linux/fs/xfs/xfs_file.c
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   1/*
   2 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#include "xfs.h"
  19#include "xfs_fs.h"
  20#include "xfs_log.h"
  21#include "xfs_sb.h"
  22#include "xfs_ag.h"
  23#include "xfs_trans.h"
  24#include "xfs_mount.h"
  25#include "xfs_bmap_btree.h"
  26#include "xfs_alloc.h"
  27#include "xfs_dinode.h"
  28#include "xfs_inode.h"
  29#include "xfs_inode_item.h"
  30#include "xfs_bmap.h"
  31#include "xfs_error.h"
  32#include "xfs_vnodeops.h"
  33#include "xfs_da_btree.h"
  34#include "xfs_ioctl.h"
  35#include "xfs_trace.h"
  36
  37#include <linux/dcache.h>
  38#include <linux/falloc.h>
  39#include <linux/pagevec.h>
  40
  41static const struct vm_operations_struct xfs_file_vm_ops;
  42
  43/*
  44 * Locking primitives for read and write IO paths to ensure we consistently use
  45 * and order the inode->i_mutex, ip->i_lock and ip->i_iolock.
  46 */
  47static inline void
  48xfs_rw_ilock(
  49        struct xfs_inode        *ip,
  50        int                     type)
  51{
  52        if (type & XFS_IOLOCK_EXCL)
  53                mutex_lock(&VFS_I(ip)->i_mutex);
  54        xfs_ilock(ip, type);
  55}
  56
  57static inline void
  58xfs_rw_iunlock(
  59        struct xfs_inode        *ip,
  60        int                     type)
  61{
  62        xfs_iunlock(ip, type);
  63        if (type & XFS_IOLOCK_EXCL)
  64                mutex_unlock(&VFS_I(ip)->i_mutex);
  65}
  66
  67static inline void
  68xfs_rw_ilock_demote(
  69        struct xfs_inode        *ip,
  70        int                     type)
  71{
  72        xfs_ilock_demote(ip, type);
  73        if (type & XFS_IOLOCK_EXCL)
  74                mutex_unlock(&VFS_I(ip)->i_mutex);
  75}
  76
  77/*
  78 *      xfs_iozero
  79 *
  80 *      xfs_iozero clears the specified range of buffer supplied,
  81 *      and marks all the affected blocks as valid and modified.  If
  82 *      an affected block is not allocated, it will be allocated.  If
  83 *      an affected block is not completely overwritten, and is not
  84 *      valid before the operation, it will be read from disk before
  85 *      being partially zeroed.
  86 */
  87STATIC int
  88xfs_iozero(
  89        struct xfs_inode        *ip,    /* inode                        */
  90        loff_t                  pos,    /* offset in file               */
  91        size_t                  count)  /* size of data to zero         */
  92{
  93        struct page             *page;
  94        struct address_space    *mapping;
  95        int                     status;
  96
  97        mapping = VFS_I(ip)->i_mapping;
  98        do {
  99                unsigned offset, bytes;
 100                void *fsdata;
 101
 102                offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
 103                bytes = PAGE_CACHE_SIZE - offset;
 104                if (bytes > count)
 105                        bytes = count;
 106
 107                status = pagecache_write_begin(NULL, mapping, pos, bytes,
 108                                        AOP_FLAG_UNINTERRUPTIBLE,
 109                                        &page, &fsdata);
 110                if (status)
 111                        break;
 112
 113                zero_user(page, offset, bytes);
 114
 115                status = pagecache_write_end(NULL, mapping, pos, bytes, bytes,
 116                                        page, fsdata);
 117                WARN_ON(status <= 0); /* can't return less than zero! */
 118                pos += bytes;
 119                count -= bytes;
 120                status = 0;
 121        } while (count);
 122
 123        return (-status);
 124}
 125
 126/*
 127 * Fsync operations on directories are much simpler than on regular files,
 128 * as there is no file data to flush, and thus also no need for explicit
 129 * cache flush operations, and there are no non-transaction metadata updates
 130 * on directories either.
