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_types.h"
  21#include "xfs_bit.h"
  22#include "xfs_log.h"
  23#include "xfs_trans.h"
  24#include "xfs_sb.h"
  25#include "xfs_ag.h"
  26#include "xfs_mount.h"
  27#include "xfs_buf_item.h"
  28#include "xfs_trans_priv.h"
  29#include "xfs_error.h"
  30#include "xfs_trace.h"
  31
  32
  33kmem_zone_t     *xfs_buf_item_zone;
  34
  35static inline struct xfs_buf_log_item *BUF_ITEM(struct xfs_log_item *lip)
  36{
  37        return container_of(lip, struct xfs_buf_log_item, bli_item);
  38}
  39
  40
  41#ifdef XFS_TRANS_DEBUG
  42/*
  43 * This function uses an alternate strategy for tracking the bytes
  44 * that the user requests to be logged.  This can then be used
  45 * in conjunction with the bli_orig array in the buf log item to
  46 * catch bugs in our callers' code.
  47 *
  48 * We also double check the bits set in xfs_buf_item_log using a
  49 * simple algorithm to check that every byte is accounted for.
  50 */
  51STATIC void
  52xfs_buf_item_log_debug(
  53        xfs_buf_log_item_t      *bip,
  54        uint                    first,
  55        uint                    last)
  56{
  57        uint    x;
  58        uint    byte;
  59        uint    nbytes;
  60        uint    chunk_num;
  61        uint    word_num;
  62        uint    bit_num;
  63        uint    bit_set;
  64        uint    *wordp;
  65
  66        ASSERT(bip->bli_logged != NULL);
  67        byte = first;
  68        nbytes = last - first + 1;
  69        bfset(bip->bli_logged, first, nbytes);
  70        for (x = 0; x < nbytes; x++) {
  71                chunk_num = byte >> XFS_BLF_SHIFT;
  72                word_num = chunk_num >> BIT_TO_WORD_SHIFT;
  73                bit_num = chunk_num & (NBWORD - 1);
  74                wordp = &(bip->bli_format.blf_data_map[word_num]);
  75                bit_set = *wordp & (1 << bit_num);
  76                ASSERT(bit_set);
  77                byte++;
  78        }
  79}
  80
  81/*
  82 * This function is called when we flush something into a buffer without
  83 * logging it.  This happens for things like inodes which are logged
  84 * separately from the buffer.
  85 */
  86void
  87xfs_buf_item_flush_log_debug(
  88        xfs_buf_t       *bp,
  89        uint            first,
  90        uint            last)
  91{
  92        xfs_buf_log_item_t      *bip = bp->b_fspriv;
  93        uint                    nbytes;
  94
  95        if (bip == NULL || (bip->bli_item.li_type != XFS_LI_BUF))
  96                return;
  97
  98        ASSERT(bip->bli_logged != NULL);
  99        nbytes = last - first + 1;
 100        bfset(bip->bli_logged, first, nbytes);
 101}
 102
 103/*
 104 * This function is called to verify that our callers have logged
 105 * all the bytes that they changed.
 106 *
 107 * It does this by comparing the original copy of the buffer stored in
 108 * the buf log item's bli_orig array to the current copy of the buffer
 109 * and ensuring that all bytes which mismatch are set in the bli_logged
 110 * array of the buf log item.
 111 */
 112STATIC void
 113xfs_buf_item_log_check(
 114        xfs_buf_log_item_t      *bip)
 115{
 116        char            *orig;
 117        char            *buffer;
 118        int             x;
 119        xfs_buf_t       *bp;
 120
 121        ASSERT(bip->bli_orig != NULL);
 122        ASSERT(bip->bli_logged != NULL);
 123
 124        bp = bip->bli_buf;
 125        ASSERT(bp->b_length > 0);
 126        ASSERT(bp->b_addr != NULL);
 127        orig = bip->bli_orig;
 128        buffer = bp->b_addr;
 129        for (x = 0; x < BBTOB(bp->b_length); x++) {
 130                if (orig[x] != buffer[x] && !btst(bip->bli_logged, x)) {
 131                        xfs_emerg(bp->b_mount,
 132                                "%s: bip %x buffer %x orig %x index %d",
 133                                __func__, bip, bp, orig, x);
 134                        ASSERT(0);
 135                }
 136        }
 137}
 138#else
 139#define         xfs_buf_item_log_debug(x,y,z)
 140#define         xfs_buf_item_log_check(x)
 141#endif
 142
 143STATIC void     xfs_buf_do_callbacks(struct xfs_buf *bp);
 144
 145/*
 146 * This returns the number of log iovecs needed to log the
 147 * given buf log item.
 148 *
 149 * It calculates this as 1 iovec for the buf log format structure
 150 * and 1 for each stretch of non-contiguous chunks to be logged.
 151 * Contiguous chunks are logged in a single iovec.
 152 *
 153 * If the XFS_BLI_STALE flag has been set, then log nothing.
 154 */
 155STATIC uint
 156xfs_buf_item_size_segment(
 157        struct xfs_buf_log_item *bip,
 158        struct xfs_buf_log_format *blfp)
 159{
 160        struct xfs_buf          *bp = bip->bli_buf;
 161        uint                    nvecs;
 162        int                     next_bit;
 163        int                     last_bit;
 164
 165        last_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
 166        if (last_bit == -1)
 167                return 0;
 168
 169        /*
 170         * initial count for a dirty buffer is 2 vectors - the format structure
 171         * and the first dirty region.
