivate(page));
 418                if (!PageUptodate(page)) {
 419                        page_count--;
 420                        if (blocksize >= PAGE_CACHE_SIZE) {
 421                                if (flags & XBF_READ)
 422                                        bp->b_flags |= _XBF_PAGE_LOCKED;
 423                        } else if (!PagePrivate(page)) {
 424                                if (test_page_region(page, offset, nbytes))
 425                                        page_count++;
 426                        }
 427                }
 428
 429                bp->b_pages[i] = page;
 430                offset = 0;
 431        }
 432
 433        if (!(bp->b_flags & _XBF_PAGE_LOCKED)) {
 434                for (i = 0; i < bp->b_page_count; i++)
 435                        unlock_page(bp->b_pages[i]);
 436        }
 437
 438        if (page_count == bp->b_page_count)
 439                bp->b_flags |= XBF_DONE;
 440
 441        XB_TRACE(bp, "lookup_pages", (long)page_count);
 442        return error;
 443}
 444
 445/*
 446 *      Map buffer into kernel address-space if nessecary.
 447 */
 448STATIC int
 449_xfs_buf_map_pages(
 450        xfs_buf_t               *bp,
 451        uint                    flags)
 452{
 453        /* A single page buffer is always mappable */
 454        if (bp->b_page_count == 1) {
 455                bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
 456                bp->b_flags |= XBF_MAPPED;
 457        } else if (flags & XBF_MAPPED) {
 458                if (as_list_len > 64)
 459                        purge_addresses();
 460                bp->b_addr = vmap(bp->b_pages, bp->b_page_count,
 461                                        VM_MAP, PAGE_KERNEL);
 462                if (unlikely(bp->b_addr == NULL))
 463                        return -ENOMEM;
 464                bp->b_addr += bp->b_offset;
 465                bp->b_flags |= XBF_MAPPED;
 466        }
 467
 468        return 0;
 469}
 470
 471/*
 472 *      Finding and Reading Buffers
 473 */
 474
 475/*
 476 *      Look up, and creates if absent, a lockable buffer for
 477 *      a given range of an inode.  The buffer is returned
 478 *      locked.  If other overlapping buffers exist, they are
 479 *      released before the new buffer is created and locked,
 480 *      which may imply that this call will block until those buffers
 481 *      are unlocked.  No I/O is implied by this call.
 482 */
 483xfs_buf_t *
 484_xfs_buf_find(
 485        xfs_buftarg_t           *btp,   /* block device target          */
 486        xfs_off_t               ioff,   /* starting offset of range     */
 487        size_t                  isize,  /* length of range              */
 488        xfs_buf_flags_t         flags,
 489        xfs_buf_t               *new_bp)
 490{
 491        xfs_off_t               range_base;
 492        size_t                  range_length;
 493        xfs_bufhash_t           *hash;
 494        xfs_buf_t               *bp, *n;
 495
 496        range_base = (ioff << BBSHIFT);
 497        range_length = (isize << BBSHIFT);
 498
 499        /* Check for IOs smaller than the sector size / not sector aligned */
 500        ASSERT(!(range_length < (1 << btp->bt_sshift)));
 501        ASSERT(!(range_base & (xfs_off_t)btp->bt_smask));
 502
 503        hash = &btp->bt_hash[hash_long((unsigned long)ioff, btp->bt_hashshift)];
 504
 505        spin_lock(&hash->bh_lock);
 506
 507        list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
 508                ASSERT(btp == bp->b_target);
 509                if (bp->b_file_offset == range_base &&
 510                    bp->b_buffer_length == range_length) {
 511                        /*
 512                         * If we look at something, bring it to the
 513                         * front of the list for next time.
 514                         */
 515                        atomic_inc(&bp->b_hold);
 516                        list_move(&bp->b_hash_list, &hash->bh_list);
 517                        goto found;
 518                }
 519        }
 520
 521        /* No match found */
 522        if (new_bp) {
 523                _xfs_buf_initialize(new_bp, btp, range_base,
 524                                range_length, flags);
 525                new_bp->b_hash = hash;
 526                list_add(&new_bp->b_hash_list, &hash->bh_list);
 527        } else {
 528                XFS_STATS_INC(xb_miss_locked);
 529        }
 530
 531        spin_unlock(&hash->bh_lock);
 532        return new_bp;
 533
 534found:
 535        spin_unlock(&hash->bh_lock);
 536
 537        /* Attempt to get the semaphore without sleeping,
 538         * if this does not work then we need to drop the
 539         * spinlock and do a hard attempt on the semaphore.
 540         */
 541        if (down_trylock(&bp->b_sema)) {
 542                if (!(flags & XBF_TRYLOCK)) {
 543                        /* wait for buffer ownership */
 544                        XB_TRACE(bp, "get_lock", 0);
 545                        xfs_buf_lock(bp);
 546                        XFS_STATS_INC(xb_get_locked_waited);
 547                } else {
 548                        /* We asked for a trylock and failed, no need
 549                         * to look at file offset and length here, we
 550                         * know that this buffer at least overlaps our
 551                         * buffer and is locked, therefore our buffer
 552                         * either does not exist, or is this buffer.
 553                         */
 554                        xfs_buf_rele(bp);
 555                        XFS_STATS_INC(xb_busy_locked);
 556                        return NULL;
 557                }
 558        } else {
 559                /* trylock worked */
 560                XB_SET_OWNER(bp);
 561        }
 562
 563        if (bp->b_flags & XBF_STALE) {
 564                ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
 565                bp->b_flags &= XBF_MAPPED;
 566        }
 567        XB_TRACE(bp, "got_lock", 0);
 568        XFS_STATS_INC(xb_get_locked);
 569        return bp;
 570}
 571
 572/*
 573 *      Assembles a buffer covering the specified range.
 574 *      Storage in memory for all portions of the buffer will be allocated,
 575 *      although backing storage may not be.
