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#include "xfs_icache.h"
  45
  46
  47#define XFS_WRITEIO_ALIGN(mp,off)       (((off) >> mp->m_writeio_log) \
  48                                                << mp->m_writeio_log)
  49#define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
  50
  51STATIC int
  52xfs_iomap_eof_align_last_fsb(
  53        xfs_mount_t     *mp,
  54        xfs_inode_t     *ip,
  55        xfs_extlen_t    extsize,
  56        xfs_fileoff_t   *last_fsb)
  57{
  58        xfs_fileoff_t   new_last_fsb = 0;
  59        xfs_extlen_t    align = 0;
  60        int             eof, error;
  61
  62        if (!XFS_IS_REALTIME_INODE(ip)) {
  63                /*
  64                 * Round up the allocation request to a stripe unit
  65                 * (m_dalign) boundary if the file size is >= stripe unit
  66                 * size, and we are allocating past the allocation eof.
  67                 *
  68                 * If mounted with the "-o swalloc" option the alignment is
  69                 * increased from the strip unit size to the stripe width.
  70                 */
  71                if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
  72                        align = mp->m_swidth;
  73                else if (mp->m_dalign)
  74                        align = mp->m_dalign;
  75
  76                if (align && XFS_ISIZE(ip) >= XFS_FSB_TO_B(mp, align))
  77                        new_last_fsb = roundup_64(*last_fsb, align);
  78        }
  79
  80        /*
  81         * Always round up the allocation request to an extent boundary
  82         * (when file on a real-time subvolume or has di_extsize hint).
  83         */
  84        if (extsize) {
  85                if (new_last_fsb)
  86                        align = roundup_64(new_last_fsb, extsize);
  87                else
  88                        align = extsize;
  89                new_last_fsb = roundup_64(*last_fsb, align);
  90        }
  91
  92        if (new_last_fsb) {
  93                error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
  94                if (error)
  95                        return error;
  96                if (eof)
  97                        *last_fsb = new_last_fsb;
  98        }
  99        return 0;
 100}
 101
 102STATIC int
 103xfs_alert_fsblock_zero(
 104        xfs_inode_t     *ip,
 105        xfs_bmbt_irec_t *imap)
 106{
 107        xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
 108                        "Access to block zero in inode %llu "
 109                        "start_block: %llx start_off: %llx "
 110                        "blkcnt: %llx extent-state: %x\n",
 111                (unsigned long long)ip->i_ino,
 112                (unsigned long long)imap->br_startblock,
 113                (unsigned long long)imap->br_startoff,
 114                (unsigned long long)imap->br_blockcount,
 115                imap->br_state);
 116        return EFSCORRUPTED;
 117}
 118
 119int
 120xfs_iomap_write_direct(
 121        xfs_inode_t     *ip,
 122        xfs_off_t       offset,
 123        size_t          count,
 124        xfs_bmbt_irec_t *imap,
 125        int             nmaps)
 126{
 127        xfs_mount_t     *mp = ip->i_mount;
 128        xfs_fileoff_t   offset_fsb;
 129        xfs_fileoff_t   last_fsb;
 130        xfs_filblks_t   count_fsb, resaligned;
 131        xfs_fsblock_t   firstfsb;
 132        xfs_extlen_t    extsz, temp;
 133        int             nimaps;
 134        int             bmapi_flag;
 135        int             quota_flag;
 136        int             rt;
 137        xfs_trans_t     *tp;
 138        xfs_bmap_free_t free_list;
 139        uint            qblocks, resblks, resrtextents;
 140        int             committed;
 141        int             error;
 142
 143        error = xfs_qm_dqattach(ip, 0);
 144        if (error)
 145                return XFS_ERROR(error);
 146
 147        rt = XFS_IS_REALTIME_INODE(ip);
 148        extsz = xfs_get_extsz_hint(ip);
 149
 150        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 151        last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 152        if ((offset + count) > XFS_ISIZE(ip)) {
 153                error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 154                if (error)
 155                        return XFS_ERROR(error);
 156        } else {
 157                if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
 158                        last_fsb = MIN(last_fsb, (xfs_fileoff_t)
 159                                        imap->br_blockcount +
