linux/fs/xfs/xfs_iomap.c
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   1/*
   2 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#include "xfs.h"
  19#include "xfs_fs.h"
  20#include "xfs_log.h"
  21#include "xfs_trans.h"
  22#include "xfs_sb.h"
  23#include "xfs_ag.h"
  24#include "xfs_alloc.h"
  25#include "xfs_quota.h"
  26#include "xfs_mount.h"
  27#include "xfs_bmap_btree.h"
  28#include "xfs_alloc_btree.h"
  29#include "xfs_ialloc_btree.h"
  30#include "xfs_dinode.h"
  31#include "xfs_inode.h"
  32#include "xfs_inode_item.h"
  33#include "xfs_btree.h"
  34#include "xfs_bmap.h"
  35#include "xfs_rtalloc.h"
  36#include "xfs_error.h"
  37#include "xfs_itable.h"
  38#include "xfs_attr.h"
  39#include "xfs_buf_item.h"
  40#include "xfs_trans_space.h"
  41#include "xfs_utils.h"
  42#include "xfs_iomap.h"
  43#include "xfs_trace.h"
  44
  45
  46#define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
  47                                                << mp->m_writeio_log)
  48#define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
  49
  50STATIC int
  51xfs_iomap_eof_align_last_fsb(
  52        xfs_mount_t     *mp,
  53        xfs_inode_t     *ip,
  54        xfs_extlen_t    extsize,
  55        xfs_fileoff_t   *last_fsb)
  56{
  57        xfs_fileoff_t   new_last_fsb = 0;
  58        xfs_extlen_t    align = 0;
  59        int             eof, error;
  60
  61        if (!XFS_IS_REALTIME_INODE(ip)) {
  62                /*
  63                 * Round up the allocation request to a stripe unit
  64                 * (m_dalign) boundary if the file size is >= stripe unit
  65                 * size, and we are allocating past the allocation eof.
  66                 *
  67                 * If mounted with the "-o swalloc" option the alignment is
  68                 * increased from the strip unit size to the stripe width.
  69                 */
  70                if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
  71                        align = mp->m_swidth;
  72                else if (mp->m_dalign)
  73                        align = mp->m_dalign;
  74
  75                if (align && XFS_ISIZE(ip) >= XFS_FSB_TO_B(mp, align))
  76                        new_last_fsb = roundup_64(*last_fsb, align);
  77        }
  78
  79        /*
  80         * Always round up the allocation request to an extent boundary
  81         * (when file on a real-time subvolume or has di_extsize hint).
  82         */
  83        if (extsize) {
  84                if (new_last_fsb)
  85                        align = roundup_64(new_last_fsb, extsize);
  86                else
  87                        align = extsize;
  88                new_last_fsb = roundup_64(*last_fsb, align);
  89        }
  90
  91        if (new_last_fsb) {
  92                error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
  93                if (error)
  94                        return error;
  95                if (eof)
  96                        *last_fsb = new_last_fsb;
  97        }
  98        return 0;
  99}
 100
 101STATIC int
 102xfs_alert_fsblock_zero(
 103        xfs_inode_t     *ip,
 104        xfs_bmbt_irec_t *imap)
 105{
 106        xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
 107                        "Access to block zero in inode %llu "
 108                        "start_block: %llx start_off: %llx "
 109                        "blkcnt: %llx extent-state: %x\n",
 110                (unsigned long long)ip->i_ino,
 111                (unsigned long long)imap->br_startblock,
 112                (unsigned long long)imap->br_startoff,
 113                (unsigned long long)imap->br_blockcount,
 114                imap->br_state);
 115        return EFSCORRUPTED;
 116}
 117
 118int
 119xfs_iomap_write_direct(
 120        xfs_inode_t     *ip,
 121        xfs_off_t       offset,
 122        size_t          count,
 123        xfs_bmbt_irec_t *imap,
 124        int             nmaps)
 125{
 126        xfs_mount_t     *mp = ip->i_mount;
 127        xfs_fileoff_t   offset_fsb;
 128        xfs_fileoff_t   last_fsb;
 129        xfs_filblks_t   count_fsb, resaligned;
 130        xfs_fsblock_t   firstfsb;
 131        xfs_extlen_t    extsz, temp;
 132        int             nimaps;
 133        int             bmapi_flag;
 134        int             quota_flag;
 135        int             rt;
 136        xfs_trans_t     *tp;
 137        xfs_bmap_free_t free_list;
 138        uint            qblocks, resblks, resrtextents;