 576 */
 577xfs_buf_t *
 578xfs_buf_get_flags(
 579        xfs_buftarg_t           *target,/* target for buffer            */
 580        xfs_off_t               ioff,   /* starting offset of range     */
 581        size_t                  isize,  /* length of range              */
 582        xfs_buf_flags_t         flags)
 583{
 584        xfs_buf_t               *bp, *new_bp;
 585        int                     error = 0, i;
 586
 587        new_bp = xfs_buf_allocate(flags);
 588        if (unlikely(!new_bp))
 589                return NULL;
 590
 591        bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
 592        if (bp == new_bp) {
 593                error = _xfs_buf_lookup_pages(bp, flags);
 594                if (error)
 595                        goto no_buffer;
 596        } else {
 597                xfs_buf_deallocate(new_bp);
 598                if (unlikely(bp == NULL))
 599                        return NULL;
 600        }
 601
 602        for (i = 0; i < bp->b_page_count; i++)
 603                mark_page_accessed(bp->b_pages[i]);
 604
 605        if (!(bp->b_flags & XBF_MAPPED)) {
 606                error = _xfs_buf_map_pages(bp, flags);
 607                if (unlikely(error)) {
 608                        printk(KERN_WARNING "%s: failed to map pages\n",
 609                                        __func__);
 610                        goto no_buffer;
 611                }
 612        }
 613
 614        XFS_STATS_INC(xb_get);
 615
 616        /*
 617         * Always fill in the block number now, the mapped cases can do
 618         * their own overlay of this later.
 619         */
 620        bp->b_bn = ioff;
 621        bp->b_count_desired = bp->b_buffer_length;
 622
 623        XB_TRACE(bp, "get", (unsigned long)flags);
 624        return bp;
 625
 626 no_buffer:
 627        if (flags & (XBF_LOCK | XBF_TRYLOCK))
 628                xfs_buf_unlock(bp);
 629        xfs_buf_rele(bp);
 630        return NULL;
 631}
 632
 633xfs_buf_t *
 634xfs_buf_read_flags(
 635        xfs_buftarg_t           *target,
 636        xfs_off_t               ioff,
 637        size_t                  isize,
 638        xfs_buf_flags_t         flags)
 639{
 640        xfs_buf_t               *bp;
 641
 642        flags |= XBF_READ;
 643
 644        bp = xfs_buf_get_flags(target, ioff, isize, flags);
 645        if (bp) {
 646                if (!XFS_BUF_ISDONE(bp)) {
 647                        XB_TRACE(bp, "read", (unsigned long)flags);
 648                        XFS_STATS_INC(xb_get_read);
 649                        xfs_buf_iostart(bp, flags);
 650                } else if (flags & XBF_ASYNC) {
 651                        XB_TRACE(bp, "read_async", (unsigned long)flags);
 652                        /*
 653                         * Read ahead call which is already satisfied,
 654                         * drop the buffer
 655                         */
 656                        goto no_buffer;
 657                } else {
 658                        XB_TRACE(bp, "read_done", (unsigned long)flags);
 659                        /* We do not want read in the flags */
 660                        bp->b_flags &= ~XBF_READ;
 661                }
 662        }
 663
 664        return bp;
 665
 666 no_buffer:
 667        if (flags & (XBF_LOCK | XBF_TRYLOCK))
 668                xfs_buf_unlock(bp);
 669        xfs_buf_rele(bp);
 670        return NULL;
 671}
 672
 673/*
 674 *      If we are not low on memory then do the readahead in a deadlock
 675 *      safe manner.
 676 */
 677void
 678xfs_buf_readahead(
 679        xfs_buftarg_t           *target,
 680        xfs_off_t               ioff,
 681        size_t                  isize,
 682        xfs_buf_flags_t         flags)
 683{
 684        struct backing_dev_info *bdi;
 685
 686        bdi = target->bt_mapping->backing_dev_info;
 687        if (bdi_read_congested(bdi))
 688                return;
 689
 690        flags |= (XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD);
 691        xfs_buf_read_flags(target, ioff, isize, flags);
 692}
 693
 694xfs_buf_t *
 695xfs_buf_get_empty(
 696        size_t                  len,
 697        xfs_buftarg_t           *target)
 698{
 699        xfs_buf_t               *bp;
 700
 701        bp = xfs_buf_allocate(0);
 702        if (bp)
 703                _xfs_buf_initialize(bp, target, 0, len, 0);
 704        return bp;
 705}
 706
 707static inline struct page *
 708mem_to_page(
 709        void                    *addr)
 710{
 711        if ((!is_vmalloc_addr(addr))) {
 712                return virt_to_page(addr);
 713        } else {
 714                return vmalloc_to_page(addr);
 715        }
 716}
 717
 718int
 719xfs_buf_associate_memory(
 720        xfs_buf_t               *bp,
 721        void                    *mem,
 722        size_t                  len)
 723{
 724        int                     rval;
 725        int                     i = 0;
 726        unsigned long           pageaddr;
 727        unsigned long           offset;
 728        size_t                  buflen;
 729        int                     page_count;
 730
 731        pageaddr = (unsigned long)mem & PAGE_CACHE_MASK;
 732        offset = (unsigned long)mem - pageaddr;
 733        buflen = PAGE_CACHE_ALIGN(len + offset);
 734        page_count = buflen >> PAGE_CACHE_SHIFT;
 735
 736        /* Free any previous set of page pointers */
 737        if (bp->b_pages)
 738                _xfs_buf_free_pages(bp);
 739
 740        bp->b_pages = NULL;
 741        bp->b_addr = mem;
 742
 743        rval = _xfs_buf_get_pages(bp, page_count, 0);
 744        if (rval)
 745                return rval;
 746
 747        bp->b_offset = offset;
 748
 749        for (i = 0; i < bp->b_page_count; i++) {
 750                bp->b_pages[i] = mem_to_page((void *)pageaddr);
 751                pageaddr += PAGE_CACHE_SIZE;
 752        }
 753
 754        bp->b_count_desired = len;
 755        bp->b_buffer_length = buflen;
 756        bp->b_flags |= XBF_MAPPED;
 757        bp->b_flags &= ~_XBF_PAGE_LOCKED;
 758
 759        return 0;
 760}
 761
 762xfs_buf_t *
 763xfs_buf_get_noaddr(
 764        size_t                  len,
 765        xfs_buftarg_t           *target)
 766{
 767        unsigned long           page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
 768        int                     error, i;
 769        xfs_buf_t               *bp;
 770
 771        bp = xfs_buf_allocate(0);
 772        if (unlikely(bp == NULL))
 773                goto fail;
 774        _xfs_buf_initialize(bp, target, 0, len, 0);
 775
 776        error = _xfs_buf_get_pages(bp, page_count, 0);
 777        if (error)
 778                goto fail_free_buf;
 779
 780        for (i = 0; i < page_count; i++) {
 781                bp->b_pages[i] = alloc_page(GFP_KERNEL);
 782                if (!bp->b_pages[i])
 783                        goto fail_free_mem;
 784        }
 785        bp->b_flags |= _XBF_PAGES;
 786
 787        error = _xfs_buf_map_pages(bp, XBF_MAPPED);
 788        if (unlikely(error)) {
 789                printk(KERN_WARNING "%s: failed to map pages\n",
 790                                __func__);
 791                goto fail_free_mem;
 792        }
 793
 794        xfs_buf_unlock(bp);
 795
 796        XB_TRACE(bp, "no_daddr", len);
 797        return bp;
 798
 799 fail_free_mem:
 800        while (--i >= 0)
 801                __free_page(bp->b_pages[i]);
 802        _xfs_buf_free_pages(bp);
 803 fail_free_buf:
 804        xfs_buf_deallocate(bp);
 805 fail:
 806        return NULL;
 807}
 808
 809/*
 810 *      Increment reference count on buffer, to hold the buffer concurrently
 811 *      with another thread which may release (free) the buffer asynchronously.
