linux/fs/xfs/xfs_buf_item.c
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   1/*
   2 * Copyright (c) 2000-2005 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 "xfs_fs.h"
  20#include "xfs_log_format.h"
  21#include "xfs_trans_resv.h"
  22#include "xfs_bit.h"
  23#include "xfs_sb.h"
  24#include "xfs_ag.h"
  25#include "xfs_mount.h"
  26#include "xfs_trans.h"
  27#include "xfs_buf_item.h"
  28#include "xfs_trans_priv.h"
  29#include "xfs_error.h"
  30#include "xfs_trace.h"
  31#include "xfs_log.h"
  32
  33
  34kmem_zone_t     *xfs_buf_item_zone;
  35
  36static inline struct xfs_buf_log_item *BUF_ITEM(struct xfs_log_item *lip)
  37{
  38        return container_of(lip, struct xfs_buf_log_item, bli_item);
  39}
  40
  41STATIC void     xfs_buf_do_callbacks(struct xfs_buf *bp);
  42
  43static inline int
  44xfs_buf_log_format_size(
  45        struct xfs_buf_log_format *blfp)
  46{
  47        return offsetof(struct xfs_buf_log_format, blf_data_map) +
  48                        (blfp->blf_map_size * sizeof(blfp->blf_data_map[0]));
  49}
  50
  51/*
  52 * This returns the number of log iovecs needed to log the
  53 * given buf log item.
  54 *
  55 * It calculates this as 1 iovec for the buf log format structure
  56 * and 1 for each stretch of non-contiguous chunks to be logged.
  57 * Contiguous chunks are logged in a single iovec.
  58 *
  59 * If the XFS_BLI_STALE flag has been set, then log nothing.
  60 */
  61STATIC void
  62xfs_buf_item_size_segment(
  63        struct xfs_buf_log_item *bip,
  64        struct xfs_buf_log_format *blfp,
  65        int                     *nvecs,
  66        int                     *nbytes)
  67{
  68        struct xfs_buf          *bp = bip->bli_buf;
  69        int                     next_bit;
  70        int                     last_bit;
  71
  72        last_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
  73        if (last_bit == -1)
  74                return;
  75
  76        /*
  77         * initial count for a dirty buffer is 2 vectors - the format structure
  78         * and the first dirty region.
  79         */
  80        *nvecs += 2;
  81        *nbytes += xfs_buf_log_format_size(blfp) + XFS_BLF_CHUNK;
  82
  83        while (last_bit != -1) {
  84                /*
  85                 * This takes the bit number to start looking from and
  86                 * returns the next set bit from there.  It returns -1
  87                 * if there are no more bits set or the start bit is
  88                 * beyond the end of the bitmap.
  89                 */
  90                next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,
  91                                        last_bit + 1);
  92                /*
  93                 * If we run out of bits, leave the loop,
  94                 * else if we find a new set of bits bump the number of vecs,
  95                 * else keep scanning the current set of bits.
  96                 */
  97                if (next_bit == -1) {
  98                        break;
  99                } else if (next_bit != last_bit + 1) {
 100                        last_bit = next_bit;
 101                        (*nvecs)++;
 102                } else if (xfs_buf_offset(bp, next_bit * XFS_BLF_CHUNK) !=
 103                           (xfs_buf_offset(bp, last_bit * XFS_BLF_CHUNK) +
 104                            XFS_BLF_CHUNK)) {
 105                        last_bit = next_bit;
 106                        (*nvecs)++;
 107                } else {
 108                        last_bit++;
 109                }
 110                *nbytes += XFS_BLF_CHUNK;
 111        }
 112}
 113
 114/*
 115 * This returns the number of log iovecs needed to log the given buf log item.
 116 *
 117 * It calculates this as 1 iovec for the buf log format structure and 1 for each
 118 * stretch of non-contiguous chunks to be logged.  Contiguous chunks are logged
 119 * in a single iovec.
 120 *
 121 * Discontiguous buffers need a format structure per region that that is being
 122 * logged. This makes the changes in the buffer appear to log recovery as though
 123 * they came from separate buffers, just like would occur if multiple buffers
 124 * were used instead of a single discontiguous buffer. This enables
 125 * discontiguous buffers to be in-memory constructs, completely transparent to
 126 * what ends up on disk.
 127 *
 128 * If the XFS_BLI_STALE flag has been set, then log nothing but the buf log
 129 * format structures.
 130 */
 131STATIC void
 132xfs_buf_item_size(
 133        struct xfs_log_item     *lip,
 134        int                     *nvecs,
 135        int                     *nbytes)
 136{
 137        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 138        int                     i;
 139
 140        ASSERT(atomic_read(&bip->bli_refcount) > 0);
 141        if (bip->bli_flags & XFS_BLI_STALE) {
 142                /*
 143                 * The buffer is stale, so all we need to log
 144                 * is the buf log format structure with the
 145                 * cancel flag in it.
 146                 */
 147                trace_xfs_buf_item_size_stale(bip);
 148                ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
 149                *nvecs += bip->bli_format_count;
 150                for (i = 0; i < bip->bli_format_count; i++) {
 151                        *nbytes += xfs_buf_log_format_size(&bip->bli_formats[i]);
 152                }
 153                return;
 154        }
 155
 156        ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
 157
 158        if (bip->bli_flags & XFS_BLI_ORDERED) {
 159                /*
 160                 * The buffer has been logged just to order it.
 161                 * It is not being included in the transaction
 162                 * commit, so no vectors are used at all.