 131 */
 132STATIC int
 133xfs_dir_fsync(
 134        struct file             *file,
 135        loff_t                  start,
 136        loff_t                  end,
 137        int                     datasync)
 138{
 139        struct xfs_inode        *ip = XFS_I(file->f_mapping->host);
 140        struct xfs_mount        *mp = ip->i_mount;
 141        xfs_lsn_t               lsn = 0;
 142
 143        trace_xfs_dir_fsync(ip);
 144
 145        xfs_ilock(ip, XFS_ILOCK_SHARED);
 146        if (xfs_ipincount(ip))
 147                lsn = ip->i_itemp->ili_last_lsn;
 148        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 149
 150        if (!lsn)
 151                return 0;
 152        return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 153}
 154
 155STATIC int
 156xfs_file_fsync(
 157        struct file             *file,
 158        loff_t                  start,
 159        loff_t                  end,
 160        int                     datasync)
 161{
 162        struct inode            *inode = file->f_mapping->host;
 163        struct xfs_inode        *ip = XFS_I(inode);
 164        struct xfs_mount        *mp = ip->i_mount;
 165        int                     error = 0;
 166        int                     log_flushed = 0;
 167        xfs_lsn_t               lsn = 0;
 168
 169        trace_xfs_file_fsync(ip);
 170
 171        error = filemap_write_and_wait_range(inode->i_mapping, start, end);
 172        if (error)
 173                return error;
 174
 175        if (XFS_FORCED_SHUTDOWN(mp))
 176                return -XFS_ERROR(EIO);
 177
 178        xfs_iflags_clear(ip, XFS_ITRUNCATED);
 179
 180        if (mp->m_flags & XFS_MOUNT_BARRIER) {
 181                /*
 182                 * If we have an RT and/or log subvolume we need to make sure
 183                 * to flush the write cache the device used for file data
 184                 * first.  This is to ensure newly written file data make
 185                 * it to disk before logging the new inode size in case of
 186                 * an extending write.
 187                 */
 188                if (XFS_IS_REALTIME_INODE(ip))
 189                        xfs_blkdev_issue_flush(mp->m_rtdev_targp);
 190                else if (mp->m_logdev_targp != mp->m_ddev_targp)
 191                        xfs_blkdev_issue_flush(mp->m_ddev_targp);
 192        }
 193
 194        /*
 195         * All metadata updates are logged, which means that we just have
 196         * to flush the log up to the latest LSN that touched the inode.
 197         */
 198        xfs_ilock(ip, XFS_ILOCK_SHARED);
 199        if (xfs_ipincount(ip)) {
 200                if (!datasync ||
 201                    (ip->i_itemp->ili_fields & ~XFS_ILOG_TIMESTAMP))
 202                        lsn = ip->i_itemp->ili_last_lsn;
 203        }
 204        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 205
 206        if (lsn)
 207                error = _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, &log_flushed);
 208
 209        /*
 210         * If we only have a single device, and the log force about was
 211         * a no-op we might have to flush the data device cache here.
 212         * This can only happen for fdatasync/O_DSYNC if we were overwriting
 213         * an already allocated file and thus do not have any metadata to
 214         * commit.