 172         */
 173        nvecs = 2;
 174
 175        while (last_bit != -1) {
 176                /*
 177                 * This takes the bit number to start looking from and
 178                 * returns the next set bit from there.  It returns -1
 179                 * if there are no more bits set or the start bit is
 180                 * beyond the end of the bitmap.
 181                 */
 182                next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,
 183                                        last_bit + 1);
 184                /*
 185                 * If we run out of bits, leave the loop,
 186                 * else if we find a new set of bits bump the number of vecs,
 187                 * else keep scanning the current set of bits.
 188                 */
 189                if (next_bit == -1) {
 190                        break;
 191                } else if (next_bit != last_bit + 1) {
 192                        last_bit = next_bit;
 193                        nvecs++;
 194                } else if (xfs_buf_offset(bp, next_bit * XFS_BLF_CHUNK) !=
 195                           (xfs_buf_offset(bp, last_bit * XFS_BLF_CHUNK) +
 196                            XFS_BLF_CHUNK)) {
 197                        last_bit = next_bit;
 198                        nvecs++;
 199                } else {
 200                        last_bit++;
 201                }
 202        }
 203
 204        return nvecs;
 205}
 206
 207/*
 208 * This returns the number of log iovecs needed to log the given buf log item.
 209 *
 210 * It calculates this as 1 iovec for the buf log format structure and 1 for each
 211 * stretch of non-contiguous chunks to be logged.  Contiguous chunks are logged
 212 * in a single iovec.
 213 *
 214 * Discontiguous buffers need a format structure per region that that is being
 215 * logged. This makes the changes in the buffer appear to log recovery as though
 216 * they came from separate buffers, just like would occur if multiple buffers
 217 * were used instead of a single discontiguous buffer. This enables
 218 * discontiguous buffers to be in-memory constructs, completely transparent to
 219 * what ends up on disk.
 220 *
 221 * If the XFS_BLI_STALE flag has been set, then log nothing but the buf log
 222 * format structures.
 223 */
 224STATIC uint
 225xfs_buf_item_size(
 226        struct xfs_log_item     *lip)
 227{
 228        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 229        uint                    nvecs;
 230        int                     i;
 231
 232        ASSERT(atomic_read(&bip->bli_refcount) > 0);
 233        if (bip->bli_flags & XFS_BLI_STALE) {
 234                /*
 235                 * The buffer is stale, so all we need to log
 236                 * is the buf log format structure with the
 237                 * cancel flag in it.
 238                 */
 239                trace_xfs_buf_item_size_stale(bip);
 240                ASSERT(bip->bli_format.blf_flags & XFS_BLF_CANCEL);
 241                return bip->bli_format_count;
 242        }
 243
 244        ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
 245
 246        /*
 247         * the vector count is based on the number of buffer vectors we have
 248         * dirty bits in. This will only be greater than one when we have a
 249         * compound buffer with more than one segment dirty. Hence for compound
 250         * buffers we need to track which segment the dirty bits correspond to,
 251         * and when we move from one segment to the next increment the vector
 252         * count for the extra buf log format structure that will need to be
 253         * written.
 254         */
 255        nvecs = 0;
 256        for (i = 0; i < bip->bli_format_count; i++) {
 257                nvecs += xfs_buf_item_size_segment(bip, &bip->bli_formats[i]);
 258        }
 259
 260        trace_xfs_buf_item_size(bip);
 261        return nvecs;
 262}
 263
 264static struct xfs_log_iovec *
 265xfs_buf_item_format_segment(
 266        struct xfs_buf_log_item *bip,
 267        struct xfs_log_iovec    *vecp,
 268        uint                    offset,
 269        struct xfs_buf_log_format *blfp)
 270{
 271        struct xfs_buf  *bp = bip->bli_buf;
 272        uint            base_size;
 273        uint            nvecs;
 274        int             first_bit;
 275        int             last_bit;
 276        int             next_bit;
 277        uint            nbits;
 278        uint            buffer_offset;
 279
 280        /* copy the flags across from the base format item */
 281        blfp->blf_flags = bip->bli_format.blf_flags;
 282
 283        /*
 284         * Base size is the actual size of the ondisk structure - it reflects
 285         * the actual size of the dirty bitmap rather than the size of the in
 286         * memory structure.
 287         */
 288        base_size = offsetof(struct xfs_buf_log_format, blf_data_map) +
 289                        (blfp->blf_map_size * sizeof(blfp->blf_data_map[0]));
 290        vecp->i_addr = blfp;
 291        vecp->i_len = base_size;
 292        vecp->i_type = XLOG_REG_TYPE_BFORMAT;
 293        vecp++;
 294        nvecs = 1;
 295
 296        if (bip->bli_flags & XFS_BLI_STALE) {
 297                /*
 298                 * The buffer is stale, so all we need to log
 299                 * is the buf log format structure with the
 300                 * cancel flag in it.
 301                 */
 302                trace_xfs_buf_item_format_stale(bip);
 303                ASSERT(blfp->blf_flags & XFS_BLF_CANCEL);
 304                blfp->blf_size = nvecs;
 305                return vecp;
 306        }
 307
 308        /*
 309         * Fill in an iovec for each set of contiguous chunks.
 310         */
 311        first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
 312        ASSERT(first_bit != -1);
 313        last_bit = first_bit;
 314        nbits = 1;
 315        for (;;) {
 316                /*
 317                 * This takes the bit number to start looking from and
 318                 * returns the next set bit from there.  It returns -1
 319                 * if there are no more bits set or the start bit is
 320                 * beyond the end of the bitmap.