 163                 */
 164                trace_xfs_buf_item_size_ordered(bip);
 165                *nvecs = XFS_LOG_VEC_ORDERED;
 166                return;
 167        }
 168
 169        /*
 170         * the vector count is based on the number of buffer vectors we have
 171         * dirty bits in. This will only be greater than one when we have a
 172         * compound buffer with more than one segment dirty. Hence for compound
 173         * buffers we need to track which segment the dirty bits correspond to,
 174         * and when we move from one segment to the next increment the vector
 175         * count for the extra buf log format structure that will need to be
 176         * written.
 177         */
 178        for (i = 0; i < bip->bli_format_count; i++) {
 179                xfs_buf_item_size_segment(bip, &bip->bli_formats[i],
 180                                          nvecs, nbytes);
 181        }
 182        trace_xfs_buf_item_size(bip);
 183}
 184
 185static inline void
 186xfs_buf_item_copy_iovec(
 187        struct xfs_log_vec      *lv,
 188        struct xfs_log_iovec    **vecp,
 189        struct xfs_buf          *bp,
 190        uint                    offset,
 191        int                     first_bit,
 192        uint                    nbits)
 193{
 194        offset += first_bit * XFS_BLF_CHUNK;
 195        xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_BCHUNK,
 196                        xfs_buf_offset(bp, offset),
 197                        nbits * XFS_BLF_CHUNK);
 198}
 199
 200static inline bool
 201xfs_buf_item_straddle(
 202        struct xfs_buf          *bp,
 203        uint                    offset,
 204        int                     next_bit,
 205        int                     last_bit)
 206{
 207        return xfs_buf_offset(bp, offset + (next_bit << XFS_BLF_SHIFT)) !=
 208                (xfs_buf_offset(bp, offset + (last_bit << XFS_BLF_SHIFT)) +
 209                 XFS_BLF_CHUNK);
 210}
 211
 212static void
 213xfs_buf_item_format_segment(
 214        struct xfs_buf_log_item *bip,
 215        struct xfs_log_vec      *lv,
 216        struct xfs_log_iovec    **vecp,
 217        uint                    offset,
 218        struct xfs_buf_log_format *blfp)
 219{
 220        struct xfs_buf  *bp = bip->bli_buf;
 221        uint            base_size;
 222        int             first_bit;
 223        int             last_bit;
 224        int             next_bit;
 225        uint            nbits;
 226
 227        /* copy the flags across from the base format item */
 228        blfp->blf_flags = bip->__bli_format.blf_flags;
 229
 230        /*
 231         * Base size is the actual size of the ondisk structure - it reflects
 232         * the actual size of the dirty bitmap rather than the size of the in
 233         * memory structure.
 234         */
 235        base_size = xfs_buf_log_format_size(blfp);
 236
 237        first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
 238        if (!(bip->bli_flags & XFS_BLI_STALE) && first_bit == -1) {
 239                /*
 240                 * If the map is not be dirty in the transaction, mark
 241                 * the size as zero and do not advance the vector pointer.
 242                 */
 243                return;
 244        }
 245
 246        blfp = xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_BFORMAT, blfp, base_size);
 247        blfp->blf_size = 1;
 248
 249        if (bip->bli_flags & XFS_BLI_STALE) {
 250                /*
 251                 * The buffer is stale, so all we need to log
 252                 * is the buf log format structure with the
 253                 * cancel flag in it.
 254                 */
 255                trace_xfs_buf_item_format_stale(bip);
 256                ASSERT(blfp->blf_flags & XFS_BLF_CANCEL);
 257                return;
 258        }
 259
 260
 261        /*
 262         * Fill in an iovec for each set of contiguous chunks.
 263         */
 264        last_bit = first_bit;
 265        nbits = 1;
 266        for (;;) {
 267                /*
 268                 * This takes the bit number to start looking from and
 269                 * returns the next set bit from there.  It returns -1
 270                 * if there are no more bits set or the start bit is
 271                 * beyond the end of the bitmap.
 272                 */
 273                next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,
 274                                        (uint)last_bit + 1);
 275                /*
 276                 * If we run out of bits fill in the last iovec and get out of
 277                 * the loop.  Else if we start a new set of bits then fill in
 278                 * the iovec for the series we were looking at and start
 279                 * counting the bits in the new one.  Else we're still in the
 280                 * same set of bits so just keep counting and scanning.
 281                 */
 282                if (next_bit == -1) {
 283                        xfs_buf_item_copy_iovec(lv, vecp, bp, offset,
 284                                                first_bit, nbits);
 285                        blfp->blf_size++;
 286                        break;
 287                } else if (next_bit != last_bit + 1 ||
 288                           xfs_buf_item_straddle(bp, offset, next_bit, last_bit)) {
 289                        xfs_buf_item_copy_iovec(lv, vecp, bp, offset,
 290                                                first_bit, nbits);
 291                        blfp->blf_size++;
 292                        first_bit = next_bit;
 293                        last_bit = next_bit;
 294                        nbits = 1;
 295                } else {
 296                        last_bit++;
 297                        nbits++;
 298                }
 299        }
 300}
 301
 302/*
 303 * This is called to fill in the vector of log iovecs for the
 304 * given log buf item.  It fills the first entry with a buf log
 305 * format structure, and the rest point to contiguous chunks
 306 * within the buffer.