 812 *      Must hold the buffer already to call this function.
 813 */
 814void
 815xfs_buf_hold(
 816        xfs_buf_t               *bp)
 817{
 818        atomic_inc(&bp->b_hold);
 819        XB_TRACE(bp, "hold", 0);
 820}
 821
 822/*
 823 *      Releases a hold on the specified buffer.  If the
 824 *      the hold count is 1, calls xfs_buf_free.
 825 */
 826void
 827xfs_buf_rele(
 828        xfs_buf_t               *bp)
 829{
 830        xfs_bufhash_t           *hash = bp->b_hash;
 831
 832        XB_TRACE(bp, "rele", bp->b_relse);
 833
 834        if (unlikely(!hash)) {
 835                ASSERT(!bp->b_relse);
 836                if (atomic_dec_and_test(&bp->b_hold))
 837                        xfs_buf_free(bp);
 838                return;
 839        }
 840
 841        ASSERT(atomic_read(&bp->b_hold) > 0);
 842        if (atomic_dec_and_lock(&bp->b_hold, &hash->bh_lock)) {
 843                if (bp->b_relse) {
 844                        atomic_inc(&bp->b_hold);
 845                        spin_unlock(&hash->bh_lock);
 846                        (*(bp->b_relse)) (bp);
 847                } else if (bp->b_flags & XBF_FS_MANAGED) {
 848                        spin_unlock(&hash->bh_lock);
 849                } else {
 850                        ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
 851                        list_del_init(&bp->b_hash_list);
 852                        spin_unlock(&hash->bh_lock);
 853                        xfs_buf_free(bp);
 854                }
 855        }
 856}
 857
 858
 859/*
 860 *      Mutual exclusion on buffers.  Locking model:
 861 *
 862 *      Buffers associated with inodes for which buffer locking
 863 *      is not enabled are not protected by semaphores, and are
 864 *      assumed to be exclusively owned by the caller.  There is a
 865 *      spinlock in the buffer, used by the caller when concurrent
 866 *      access is possible.
 867 */
 868
 869/*
 870 *      Locks a buffer object, if it is not already locked.
 871 *      Note that this in no way locks the underlying pages, so it is only
 872 *      useful for synchronizing concurrent use of buffer objects, not for
 873 *      synchronizing independent access to the underlying pages.
 874 */
 875int
 876xfs_buf_cond_lock(
 877        xfs_buf_t               *bp)
 878{
 879        int                     locked;
 880
 881        locked = down_trylock(&bp->b_sema) == 0;
 882        if (locked) {
 883                XB_SET_OWNER(bp);
 884        }
 885        XB_TRACE(bp, "cond_lock", (long)locked);
 886        return locked ? 0 : -EBUSY;
 887}
 888
 889#if defined(DEBUG) || defined(XFS_BLI_TRACE)
 890int
 891xfs_buf_lock_value(
 892        xfs_buf_t               *bp)
 893{
 894        return bp->b_sema.count;
 895}
 896#endif
 897
 898/*
 899 *      Locks a buffer object.
 900 *      Note that this in no way locks the underlying pages, so it is only
 901 *      useful for synchronizing concurrent use of buffer objects, not for
 902 *      synchronizing independent access to the underlying pages.
 903 */
 904void
 905xfs_buf_lock(
 906        xfs_buf_t               *bp)
 907{
 908        XB_TRACE(bp, "lock", 0);
 909        if (atomic_read(&bp->b_io_remaining))
 910                blk_run_address_space(bp->b_target->bt_mapping);
 911        down(&bp->b_sema);
 912        XB_SET_OWNER(bp);
 913        XB_TRACE(bp, "locked", 0);
 914}
 915
 916/*
 917 *      Releases the lock on the buffer object.
 918 *      If the buffer is marked delwri but is not queued, do so before we
 919 *      unlock the buffer as we need to set flags correctly.  We also need to
 920 *      take a reference for the delwri queue because the unlocker is going to
 921 *      drop their's and they don't know we just queued it.
 922 */
 923void
 924xfs_buf_unlock(
 925        xfs_buf_t               *bp)
 926{
 927        if ((bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)) == XBF_DELWRI) {
 928                atomic_inc(&bp->b_hold);
 929                bp->b_flags |= XBF_ASYNC;
 930                xfs_buf_delwri_queue(bp, 0);
 931        }
 932
 933        XB_CLEAR_OWNER(bp);
 934        up(&bp->b_sema);
 935        XB_TRACE(bp, "unlock", 0);
 936}
 937
 938
 939/*
 940 *      Pinning Buffer Storage in Memory
 941 *      Ensure that no attempt to force a buffer to disk will succeed.