 321                 */
 322                next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,
 323                                        (uint)last_bit + 1);
 324                /*
 325                 * If we run out of bits fill in the last iovec and get
 326                 * out of the loop.
 327                 * Else if we start a new set of bits then fill in the
 328                 * iovec for the series we were looking at and start
 329                 * counting the bits in the new one.
 330                 * Else we're still in the same set of bits so just
 331                 * keep counting and scanning.
 332                 */
 333                if (next_bit == -1) {
 334                        buffer_offset = offset + first_bit * XFS_BLF_CHUNK;
 335                        vecp->i_addr = xfs_buf_offset(bp, buffer_offset);
 336                        vecp->i_len = nbits * XFS_BLF_CHUNK;
 337                        vecp->i_type = XLOG_REG_TYPE_BCHUNK;
 338                        nvecs++;
 339                        break;
 340                } else if (next_bit != last_bit + 1) {
 341                        buffer_offset = offset + first_bit * XFS_BLF_CHUNK;
 342                        vecp->i_addr = xfs_buf_offset(bp, buffer_offset);
 343                        vecp->i_len = nbits * XFS_BLF_CHUNK;
 344                        vecp->i_type = XLOG_REG_TYPE_BCHUNK;
 345                        nvecs++;
 346                        vecp++;
 347                        first_bit = next_bit;
 348                        last_bit = next_bit;
 349                        nbits = 1;
 350                } else if (xfs_buf_offset(bp, offset +
 351                                              (next_bit << XFS_BLF_SHIFT)) !=
 352                           (xfs_buf_offset(bp, offset +
 353                                               (last_bit << XFS_BLF_SHIFT)) +
 354                            XFS_BLF_CHUNK)) {
 355                        buffer_offset = offset + first_bit * XFS_BLF_CHUNK;
 356                        vecp->i_addr = xfs_buf_offset(bp, buffer_offset);
 357                        vecp->i_len = nbits * XFS_BLF_CHUNK;
 358                        vecp->i_type = XLOG_REG_TYPE_BCHUNK;
 359/*
 360 * You would think we need to bump the nvecs here too, but we do not
 361 * this number is used by recovery, and it gets confused by the boundary
 362 * split here
 363 *                      nvecs++;
 364 */
 365                        vecp++;
 366                        first_bit = next_bit;
 367                        last_bit = next_bit;
 368                        nbits = 1;
 369                } else {
 370                        last_bit++;
 371                        nbits++;
 372                }
 373        }
 374        bip->bli_format.blf_size = nvecs;
 375        return vecp;
 376}
 377
 378/*
 379 * This is called to fill in the vector of log iovecs for the
 380 * given log buf item.  It fills the first entry with a buf log
 381 * format structure, and the rest point to contiguous chunks
 382 * within the buffer.
 383 */
 384STATIC void
 385xfs_buf_item_format(
 386        struct xfs_log_item     *lip,
 387        struct xfs_log_iovec    *vecp)
 388{
 389        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 390        struct xfs_buf          *bp = bip->bli_buf;
 391        uint                    offset = 0;
 392        int                     i;
 393
 394        ASSERT(atomic_read(&bip->bli_refcount) > 0);
 395        ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
 396               (bip->bli_flags & XFS_BLI_STALE));
 397
 398        /*
 399         * If it is an inode buffer, transfer the in-memory state to the
 400         * format flags and clear the in-memory state. We do not transfer
 401         * this state if the inode buffer allocation has not yet been committed
 402         * to the log as setting the XFS_BLI_INODE_BUF flag will prevent
 403         * correct replay of the inode allocation.
 404         */
 405        if (bip->bli_flags & XFS_BLI_INODE_BUF) {
 406                if (!((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) &&
 407                      xfs_log_item_in_current_chkpt(lip)))
 408                        bip->bli_format.blf_flags |= XFS_BLF_INODE_BUF;
 409                bip->bli_flags &= ~XFS_BLI_INODE_BUF;
 410        }
 411
 412        for (i = 0; i < bip->bli_format_count; i++) {
 413                vecp = xfs_buf_item_format_segment(bip, vecp, offset,
 414                                                &bip->bli_formats[i]);
 415                offset += bp->b_maps[i].bm_len;
 416        }
 417
 418        /*
 419         * Check to make sure everything is consistent.
 420         */
 421        trace_xfs_buf_item_format(bip);
 422        xfs_buf_item_log_check(bip);
 423}
 424
 425/*
 426 * This is called to pin the buffer associated with the buf log item in memory
 427 * so it cannot be written out.
 428 *
 429 * We also always take a reference to the buffer log item here so that the bli
 430 * is held while the item is pinned in memory. This means that we can
 431 * unconditionally drop the reference count a transaction holds when the
 432 * transaction is completed.
 433 */
 434STATIC void
 435xfs_buf_item_pin(
 436        struct xfs_log_item     *lip)
 437{
 438        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 439
 440        ASSERT(atomic_read(&bip->bli_refcount) > 0);
 441        ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
 442               (bip->bli_flags & XFS_BLI_STALE));
 443
 444        trace_xfs_buf_item_pin(bip);
 445
 446        atomic_inc(&bip->bli_refcount);
 447        atomic_inc(&bip->bli_buf->b_pin_count);
 448}
 449
 450/*
 451 * This is called to unpin the buffer associated with the buf log
 452 * item which was previously pinned with a call to xfs_buf_item_pin().
 453 *
 454 * Also drop the reference to the buf item for the current transaction.
 455 * If the XFS_BLI_STALE flag is set and we are the last reference,
 456 * then free up the buf log item and unlock the buffer.