 307 */
 308STATIC void
 309xfs_buf_item_format(
 310        struct xfs_log_item     *lip,
 311        struct xfs_log_vec      *lv)
 312{
 313        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 314        struct xfs_buf          *bp = bip->bli_buf;
 315        struct xfs_log_iovec    *vecp = NULL;
 316        uint                    offset = 0;
 317        int                     i;
 318
 319        ASSERT(atomic_read(&bip->bli_refcount) > 0);
 320        ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
 321               (bip->bli_flags & XFS_BLI_STALE));
 322
 323        /*
 324         * If it is an inode buffer, transfer the in-memory state to the
 325         * format flags and clear the in-memory state.
 326         *
 327         * For buffer based inode allocation, we do not transfer
 328         * this state if the inode buffer allocation has not yet been committed
 329         * to the log as setting the XFS_BLI_INODE_BUF flag will prevent
 330         * correct replay of the inode allocation.
 331         *
 332         * For icreate item based inode allocation, the buffers aren't written
 333         * to the journal during allocation, and hence we should always tag the
 334         * buffer as an inode buffer so that the correct unlinked list replay
 335         * occurs during recovery.
 336         */
 337        if (bip->bli_flags & XFS_BLI_INODE_BUF) {
 338                if (xfs_sb_version_hascrc(&lip->li_mountp->m_sb) ||
 339                    !((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) &&
 340                      xfs_log_item_in_current_chkpt(lip)))
 341                        bip->__bli_format.blf_flags |= XFS_BLF_INODE_BUF;
 342                bip->bli_flags &= ~XFS_BLI_INODE_BUF;
 343        }
 344
 345        if ((bip->bli_flags & (XFS_BLI_ORDERED|XFS_BLI_STALE)) ==
 346                                                        XFS_BLI_ORDERED) {
 347                /*
 348                 * The buffer has been logged just to order it.  It is not being
 349                 * included in the transaction commit, so don't format it.
 350                 */
 351                trace_xfs_buf_item_format_ordered(bip);
 352                return;
 353        }
 354
 355        for (i = 0; i < bip->bli_format_count; i++) {
 356                xfs_buf_item_format_segment(bip, lv, &vecp, offset,
 357                                            &bip->bli_formats[i]);
 358                offset += bp->b_maps[i].bm_len;
 359        }
 360
 361        /*
 362         * Check to make sure everything is consistent.
 363         */
 364        trace_xfs_buf_item_format(bip);
 365}
 366
 367/*
 368 * This is called to pin the buffer associated with the buf log item in memory
 369 * so it cannot be written out.
 370 *
 371 * We also always take a reference to the buffer log item here so that the bli
 372 * is held while the item is pinned in memory. This means that we can
 373 * unconditionally drop the reference count a transaction holds when the
 374 * transaction is completed.
 375 */
 376STATIC void
 377xfs_buf_item_pin(
 378        struct xfs_log_item     *lip)
 379{
 380        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 381
 382        ASSERT(atomic_read(&bip->bli_refcount) > 0);
 383        ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
 384               (bip->bli_flags & XFS_BLI_ORDERED) ||
 385               (bip->bli_flags & XFS_BLI_STALE));
 386
 387        trace_xfs_buf_item_pin(bip);
 388
 389        atomic_inc(&bip->bli_refcount);
 390        atomic_inc(&bip->bli_buf->b_pin_count);
 391}
 392
 393/*
 394 * This is called to unpin the buffer associated with the buf log
 395 * item which was previously pinned with a call to xfs_buf_item_pin().
 396 *
 397 * Also drop the reference to the buf item for the current transaction.
 398 * If the XFS_BLI_STALE flag is set and we are the last reference,
 399 * then free up the buf log item and unlock the buffer.
 400 *
 401 * If the remove flag is set we are called from uncommit in the
 402 * forced-shutdown path.  If that is true and the reference count on
 403 * the log item is going to drop to zero we need to free the item's
 404 * descriptor in the transaction.
 405 */
 406STATIC void
 407xfs_buf_item_unpin(
 408        struct xfs_log_item     *lip,
 409        int                     remove)
 410{
 411        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 412        xfs_buf_t       *bp = bip->bli_buf;
 413        struct xfs_ail  *ailp = lip->li_ailp;
 414        int             stale = bip->bli_flags & XFS_BLI_STALE;
 415        int             freed;
 416
 417        ASSERT(bp->b_fspriv == bip);
 418        ASSERT(atomic_read(&bip->bli_refcount) > 0);
 419
 420        trace_xfs_buf_item_unpin(bip);
 421
 422        freed = atomic_dec_and_test(&bip->bli_refcount);
 423
 424        if (atomic_dec_and_test(&bp->b_pin_count))
 425                wake_up_all(&bp->b_waiters);
 426
 427        if (freed && stale) {
 428                ASSERT(bip->bli_flags & XFS_BLI_STALE);
 429                ASSERT(xfs_buf_islocked(bp));
 430                ASSERT(XFS_BUF_ISSTALE(bp));
 431                ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
 432
 433                trace_xfs_buf_item_unpin_stale(bip);
 434
 435                if (remove) {
 436                        /*
 437                         * If we are in a transaction context, we have to
 438                         * remove the log item from the transaction as we are
 439                         * about to release our reference to the buffer.  If we
 440                         * don't, the unlock that occurs later in
 441                         * xfs_trans_uncommit() will try to reference the
 442                         * buffer which we no longer have a hold on.
 443                         */
 444                        if (lip->li_desc)
 445                                xfs_trans_del_item(lip);
 446
 447                        /*
 448                         * Since the transaction no longer refers to the buffer,
 449                         * the buffer should no longer refer to the transaction.