 942 */
 943void
 944xfs_buf_pin(
 945        xfs_buf_t               *bp)
 946{
 947        atomic_inc(&bp->b_pin_count);
 948        XB_TRACE(bp, "pin", (long)bp->b_pin_count.counter);
 949}
 950
 951void
 952xfs_buf_unpin(
 953        xfs_buf_t               *bp)
 954{
 955        if (atomic_dec_and_test(&bp->b_pin_count))
 956                wake_up_all(&bp->b_waiters);
 957        XB_TRACE(bp, "unpin", (long)bp->b_pin_count.counter);
 958}
 959
 960int
 961xfs_buf_ispin(
 962        xfs_buf_t               *bp)
 963{
 964        return atomic_read(&bp->b_pin_count);
 965}
 966
 967STATIC void
 968xfs_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                if (atomic_read(&bp->b_io_remaining))
 982                        blk_run_address_space(bp->b_target->bt_mapping);
 983                schedule();
 984        }
 985        remove_wait_queue(&bp->b_waiters, &wait);
 986        set_current_state(TASK_RUNNING);
 987}
 988
 989/*
 990 *      Buffer Utility Routines
 991 */
 992
 993STATIC void
 994xfs_buf_iodone_work(
 995        struct work_struct      *work)
 996{
 997        xfs_buf_t               *bp =
 998                container_of(work, xfs_buf_t, b_iodone_work);
 999
1000        /*
1001         * We can get an EOPNOTSUPP to ordered writes.  Here we clear the
1002         * ordered flag and reissue them.  Because we can't tell the higher
1003         * layers directly that they should not issue ordered I/O anymore, they
1004         * need to check if the _XFS_BARRIER_FAILED flag was set during I/O completion.
1005         */
1006        if ((bp->b_error == EOPNOTSUPP) &&
1007            (bp->b_flags & (XBF_ORDERED|XBF_ASYNC)) == (XBF_ORDERED|XBF_ASYNC)) {
1008                XB_TRACE(bp, "ordered_retry", bp->b_iodone);
1009                bp->b_flags &= ~XBF_ORDERED;
1010                bp->b_flags |= _XFS_BARRIER_FAILED;
1011                xfs_buf_iorequest(bp);
1012        } else if (bp->b_iodone)
1013                (*(bp->b_iodone))(bp);
1014        else if (bp->b_flags & XBF_ASYNC)
1015                xfs_buf_relse(bp);
1016}
1017
1018void
1019xfs_buf_ioend(
1020        xfs_buf_t               *bp,
1021        int                     schedule)
1022{
1023        bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
1024        if (bp->b_error == 0)
1025                bp->b_flags |= XBF_DONE;
1026
1027        XB_TRACE(bp, "iodone", bp->b_iodone);
1028
1029        if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
1030                if (schedule) {
1031                        INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
1032                        queue_work(xfslogd_workqueue, &bp->b_iodone_work);
1033                } else {
1034                        xfs_buf_iodone_work(&bp->b_iodone_work);
1035                }
1036        } else {
1037                complete(&bp->b_iowait);
1038        }
1039}
1040
1041void
1042xfs_buf_ioerror(
1043        xfs_buf_t               *bp,
1044        int                     error)
1045{
1046        ASSERT(error >= 0 && error <= 0xffff);
1047        bp->b_error = (unsigned short)error;
1048        XB_TRACE(bp, "ioerror", (unsigned long)error);
1049}
1050
1051/*
1052 *      Initiate I/O on a buffer, based on the flags supplied.
1053 *      The b_iodone routine in the buffer supplied will only be called
1054 *      when all of the subsidiary I/O requests, if any, have been completed.
1055 */
1056int
1057xfs_buf_iostart(
1058        xfs_buf_t               *bp,
1059        xfs_buf_flags_t         flags)
1060{
1061        int                     status = 0;
1062
1063        XB_TRACE(bp, "iostart", (unsigned long)flags);
1064
1065        if (flags & XBF_DELWRI) {
1066                bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_ASYNC);
1067                bp->b_flags |= flags & (XBF_DELWRI | XBF_ASYNC);
1068                xfs_buf_delwri_queue(bp, 1);
1069                return 0;
1070        }
1071
1072        bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_ASYNC | XBF_DELWRI | \
1073                        XBF_READ_AHEAD | _XBF_RUN_QUEUES);
1074        bp->b_flags |= flags & (XBF_READ | XBF_WRITE | XBF_ASYNC | \
1075                        XBF_READ_AHEAD | _XBF_RUN_QUEUES);
1076
1077        BUG_ON(bp->b_bn == XFS_BUF_DADDR_NULL);
1078
1079        /* For writes allow an alternate strategy routine to precede
1080         * the actual I/O request (which may not be issued at all in
1081         * a shutdown situation, for example).
1082         */
1083        status = (flags & XBF_WRITE) ?
1084                xfs_buf_iostrategy(bp) : xfs_buf_iorequest(bp);
1085
1086        /* Wait for I/O if we are not an async request.
1087         * Note: async I/O request completion will release the buffer,
1088         * and that can already be done by this point.  So using the
1089         * buffer pointer from here on, after async I/O, is invalid.