 215         */
 216        if ((mp->m_flags & XFS_MOUNT_BARRIER) &&
 217            mp->m_logdev_targp == mp->m_ddev_targp &&
 218            !XFS_IS_REALTIME_INODE(ip) &&
 219            !log_flushed)
 220                xfs_blkdev_issue_flush(mp->m_ddev_targp);
 221
 222        return -error;
 223}
 224
 225STATIC ssize_t
 226xfs_file_aio_read(
 227        struct kiocb            *iocb,
 228        const struct iovec      *iovp,
 229        unsigned long           nr_segs,
 230        loff_t                  pos)
 231{
 232        struct file             *file = iocb->ki_filp;
 233        struct inode            *inode = file->f_mapping->host;
 234        struct xfs_inode        *ip = XFS_I(inode);
 235        struct xfs_mount        *mp = ip->i_mount;
 236        size_t                  size = 0;
 237        ssize_t                 ret = 0;
 238        int                     ioflags = 0;
 239        xfs_fsize_t             n;
 240
 241        XFS_STATS_INC(xs_read_calls);
 242
 243        BUG_ON(iocb->ki_pos != pos);
 244
 245        if (unlikely(file->f_flags & O_DIRECT))
 246                ioflags |= IO_ISDIRECT;
 247        if (file->f_mode & FMODE_NOCMTIME)
 248                ioflags |= IO_INVIS;
 249
 250        ret = generic_segment_checks(iovp, &nr_segs, &size, VERIFY_WRITE);
 251        if (ret < 0)
 252                return ret;
 253
 254        if (unlikely(ioflags & IO_ISDIRECT)) {
 255                xfs_buftarg_t   *target =
 256                        XFS_IS_REALTIME_INODE(ip) ?
 257                                mp->m_rtdev_targp : mp->m_ddev_targp;
 258                if ((iocb->ki_pos & target->bt_smask) ||
 259                    (size & target->bt_smask)) {
 260                        if (iocb->ki_pos == i_size_read(inode))
 261                                return 0;
 262                        return -XFS_ERROR(EINVAL);
 263                }
 264        }
 265
 266        n = mp->m_super->s_maxbytes - iocb->ki_pos;
 267        if (n <= 0 || size == 0)
 268                return 0;
 269
 270        if (n < size)
 271                size = n;
 272
 273        if (XFS_FORCED_SHUTDOWN(mp))
 274                return -EIO;
 275
 276        /*
 277         * Locking is a bit tricky here. If we take an exclusive lock
 278         * for direct IO, we effectively serialise all new concurrent
 279         * read IO to this file and block it behind IO that is currently in
 280         * progress because IO in progress holds the IO lock shared. We only
 281         * need to hold the lock exclusive to blow away the page cache, so
 282         * only take lock exclusively if the page cache needs invalidation.
 283         * This allows the normal direct IO case of no page cache pages to
 284         * proceeed concurrently without serialisation.
 285         */
 286        xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
 287        if ((ioflags & IO_ISDIRECT) && inode->i_mapping->nrpages) {
 288                xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
 289                xfs_rw_ilock(ip, XFS_IOLOCK_EXCL);
 290
 291                if (inode->i_mapping->nrpages) {
 292                        ret = -xfs_flushinval_pages(ip,
 293                                        (iocb->ki_pos & PAGE_CACHE_MASK),
 294                                        -1, FI_REMAPF_LOCKED);
 295                        if (ret) {
 296                                xfs_rw_iunlock(ip, XFS_IOLOCK_EXCL);
 297                                return ret;
 298                        }
 299                }
 300                xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
 301        }
 302
 303        trace_xfs_file_read(ip, size, iocb->ki_pos, ioflags);
 304
 305        ret = generic_file_aio_read(iocb, iovp, nr_segs, iocb->ki_pos);
 306        if (ret > 0)
 307                XFS_STATS_ADD(xs_read_bytes, ret);
 308
 309        xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
 310        return ret;
 311}
 312
 313STATIC ssize_t
 314xfs_file_splice_read(
 315        struct file             *infilp,
 316        loff_t                  *ppos,
 317        struct pipe_inode_info  *pipe,
 318        size_t                  count,
 319        unsigned int            flags)
 320{
 321        struct xfs_inode        *ip = XFS_I(infilp->f_mapping->host);
 322        int                     ioflags = 0;
 323        ssize_t                 ret;
 324
 325        XFS_STATS_INC(xs_read_calls);
 326
 327        if (infilp->f_mode & FMODE_NOCMTIME)
 328                ioflags |= IO_INVIS;
 329
 330        if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 331                return -EIO;
 332
 333        xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
 334
 335        trace_xfs_file_splice_read(ip, count, *ppos, ioflags);
 336
 337        ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
 338        if (ret > 0)
 339                XFS_STATS_ADD(xs_read_bytes, ret);
 340
 341        xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
 342        return ret;
 343}
 344
 345/*
 346 * xfs_file_splice_write() does not use xfs_rw_ilock() because
 347 * generic_file_splice_write() takes the i_mutex itself. This, in theory,
 348 * couuld cause lock inversions between the aio_write path and the splice path
 349 * if someone is doing concurrent splice(2) based writes and write(2) based
 350 * writes to the same inode. The only real way to fix this is to re-implement
 351 * the generic code here with correct locking orders.