 450                         */
 451                        bp->b_transp = NULL;
 452                }
 453
 454                /*
 455                 * If we get called here because of an IO error, we may
 456                 * or may not have the item on the AIL. xfs_trans_ail_delete()
 457                 * will take care of that situation.
 458                 * xfs_trans_ail_delete() drops the AIL lock.
 459                 */
 460                if (bip->bli_flags & XFS_BLI_STALE_INODE) {
 461                        xfs_buf_do_callbacks(bp);
 462                        bp->b_fspriv = NULL;
 463                        bp->b_iodone = NULL;
 464                } else {
 465                        spin_lock(&ailp->xa_lock);
 466                        xfs_trans_ail_delete(ailp, lip, SHUTDOWN_LOG_IO_ERROR);
 467                        xfs_buf_item_relse(bp);
 468                        ASSERT(bp->b_fspriv == NULL);
 469                }
 470                xfs_buf_relse(bp);
 471        } else if (freed && remove) {
 472                /*
 473                 * There are currently two references to the buffer - the active
 474                 * LRU reference and the buf log item. What we are about to do
 475                 * here - simulate a failed IO completion - requires 3
 476                 * references.
 477                 *
 478                 * The LRU reference is removed by the xfs_buf_stale() call. The
 479                 * buf item reference is removed by the xfs_buf_iodone()
 480                 * callback that is run by xfs_buf_do_callbacks() during ioend
 481                 * processing (via the bp->b_iodone callback), and then finally
 482                 * the ioend processing will drop the IO reference if the buffer
 483                 * is marked XBF_ASYNC.
 484                 *
 485                 * Hence we need to take an additional reference here so that IO
 486                 * completion processing doesn't free the buffer prematurely.
 487                 */
 488                xfs_buf_lock(bp);
 489                xfs_buf_hold(bp);
 490                bp->b_flags |= XBF_ASYNC;
 491                xfs_buf_ioerror(bp, EIO);
 492                XFS_BUF_UNDONE(bp);
 493                xfs_buf_stale(bp);
 494                xfs_buf_ioend(bp, 0);
 495        }
 496}
 497
 498/*
 499 * Buffer IO error rate limiting. Limit it to no more than 10 messages per 30
 500 * seconds so as to not spam logs too much on repeated detection of the same
 501 * buffer being bad..
 502 */
 503
 504DEFINE_RATELIMIT_STATE(xfs_buf_write_fail_rl_state, 30 * HZ, 10);
 505
 506STATIC uint
 507xfs_buf_item_push(
 508        struct xfs_log_item     *lip,
 509        struct list_head        *buffer_list)
 510{
 511        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 512        struct xfs_buf          *bp = bip->bli_buf;
 513        uint                    rval = XFS_ITEM_SUCCESS;
 514
 515        if (xfs_buf_ispinned(bp))
 516                return XFS_ITEM_PINNED;
 517        if (!xfs_buf_trylock(bp)) {
 518                /*
 519                 * If we have just raced with a buffer being pinned and it has
 520                 * been marked stale, we could end up stalling until someone else
 521                 * issues a log force to unpin the stale buffer. Check for the
 522                 * race condition here so xfsaild recognizes the buffer is pinned
 523                 * and queues a log force to move it along.
 524                 */
 525                if (xfs_buf_ispinned(bp))
 526                        return XFS_ITEM_PINNED;
 527                return XFS_ITEM_LOCKED;
 528        }
 529
 530        ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
 531
 532        trace_xfs_buf_item_push(bip);
 533
 534        /* has a previous flush failed due to IO errors? */
 535        if ((bp->b_flags & XBF_WRITE_FAIL) &&
 536            ___ratelimit(&xfs_buf_write_fail_rl_state, "XFS:")) {
 537                xfs_warn(bp->b_target->bt_mount,
 538"Detected failing async write on buffer block 0x%llx. Retrying async write.\n",
 539                         (long long)bp->b_bn);
 540        }
 541
 542        if (!xfs_buf_delwri_queue(bp, buffer_list))
 543                rval = XFS_ITEM_FLUSHING;
 544        xfs_buf_unlock(bp);
 545        return rval;
 546}
 547
 548/*
 549 * Release the buffer associated with the buf log item.  If there is no dirty
 550 * logged data associated with the buffer recorded in the buf log item, then
 551 * free the buf log item and remove the reference to it in the buffer.
 552 *
 553 * This call ignores the recursion count.  It is only called when the buffer
 554 * should REALLY be unlocked, regardless of the recursion count.
 555 *
 556 * We unconditionally drop the transaction's reference to the log item. If the
 557 * item was logged, then another reference was taken when it was pinned, so we
 558 * can safely drop the transaction reference now.  This also allows us to avoid
 559 * potential races with the unpin code freeing the bli by not referencing the
 560 * bli after we've dropped the reference count.
 561 *
 562 * If the XFS_BLI_HOLD flag is set in the buf log item, then free the log item
 563 * if necessary but do not unlock the buffer.  This is for support of
 564 * xfs_trans_bhold(). Make sure the XFS_BLI_HOLD field is cleared if we don't
 565 * free the item.