1090         */
1091        if (!status && !(flags & XBF_ASYNC))
1092                status = xfs_buf_iowait(bp);
1093
1094        return status;
1095}
1096
1097STATIC_INLINE void
1098_xfs_buf_ioend(
1099        xfs_buf_t               *bp,
1100        int                     schedule)
1101{
1102        if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1103                bp->b_flags &= ~_XBF_PAGE_LOCKED;
1104                xfs_buf_ioend(bp, schedule);
1105        }
1106}
1107
1108STATIC void
1109xfs_buf_bio_end_io(
1110        struct bio              *bio,
1111        int                     error)
1112{
1113        xfs_buf_t               *bp = (xfs_buf_t *)bio->bi_private;
1114        unsigned int            blocksize = bp->b_target->bt_bsize;
1115        struct bio_vec          *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1116
1117        if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1118                bp->b_error = EIO;
1119
1120        do {
1121                struct page     *page = bvec->bv_page;
1122
1123                ASSERT(!PagePrivate(page));
1124                if (unlikely(bp->b_error)) {
1125                        if (bp->b_flags & XBF_READ)
1126                                ClearPageUptodate(page);
1127                } else if (blocksize >= PAGE_CACHE_SIZE) {
1128                        SetPageUptodate(page);
1129                } else if (!PagePrivate(page) &&
1130                                (bp->b_flags & _XBF_PAGE_CACHE)) {
1131                        set_page_region(page, bvec->bv_offset, bvec->bv_len);
1132                }
1133
1134                if (--bvec >= bio->bi_io_vec)
1135                        prefetchw(&bvec->bv_page->flags);
1136
1137                if (bp->b_flags & _XBF_PAGE_LOCKED)
1138                        unlock_page(page);
1139        } while (bvec >= bio->bi_io_vec);
1140
1141        _xfs_buf_ioend(bp, 1);
1142        bio_put(bio);
1143}
1144
1145STATIC void
1146_xfs_buf_ioapply(
1147        xfs_buf_t               *bp)
1148{
1149        int                     rw, map_i, total_nr_pages, nr_pages;
1150        struct bio              *bio;
1151        int                     offset = bp->b_offset;
1152        int                     size = bp->b_count_desired;
1153        sector_t                sector = bp->b_bn;
1154        unsigned int            blocksize = bp->b_target->bt_bsize;
1155
1156        total_nr_pages = bp->b_page_count;
1157        map_i = 0;
1158
1159        if (bp->b_flags & XBF_ORDERED) {
1160                ASSERT(!(bp->b_flags & XBF_READ));
1161                rw = WRITE_BARRIER;
1162        } else if (bp->b_flags & _XBF_RUN_QUEUES) {
1163                ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
1164                bp->b_flags &= ~_XBF_RUN_QUEUES;
1165                rw = (bp->b_flags & XBF_WRITE) ? WRITE_SYNC : READ_SYNC;
1166        } else {
1167                rw = (bp->b_flags & XBF_WRITE) ? WRITE :
1168                     (bp->b_flags & XBF_READ_AHEAD) ? READA : READ;
1169        }
1170
1171        /* Special code path for reading a sub page size buffer in --
1172         * we populate up the whole page, and hence the other metadata
1173         * in the same page.  This optimization is only valid when the
1174         * filesystem block size is not smaller than the page size.
1175         */
1176        if ((bp->b_buffer_length < PAGE_CACHE_SIZE) &&
1177            ((bp->b_flags & (XBF_READ|_XBF_PAGE_LOCKED)) ==
1178              (XBF_READ|_XBF_PAGE_LOCKED)) &&
1179            (blocksize >= PAGE_CACHE_SIZE)) {
1180                bio = bio_alloc(GFP_NOIO, 1);
1181
1182                bio->bi_bdev = bp->b_target->bt_bdev;
1183                bio->bi_sector = sector - (offset >> BBSHIFT);
1184                bio->bi_end_io = xfs_buf_bio_end_io;
1185                bio->bi_private = bp;
1186
1187                bio_add_page(bio, bp->b_pages[0], PAGE_CACHE_SIZE, 0);
1188                size = 0;
1189
1190                atomic_inc(&bp->b_io_remaining);
1191
1192                goto submit_io;
1193        }
1194
1195next_chunk:
1196        atomic_inc(&bp->b_io_remaining);
1197        nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1198        if (nr_pages > total_nr_pages)
1199                nr_pages = total_nr_pages;
1200
1201        bio = bio_alloc(GFP_NOIO, nr_pages);
1202        bio->bi_bdev = bp->b_target->bt_bdev;
1203        bio->bi_sector = sector;
1204        bio->bi_end_io = xfs_buf_bio_end_io;
1205        bio->bi_private = bp;
1206
1207        for (; size && nr_pages; nr_pages--, map_i++) {
1208                int     rbytes, nbytes = PAGE_CACHE_SIZE - offset;
1209
1210                if (nbytes > size)
1211                        nbytes = size;
1212
1213                rbytes = bio_add_page(bio, bp->b_pages[map_i], nbytes, offset);
1214                if (rbytes < nbytes)
1215                        break;
1216
1217                offset = 0;
1218                sector += nbytes >> BBSHIFT;
1219                size -= nbytes;
1220                total_nr_pages--;
1221        }
1222
1223submit_io:
1224        if (likely(bio->bi_size)) {
1225                submit_bio(rw, bio);
1226                if (size)
1227                        goto next_chunk;
1228        } else {
1229                bio_put(bio);
1230                xfs_buf_ioerror(bp, EIO);
1231        }
1232}
1233
1234int
1235xfs_buf_iorequest(
1236        xfs_buf_t               *bp)
1237{
1238        XB_TRACE(bp, "iorequest", 0);
1239
1240        if (bp->b_flags & XBF_DELWRI) {
1241                xfs_buf_delwri_queue(bp, 1);
1242                return 0;
1243        }
1244
1245        if (bp->b_flags & XBF_WRITE) {
1246                xfs_buf_wait_unpin(bp);
1247        }
1248
1249        xfs_buf_hold(bp);
1250
1251        /* Set the count to 1 initially, this will stop an I/O
1252         * completion callout which happens before we have started
1253         * all the I/O from calling xfs_buf_ioend too early.
1254         */
1255        atomic_set(&bp->b_io_remaining, 1);
1256        _xfs_buf_ioapply(bp);
1257        _xfs_buf_ioend(bp, 0);
1258
1259        xfs_buf_rele(bp);
1260        return 0;
1261}
1262
1263/*
1264 *      Waits for I/O to complete on the buffer supplied.
1265 *      It returns immediately if no I/O is pending.
1266 *      It returns the I/O error code, if any, or 0 if there was no error.
1267 */
1268int
1269xfs_buf_iowait(
1270        xfs_buf_t               *bp)
1271{
1272        XB_TRACE(bp, "iowait", 0);
1273        if (atomic_read(&bp->b_io_remaining))
1274                blk_run_address_space(bp->b_target->bt_mapping);
1275        wait_for_completion(&bp->b_iowait);
1276        XB_TRACE(bp, "iowaited", (long)bp->b_error);
1277        return bp->b_error;
1278}
1279
1280xfs_caddr_t
1281xfs_buf_offset(
1282        xfs_buf_t               *bp,
1283        size_t                  offset)
1284{
1285        struct page             *page;
1286
1287        if (bp->b_flags & XBF_MAPPED)
1288                return XFS_BUF_PTR(bp) + offset;
1289
1290        offset += bp->b_offset;
1291        page = bp->b_pages[offset >> PAGE_CACHE_SHIFT];
1292        return (xfs_caddr_t)page_address(page) + (offset & (PAGE_CACHE_SIZE-1));
1293}
1294
1295/*
1296 *      Move data into or out of a buffer.