 457 *
 458 * If the remove flag is set we are called from uncommit in the
 459 * forced-shutdown path.  If that is true and the reference count on
 460 * the log item is going to drop to zero we need to free the item's
 461 * descriptor in the transaction.
 462 */
 463STATIC void
 464xfs_buf_item_unpin(
 465        struct xfs_log_item     *lip,
 466        int                     remove)
 467{
 468        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 469        xfs_buf_t       *bp = bip->bli_buf;
 470        struct xfs_ail  *ailp = lip->li_ailp;
 471        int             stale = bip->bli_flags & XFS_BLI_STALE;
 472        int             freed;
 473
 474        ASSERT(bp->b_fspriv == bip);
 475        ASSERT(atomic_read(&bip->bli_refcount) > 0);
 476
 477        trace_xfs_buf_item_unpin(bip);
 478
 479        freed = atomic_dec_and_test(&bip->bli_refcount);
 480
 481        if (atomic_dec_and_test(&bp->b_pin_count))
 482                wake_up_all(&bp->b_waiters);
 483
 484        if (freed && stale) {
 485                ASSERT(bip->bli_flags & XFS_BLI_STALE);
 486                ASSERT(xfs_buf_islocked(bp));
 487                ASSERT(XFS_BUF_ISSTALE(bp));
 488                ASSERT(bip->bli_format.blf_flags & XFS_BLF_CANCEL);
 489
 490                trace_xfs_buf_item_unpin_stale(bip);
 491
 492                if (remove) {
 493                        /*
 494                         * If we are in a transaction context, we have to
 495                         * remove the log item from the transaction as we are
 496                         * about to release our reference to the buffer.  If we
 497                         * don't, the unlock that occurs later in
 498                         * xfs_trans_uncommit() will try to reference the
 499                         * buffer which we no longer have a hold on.
 500                         */
 501                        if (lip->li_desc)
 502                                xfs_trans_del_item(lip);
 503
 504                        /*
 505                         * Since the transaction no longer refers to the buffer,
 506                         * the buffer should no longer refer to the transaction.
 507                         */
 508                        bp->b_transp = NULL;
 509                }
 510
 511                /*
 512                 * If we get called here because of an IO error, we may
 513                 * or may not have the item on the AIL. xfs_trans_ail_delete()
 514                 * will take care of that situation.
 515                 * xfs_trans_ail_delete() drops the AIL lock.
 516                 */
 517                if (bip->bli_flags & XFS_BLI_STALE_INODE) {
 518                        xfs_buf_do_callbacks(bp);
 519                        bp->b_fspriv = NULL;
 520                        bp->b_iodone = NULL;
 521                } else {
 522                        spin_lock(&ailp->xa_lock);
 523                        xfs_trans_ail_delete(ailp, lip, SHUTDOWN_LOG_IO_ERROR);
 524                        xfs_buf_item_relse(bp);
 525                        ASSERT(bp->b_fspriv == NULL);
 526                }
 527                xfs_buf_relse(bp);
 528        } else if (freed && remove) {
 529                /*
 530                 * There are currently two references to the buffer - the active
 531                 * LRU reference and the buf log item. What we are about to do
 532                 * here - simulate a failed IO completion - requires 3
 533                 * references.
 534                 *
 535                 * The LRU reference is removed by the xfs_buf_stale() call. The
 536                 * buf item reference is removed by the xfs_buf_iodone()
 537                 * callback that is run by xfs_buf_do_callbacks() during ioend
 538                 * processing (via the bp->b_iodone callback), and then finally
 539                 * the ioend processing will drop the IO reference if the buffer
 540                 * is marked XBF_ASYNC.
 541                 *
 542                 * Hence we need to take an additional reference here so that IO
 543                 * completion processing doesn't free the buffer prematurely.
 544                 */
 545                xfs_buf_lock(bp);
 546                xfs_buf_hold(bp);
 547                bp->b_flags |= XBF_ASYNC;
 548                xfs_buf_ioerror(bp, EIO);
 549                XFS_BUF_UNDONE(bp);
 550                xfs_buf_stale(bp);
 551                xfs_buf_ioend(bp, 0);
 552        }
 553}
 554
 555STATIC uint
 556xfs_buf_item_push(
 557        struct xfs_log_item     *lip,
 558        struct list_head        *buffer_list)
 559{
 560        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 561        struct xfs_buf          *bp = bip->bli_buf;
 562        uint                    rval = XFS_ITEM_SUCCESS;
 563
 564        if (xfs_buf_ispinned(bp))
 565                return XFS_ITEM_PINNED;
 566        if (!xfs_buf_trylock(bp))
 567                return XFS_ITEM_LOCKED;
 568
 569        ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
 570
 571        trace_xfs_buf_item_push(bip);
 572
 573        if (!xfs_buf_delwri_queue(bp, buffer_list))
 574                rval = XFS_ITEM_FLUSHING;
 575        xfs_buf_unlock(bp);
 576        return rval;
 577}
 578
 579/*
 580 * Release the buffer associated with the buf log item.  If there is no dirty
 581 * logged data associated with the buffer recorded in the buf log item, then
 582 * free the buf log item and remove the reference to it in the buffer.
 583 *
 584 * This call ignores the recursion count.  It is only called when the buffer
 585 * should REALLY be unlocked, regardless of the recursion count.
 586 *
 587 * We unconditionally drop the transaction's reference to the log item. If the
 588 * item was logged, then another reference was taken when it was pinned, so we
 589 * can safely drop the transaction reference now.  This also allows us to avoid
 590 * potential races with the unpin code freeing the bli by not referencing the
 591 * bli after we've dropped the reference count.