 139        int             committed;
 140        int             error;
 141
 142        error = xfs_qm_dqattach(ip, 0);
 143        if (error)
 144                return XFS_ERROR(error);
 145
 146        rt = XFS_IS_REALTIME_INODE(ip);
 147        extsz = xfs_get_extsz_hint(ip);
 148
 149        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 150        last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 151        if ((offset + count) > XFS_ISIZE(ip)) {
 152                error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 153                if (error)
 154                        return XFS_ERROR(error);
 155        } else {
 156                if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
 157                        last_fsb = MIN(last_fsb, (xfs_fileoff_t)
 158                                        imap->br_blockcount +
 159                                        imap->br_startoff);
 160        }
 161        count_fsb = last_fsb - offset_fsb;
 162        ASSERT(count_fsb > 0);
 163
 164        resaligned = count_fsb;
 165        if (unlikely(extsz)) {
 166                if ((temp = do_mod(offset_fsb, extsz)))
 167                        resaligned += temp;
 168                if ((temp = do_mod(resaligned, extsz)))
 169                        resaligned += extsz - temp;
 170        }
 171
 172        if (unlikely(rt)) {
 173                resrtextents = qblocks = resaligned;
 174                resrtextents /= mp->m_sb.sb_rextsize;
 175                resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 176                quota_flag = XFS_QMOPT_RES_RTBLKS;
 177        } else {
 178                resrtextents = 0;
 179                resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 180                quota_flag = XFS_QMOPT_RES_REGBLKS;
 181        }
 182
 183        /*
 184         * Allocate and setup the transaction
 185         */
 186        tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
 187        error = xfs_trans_reserve(tp, resblks,
 188                        XFS_WRITE_LOG_RES(mp), resrtextents,
 189                        XFS_TRANS_PERM_LOG_RES,
 190                        XFS_WRITE_LOG_COUNT);
 191        /*
 192         * Check for running out of space, note: need lock to return
 193         */
 194        if (error) {
 195                xfs_trans_cancel(tp, 0);
 196                return XFS_ERROR(error);
 197        }
 198
 199        xfs_ilock(ip, XFS_ILOCK_EXCL);
 200
 201        error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
 202        if (error)
 203                goto out_trans_cancel;
 204
 205        xfs_trans_ijoin(tp, ip, 0);
 206
 207        bmapi_flag = 0;
 208        if (offset < XFS_ISIZE(ip) || extsz)
 209                bmapi_flag |= XFS_BMAPI_PREALLOC;
 210
 211        /*
 212         * From this point onwards we overwrite the imap pointer that the
 213         * caller gave to us.
 214         */
 215        xfs_bmap_init(&free_list, &firstfsb);
 216        nimaps = 1;
 217        error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
 218                                &firstfsb, 0, imap, &nimaps, &free_list);
 219        if (error)
 220                goto out_bmap_cancel;
 221
 222        /*
 223         * Complete the transaction
 224         */
 225        error = xfs_bmap_finish(&tp, &free_list, &committed);
 226        if (error)
 227                goto out_bmap_cancel;
 228        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 229        if (error)
 230                goto out_unlock;
 231
 232        /*
 233         * Copy any maps to caller's array and return any error.
 234         */
 235        if (nimaps == 0) {
 236                error = XFS_ERROR(ENOSPC);
 237                goto out_unlock;
 238        }
 239
 240        if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
 241                error = xfs_alert_fsblock_zero(ip, imap);
 242
 243out_unlock:
 244        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 245        return error;
 246
 247out_bmap_cancel:
 248        xfs_bmap_cancel(&free_list);
 249        xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
 250out_trans_cancel:
 251        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 252        goto out_unlock;
 253}
 254
 255/*
 256 * If the caller is doing a write at the end of the file, then extend the
 257 * allocation out to the file system's write iosize.  We clean up any extra
 258 * space left over when the file is closed in xfs_inactive().