1297 */
1298void
1299xfs_buf_iomove(
1300        xfs_buf_t               *bp,    /* buffer to process            */
1301        size_t                  boff,   /* starting buffer offset       */
1302        size_t                  bsize,  /* length to copy               */
1303        caddr_t                 data,   /* data address                 */
1304        xfs_buf_rw_t            mode)   /* read/write/zero flag         */
1305{
1306        size_t                  bend, cpoff, csize;
1307        struct page             *page;
1308
1309        bend = boff + bsize;
1310        while (boff < bend) {
1311                page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
1312                cpoff = xfs_buf_poff(boff + bp->b_offset);
1313                csize = min_t(size_t,
1314                              PAGE_CACHE_SIZE-cpoff, bp->b_count_desired-boff);
1315
1316                ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE));
1317
1318                switch (mode) {
1319                case XBRW_ZERO:
1320                        memset(page_address(page) + cpoff, 0, csize);
1321                        break;
1322                case XBRW_READ:
1323                        memcpy(data, page_address(page) + cpoff, csize);
1324                        break;
1325                case XBRW_WRITE:
1326                        memcpy(page_address(page) + cpoff, data, csize);
1327                }
1328
1329                boff += csize;
1330                data += csize;
1331        }
1332}
1333
1334/*
1335 *      Handling of buffer targets (buftargs).
1336 */
1337
1338/*
1339 *      Wait for any bufs with callbacks that have been submitted but
1340 *      have not yet returned... walk the hash list for the target.
1341 */
1342void
1343xfs_wait_buftarg(
1344        xfs_buftarg_t   *btp)
1345{
1346        xfs_buf_t       *bp, *n;
1347        xfs_bufhash_t   *hash;
1348        uint            i;
1349
1350        for (i = 0; i < (1 << btp->bt_hashshift); i++) {
1351                hash = &btp->bt_hash[i];
1352again:
1353                spin_lock(&hash->bh_lock);
1354                list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
1355                        ASSERT(btp == bp->b_target);
1356                        if (!(bp->b_flags & XBF_FS_MANAGED)) {
1357                                spin_unlock(&hash->bh_lock);
1358                                /*
1359                                 * Catch superblock reference count leaks
1360                                 * immediately
1361                                 */
1362                                BUG_ON(bp->b_bn == 0);
1363                                delay(100);
1364                                goto again;
1365                        }
1366                }
1367                spin_unlock(&hash->bh_lock);
1368        }
1369}
1370
1371/*
1372 *      Allocate buffer hash table for a given target.
1373 *      For devices containing metadata (i.e. not the log/realtime devices)
1374 *      we need to allocate a much larger hash table.
1375 */
1376STATIC void
1377xfs_alloc_bufhash(
1378        xfs_buftarg_t           *btp,
1379        int                     external)
1380{
1381        unsigned int            i;
1382
1383        btp->bt_hashshift = external ? 3 : 8;   /* 8 or 256 buckets */
1384        btp->bt_hashmask = (1 << btp->bt_hashshift) - 1;
1385        btp->bt_hash = kmem_zalloc((1 << btp->bt_hashshift) *
1386                                        sizeof(xfs_bufhash_t), KM_SLEEP | KM_LARGE);
1387        for (i = 0; i < (1 << btp->bt_hashshift); i++) {
1388                spin_lock_init(&btp->bt_hash[i].bh_lock);
1389                INIT_LIST_HEAD(&btp->bt_hash[i].bh_list);
1390        }
1391}
1392
1393STATIC void
1394xfs_free_bufhash(
1395        xfs_buftarg_t           *btp)
1396{
1397        kmem_free(btp->bt_hash);
1398        btp->bt_hash = NULL;
1399}
1400
1401/*
1402 *      buftarg list for delwrite queue processing
1403 */
1404static LIST_HEAD(xfs_buftarg_list);
1405static DEFINE_SPINLOCK(xfs_buftarg_lock);
1406
1407STATIC void
1408xfs_register_buftarg(
1409        xfs_buftarg_t           *btp)
1410{
1411        spin_lock(&xfs_buftarg_lock);
1412        list_add(&btp->bt_list, &xfs_buftarg_list);
1413        spin_unlock(&xfs_buftarg_lock);
1414}
1415
1416STATIC void
1417xfs_unregister_buftarg(
1418        xfs_buftarg_t           *btp)
1419{
1420        spin_lock(&xfs_buftarg_lock);
1421        list_del(&btp->bt_list);
1422        spin_unlock(&xfs_buftarg_lock);
1423}
1424
1425void
1426xfs_free_buftarg(
1427        xfs_buftarg_t           *btp)
1428{
1429        xfs_flush_buftarg(btp, 1);
1430        xfs_blkdev_issue_flush(btp);
1431        xfs_free_bufhash(btp);
1432        iput(btp->bt_mapping->host);
1433
1434        /* Unregister the buftarg first so that we don't get a
1435         * wakeup finding a non-existent task
1436         */
1437        xfs_unregister_buftarg(btp);
1438        kthread_stop(btp->bt_task);
1439
1440        kmem_free(btp);
1441}
1442
1443STATIC int
1444xfs_setsize_buftarg_flags(
1445        xfs_buftarg_t           *btp,
1446        unsigned int            blocksize,
1447        unsigned int            sectorsize,
1448        int                     verbose)
1449{
1450        btp->bt_bsize = blocksize;
1451        btp->bt_sshift = ffs(sectorsize) - 1;
1452        btp->bt_smask = sectorsize - 1;
1453
1454        if (set_blocksize(btp->bt_bdev, sectorsize)) {
1455                printk(KERN_WARNING
1456                        "XFS: Cannot set_blocksize to %u on device %s\n",
1457                        sectorsize, XFS_BUFTARG_NAME(btp));
1458                return EINVAL;
1459        }
1460
1461        if (verbose &&
1462            (PAGE_CACHE_SIZE / BITS_PER_LONG) > sectorsize) {
1463                printk(KERN_WARNING
1464                        "XFS: %u byte sectors in use on device %s.  "
1465                        "This is suboptimal; %u or greater is ideal.\n",
1466                        sectorsize, XFS_BUFTARG_NAME(btp),
1467                        (unsigned int)PAGE_CACHE_SIZE / BITS_PER_LONG);
1468        }
1469
1470        return 0;
1471}
1472
1473/*
1474 *      When allocating the initial buffer target we have not yet
1475 *      read in the superblock, so don't know what sized sectors
1476 *      are being used is at this early stage.  Play safe.