 592 *
 593 * If the XFS_BLI_HOLD flag is set in the buf log item, then free the log item
 594 * if necessary but do not unlock the buffer.  This is for support of
 595 * xfs_trans_bhold(). Make sure the XFS_BLI_HOLD field is cleared if we don't
 596 * free the item.
 597 */
 598STATIC void
 599xfs_buf_item_unlock(
 600        struct xfs_log_item     *lip)
 601{
 602        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 603        struct xfs_buf          *bp = bip->bli_buf;
 604        int                     aborted;
 605        uint                    hold;
 606
 607        /* Clear the buffer's association with this transaction. */
 608        bp->b_transp = NULL;
 609
 610        /*
 611         * If this is a transaction abort, don't return early.  Instead, allow
 612         * the brelse to happen.  Normally it would be done for stale
 613         * (cancelled) buffers at unpin time, but we'll never go through the
 614         * pin/unpin cycle if we abort inside commit.
 615         */
 616        aborted = (lip->li_flags & XFS_LI_ABORTED) != 0;
 617
 618        /*
 619         * Before possibly freeing the buf item, determine if we should
 620         * release the buffer at the end of this routine.
 621         */
 622        hold = bip->bli_flags & XFS_BLI_HOLD;
 623
 624        /* Clear the per transaction state. */
 625        bip->bli_flags &= ~(XFS_BLI_LOGGED | XFS_BLI_HOLD);
 626
 627        /*
 628         * If the buf item is marked stale, then don't do anything.  We'll
 629         * unlock the buffer and free the buf item when the buffer is unpinned
 630         * for the last time.
 631         */
 632        if (bip->bli_flags & XFS_BLI_STALE) {
 633                trace_xfs_buf_item_unlock_stale(bip);
 634                ASSERT(bip->bli_format.blf_flags & XFS_BLF_CANCEL);
 635                if (!aborted) {
 636                        atomic_dec(&bip->bli_refcount);
 637                        return;
 638                }
 639        }
 640
 641        trace_xfs_buf_item_unlock(bip);
 642
 643        /*
 644         * If the buf item isn't tracking any data, free it, otherwise drop the
 645         * reference we hold to it.
 646         */
 647        if (xfs_bitmap_empty(bip->bli_format.blf_data_map,
 648                             bip->bli_format.blf_map_size))
 649                xfs_buf_item_relse(bp);
 650        else
 651                atomic_dec(&bip->bli_refcount);
 652
 653        if (!hold)
 654                xfs_buf_relse(bp);
 655}
 656
 657/*
 658 * This is called to find out where the oldest active copy of the
 659 * buf log item in the on disk log resides now that the last log
 660 * write of it completed at the given lsn.
 661 * We always re-log all the dirty data in a buffer, so usually the
 662 * latest copy in the on disk log is the only one that matters.  For
 663 * those cases we simply return the given lsn.
 664 *
 665 * The one exception to this is for buffers full of newly allocated
 666 * inodes.  These buffers are only relogged with the XFS_BLI_INODE_BUF
 667 * flag set, indicating that only the di_next_unlinked fields from the
 668 * inodes in the buffers will be replayed during recovery.  If the
 669 * original newly allocated inode images have not yet been flushed
 670 * when the buffer is so relogged, then we need to make sure that we
 671 * keep the old images in the 'active' portion of the log.  We do this
 672 * by returning the original lsn of that transaction here rather than
 673 * the current one.
 674 */
 675STATIC xfs_lsn_t
 676xfs_buf_item_committed(
 677        struct xfs_log_item     *lip,
 678        xfs_lsn_t               lsn)
 679{
 680        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
 681
 682        trace_xfs_buf_item_committed(bip);
 683
 684        if ((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) && lip->li_lsn != 0)
 685                return lip->li_lsn;
 686        return lsn;
 687}
 688
 689STATIC void
 690xfs_buf_item_committing(
 691        struct xfs_log_item     *lip,
 692        xfs_lsn_t               commit_lsn)
 693{
 694}
 695
 696/*
 697 * This is the ops vector shared by all buf log items.
 698 */
 699static const struct xfs_item_ops xfs_buf_item_ops = {
 700        .iop_size       = xfs_buf_item_size,
 701        .iop_format     = xfs_buf_item_format,
 702        .iop_pin        = xfs_buf_item_pin,
 703        .iop_unpin      = xfs_buf_item_unpin,
 704        .iop_unlock     = xfs_buf_item_unlock,
 705        .iop_committed  = xfs_buf_item_committed,
 706        .iop_push       = xfs_buf_item_push,
 707        .iop_committing = xfs_buf_item_committing
 708};
 709
 710STATIC int
 711xfs_buf_item_get_format(
 712        struct xfs_buf_log_item *bip,
 713        int                     count)
 714{
 715        ASSERT(bip->bli_formats == NULL);
 716        bip->bli_format_count = count;
 717
 718        if (count == 1) {
 719                bip->bli_formats = &bip->bli_format;
 720                return 0;
 721        }
 722
 723        bip->bli_formats = kmem_zalloc(count * sizeof(struct xfs_buf_log_format),
 724                                KM_SLEEP);
 725        if (!bip->bli_formats)
 726                return ENOMEM;
 727        return 0;
 728}
 729
 730STATIC void
 731xfs_buf_item_free_format(
 732        struct xfs_buf_log_item *bip)
 733{
 734        if (bip->bli_formats != &bip->bli_format) {
 735                kmem_free(bip->bli_formats);
 736                bip->bli_formats = NULL;
 737        }
 738}
 739
 740/*
 741 * Allocate a new buf log item to go with the given buffer.