 259 *
 260 * If we find we already have delalloc preallocation beyond EOF, don't do more
 261 * preallocation as it it not needed.
 262 */
 263STATIC int
 264xfs_iomap_eof_want_preallocate(
 265        xfs_mount_t     *mp,
 266        xfs_inode_t     *ip,
 267        xfs_off_t       offset,
 268        size_t          count,
 269        xfs_bmbt_irec_t *imap,
 270        int             nimaps,
 271        int             *prealloc)
 272{
 273        xfs_fileoff_t   start_fsb;
 274        xfs_filblks_t   count_fsb;
 275        xfs_fsblock_t   firstblock;
 276        int             n, error, imaps;
 277        int             found_delalloc = 0;
 278
 279        *prealloc = 0;
 280        if (offset + count <= XFS_ISIZE(ip))
 281                return 0;
 282
 283        /*
 284         * If there are any real blocks past eof, then don't
 285         * do any speculative allocation.
 286         */
 287        start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
 288        count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
 289        while (count_fsb > 0) {
 290                imaps = nimaps;
 291                firstblock = NULLFSBLOCK;
 292                error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
 293                                       0);
 294                if (error)
 295                        return error;
 296                for (n = 0; n < imaps; n++) {
 297                        if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
 298                            (imap[n].br_startblock != DELAYSTARTBLOCK))
 299                                return 0;
 300                        start_fsb += imap[n].br_blockcount;
 301                        count_fsb -= imap[n].br_blockcount;
 302
 303                        if (imap[n].br_startblock == DELAYSTARTBLOCK)
 304                                found_delalloc = 1;
 305                }
 306        }
 307        if (!found_delalloc)
 308                *prealloc = 1;
 309        return 0;
 310}
 311
 312/*
 313 * If we don't have a user specified preallocation size, dynamically increase
 314 * the preallocation size as the size of the file grows. Cap the maximum size
 315 * at a single extent or less if the filesystem is near full. The closer the
 316 * filesystem is to full, the smaller the maximum prealocation.
 317 */
 318STATIC xfs_fsblock_t
 319xfs_iomap_prealloc_size(
 320        struct xfs_mount        *mp,
 321        struct xfs_inode        *ip)
 322{
 323        xfs_fsblock_t           alloc_blocks = 0;
 324
 325        if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
 326                int shift = 0;
 327                int64_t freesp;
 328
 329                /*
 330                 * rounddown_pow_of_two() returns an undefined result
 331                 * if we pass in alloc_blocks = 0. Hence the "+ 1" to
 332                 * ensure we always pass in a non-zero value.
 333                 */
 334                alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1;
 335                alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN,
 336                                        rounddown_pow_of_two(alloc_blocks));
 337
 338                xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
 339                freesp = mp->m_sb.sb_fdblocks;
 340                if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
 341                        shift = 2;
 342                        if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
 343                                shift++;
 344                        if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
 345                                shift++;
 346                        if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
 347                                shift++;
 348                        if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
 349                                shift++;
 350                }
 351                if (shift)
 352                        alloc_blocks >>= shift;
 353        }
 354
 355        if (alloc_blocks < mp->m_writeio_blocks)
 356                alloc_blocks = mp->m_writeio_blocks;
 357
 358        return alloc_blocks;
 359}
 360
 361int
 362xfs_iomap_write_delay(
 363        xfs_inode_t     *ip,
 364        xfs_off_t       offset,
 365        size_t          count,
 366        xfs_bmbt_irec_t *ret_imap)
 367{
 368        xfs_mount_t     *mp = ip->i_mount;
 369        xfs_fileoff_t   offset_fsb;
 370        xfs_fileoff_t   last_fsb;
 371        xfs_off_t       aligned_offset;
 372        xfs_fileoff_t   ioalign;
 373        xfs_extlen_t    extsz;
 374        int             nimaps;
 375        xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
 376        int             prealloc, flushed = 0;
 377        int             error;
 378
 379        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 380
 381        /*
 382         * Make sure that the dquots are there. This doesn't hold
 383         * the ilock across a disk read.