1477 */
1478STATIC int
1479xfs_setsize_buftarg_early(
1480        xfs_buftarg_t           *btp,
1481        struct block_device     *bdev)
1482{
1483        return xfs_setsize_buftarg_flags(btp,
1484                        PAGE_CACHE_SIZE, bdev_hardsect_size(bdev), 0);
1485}
1486
1487int
1488xfs_setsize_buftarg(
1489        xfs_buftarg_t           *btp,
1490        unsigned int            blocksize,
1491        unsigned int            sectorsize)
1492{
1493        return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
1494}
1495
1496STATIC int
1497xfs_mapping_buftarg(
1498        xfs_buftarg_t           *btp,
1499        struct block_device     *bdev)
1500{
1501        struct backing_dev_info *bdi;
1502        struct inode            *inode;
1503        struct address_space    *mapping;
1504        static const struct address_space_operations mapping_aops = {
1505                .sync_page = block_sync_page,
1506                .migratepage = fail_migrate_page,
1507        };
1508
1509        inode = new_inode(bdev->bd_inode->i_sb);
1510        if (!inode) {
1511                printk(KERN_WARNING
1512                        "XFS: Cannot allocate mapping inode for device %s\n",
1513                        XFS_BUFTARG_NAME(btp));
1514                return ENOMEM;
1515        }
1516        inode->i_mode = S_IFBLK;
1517        inode->i_bdev = bdev;
1518        inode->i_rdev = bdev->bd_dev;
1519        bdi = blk_get_backing_dev_info(bdev);
1520        if (!bdi)
1521                bdi = &default_backing_dev_info;
1522        mapping = &inode->i_data;
1523        mapping->a_ops = &mapping_aops;
1524        mapping->backing_dev_info = bdi;
1525        mapping_set_gfp_mask(mapping, GFP_NOFS);
1526        btp->bt_mapping = mapping;
1527        return 0;
1528}
1529
1530STATIC int
1531xfs_alloc_delwrite_queue(
1532        xfs_buftarg_t           *btp)
1533{
1534        int     error = 0;
1535
1536        INIT_LIST_HEAD(&btp->bt_list);
1537        INIT_LIST_HEAD(&btp->bt_delwrite_queue);
1538        spin_lock_init(&btp->bt_delwrite_lock);
1539        btp->bt_flags = 0;
1540        btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd");
1541        if (IS_ERR(btp->bt_task)) {
1542                error = PTR_ERR(btp->bt_task);
1543                goto out_error;
1544        }
1545        xfs_register_buftarg(btp);
1546out_error:
1547        return error;
1548}
1549
1550xfs_buftarg_t *
1551xfs_alloc_buftarg(
1552        struct block_device     *bdev,
1553        int                     external)
1554{
1555        xfs_buftarg_t           *btp;
1556
1557        btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
1558
1559        btp->bt_dev =  bdev->bd_dev;
1560        btp->bt_bdev = bdev;
1561        if (xfs_setsize_buftarg_early(btp, bdev))
1562                goto error;
1563        if (xfs_mapping_buftarg(btp, bdev))
1564                goto error;
1565        if (xfs_alloc_delwrite_queue(btp))
1566                goto error;
1567        xfs_alloc_bufhash(btp, external);
1568        return btp;
1569
1570error:
1571        kmem_free(btp);
1572        return NULL;
1573}
1574
1575
1576/*
1577 *      Delayed write buffer handling
1578 */
1579STATIC void
1580xfs_buf_delwri_queue(
1581        xfs_buf_t               *bp,
1582        int                     unlock)
1583{
1584        struct list_head        *dwq = &bp->b_target->bt_delwrite_queue;
1585        spinlock_t              *dwlk = &bp->b_target->bt_delwrite_lock;
1586
1587        XB_TRACE(bp, "delwri_q", (long)unlock);
1588        ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));
1589
1590        spin_lock(dwlk);
1591        /* If already in the queue, dequeue and place at tail */
1592        if (!list_empty(&bp->b_list)) {
1593                ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1594                if (unlock)
1595                        atomic_dec(&bp->b_hold);
1596                list_del(&bp->b_list);
1597        }
1598
1599        bp->b_flags |= _XBF_DELWRI_Q;
1600        list_add_tail(&bp->b_list, dwq);
1601        bp->b_queuetime = jiffies;
1602        spin_unlock(dwlk);
1603
1604        if (unlock)
1605                xfs_buf_unlock(bp);
1606}
1607
1608void
1609xfs_buf_delwri_dequeue(
1610        xfs_buf_t               *bp)
1611{
1612        spinlock_t              *dwlk = &bp->b_target->bt_delwrite_lock;
1613        int                     dequeued = 0;
1614
1615        spin_lock(dwlk);
1616        if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
1617                ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1618                list_del_init(&bp->b_list);
1619                dequeued = 1;
1620        }
1621        bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
1622        spin_unlock(dwlk);
1623
1624        if (dequeued)
1625                xfs_buf_rele(bp);
1626
1627        XB_TRACE(bp, "delwri_dq", (long)dequeued);
1628}
1629
1630STATIC void
1631xfs_buf_runall_queues(
1632        struct workqueue_struct *queue)
1633{
1634        flush_workqueue(queue);
1635}
1636
1637STATIC int
1638xfsbufd_wakeup(
1639        int                     priority,
1640        gfp_t                   mask)
1641{
1642        xfs_buftarg_t           *btp;
1643
1644        spin_lock(&xfs_buftarg_lock);
1645        list_for_each_entry(btp, &xfs_buftarg_list, bt_list) {
1646                if (test_bit(XBT_FORCE_SLEEP, &btp->bt_flags))
1647                        continue;
1648                set_bit(XBT_FORCE_FLUSH, &btp->bt_flags);
1649                wake_up_process(btp->bt_task);
1650        }
1651        spin_unlock(&xfs_buftarg_lock);
1652        return 0;
1653}
1654
1655/*
1656 * Move as many buffers as specified to the supplied list
1657 * idicating if we skipped any buffers to prevent deadlocks.