 742 * Set the buffer's b_fsprivate field to point to the new
 743 * buf log item.  If there are other item's attached to the
 744 * buffer (see xfs_buf_attach_iodone() below), then put the
 745 * buf log item at the front.
 746 */
 747void
 748xfs_buf_item_init(
 749        xfs_buf_t       *bp,
 750        xfs_mount_t     *mp)
 751{
 752        xfs_log_item_t          *lip = bp->b_fspriv;
 753        xfs_buf_log_item_t      *bip;
 754        int                     chunks;
 755        int                     map_size;
 756        int                     error;
 757        int                     i;
 758
 759        /*
 760         * Check to see if there is already a buf log item for
 761         * this buffer.  If there is, it is guaranteed to be
 762         * the first.  If we do already have one, there is
 763         * nothing to do here so return.
 764         */
 765        ASSERT(bp->b_target->bt_mount == mp);
 766        if (lip != NULL && lip->li_type == XFS_LI_BUF)
 767                return;
 768
 769        bip = kmem_zone_zalloc(xfs_buf_item_zone, KM_SLEEP);
 770        xfs_log_item_init(mp, &bip->bli_item, XFS_LI_BUF, &xfs_buf_item_ops);
 771        bip->bli_buf = bp;
 772        xfs_buf_hold(bp);
 773
 774        /*
 775         * chunks is the number of XFS_BLF_CHUNK size pieces the buffer
 776         * can be divided into. Make sure not to truncate any pieces.
 777         * map_size is the size of the bitmap needed to describe the
 778         * chunks of the buffer.
 779         *
 780         * Discontiguous buffer support follows the layout of the underlying
 781         * buffer. This makes the implementation as simple as possible.
 782         */
 783        error = xfs_buf_item_get_format(bip, bp->b_map_count);
 784        ASSERT(error == 0);
 785
 786        for (i = 0; i < bip->bli_format_count; i++) {
 787                chunks = DIV_ROUND_UP(BBTOB(bp->b_maps[i].bm_len),
 788                                      XFS_BLF_CHUNK);
 789                map_size = DIV_ROUND_UP(chunks, NBWORD);
 790
 791                bip->bli_formats[i].blf_type = XFS_LI_BUF;
 792                bip->bli_formats[i].blf_blkno = bp->b_maps[i].bm_bn;
 793                bip->bli_formats[i].blf_len = bp->b_maps[i].bm_len;
 794                bip->bli_formats[i].blf_map_size = map_size;
 795        }
 796
 797#ifdef XFS_TRANS_DEBUG
 798        /*
 799         * Allocate the arrays for tracking what needs to be logged
 800         * and what our callers request to be logged.  bli_orig
 801         * holds a copy of the original, clean buffer for comparison
 802         * against, and bli_logged keeps a 1 bit flag per byte in
 803         * the buffer to indicate which bytes the callers have asked
 804         * to have logged.
 805         */
 806        bip->bli_orig = kmem_alloc(BBTOB(bp->b_length), KM_SLEEP);
 807        memcpy(bip->bli_orig, bp->b_addr, BBTOB(bp->b_length));
 808        bip->bli_logged = kmem_zalloc(BBTOB(bp->b_length) / NBBY, KM_SLEEP);
 809#endif
 810
 811        /*
 812         * Put the buf item into the list of items attached to the
 813         * buffer at the front.
 814         */
 815        if (bp->b_fspriv)
 816                bip->bli_item.li_bio_list = bp->b_fspriv;
 817        bp->b_fspriv = bip;
 818}
 819
 820
 821/*
 822 * Mark bytes first through last inclusive as dirty in the buf
 823 * item's bitmap.
 824 */
 825void
 826xfs_buf_item_log_segment(
 827        struct xfs_buf_log_item *bip,
 828        uint                    first,
 829        uint                    last,
 830        uint                    *map)
 831{
 832        uint            first_bit;
 833        uint            last_bit;
 834        uint            bits_to_set;
 835        uint            bits_set;
 836        uint            word_num;
 837        uint            *wordp;
 838        uint            bit;
 839        uint            end_bit;
 840        uint            mask;
 841
 842        /*
 843         * Convert byte offsets to bit numbers.
 844         */
 845        first_bit = first >> XFS_BLF_SHIFT;
 846        last_bit = last >> XFS_BLF_SHIFT;
 847
 848        /*
 849         * Calculate the total number of bits to be set.
 850         */
 851        bits_to_set = last_bit - first_bit + 1;
 852
 853        /*
 854         * Get a pointer to the first word in the bitmap
 855         * to set a bit in.
 856         */
 857        word_num = first_bit >> BIT_TO_WORD_SHIFT;
 858        wordp = &map[word_num];
 859
 860        /*
 861         * Calculate the starting bit in the first word.
 862         */
 863        bit = first_bit & (uint)(NBWORD - 1);
 864
 865        /*
 866         * First set any bits in the first word of our range.
 867         * If it starts at bit 0 of the word, it will be
 868         * set below rather than here.  That is what the variable
 869         * bit tells us. The variable bits_set tracks the number
 870         * of bits that have been set so far.  End_bit is the number
 871         * of the last bit to be set in this word plus one.