 384         */
 385        error = xfs_qm_dqattach_locked(ip, 0);
 386        if (error)
 387                return XFS_ERROR(error);
 388
 389        extsz = xfs_get_extsz_hint(ip);
 390        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 391
 392
 393        error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
 394                                imap, XFS_WRITE_IMAPS, &prealloc);
 395        if (error)
 396                return error;
 397
 398retry:
 399        if (prealloc) {
 400                xfs_fsblock_t   alloc_blocks = xfs_iomap_prealloc_size(mp, ip);
 401
 402                aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
 403                ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
 404                last_fsb = ioalign + alloc_blocks;
 405        } else {
 406                last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 407        }
 408
 409        if (prealloc || extsz) {
 410                error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 411                if (error)
 412                        return error;
 413        }
 414
 415        /*
 416         * Make sure preallocation does not create extents beyond the range we
 417         * actually support in this filesystem.
 418         */
 419        if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
 420                last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
 421
 422        ASSERT(last_fsb > offset_fsb);
 423
 424        nimaps = XFS_WRITE_IMAPS;
 425        error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
 426                                imap, &nimaps, XFS_BMAPI_ENTIRE);
 427        switch (error) {
 428        case 0:
 429        case ENOSPC:
 430        case EDQUOT:
 431                break;
 432        default:
 433                return XFS_ERROR(error);
 434        }
 435
 436        /*
 437         * If bmapi returned us nothing, we got either ENOSPC or EDQUOT.  For
 438         * ENOSPC, * flush all other inodes with delalloc blocks to free up
 439         * some of the excess reserved metadata space. For both cases, retry
 440         * without EOF preallocation.
 441         */
 442        if (nimaps == 0) {
 443                trace_xfs_delalloc_enospc(ip, offset, count);
 444                if (flushed)
 445                        return XFS_ERROR(error ? error : ENOSPC);
 446
 447                if (error == ENOSPC) {
 448                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 449                        xfs_flush_inodes(ip);
 450                        xfs_ilock(ip, XFS_ILOCK_EXCL);
 451                }
 452
 453                flushed = 1;
 454                error = 0;
 455                prealloc = 0;
 456                goto retry;
 457        }
 458
 459        if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
 460                return xfs_alert_fsblock_zero(ip, &imap[0]);
 461
 462        *ret_imap = imap[0];
 463        return 0;
 464}
 465
 466/*
 467 * Pass in a delayed allocate extent, convert it to real extents;
 468 * return to the caller the extent we create which maps on top of
 469 * the originating callers request.
 470 *
 471 * Called without a lock on the inode.
 472 *
 473 * We no longer bother to look at the incoming map - all we have to
 474 * guarantee is that whatever we allocate fills the required range.
 475 */
 476int
 477xfs_iomap_write_allocate(
 478        xfs_inode_t     *ip,
 479        xfs_off_t       offset,
 480        size_t          count,
 481        xfs_bmbt_irec_t *imap)
 482{
 483        xfs_mount_t     *mp = ip->i_mount;
 484        xfs_fileoff_t   offset_fsb, last_block;
 485        xfs_fileoff_t   end_fsb, map_start_fsb;
 486        xfs_fsblock_t   first_block;
 487        xfs_bmap_free_t free_list;
 488        xfs_filblks_t   count_fsb;
 489        xfs_trans_t     *tp;
 490        int             nimaps, committed;
 491        int             error = 0;
 492        int             nres;
 493
 494        /*
 495         * Make sure that the dquots are there.
 496         */
 497        error = xfs_qm_dqattach(ip, 0);
 498        if (error)
 499                return XFS_ERROR(error);
 500
 501        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 502        count_fsb = imap->br_blockcount;
 503        map_start_fsb = imap->br_startoff;
 504
 505        XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
 506
 507        while (count_fsb != 0) {
 508                /*
 509                 * Set up a transaction with which to allocate the
 510                 * backing store for the file.  Do allocations in a
 511                 * loop until we get some space in the range we are
 512                 * interested in.  The other space that might be allocated
 513                 * is in the delayed allocation extent on which we sit
 514                 * but before our buffer starts.