 352 */
 353STATIC ssize_t
 354xfs_file_splice_write(
 355        struct pipe_inode_info  *pipe,
 356        struct file             *outfilp,
 357        loff_t                  *ppos,
 358        size_t                  count,
 359        unsigned int            flags)
 360{
 361        struct inode            *inode = outfilp->f_mapping->host;
 362        struct xfs_inode        *ip = XFS_I(inode);
 363        int                     ioflags = 0;
 364        ssize_t                 ret;
 365
 366        XFS_STATS_INC(xs_write_calls);
 367
 368        if (outfilp->f_mode & FMODE_NOCMTIME)
 369                ioflags |= IO_INVIS;
 370
 371        if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 372                return -EIO;
 373
 374        xfs_ilock(ip, XFS_IOLOCK_EXCL);
 375
 376        trace_xfs_file_splice_write(ip, count, *ppos, ioflags);
 377
 378        ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
 379        if (ret > 0)
 380                XFS_STATS_ADD(xs_write_bytes, ret);
 381
 382        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 383        return ret;
 384}
 385
 386/*
 387 * This routine is called to handle zeroing any space in the last block of the
 388 * file that is beyond the EOF.  We do this since the size is being increased
 389 * without writing anything to that block and we don't want to read the
 390 * garbage on the disk.
 391 */
 392STATIC int                              /* error (positive) */
 393xfs_zero_last_block(
 394        struct xfs_inode        *ip,
 395        xfs_fsize_t             offset,
 396        xfs_fsize_t             isize)
 397{
 398        struct xfs_mount        *mp = ip->i_mount;
 399        xfs_fileoff_t           last_fsb = XFS_B_TO_FSBT(mp, isize);
 400        int                     zero_offset = XFS_B_FSB_OFFSET(mp, isize);
 401        int                     zero_len;
 402        int                     nimaps = 1;
 403        int                     error = 0;
 404        struct xfs_bmbt_irec    imap;
 405
 406        xfs_ilock(ip, XFS_ILOCK_EXCL);
 407        error = xfs_bmapi_read(ip, last_fsb, 1, &imap, &nimaps, 0);
 408        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 409        if (error)
 410                return error;
 411
 412        ASSERT(nimaps > 0);
 413
 414        /*
 415         * If the block underlying isize is just a hole, then there
 416         * is nothing to zero.
 417         */
 418        if (imap.br_startblock == HOLESTARTBLOCK)
 419                return 0;
 420
 421        zero_len = mp->m_sb.sb_blocksize - zero_offset;
 422        if (isize + zero_len > offset)
 423                zero_len = offset - isize;
 424        return xfs_iozero(ip, isize, zero_len);
 425}
 426
 427/*
 428 * Zero any on disk space between the current EOF and the new, larger EOF.
 429 *
 430 * This handles the normal case of zeroing the remainder of the last block in
 431 * the file and the unusual case of zeroing blocks out beyond the size of the
 432 * file.  This second case only happens with fixed size extents and when the
 433 * system crashes before the inode size was updated but after blocks were
 434 * allocated.