 566 */
 567STATIC void
 568xfs_buf_item_unlock(
 569        struct xfs_log_item     *lip)
 570{
 571        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 572        struct xfs_buf          *bp = bip->bli_buf;
 573        bool                    clean;
 574        bool                    aborted;
 575        int                     flags;
 576
 577        /* Clear the buffer's association with this transaction. */
 578        bp->b_transp = NULL;
 579
 580        /*
 581         * If this is a transaction abort, don't return early.  Instead, allow
 582         * the brelse to happen.  Normally it would be done for stale
 583         * (cancelled) buffers at unpin time, but we'll never go through the
 584         * pin/unpin cycle if we abort inside commit.
 585         */
 586        aborted = (lip->li_flags & XFS_LI_ABORTED) ? true : false;
 587        /*
 588         * Before possibly freeing the buf item, copy the per-transaction state
 589         * so we can reference it safely later after clearing it from the
 590         * buffer log item.
 591         */
 592        flags = bip->bli_flags;
 593        bip->bli_flags &= ~(XFS_BLI_LOGGED | XFS_BLI_HOLD | XFS_BLI_ORDERED);
 594
 595        /*
 596         * If the buf item is marked stale, then don't do anything.  We'll
 597         * unlock the buffer and free the buf item when the buffer is unpinned
 598         * for the last time.
 599         */
 600        if (flags & XFS_BLI_STALE) {
 601                trace_xfs_buf_item_unlock_stale(bip);
 602                ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
 603                if (!aborted) {
 604                        atomic_dec(&bip->bli_refcount);
 605                        return;
 606                }
 607        }
 608
 609        trace_xfs_buf_item_unlock(bip);
 610
 611        /*
 612         * If the buf item isn't tracking any data, free it, otherwise drop the
 613         * reference we hold to it. If we are aborting the transaction, this may
 614         * be the only reference to the buf item, so we free it anyway
 615         * regardless of whether it is dirty or not. A dirty abort implies a
 616         * shutdown, anyway.
 617         *
 618         * Ordered buffers are dirty but may have no recorded changes, so ensure
 619         * we only release clean items here.
 620         */
 621        clean = (flags & XFS_BLI_DIRTY) ? false : true;
 622        if (clean) {
 623                int i;
 624                for (i = 0; i < bip->bli_format_count; i++) {
 625                        if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
 626                                     bip->bli_formats[i].blf_map_size)) {
 627                                clean = false;
 628                                break;
 629                        }
 630                }
 631        }
 632
 633        /*
 634         * Clean buffers, by definition, cannot be in the AIL. However, aborted
 635         * buffers may be dirty and hence in the AIL. Therefore if we are
 636         * aborting a buffer and we've just taken the last refernce away, we
 637         * have to check if it is in the AIL before freeing it. We need to free
 638         * it in this case, because an aborted transaction has already shut the
 639         * filesystem down and this is the last chance we will have to do so.
 640         */
 641        if (atomic_dec_and_test(&bip->bli_refcount)) {
 642                if (clean)
 643                        xfs_buf_item_relse(bp);
 644                else if (aborted) {
 645                        ASSERT(XFS_FORCED_SHUTDOWN(lip->li_mountp));
 646                        if (lip->li_flags & XFS_LI_IN_AIL) {
 647                                spin_lock(&lip->li_ailp->xa_lock);
 648                                xfs_trans_ail_delete(lip->li_ailp, lip,
 649                                                     SHUTDOWN_LOG_IO_ERROR);
 650                        }
 651                        xfs_buf_item_relse(bp);
 652                }
 653        }
 654
 655        if (!(flags & XFS_BLI_HOLD))
 656                xfs_buf_relse(bp);
 657}
 658
 659/*
 660 * This is called to find out where the oldest active copy of the
 661 * buf log item in the on disk log resides now that the last log
 662 * write of it completed at the given lsn.
 663 * We always re-log all the dirty data in a buffer, so usually the
 664 * latest copy in the on disk log is the only one that matters.  For
 665 * those cases we simply return the given lsn.
 666 *
 667 * The one exception to this is for buffers full of newly allocated
 668 * inodes.  These buffers are only relogged with the XFS_BLI_INODE_BUF
 669 * flag set, indicating that only the di_next_unlinked fields from the
 670 * inodes in the buffers will be replayed during recovery.  If the
 671 * original newly allocated inode images have not yet been flushed
 672 * when the buffer is so relogged, then we need to make sure that we
 673 * keep the old images in the 'active' portion of the log.  We do this
 674 * by returning the original lsn of that transaction here rather than
 675 * the current one.
 676 */
 677STATIC xfs_lsn_t
 678xfs_buf_item_committed(
 679        struct xfs_log_item     *lip,
 680        xfs_lsn_t               lsn)
 681{
 682        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 683
 684        trace_xfs_buf_item_committed(bip);
 685
 686        if ((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) && lip->li_lsn != 0)
 687                return lip->li_lsn;
 688        return lsn;
 689}
 690
 691STATIC void
 692xfs_buf_item_committing(
 693        struct xfs_log_item     *lip,
 694        xfs_lsn_t               commit_lsn)
 695{
 696}
 697
 698/*
 699 * This is the ops vector shared by all buf log items.