 515                 */
 516
 517                nimaps = 0;
 518                while (nimaps == 0) {
 519                        tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
 520                        tp->t_flags |= XFS_TRANS_RESERVE;
 521                        nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
 522                        error = xfs_trans_reserve(tp, nres,
 523                                        XFS_WRITE_LOG_RES(mp),
 524                                        0, XFS_TRANS_PERM_LOG_RES,
 525                                        XFS_WRITE_LOG_COUNT);
 526                        if (error) {
 527                                xfs_trans_cancel(tp, 0);
 528                                return XFS_ERROR(error);
 529                        }
 530                        xfs_ilock(ip, XFS_ILOCK_EXCL);
 531                        xfs_trans_ijoin(tp, ip, 0);
 532
 533                        xfs_bmap_init(&free_list, &first_block);
 534
 535                        /*
 536                         * it is possible that the extents have changed since
 537                         * we did the read call as we dropped the ilock for a
 538                         * while. We have to be careful about truncates or hole
 539                         * punchs here - we are not allowed to allocate
 540                         * non-delalloc blocks here.
 541                         *
 542                         * The only protection against truncation is the pages
 543                         * for the range we are being asked to convert are
 544                         * locked and hence a truncate will block on them
 545                         * first.
 546                         *
 547                         * As a result, if we go beyond the range we really
 548                         * need and hit an delalloc extent boundary followed by
 549                         * a hole while we have excess blocks in the map, we
 550                         * will fill the hole incorrectly and overrun the
 551                         * transaction reservation.
 552                         *
 553                         * Using a single map prevents this as we are forced to
 554                         * check each map we look for overlap with the desired
 555                         * range and abort as soon as we find it. Also, given
 556                         * that we only return a single map, having one beyond
 557                         * what we can return is probably a bit silly.
 558                         *
 559                         * We also need to check that we don't go beyond EOF;
 560                         * this is a truncate optimisation as a truncate sets
 561                         * the new file size before block on the pages we
 562                         * currently have locked under writeback. Because they
 563                         * are about to be tossed, we don't need to write them
 564                         * back....
 565                         */
 566                        nimaps = 1;
 567                        end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
 568                        error = xfs_bmap_last_offset(NULL, ip, &last_block,
 569                                                        XFS_DATA_FORK);
 570                        if (error)
 571                                goto trans_cancel;
 572
 573                        last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
 574                        if ((map_start_fsb + count_fsb) > last_block) {
 575                                count_fsb = last_block - map_start_fsb;
 576                                if (count_fsb == 0) {
 577                                        error = EAGAIN;
 578                                        goto trans_cancel;
 579                                }
 580                        }
 581
 582                        /*
 583                         * From this point onwards we overwrite the imap
 584                         * pointer that the caller gave to us.
 585                         */
 586                        error = xfs_bmapi_write(tp, ip, map_start_fsb,
 587                                                count_fsb,
 588                                                XFS_BMAPI_STACK_SWITCH,
 589                                                &first_block, 1,
 590                                                imap, &nimaps, &free_list);
 591                        if (error)
 592                                goto trans_cancel;
 593
 594                        error = xfs_bmap_finish(&tp, &free_list, &committed);
 595                        if (error)
 596                                goto trans_cancel;
 597
 598                        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 599                        if (error)
 600                                goto error0;
 601
 602                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 603                }
 604
 605                /*
 606                 * See if we were able to allocate an extent that
 607                 * covers at least part of the callers request
 608                 */
 609                if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
 610                        return xfs_alert_fsblock_zero(ip, imap);
 611
 612                if ((offset_fsb >= imap->br_startoff) &&
 613                    (offset_fsb < (imap->br_startoff +
 614                                   imap->br_blockcount))) {
 615                        XFS_STATS_INC(xs_xstrat_quick);
 616                        return 0;
 617                }
 618
 619                /*
 620                 * So far we have not mapped the requested part of the
 621                 * file, just surrounding data, try again.