 160                                        imap->br_startoff);
 161        }
 162        count_fsb = last_fsb - offset_fsb;
 163        ASSERT(count_fsb > 0);
 164
 165        resaligned = count_fsb;
 166        if (unlikely(extsz)) {
 167                if ((temp = do_mod(offset_fsb, extsz)))
 168                        resaligned += temp;
 169                if ((temp = do_mod(resaligned, extsz)))
 170                        resaligned += extsz - temp;
 171        }
 172
 173        if (unlikely(rt)) {
 174                resrtextents = qblocks = resaligned;
 175                resrtextents /= mp->m_sb.sb_rextsize;
 176                resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 177                quota_flag = XFS_QMOPT_RES_RTBLKS;
 178        } else {
 179                resrtextents = 0;
 180                resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 181                quota_flag = XFS_QMOPT_RES_REGBLKS;
 182        }
 183
 184        /*
 185         * Allocate and setup the transaction
 186         */
 187        tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
 188        error = xfs_trans_reserve(tp, resblks,
 189                        XFS_WRITE_LOG_RES(mp), resrtextents,
 190                        XFS_TRANS_PERM_LOG_RES,
 191                        XFS_WRITE_LOG_COUNT);
 192        /*
 193         * Check for running out of space, note: need lock to return
 194         */
 195        if (error) {
 196                xfs_trans_cancel(tp, 0);
 197                return XFS_ERROR(error);
 198        }
 199
 200        xfs_ilock(ip, XFS_ILOCK_EXCL);
 201
 202        error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
 203        if (error)
 204                goto out_trans_cancel;
 205
 206        xfs_trans_ijoin(tp, ip, 0);
 207
 208        bmapi_flag = 0;
 209        if (offset < XFS_ISIZE(ip) || extsz)
 210                bmapi_flag |= XFS_BMAPI_PREALLOC;
 211
 212        /*
 213         * From this point onwards we overwrite the imap pointer that the
 214         * caller gave to us.
 215         */
 216        xfs_bmap_init(&free_list, &firstfsb);
 217        nimaps = 1;
 218        error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
 219                                &firstfsb, 0, imap, &nimaps, &free_list);
 220        if (error)
 221                goto out_bmap_cancel;
 222
 223        /*
 224         * Complete the transaction
 225         */
 226        error = xfs_bmap_finish(&tp, &free_list, &committed);
 227        if (error)
 228                goto out_bmap_cancel;
 229        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 230        if (error)
 231                goto out_unlock;
 232
 233        /*
 234         * Copy any maps to caller's array and return any error.
 235         */
 236        if (nimaps == 0) {
 237                error = XFS_ERROR(ENOSPC);
 238                goto out_unlock;
 239        }
 240
 241        if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
 242                error = xfs_alert_fsblock_zero(ip, imap);
 243
 244out_unlock:
 245        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 246        return error;
 247
 248out_bmap_cancel:
 249        xfs_bmap_cancel(&free_list);
 250        xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
 251out_trans_cancel:
 252        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 253        goto out_unlock;
 254}
 255
 256/*
 257 * If the caller is doing a write at the end of the file, then extend the
 258 * allocation out to the file system's write iosize.  We clean up any extra
 259 * space left over when the file is closed in xfs_inactive().
 260 *
 261 * If we find we already have delalloc preallocation beyond EOF, don't do more
 262 * preallocation as it it not needed.
 263 */
 264STATIC int
 265xfs_iomap_eof_want_preallocate(
 266        xfs_mount_t     *mp,
 267        xfs_inode_t     *ip,
 268        xfs_off_t       offset,
 269        size_t          count,
 270        xfs_bmbt_irec_t *imap,
 271        int             nimaps,
 272        int             *prealloc)
 273{
 274        xfs_fileoff_t   start_fsb;
 275        xfs_filblks_t   count_fsb;
 276        xfs_fsblock_t   firstblock;
 277        int             n, error, imaps;
 278        int             found_delalloc = 0;
 279
 280        *prealloc = 0;
 281        if (offset + count <= XFS_ISIZE(ip))
 282                return 0;
 283
 284        /*
 285         * If there are any real blocks past eof, then don't
 286         * do any speculative allocation.