 872         */
 873        if (bit) {
 874                end_bit = MIN(bit + bits_to_set, (uint)NBWORD);
 875                mask = ((1 << (end_bit - bit)) - 1) << bit;
 876                *wordp |= mask;
 877                wordp++;
 878                bits_set = end_bit - bit;
 879        } else {
 880                bits_set = 0;
 881        }
 882
 883        /*
 884         * Now set bits a whole word at a time that are between
 885         * first_bit and last_bit.
 886         */
 887        while ((bits_to_set - bits_set) >= NBWORD) {
 888                *wordp |= 0xffffffff;
 889                bits_set += NBWORD;
 890                wordp++;
 891        }
 892
 893        /*
 894         * Finally, set any bits left to be set in one last partial word.
 895         */
 896        end_bit = bits_to_set - bits_set;
 897        if (end_bit) {
 898                mask = (1 << end_bit) - 1;
 899                *wordp |= mask;
 900        }
 901
 902        xfs_buf_item_log_debug(bip, first, last);
 903}
 904
 905/*
 906 * Mark bytes first through last inclusive as dirty in the buf
 907 * item's bitmap.
 908 */
 909void
 910xfs_buf_item_log(
 911        xfs_buf_log_item_t      *bip,
 912        uint                    first,
 913        uint                    last)
 914{
 915        int                     i;
 916        uint                    start;
 917        uint                    end;
 918        struct xfs_buf          *bp = bip->bli_buf;
 919
 920        /*
 921         * Mark the item as having some dirty data for
 922         * quick reference in xfs_buf_item_dirty.
 923         */
 924        bip->bli_flags |= XFS_BLI_DIRTY;
 925
 926        /*
 927         * walk each buffer segment and mark them dirty appropriately.
 928         */
 929        start = 0;
 930        for (i = 0; i < bip->bli_format_count; i++) {
 931                if (start > last)
 932                        break;
 933                end = start + BBTOB(bp->b_maps[i].bm_len);
 934                if (first > end) {
 935                        start += BBTOB(bp->b_maps[i].bm_len);
 936                        continue;
 937                }
 938                if (first < start)
 939                        first = start;
 940                if (end > last)
 941                        end = last;
 942
 943                xfs_buf_item_log_segment(bip, first, end,
 944                                         &bip->bli_formats[i].blf_data_map[0]);
 945
 946                start += bp->b_maps[i].bm_len;
 947        }
 948}
 949
 950
 951/*
 952 * Return 1 if the buffer has some data that has been logged (at any
 953 * point, not just the current transaction) and 0 if not.
 954 */
 955uint
 956xfs_buf_item_dirty(
 957        xfs_buf_log_item_t      *bip)
 958{
 959        return (bip->bli_flags & XFS_BLI_DIRTY);
 960}
 961
 962STATIC void
 963xfs_buf_item_free(
 964        xfs_buf_log_item_t      *bip)
 965{
 966#ifdef XFS_TRANS_DEBUG
 967        kmem_free(bip->bli_orig);
 968        kmem_free(bip->bli_logged);
 969#endif /* XFS_TRANS_DEBUG */
 970
 971        xfs_buf_item_free_format(bip);
 972        kmem_zone_free(xfs_buf_item_zone, bip);
 973}
 974
 975/*
 976 * This is called when the buf log item is no longer needed.  It should
 977 * free the buf log item associated with the given buffer and clear
 978 * the buffer's pointer to the buf log item.  If there are no more
 979 * items in the list, clear the b_iodone field of the buffer (see
 980 * xfs_buf_attach_iodone() below).
 981 */
 982void
 983xfs_buf_item_relse(
 984        xfs_buf_t       *bp)
 985{
 986        xfs_buf_log_item_t      *bip;
 987
 988        trace_xfs_buf_item_relse(bp, _RET_IP_);
 989
 990        bip = bp->b_fspriv;
 991        bp->b_fspriv = bip->bli_item.li_bio_list;
 992        if (bp->b_fspriv == NULL)
 993                bp->b_iodone = NULL;
 994
 995        xfs_buf_rele(bp);
 996        xfs_buf_item_free(bip);
 997}
 998
 999
1000/*
1001 * Add the given log item with its callback to the list of callbacks
1002 * to be called when the buffer's I/O completes.  If it is not set
1003 * already, set the buffer's b_iodone() routine to be
1004 * xfs_buf_iodone_callbacks() and link the log item into the list of
1005 * items rooted at b_fsprivate.  Items are always added as the second
1006 * entry in the list if there is a first, because the buf item code
1007 * assumes that the buf log item is first.
1008 */
1009void
1010xfs_buf_attach_iodone(
1011        xfs_buf_t       *bp,
1012        void            (*cb)(xfs_buf_t *, xfs_log_item_t *),
1013        xfs_log_item_t  *lip)
1014{
1015        xfs_log_item_t  *head_lip;
1016
1017        ASSERT(xfs_buf_islocked(bp));
1018
1019        lip->li_cb = cb;
1020        head_lip = bp->b_fspriv;
1021        if (head_lip) {
1022                lip->li_bio_list = head_lip->li_bio_list;
1023                head_lip->li_bio_list = lip;
1024        } else {
1025                bp->b_fspriv = lip;
1026        }
1027
1028        ASSERT(bp->b_iodone == NULL ||
1029               bp->b_iodone == xfs_buf_iodone_callbacks);
1030        bp->b_iodone = xfs_buf_iodone_callbacks;
1031}
1032
1033/*
1034 * We can have many callbacks on a buffer. Running the callbacks individually
1035 * can cause a lot of contention on the AIL lock, so we allow for a single
1036 * callback to be able to scan the remaining lip->li_bio_list for other items
1037 * of the same type and callback to be processed in the first call.