1658 */
1659STATIC int
1660xfs_buf_delwri_split(
1661        xfs_buftarg_t   *target,
1662        struct list_head *list,
1663        unsigned long   age)
1664{
1665        xfs_buf_t       *bp, *n;
1666        struct list_head *dwq = &target->bt_delwrite_queue;
1667        spinlock_t      *dwlk = &target->bt_delwrite_lock;
1668        int             skipped = 0;
1669        int             force;
1670
1671        force = test_and_clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1672        INIT_LIST_HEAD(list);
1673        spin_lock(dwlk);
1674        list_for_each_entry_safe(bp, n, dwq, b_list) {
1675                XB_TRACE(bp, "walkq1", (long)xfs_buf_ispin(bp));
1676                ASSERT(bp->b_flags & XBF_DELWRI);
1677
1678                if (!xfs_buf_ispin(bp) && !xfs_buf_cond_lock(bp)) {
1679                        if (!force &&
1680                            time_before(jiffies, bp->b_queuetime + age)) {
1681                                xfs_buf_unlock(bp);
1682                                break;
1683                        }
1684
1685                        bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q|
1686                                         _XBF_RUN_QUEUES);
1687                        bp->b_flags |= XBF_WRITE;
1688                        list_move_tail(&bp->b_list, list);
1689                } else
1690                        skipped++;
1691        }
1692        spin_unlock(dwlk);
1693
1694        return skipped;
1695
1696}
1697
1698STATIC int
1699xfsbufd(
1700        void            *data)
1701{
1702        struct list_head tmp;
1703        xfs_buftarg_t   *target = (xfs_buftarg_t *)data;
1704        int             count;
1705        xfs_buf_t       *bp;
1706
1707        current->flags |= PF_MEMALLOC;
1708
1709        set_freezable();
1710
1711        do {
1712                if (unlikely(freezing(current))) {
1713                        set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1714                        refrigerator();
1715                } else {
1716                        clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1717                }
1718
1719                schedule_timeout_interruptible(
1720                        xfs_buf_timer_centisecs * msecs_to_jiffies(10));
1721
1722                xfs_buf_delwri_split(target, &tmp,
1723                                xfs_buf_age_centisecs * msecs_to_jiffies(10));
1724
1725                count = 0;
1726                while (!list_empty(&tmp)) {
1727                        bp = list_entry(tmp.next, xfs_buf_t, b_list);
1728                        ASSERT(target == bp->b_target);
1729
1730                        list_del_init(&bp->b_list);
1731                        xfs_buf_iostrategy(bp);
1732                        count++;
1733                }
1734
1735                if (as_list_len > 0)
1736                        purge_addresses();
1737                if (count)
1738                        blk_run_address_space(target->bt_mapping);
1739
1740        } while (!kthread_should_stop());
1741
1742        return 0;
1743}
1744
1745/*
1746 *      Go through all incore buffers, and release buffers if they belong to
1747 *      the given device. This is used in filesystem error handling to
1748 *      preserve the consistency of its metadata.
1749 */
1750int
1751xfs_flush_buftarg(
1752        xfs_buftarg_t   *target,
1753        int             wait)
1754{
1755        struct list_head tmp;
1756        xfs_buf_t       *bp, *n;
1757        int             pincount = 0;
1758
1759        xfs_buf_runall_queues(xfsdatad_workqueue);
1760        xfs_buf_runall_queues(xfslogd_workqueue);
1761
1762        set_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1763        pincount = xfs_buf_delwri_split(target, &tmp, 0);
1764
1765        /*
1766         * Dropped the delayed write list lock, now walk the temporary list
1767         */
1768        list_for_each_entry_safe(bp, n, &tmp, b_list) {
1769                ASSERT(target == bp->b_target);
1770                if (wait)
1771                        bp->b_flags &= ~XBF_ASYNC;
1772                else
1773                        list_del_init(&bp->b_list);
1774
1775                xfs_buf_iostrategy(bp);
1776        }
1777
1778        if (wait)
1779                blk_run_address_space(target->bt_mapping);
1780
1781        /*
1782         * Remaining list items must be flushed before returning
1783         */
1784        while (!list_empty(&tmp)) {
1785                bp = list_entry(tmp.next, xfs_buf_t, b_list);
1786
1787                list_del_init(&bp->b_list);
1788                xfs_iowait(bp);
1789                xfs_buf_relse(bp);
1790        }
1791
1792        return pincount;
1793}
1794
1795int __init
1796xfs_buf_init(void)
1797{
1798#ifdef XFS_BUF_TRACE
1799        xfs_buf_trace_buf = ktrace_alloc(XFS_BUF_TRACE_SIZE, KM_NOFS);
1800#endif
1801
1802        xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
1803                                                KM_ZONE_HWALIGN, NULL);
1804        if (!xfs_buf_zone)
1805                goto out_free_trace_buf;
1806
1807        xfslogd_workqueue = create_workqueue("xfslogd");
1808        if (!xfslogd_workqueue)
1809                goto out_free_buf_zone;
1810
1811        xfsdatad_workqueue = create_workqueue("xfsdatad");
1812        if (!xfsdatad_workqueue)
1813                goto out_destroy_xfslogd_workqueue;
1814
1815        register_shrinker(&xfs_buf_shake);
1816        return 0;
1817
1818 out_destroy_xfslogd_workqueue:
1819        destroy_workqueue(xfslogd_workqueue);
1820 out_free_buf_zone:
1821        kmem_zone_destroy(xfs_buf_zone);
1822 out_free_trace_buf:
1823#ifdef XFS_BUF_TRACE
1824        ktrace_free(xfs_buf_trace_buf);
1825#endif
1826        return -ENOMEM;
1827}
1828
1829void
1830xfs_buf_terminate(void)
1831{
1832        unregister_shrinker(&xfs_buf_shake);
1833        destroy_workqueue(xfsdatad_workqueue);
1834        destroy_workqueue(xfslogd_workqueue);
1835        kmem_zone_destroy(xfs_buf_zone);
1836#ifdef XFS_BUF_TRACE
1837        ktrace_free(xfs_buf_trace_buf);
1838#endif
1839}
1840
1841#ifdef CONFIG_KDB_MODULES
1842struct list_head *
1843xfs_get_buftarg_list(void)
1844{
1845        return &xfs_buftarg_list;
1846}
1847#endif
1848
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