 287         */
 288        start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
 289        count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
 290        while (count_fsb > 0) {
 291                imaps = nimaps;
 292                firstblock = NULLFSBLOCK;
 293                error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
 294                                       0);
 295                if (error)
 296                        return error;
 297                for (n = 0; n < imaps; n++) {
 298                        if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
 299                            (imap[n].br_startblock != DELAYSTARTBLOCK))
 300                                return 0;
 301                        start_fsb += imap[n].br_blockcount;
 302                        count_fsb -= imap[n].br_blockcount;
 303
 304                        if (imap[n].br_startblock == DELAYSTARTBLOCK)
 305                                found_delalloc = 1;
 306                }
 307        }
 308        if (!found_delalloc)
 309                *prealloc = 1;
 310        return 0;
 311}
 312
 313/*
 314 * If we don't have a user specified preallocation size, dynamically increase
 315 * the preallocation size as the size of the file grows. Cap the maximum size
 316 * at a single extent or less if the filesystem is near full. The closer the
 317 * filesystem is to full, the smaller the maximum prealocation.
 318 */
 319STATIC xfs_fsblock_t
 320xfs_iomap_prealloc_size(
 321        struct xfs_mount        *mp,
 322        struct xfs_inode        *ip)
 323{
 324        xfs_fsblock_t           alloc_blocks = 0;
 325
 326        if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
 327                int shift = 0;
 328                int64_t freesp;
 329
 330                /*
 331                 * rounddown_pow_of_two() returns an undefined result
 332                 * if we pass in alloc_blocks = 0. Hence the "+ 1" to
 333                 * ensure we always pass in a non-zero value.
 334                 */
 335                alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1;
 336                alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN,
 337                                        rounddown_pow_of_two(alloc_blocks));
 338
 339                xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
 340                freesp = mp->m_sb.sb_fdblocks;
 341                if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
 342                        shift = 2;
 343                        if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
 344                                shift++;
 345                        if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
 346                                shift++;
 347                        if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
 348                                shift++;
 349                        if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
 350                                shift++;
 351                }
 352                if (shift)
 353                        alloc_blocks >>= shift;
 354
 355                /*
 356                 * If we are still trying to allocate more space than is
 357                 * available, squash the prealloc hard. This can happen if we
 358                 * have a large file on a small filesystem and the above
 359                 * lowspace thresholds are smaller than MAXEXTLEN.
 360                 */
 361                while (alloc_blocks >= freesp)
 362                        alloc_blocks >>= 4;
 363        }
 364
 365        if (alloc_blocks < mp->m_writeio_blocks)
 366                alloc_blocks = mp->m_writeio_blocks;
 367
 368        return alloc_blocks;
 369}
 370
 371int
 372xfs_iomap_write_delay(
 373        xfs_inode_t     *ip,
 374        xfs_off_t       offset,
 375        size_t          count,
 376        xfs_bmbt_irec_t *ret_imap)
 377{
 378        xfs_mount_t     *mp = ip->i_mount;
 379        xfs_fileoff_t   offset_fsb;
 380        xfs_fileoff_t   last_fsb;
 381        xfs_off_t       aligned_offset;
 382        xfs_fileoff_t   ioalign;
 383        xfs_extlen_t    extsz;
 384        int             nimaps;
 385        xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
 386        int             prealloc;
 387        int             error;
 388
 389        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 390
 391        /*
 392         * Make sure that the dquots are there. This doesn't hold
 393         * the ilock across a disk read.