 700 */
 701static const struct xfs_item_ops xfs_buf_item_ops = {
 702        .iop_size       = xfs_buf_item_size,
 703        .iop_format     = xfs_buf_item_format,
 704        .iop_pin        = xfs_buf_item_pin,
 705        .iop_unpin      = xfs_buf_item_unpin,
 706        .iop_unlock     = xfs_buf_item_unlock,
 707        .iop_committed  = xfs_buf_item_committed,
 708        .iop_push       = xfs_buf_item_push,
 709        .iop_committing = xfs_buf_item_committing
 710};
 711
 712STATIC int
 713xfs_buf_item_get_format(
 714        struct xfs_buf_log_item *bip,
 715        int                     count)
 716{
 717        ASSERT(bip->bli_formats == NULL);
 718        bip->bli_format_count = count;
 719
 720        if (count == 1) {
 721                bip->bli_formats = &bip->__bli_format;
 722                return 0;
 723        }
 724
 725        bip->bli_formats = kmem_zalloc(count * sizeof(struct xfs_buf_log_format),
 726                                KM_SLEEP);
 727        if (!bip->bli_formats)
 728                return ENOMEM;
 729        return 0;
 730}
 731
 732STATIC void
 733xfs_buf_item_free_format(
 734        struct xfs_buf_log_item *bip)
 735{
 736        if (bip->bli_formats != &bip->__bli_format) {
 737                kmem_free(bip->bli_formats);
 738                bip->bli_formats = NULL;
 739        }
 740}
 741
 742/*
 743 * Allocate a new buf log item to go with the given buffer.
 744 * Set the buffer's b_fsprivate field to point to the new
 745 * buf log item.  If there are other item's attached to the
 746 * buffer (see xfs_buf_attach_iodone() below), then put the
 747 * buf log item at the front.
 748 */
 749void
 750xfs_buf_item_init(
 751        xfs_buf_t       *bp,
 752        xfs_mount_t     *mp)
 753{
 754        xfs_log_item_t          *lip = bp->b_fspriv;
 755        xfs_buf_log_item_t      *bip;
 756        int                     chunks;
 757        int                     map_size;
 758        int                     error;
 759        int                     i;
 760
 761        /*
 762         * Check to see if there is already a buf log item for
 763         * this buffer.  If there is, it is guaranteed to be
 764         * the first.  If we do already have one, there is
 765         * nothing to do here so return.
 766         */
 767        ASSERT(bp->b_target->bt_mount == mp);
 768        if (lip != NULL && lip->li_type == XFS_LI_BUF)
 769                return;
 770
 771        bip = kmem_zone_zalloc(xfs_buf_item_zone, KM_SLEEP);
 772        xfs_log_item_init(mp, &bip->bli_item, XFS_LI_BUF, &xfs_buf_item_ops);
 773        bip->bli_buf = bp;
 774        xfs_buf_hold(bp);
 775
 776        /*
 777         * chunks is the number of XFS_BLF_CHUNK size pieces the buffer
 778         * can be divided into. Make sure not to truncate any pieces.
 779         * map_size is the size of the bitmap needed to describe the
 780         * chunks of the buffer.
 781         *
 782         * Discontiguous buffer support follows the layout of the underlying
 783         * buffer. This makes the implementation as simple as possible.
 784         */
 785        error = xfs_buf_item_get_format(bip, bp->b_map_count);
 786        ASSERT(error == 0);
 787
 788        for (i = 0; i < bip->bli_format_count; i++) {
 789                chunks = DIV_ROUND_UP(BBTOB(bp->b_maps[i].bm_len),
 790                                      XFS_BLF_CHUNK);
 791                map_size = DIV_ROUND_UP(chunks, NBWORD);
 792
 793                bip->bli_formats[i].blf_type = XFS_LI_BUF;
 794                bip->bli_formats[i].blf_blkno = bp->b_maps[i].bm_bn;
 795                bip->bli_formats[i].blf_len = bp->b_maps[i].bm_len;
 796                bip->bli_formats[i].blf_map_size = map_size;
 797        }
 798
 799        /*
 800         * Put the buf item into the list of items attached to the
 801         * buffer at the front.
 802         */
 803        if (bp->b_fspriv)
 804                bip->bli_item.li_bio_list = bp->b_fspriv;
 805        bp->b_fspriv = bip;
 806}
 807
 808
 809/*
 810 * Mark bytes first through last inclusive as dirty in the buf
 811 * item's bitmap.
 812 */
 813static void
 814xfs_buf_item_log_segment(
 815        uint                    first,
 816        uint                    last,
 817        uint                    *map)
 818{
 819        uint            first_bit;
 820        uint            last_bit;
 821        uint            bits_to_set;
 822        uint            bits_set;
 823        uint            word_num;
 824        uint            *wordp;
 825        uint            bit;
 826        uint            end_bit;
 827        uint            mask;
 828
 829        /*
 830         * Convert byte offsets to bit numbers.
 831         */
 832        first_bit = first >> XFS_BLF_SHIFT;
 833        last_bit = last >> XFS_BLF_SHIFT;
 834
 835        /*
 836         * Calculate the total number of bits to be set.
 837         */
 838        bits_to_set = last_bit - first_bit + 1;
 839
 840        /*
 841         * Get a pointer to the first word in the bitmap
 842         * to set a bit in.
 843         */
 844        word_num = first_bit >> BIT_TO_WORD_SHIFT;
 845        wordp = &map[word_num];
 846
 847        /*
 848         * Calculate the starting bit in the first word.
 849         */
 850        bit = first_bit & (uint)(NBWORD - 1);
 851
 852        /*
 853         * First set any bits in the first word of our range.
 854         * If it starts at bit 0 of the word, it will be
 855         * set below rather than here.  That is what the variable
 856         * bit tells us. The variable bits_set tracks the number
 857         * of bits that have been set so far.  End_bit is the number
 858         * of the last bit to be set in this word plus one.