1038 *
1039 * As a result, the loop walking the callback list below will also modify the
1040 * list. it removes the first item from the list and then runs the callback.
1041 * The loop then restarts from the new head of the list. This allows the
1042 * callback to scan and modify the list attached to the buffer and we don't
1043 * have to care about maintaining a next item pointer.
1044 */
1045STATIC void
1046xfs_buf_do_callbacks(
1047        struct xfs_buf          *bp)
1048{
1049        struct xfs_log_item     *lip;
1050
1051        while ((lip = bp->b_fspriv) != NULL) {
1052                bp->b_fspriv = lip->li_bio_list;
1053                ASSERT(lip->li_cb != NULL);
1054                /*
1055                 * Clear the next pointer so we don't have any
1056                 * confusion if the item is added to another buf.
1057                 * Don't touch the log item after calling its
1058                 * callback, because it could have freed itself.
1059                 */
1060                lip->li_bio_list = NULL;
1061                lip->li_cb(bp, lip);
1062        }
1063}
1064
1065/*
1066 * This is the iodone() function for buffers which have had callbacks
1067 * attached to them by xfs_buf_attach_iodone().  It should remove each
1068 * log item from the buffer's list and call the callback of each in turn.
1069 * When done, the buffer's fsprivate field is set to NULL and the buffer
1070 * is unlocked with a call to iodone().
1071 */
1072void
1073xfs_buf_iodone_callbacks(
1074        struct xfs_buf          *bp)
1075{
1076        struct xfs_log_item     *lip = bp->b_fspriv;
1077        struct xfs_mount        *mp = lip->li_mountp;
1078        static ulong            lasttime;
1079        static xfs_buftarg_t    *lasttarg;
1080
1081        if (likely(!xfs_buf_geterror(bp)))
1082                goto do_callbacks;
1083
1084        /*
1085         * If we've already decided to shutdown the filesystem because of
1086         * I/O errors, there's no point in giving this a retry.
1087         */
1088        if (XFS_FORCED_SHUTDOWN(mp)) {
1089                xfs_buf_stale(bp);
1090                XFS_BUF_DONE(bp);
1091                trace_xfs_buf_item_iodone(bp, _RET_IP_);
1092                goto do_callbacks;
1093        }
1094
1095        if (bp->b_target != lasttarg ||
1096            time_after(jiffies, (lasttime + 5*HZ))) {
1097                lasttime = jiffies;
1098                xfs_buf_ioerror_alert(bp, __func__);
1099        }
1100        lasttarg = bp->b_target;
1101
1102        /*
1103         * If the write was asynchronous then no one will be looking for the
1104         * error.  Clear the error state and write the buffer out again.
1105         *
1106         * XXX: This helps against transient write errors, but we need to find
1107         * a way to shut the filesystem down if the writes keep failing.
1108         *
1109         * In practice we'll shut the filesystem down soon as non-transient
1110         * erorrs tend to affect the whole device and a failing log write
1111         * will make us give up.  But we really ought to do better here.
1112         */
1113        if (XFS_BUF_ISASYNC(bp)) {
1114                ASSERT(bp->b_iodone != NULL);
1115
1116                trace_xfs_buf_item_iodone_async(bp, _RET_IP_);
1117
1118                xfs_buf_ioerror(bp, 0); /* errno of 0 unsets the flag */
1119
1120                if (!XFS_BUF_ISSTALE(bp)) {
1121                        bp->b_flags |= XBF_WRITE | XBF_ASYNC | XBF_DONE;
1122                        xfs_buf_iorequest(bp);
1123                } else {
1124                        xfs_buf_relse(bp);
1125                }
1126
1127                return;
1128        }
1129
1130        /*
1131         * If the write of the buffer was synchronous, we want to make
1132         * sure to return the error to the caller of xfs_bwrite().
1133         */
1134        xfs_buf_stale(bp);
1135        XFS_BUF_DONE(bp);
1136
1137        trace_xfs_buf_error_relse(bp, _RET_IP_);
1138
1139do_callbacks:
1140        xfs_buf_do_callbacks(bp);
1141        bp->b_fspriv = NULL;
1142        bp->b_iodone = NULL;
1143        xfs_buf_ioend(bp, 0);
1144}
1145
1146/*
1147 * This is the iodone() function for buffers which have been
1148 * logged.  It is called when they are eventually flushed out.
1149 * It should remove the buf item from the AIL, and free the buf item.
1150 * It is called by xfs_buf_iodone_callbacks() above which will take
1151 * care of cleaning up the buffer itself.
1152 */
1153void
1154xfs_buf_iodone(
1155        struct xfs_buf          *bp,
1156        struct xfs_log_item     *lip)
1157{
1158        struct xfs_ail          *ailp = lip->li_ailp;
1159
1160        ASSERT(BUF_ITEM(lip)->bli_buf == bp);
1161
1162        xfs_buf_rele(bp);
1163
1164        /*
1165         * If we are forcibly shutting down, this may well be
1166         * off the AIL already. That's because we simulate the
1167         * log-committed callbacks to unpin these buffers. Or we may never
1168         * have put this item on AIL because of the transaction was
1169         * aborted forcibly. xfs_trans_ail_delete() takes care of these.
1170         *
1171         * Either way, AIL is useless if we're forcing a shutdown.
1172         */
1173        spin_lock(&ailp->xa_lock);
1174        xfs_trans_ail_delete(ailp, lip, SHUTDOWN_CORRUPT_INCORE);
1175        xfs_buf_item_free(BUF_ITEM(lip));
1176}
1177
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