 394         */
 395        error = xfs_qm_dqattach_locked(ip, 0);
 396        if (error)
 397                return XFS_ERROR(error);
 398
 399        extsz = xfs_get_extsz_hint(ip);
 400        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 401
 402
 403        error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
 404                                imap, XFS_WRITE_IMAPS, &prealloc);
 405        if (error)
 406                return error;
 407
 408retry:
 409        if (prealloc) {
 410                xfs_fsblock_t   alloc_blocks = xfs_iomap_prealloc_size(mp, ip);
 411
 412                aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
 413                ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
 414                last_fsb = ioalign + alloc_blocks;
 415        } else {
 416                last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
 417        }
 418
 419        if (prealloc || extsz) {
 420                error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
 421                if (error)
 422                        return error;
 423        }
 424
 425        /*
 426         * Make sure preallocation does not create extents beyond the range we
 427         * actually support in this filesystem.
 428         */
 429        if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
 430                last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
 431
 432        ASSERT(last_fsb > offset_fsb);
 433
 434        nimaps = XFS_WRITE_IMAPS;
 435        error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
 436                                imap, &nimaps, XFS_BMAPI_ENTIRE);
 437        switch (error) {
 438        case 0:
 439        case ENOSPC:
 440        case EDQUOT:
 441                break;
 442        default:
 443                return XFS_ERROR(error);
 444        }
 445
 446        /*
 447         * If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry
 448         * without EOF preallocation.
 449         */
 450        if (nimaps == 0) {
 451                trace_xfs_delalloc_enospc(ip, offset, count);
 452                if (prealloc) {
 453                        prealloc = 0;
 454                        error = 0;
 455                        goto retry;
 456                }
 457                return XFS_ERROR(error ? error : ENOSPC);
 458        }
 459
 460        if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
 461                return xfs_alert_fsblock_zero(ip, &imap[0]);
 462
 463        /*
 464         * Tag the inode as speculatively preallocated so we can reclaim this
 465         * space on demand, if necessary.
 466         */
 467        if (prealloc)
 468                xfs_inode_set_eofblocks_tag(ip);
 469
 470        *ret_imap = imap[0];
 471        return 0;
 472}
 473
 474/*
 475 * Pass in a delayed allocate extent, convert it to real extents;
 476 * return to the caller the extent we create which maps on top of
 477 * the originating callers request.
 478 *
 479 * Called without a lock on the inode.
 480 *
 481 * We no longer bother to look at the incoming map - all we have to
 482 * guarantee is that whatever we allocate fills the required range.
 483 */
 484int
 485xfs_iomap_write_allocate(
 486        xfs_inode_t     *ip,
 487        xfs_off_t       offset,
 488        size_t          count,
 489        xfs_bmbt_irec_t *imap)
 490{
 491        xfs_mount_t     *mp = ip->i_mount;
 492        xfs_fileoff_t   offset_fsb, last_block;
 493        xfs_fileoff_t   end_fsb, map_start_fsb;
 494        xfs_fsblock_t   first_block;
 495        xfs_bmap_free_t free_list;
 496        xfs_filblks_t   count_fsb;
 497        xfs_trans_t     *tp;
 498        int             nimaps, committed;
 499        int             error = 0;
 500        int             nres;
 501
 502        /*
 503         * Make sure that the dquots are there.
 504         */
 505        error = xfs_qm_dqattach(ip, 0);
 506        if (error)
 507                return XFS_ERROR(error);
 508
 509        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 510        count_fsb = imap->br_blockcount;
 511        map_start_fsb = imap->br_startoff;
 512
 513        XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
 514
 515        while (count_fsb != 0) {
 516                /*
 517                 * Set up a transaction with which to allocate the
 518                 * backing store for the file.  Do allocations in a
 519                 * loop until we get some space in the range we are
 520                 * interested in.  The other space that might be allocated
 521                 * is in the delayed allocation extent on which we sit
 522                 * but before our buffer starts.