 622                 */
 623                count_fsb -= imap->br_blockcount;
 624                map_start_fsb = imap->br_startoff + imap->br_blockcount;
 625        }
 626
 627trans_cancel:
 628        xfs_bmap_cancel(&free_list);
 629        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 630error0:
 631        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 632        return XFS_ERROR(error);
 633}
 634
 635int
 636xfs_iomap_write_unwritten(
 637        xfs_inode_t     *ip,
 638        xfs_off_t       offset,
 639        size_t          count)
 640{
 641        xfs_mount_t     *mp = ip->i_mount;
 642        xfs_fileoff_t   offset_fsb;
 643        xfs_filblks_t   count_fsb;
 644        xfs_filblks_t   numblks_fsb;
 645        xfs_fsblock_t   firstfsb;
 646        int             nimaps;
 647        xfs_trans_t     *tp;
 648        xfs_bmbt_irec_t imap;
 649        xfs_bmap_free_t free_list;
 650        xfs_fsize_t     i_size;
 651        uint            resblks;
 652        int             committed;
 653        int             error;
 654
 655        trace_xfs_unwritten_convert(ip, offset, count);
 656
 657        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 658        count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 659        count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
 660
 661        /*
 662         * Reserve enough blocks in this transaction for two complete extent
 663         * btree splits.  We may be converting the middle part of an unwritten
 664         * extent and in this case we will insert two new extents in the btree
 665         * each of which could cause a full split.
 666         *
 667         * This reservation amount will be used in the first call to
 668         * xfs_bmbt_split() to select an AG with enough space to satisfy the
 669         * rest of the operation.
 670         */
 671        resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
 672
 673        do {
 674                /*
 675                 * set up a transaction to convert the range of extents
 676                 * from unwritten to real. Do allocations in a loop until
 677                 * we have covered the range passed in.
 678                 *
 679                 * Note that we open code the transaction allocation here
 680                 * to pass KM_NOFS--we can't risk to recursing back into
 681                 * the filesystem here as we might be asked to write out
 682                 * the same inode that we complete here and might deadlock
 683                 * on the iolock.
 684                 */
 685                sb_start_intwrite(mp->m_super);
 686                tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
 687                tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
 688                error = xfs_trans_reserve(tp, resblks,
 689                                XFS_WRITE_LOG_RES(mp), 0,
 690                                XFS_TRANS_PERM_LOG_RES,
 691                                XFS_WRITE_LOG_COUNT);
 692                if (error) {
 693                        xfs_trans_cancel(tp, 0);
 694                        return XFS_ERROR(error);
 695                }
 696
 697                xfs_ilock(ip, XFS_ILOCK_EXCL);
 698                xfs_trans_ijoin(tp, ip, 0);
 699
 700                /*
 701                 * Modify the unwritten extent state of the buffer.
 702                 */
 703                xfs_bmap_init(&free_list, &firstfsb);
 704                nimaps = 1;
 705                error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
 706                                  XFS_BMAPI_CONVERT, &firstfsb,
 707                                  1, &imap, &nimaps, &free_list);
 708                if (error)
 709                        goto error_on_bmapi_transaction;
 710
 711                /*
 712                 * Log the updated inode size as we go.  We have to be careful
 713                 * to only log it up to the actual write offset if it is
 714                 * halfway into a block.
 715                 */
 716                i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
 717                if (i_size > offset + count)
 718                        i_size = offset + count;
 719
 720                i_size = xfs_new_eof(ip, i_size);
 721                if (i_size) {
 722                        ip->i_d.di_size = i_size;
 723                        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 724                }
 725
 726                error = xfs_bmap_finish(&tp, &free_list, &committed);
 727                if (error)
 728                        goto error_on_bmapi_transaction;
 729
 730                error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 731                xfs_iunlock(ip, XFS_ILOCK_EXCL);
 732                if (error)
 733                        return XFS_ERROR(error);
 734
 735                if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
 736                        return xfs_alert_fsblock_zero(ip, &imap);
 737
 738                if ((numblks_fsb = imap.br_blockcount) == 0) {
 739                        /*
 740                         * The numblks_fsb value should always get
 741                         * smaller, otherwise the loop is stuck.
 742                         */
 743                        ASSERT(imap.br_blockcount);
 744                        break;
 745                }
 746                offset_fsb += numblks_fsb;
 747                count_fsb -= numblks_fsb;
 748        } while (count_fsb > 0);
 749
 750        return 0;
 751
 752error_on_bmapi_transaction:
 753        xfs_bmap_cancel(&free_list);
 754        xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
 755        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 756        return XFS_ERROR(error);
 757}
 758
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