 859         */
 860        if (bit) {
 861                end_bit = MIN(bit + bits_to_set, (uint)NBWORD);
 862                mask = ((1 << (end_bit - bit)) - 1) << bit;
 863                *wordp |= mask;
 864                wordp++;
 865                bits_set = end_bit - bit;
 866        } else {
 867                bits_set = 0;
 868        }
 869
 870        /*
 871         * Now set bits a whole word at a time that are between
 872         * first_bit and last_bit.
 873         */
 874        while ((bits_to_set - bits_set) >= NBWORD) {
 875                *wordp |= 0xffffffff;
 876                bits_set += NBWORD;
 877                wordp++;
 878        }
 879
 880        /*
 881         * Finally, set any bits left to be set in one last partial word.
 882         */
 883        end_bit = bits_to_set - bits_set;
 884        if (end_bit) {
 885                mask = (1 << end_bit) - 1;
 886                *wordp |= mask;
 887        }
 888}
 889
 890/*
 891 * Mark bytes first through last inclusive as dirty in the buf
 892 * item's bitmap.
 893 */
 894void
 895xfs_buf_item_log(
 896        xfs_buf_log_item_t      *bip,
 897        uint                    first,
 898        uint                    last)
 899{
 900        int                     i;
 901        uint                    start;
 902        uint                    end;
 903        struct xfs_buf          *bp = bip->bli_buf;
 904
 905        /*
 906         * walk each buffer segment and mark them dirty appropriately.
 907         */
 908        start = 0;
 909        for (i = 0; i < bip->bli_format_count; i++) {
 910                if (start > last)
 911                        break;
 912                end = start + BBTOB(bp->b_maps[i].bm_len);
 913                if (first > end) {
 914                        start += BBTOB(bp->b_maps[i].bm_len);
 915                        continue;
 916                }
 917                if (first < start)
 918                        first = start;
 919                if (end > last)
 920                        end = last;
 921
 922                xfs_buf_item_log_segment(first, end,
 923                                         &bip->bli_formats[i].blf_data_map[0]);
 924
 925                start += bp->b_maps[i].bm_len;
 926        }
 927}
 928
 929
 930/*
 931 * Return 1 if the buffer has been logged or ordered in a transaction (at any
 932 * point, not just the current transaction) and 0 if not.
 933 */
 934uint
 935xfs_buf_item_dirty(
 936        xfs_buf_log_item_t      *bip)
 937{
 938        return (bip->bli_flags & XFS_BLI_DIRTY);
 939}
 940
 941STATIC void
 942xfs_buf_item_free(
 943        xfs_buf_log_item_t      *bip)
 944{
 945        xfs_buf_item_free_format(bip);
 946        kmem_zone_free(xfs_buf_item_zone, bip);
 947}
 948
 949/*
 950 * This is called when the buf log item is no longer needed.  It should
 951 * free the buf log item associated with the given buffer and clear
 952 * the buffer's pointer to the buf log item.  If there are no more
 953 * items in the list, clear the b_iodone field of the buffer (see
 954 * xfs_buf_attach_iodone() below).
 955 */
 956void
 957xfs_buf_item_relse(
 958        xfs_buf_t       *bp)
 959{
 960        xfs_buf_log_item_t      *bip = bp->b_fspriv;
 961
 962        trace_xfs_buf_item_relse(bp, _RET_IP_);
 963        ASSERT(!(bip->bli_item.li_flags & XFS_LI_IN_AIL));
 964
 965        bp->b_fspriv = bip->bli_item.li_bio_list;
 966        if (bp->b_fspriv == NULL)
 967                bp->b_iodone = NULL;
 968
 969        xfs_buf_rele(bp);
 970        xfs_buf_item_free(bip);
 971}
 972
 973
 974/*
 975 * Add the given log item with its callback to the list of callbacks
 976 * to be called when the buffer's I/O completes.  If it is not set
 977 * already, set the buffer's b_iodone() routine to be
 978 * xfs_buf_iodone_callbacks() and link the log item into the list of
 979 * items rooted at b_fsprivate.  Items are always added as the second
 980 * entry in the list if there is a first, because the buf item code
 981 * assumes that the buf log item is first.
 982 */
 983void
 984xfs_buf_attach_iodone(
 985        xfs_buf_t       *bp,
 986        void            (*cb)(xfs_buf_t *, xfs_log_item_t *),
 987        xfs_log_item_t  *lip)
 988{
 989        xfs_log_item_t  *head_lip;
 990
 991        ASSERT(xfs_buf_islocked(bp));
 992
 993        lip->li_cb = cb;
 994        head_lip = bp->b_fspriv;
 995        if (head_lip) {
 996                lip->li_bio_list = head_lip->li_bio_list;
 997                head_lip->li_bio_list = lip;
 998        } else {
 999                bp->b_fspriv = lip;
1000        }
1001
1002        ASSERT(bp->b_iodone == NULL ||
1003               bp->b_iodone == xfs_buf_iodone_callbacks);
1004        bp->b_iodone = xfs_buf_iodone_callbacks;
1005}
1006
1007/*
1008 * We can have many callbacks on a buffer. Running the callbacks individually
1009 * can cause a lot of contention on the AIL lock, so we allow for a single
1010 * callback to be able to scan the remaining lip->li_bio_list for other items
1011 * of the same type and callback to be processed in the first call.
1012 *
1013 * As a result, the loop walking the callback list below will also modify the
1014 * list. it removes the first item from the list and then runs the callback.