 435 *
 436 * Expects the iolock to be held exclusive, and will take the ilock internally.
 437 */
 438int                                     /* error (positive) */
 439xfs_zero_eof(
 440        struct xfs_inode        *ip,
 441        xfs_off_t               offset,         /* starting I/O offset */
 442        xfs_fsize_t             isize)          /* current inode size */
 443{
 444        struct xfs_mount        *mp = ip->i_mount;
 445        xfs_fileoff_t           start_zero_fsb;
 446        xfs_fileoff_t           end_zero_fsb;
 447        xfs_fileoff_t           zero_count_fsb;
 448        xfs_fileoff_t           last_fsb;
 449        xfs_fileoff_t           zero_off;
 450        xfs_fsize_t             zero_len;
 451        int                     nimaps;
 452        int                     error = 0;
 453        struct xfs_bmbt_irec    imap;
 454
 455        ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
 456        ASSERT(offset > isize);
 457
 458        /*
 459         * First handle zeroing the block on which isize resides.
 460         *
 461         * We only zero a part of that block so it is handled specially.
 462         */
 463        if (XFS_B_FSB_OFFSET(mp, isize) != 0) {
 464                error = xfs_zero_last_block(ip, offset, isize);
 465                if (error)
 466                        return error;
 467        }
 468
 469        /*
 470         * Calculate the range between the new size and the old where blocks
 471         * needing to be zeroed may exist.
 472         *
 473         * To get the block where the last byte in the file currently resides,
 474         * we need to subtract one from the size and truncate back to a block
 475         * boundary.  We subtract 1 in case the size is exactly on a block
 476         * boundary.
 477         */
 478        last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
 479        start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
 480        end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
 481        ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
 482        if (last_fsb == end_zero_fsb) {
 483                /*
 484                 * The size was only incremented on its last block.
 485                 * We took care of that above, so just return.
 486                 */
 487                return 0;
 488        }
 489
 490        ASSERT(start_zero_fsb <= end_zero_fsb);
 491        while (start_zero_fsb <= end_zero_fsb) {
 492                nimaps = 1;
 493                zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
 494
 495                xfs_ilock(ip, XFS_ILOCK_EXCL);
 496                error = xfs_bmapi_read(ip, start_zero_fsb, zero_count_fsb,
 497                                          &imap, &nimaps, 0);
 498                xfs_iunlock(ip, XFS_ILOCK_EXCL);
 499                if (error)
 500                        return error;
 501
 502                ASSERT(nimaps > 0);
 503
 504                if (imap.br_state == XFS_EXT_UNWRITTEN ||
 505                    imap.br_startblock == HOLESTARTBLOCK) {
 506                        start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 507                        ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 508                        continue;
 509                }
 510
 511                /*
 512                 * There are blocks we need to zero.
 513                 */
 514                zero_off = XFS_FSB_TO_B(mp, start_zero_fsb);
 515                zero_len = XFS_FSB_TO_B(mp, imap.br_blockcount);
 516
 517                if ((zero_off + zero_len) > offset)
 518                        zero_len = offset - zero_off;
 519
 520                error = xfs_iozero(ip, zero_off, zero_len);
 521                if (error)
 522                        return error;
 523
 524                start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 525                ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 526        }
 527
 528        return 0;
 529}
 530
 531/*
 532 * Common pre-write limit and setup checks.
 533 *
 534 * Called with the iolocked held either shared and exclusive according to
 535 * @iolock, and returns with it held.  Might upgrade the iolock to exclusive
 536 * if called for a direct write beyond i_size.