 523                 */
 524
 525                nimaps = 0;
 526                while (nimaps == 0) {
 527                        tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
 528                        tp->t_flags |= XFS_TRANS_RESERVE;
 529                        nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
 530                        error = xfs_trans_reserve(tp, nres,
 531                                        XFS_WRITE_LOG_RES(mp),
 532                                        0, XFS_TRANS_PERM_LOG_RES,
 533                                        XFS_WRITE_LOG_COUNT);
 534                        if (error) {
 535                                xfs_trans_cancel(tp, 0);
 536                                return XFS_ERROR(error);
 537                        }
 538                        xfs_ilock(ip, XFS_ILOCK_EXCL);
 539                        xfs_trans_ijoin(tp, ip, 0);
 540
 541                        xfs_bmap_init(&free_list, &first_block);
 542
 543                        /*
 544                         * it is possible that the extents have changed since
 545                         * we did the read call as we dropped the ilock for a
 546                         * while. We have to be careful about truncates or hole
 547                         * punchs here - we are not allowed to allocate
 548                         * non-delalloc blocks here.
 549                         *
 550                         * The only protection against truncation is the pages
 551                         * for the range we are being asked to convert are
 552                         * locked and hence a truncate will block on them
 553                         * first.
 554                         *
 555                         * As a result, if we go beyond the range we really
 556                         * need and hit an delalloc extent boundary followed by
 557                         * a hole while we have excess blocks in the map, we
 558                         * will fill the hole incorrectly and overrun the
 559                         * transaction reservation.
 560                         *
 561                         * Using a single map prevents this as we are forced to
 562                         * check each map we look for overlap with the desired
 563                         * range and abort as soon as we find it. Also, given
 564                         * that we only return a single map, having one beyond
 565                         * what we can return is probably a bit silly.
 566                         *
 567                         * We also need to check that we don't go beyond EOF;
 568                         * this is a truncate optimisation as a truncate sets
 569                         * the new file size before block on the pages we
 570                         * currently have locked under writeback. Because they
 571                         * are about to be tossed, we don't need to write them
 572                         * back....
 573                         */
 574                        nimaps = 1;
 575                        end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
 576                        error = xfs_bmap_last_offset(NULL, ip, &last_block,
 577                                                        XFS_DATA_FORK);
 578                        if (error)
 579                                goto trans_cancel;
 580
 581                        last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
 582                        if ((map_start_fsb + count_fsb) > last_block) {
 583                                count_fsb = last_block - map_start_fsb;
 584                                if (count_fsb == 0) {
 585                                        error = EAGAIN;
 586                                        goto trans_cancel;
 587                                }
 588                        }
 589
 590                        /*
 591                         * From this point onwards we overwrite the imap
 592                         * pointer that the caller gave to us.
 593                         */
 594                        error = xfs_bmapi_write(tp, ip, map_start_fsb,
 595                                                count_fsb,
 596                                                XFS_BMAPI_STACK_SWITCH,
 597                                                &first_block, 1,
 598                                                imap, &nimaps, &free_list);
 599                        if (error)
 600                                goto trans_cancel;
 601
 602                        error = xfs_bmap_finish(&tp, &free_list, &committed);
 603                        if (error)
 604                                goto trans_cancel;
 605
 606                        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 607                        if (error)
 608                                goto error0;
 609
 610                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 611                }
 612
 613                /*
 614                 * See if we were able to allocate an extent that
 615                 * covers at least part of the callers request
 616                 */
 617                if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
 618                        return xfs_alert_fsblock_zero(ip, imap);
 619
 620                if ((offset_fsb >= imap->br_startoff) &&
 621                    (offset_fsb < (imap->br_startoff +
 622                                   imap->br_blockcount))) {
 623                        XFS_STATS_INC(xs_xstrat_quick);
 624                        return 0;
 625                }
 626
 627                /*
 628                 * So far we have not mapped the requested part of the
 629                 * file, just surrounding data, try again.