1015 * The loop then restarts from the new head of the list. This allows the
1016 * callback to scan and modify the list attached to the buffer and we don't
1017 * have to care about maintaining a next item pointer.
1018 */
1019STATIC void
1020xfs_buf_do_callbacks(
1021        struct xfs_buf          *bp)
1022{
1023        struct xfs_log_item     *lip;
1024
1025        while ((lip = bp->b_fspriv) != NULL) {
1026                bp->b_fspriv = lip->li_bio_list;
1027                ASSERT(lip->li_cb != NULL);
1028                /*
1029                 * Clear the next pointer so we don't have any
1030                 * confusion if the item is added to another buf.
1031                 * Don't touch the log item after calling its
1032                 * callback, because it could have freed itself.
1033                 */
1034                lip->li_bio_list = NULL;
1035                lip->li_cb(bp, lip);
1036        }
1037}
1038
1039/*
1040 * This is the iodone() function for buffers which have had callbacks
1041 * attached to them by xfs_buf_attach_iodone().  It should remove each
1042 * log item from the buffer's list and call the callback of each in turn.
1043 * When done, the buffer's fsprivate field is set to NULL and the buffer
1044 * is unlocked with a call to iodone().
1045 */
1046void
1047xfs_buf_iodone_callbacks(
1048        struct xfs_buf          *bp)
1049{
1050        struct xfs_log_item     *lip = bp->b_fspriv;
1051        struct xfs_mount        *mp = lip->li_mountp;
1052        static ulong            lasttime;
1053        static xfs_buftarg_t    *lasttarg;
1054
1055        if (likely(!bp->b_error))
1056                goto do_callbacks;
1057
1058        /*
1059         * If we've already decided to shutdown the filesystem because of
1060         * I/O errors, there's no point in giving this a retry.
1061         */
1062        if (XFS_FORCED_SHUTDOWN(mp)) {
1063                xfs_buf_stale(bp);
1064                XFS_BUF_DONE(bp);
1065                trace_xfs_buf_item_iodone(bp, _RET_IP_);
1066                goto do_callbacks;
1067        }
1068
1069        if (bp->b_target != lasttarg ||
1070            time_after(jiffies, (lasttime + 5*HZ))) {
1071                lasttime = jiffies;
1072                xfs_buf_ioerror_alert(bp, __func__);
1073        }
1074        lasttarg = bp->b_target;
1075
1076        /*
1077         * If the write was asynchronous then no one will be looking for the
1078         * error.  Clear the error state and write the buffer out again.
1079         *
1080         * XXX: This helps against transient write errors, but we need to find
1081         * a way to shut the filesystem down if the writes keep failing.
1082         *
1083         * In practice we'll shut the filesystem down soon as non-transient
1084         * erorrs tend to affect the whole device and a failing log write
1085         * will make us give up.  But we really ought to do better here.
1086         */
1087        if (XFS_BUF_ISASYNC(bp)) {
1088                ASSERT(bp->b_iodone != NULL);
1089
1090                trace_xfs_buf_item_iodone_async(bp, _RET_IP_);
1091
1092                xfs_buf_ioerror(bp, 0); /* errno of 0 unsets the flag */
1093
1094                if (!(bp->b_flags & (XBF_STALE|XBF_WRITE_FAIL))) {
1095                        bp->b_flags |= XBF_WRITE | XBF_ASYNC |
1096                                       XBF_DONE | XBF_WRITE_FAIL;
1097                        xfs_buf_iorequest(bp);
1098                } else {
1099                        xfs_buf_relse(bp);
1100                }
1101
1102                return;
1103        }
1104
1105        /*
1106         * If the write of the buffer was synchronous, we want to make
1107         * sure to return the error to the caller of xfs_bwrite().
1108         */
1109        xfs_buf_stale(bp);
1110        XFS_BUF_DONE(bp);
1111
1112        trace_xfs_buf_error_relse(bp, _RET_IP_);
1113
1114do_callbacks:
1115        xfs_buf_do_callbacks(bp);
1116        bp->b_fspriv = NULL;
1117        bp->b_iodone = NULL;
1118        xfs_buf_ioend(bp, 0);
1119}
1120
1121/*
1122 * This is the iodone() function for buffers which have been
1123 * logged.  It is called when they are eventually flushed out.
1124 * It should remove the buf item from the AIL, and free the buf item.
1125 * It is called by xfs_buf_iodone_callbacks() above which will take
1126 * care of cleaning up the buffer itself.
1127 */
1128void
1129xfs_buf_iodone(
1130        struct xfs_buf          *bp,
1131        struct xfs_log_item     *lip)
1132{
1133        struct xfs_ail          *ailp = lip->li_ailp;
1134
1135        ASSERT(BUF_ITEM(lip)->bli_buf == bp);
1136
1137        xfs_buf_rele(bp);
1138
1139        /*
1140         * If we are forcibly shutting down, this may well be
1141         * off the AIL already. That's because we simulate the
1142         * log-committed callbacks to unpin these buffers. Or we may never
1143         * have put this item on AIL because of the transaction was
1144         * aborted forcibly. xfs_trans_ail_delete() takes care of these.
1145         *
1146         * Either way, AIL is useless if we're forcing a shutdown.
1147         */
1148        spin_lock(&ailp->xa_lock);
1149        xfs_trans_ail_delete(ailp, lip, SHUTDOWN_CORRUPT_INCORE);
1150        xfs_buf_item_free(BUF_ITEM(lip));
1151}
1152