 630                 */
 631                count_fsb -= imap->br_blockcount;
 632                map_start_fsb = imap->br_startoff + imap->br_blockcount;
 633        }
 634
 635trans_cancel:
 636        xfs_bmap_cancel(&free_list);
 637        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 638error0:
 639        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 640        return XFS_ERROR(error);
 641}
 642
 643int
 644xfs_iomap_write_unwritten(
 645        xfs_inode_t     *ip,
 646        xfs_off_t       offset,
 647        size_t          count)
 648{
 649        xfs_mount_t     *mp = ip->i_mount;
 650        xfs_fileoff_t   offset_fsb;
 651        xfs_filblks_t   count_fsb;
 652        xfs_filblks_t   numblks_fsb;
 653        xfs_fsblock_t   firstfsb;
 654        int             nimaps;
 655        xfs_trans_t     *tp;
 656        xfs_bmbt_irec_t imap;
 657        xfs_bmap_free_t free_list;
 658        xfs_fsize_t     i_size;
 659        uint            resblks;
 660        int             committed;
 661        int             error;
 662
 663        trace_xfs_unwritten_convert(ip, offset, count);
 664
 665        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 666        count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 667        count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
 668
 669        /*
 670         * Reserve enough blocks in this transaction for two complete extent
 671         * btree splits.  We may be converting the middle part of an unwritten
 672         * extent and in this case we will insert two new extents in the btree
 673         * each of which could cause a full split.
 674         *
 675         * This reservation amount will be used in the first call to
 676         * xfs_bmbt_split() to select an AG with enough space to satisfy the
 677         * rest of the operation.
 678         */
 679        resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
 680
 681        do {
 682                /*
 683                 * set up a transaction to convert the range of extents
 684                 * from unwritten to real. Do allocations in a loop until
 685                 * we have covered the range passed in.
 686                 *
 687                 * Note that we open code the transaction allocation here
 688                 * to pass KM_NOFS--we can't risk to recursing back into
 689                 * the filesystem here as we might be asked to write out
 690                 * the same inode that we complete here and might deadlock
 691                 * on the iolock.
 692                 */
 693                sb_start_intwrite(mp->m_super);
 694                tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
 695                tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
 696                error = xfs_trans_reserve(tp, resblks,
 697                                XFS_WRITE_LOG_RES(mp), 0,
 698                                XFS_TRANS_PERM_LOG_RES,
 699                                XFS_WRITE_LOG_COUNT);
 700                if (error) {
 701                        xfs_trans_cancel(tp, 0);
 702                        return XFS_ERROR(error);
 703                }
 704
 705                xfs_ilock(ip, XFS_ILOCK_EXCL);
 706                xfs_trans_ijoin(tp, ip, 0);
 707
 708                /*
 709                 * Modify the unwritten extent state of the buffer.
 710                 */
 711                xfs_bmap_init(&free_list, &firstfsb);
 712                nimaps = 1;
 713                error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
 714                                  XFS_BMAPI_CONVERT, &firstfsb,
 715                                  1, &imap, &nimaps, &free_list);
 716                if (error)
 717                        goto error_on_bmapi_transaction;
 718
 719                /*
 720                 * Log the updated inode size as we go.  We have to be careful
 721                 * to only log it up to the actual write offset if it is
 722                 * halfway into a block.
 723                 */
 724                i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
 725                if (i_size > offset + count)
 726                        i_size = offset + count;
 727
 728                i_size = xfs_new_eof(ip, i_size);
 729                if (i_size) {
 730                        ip->i_d.di_size = i_size;
 731                        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 732                }
 733
 734                error = xfs_bmap_finish(&tp, &free_list, &committed);
 735                if (error)
 736                        goto error_on_bmapi_transaction;
 737
 738                error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 739                xfs_iunlock(ip, XFS_ILOCK_EXCL);
 740                if (error)
 741                        return XFS_ERROR(error);
 742
 743                if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
 744                        return xfs_alert_fsblock_zero(ip, &imap);
 745
 746                if ((numblks_fsb = imap.br_blockcount) == 0) {
 747                        /*
 748                         * The numblks_fsb value should always get
 749                         * smaller, otherwise the loop is stuck.
 750                         */
 751                        ASSERT(imap.br_blockcount);
 752                        break;
 753                }
 754                offset_fsb += numblks_fsb;
 755                count_fsb -= numblks_fsb;
 756        } while (count_fsb > 0);
 757
 758        return 0;
 759
 760error_on_bmapi_transaction:
 761        xfs_bmap_cancel(&free_list);
 762        xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
 763        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 764        return XFS_ERROR(error);
 765}
 766
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