 537 */
 538STATIC ssize_t
 539xfs_file_aio_write_checks(
 540        struct file             *file,
 541        loff_t                  *pos,
 542        size_t                  *count,
 543        int                     *iolock)
 544{
 545        struct inode            *inode = file->f_mapping->host;
 546        struct xfs_inode        *ip = XFS_I(inode);
 547        int                     error = 0;
 548
 549restart:
 550        error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode));
 551        if (error)
 552                return error;
 553
 554        /*
 555         * If the offset is beyond the size of the file, we need to zero any
 556         * blocks that fall between the existing EOF and the start of this
 557         * write.  If zeroing is needed and we are currently holding the
 558         * iolock shared, we need to update it to exclusive which implies
 559         * having to redo all checks before.
 560         */
 561        if (*pos > i_size_read(inode)) {
 562                if (*iolock == XFS_IOLOCK_SHARED) {
 563                        xfs_rw_iunlock(ip, *iolock);
 564                        *iolock = XFS_IOLOCK_EXCL;
 565                        xfs_rw_ilock(ip, *iolock);
 566                        goto restart;
 567                }
 568                error = -xfs_zero_eof(ip, *pos, i_size_read(inode));
 569                if (error)
 570                        return error;
 571        }
 572
 573        /*
 574         * Updating the timestamps will grab the ilock again from
 575         * xfs_fs_dirty_inode, so we have to call it after dropping the
 576         * lock above.  Eventually we should look into a way to avoid
 577         * the pointless lock roundtrip.
 578         */
 579        if (likely(!(file->f_mode & FMODE_NOCMTIME))) {
 580                error = file_update_time(file);
 581                if (error)
 582                        return error;
 583        }
 584
 585        /*
 586         * If we're writing the file then make sure to clear the setuid and
 587         * setgid bits if the process is not being run by root.  This keeps
 588         * people from modifying setuid and setgid binaries.
 589         */
 590        return file_remove_suid(file);
 591}
 592
 593/*
 594 * xfs_file_dio_aio_write - handle direct IO writes
 595 *
 596 * Lock the inode appropriately to prepare for and issue a direct IO write.
 597 * By separating it from the buffered write path we remove all the tricky to
 598 * follow locking changes and looping.
 599 *
 600 * If there are cached pages or we're extending the file, we need IOLOCK_EXCL
 601 * until we're sure the bytes at the new EOF have been zeroed and/or the cached
 602 * pages are flushed out.
 603 *
 604 * In most cases the direct IO writes will be done holding IOLOCK_SHARED
 605 * allowing them to be done in parallel with reads and other direct IO writes.
 606 * However, if the IO is not aligned to filesystem blocks, the direct IO layer
 607 * needs to do sub-block zeroing and that requires serialisation against other
 608 * direct IOs to the same block. In this case we need to serialise the
 609 * submission of the unaligned IOs so that we don't get racing block zeroing in
 610 * the dio layer.  To avoid the problem with aio, we also need to wait for
 611 * outstanding IOs to complete so that unwritten extent conversion is completed
 612 * before we try to map the overlapping block. This is currently implemented by
 613 * hitting it with a big hammer (i.e. inode_dio_wait()).
 614 *
 615 * Returns with locks held indicated by @iolock and errors indicated by
 616 * negative return values.
 617 */
 618STATIC ssize_t
 619xfs_file_dio_aio_write(
 620        struct kiocb            *iocb,
 621        const struct iovec      *iovp,
 622        unsigned long           nr_segs,
 623        loff_t                  pos,
 624        size_t                  ocount)
 625{
 626        struct file             *file = iocb->ki_filp;
 627        struct address_space    *mapping = file->f_mapping;
 628        struct inode            *inode = mapping->host;
 629        struct xfs_inode        *ip = XFS_I(inode);
 630        struct xfs_mount        *mp = ip->i_mount;
 631        ssize_t                 ret = 0;
 632        size_t                  count = ocount;
 633        int                     unaligned_io = 0;
 634        int                     iolock;
 635        struct xfs_buftarg      *target = XFS_IS_REALTIME_INODE(ip) ?
 636                                        mp->m_rtdev_targp : mp->m_ddev_targp;
 637
 638        if ((pos & target->bt_smask) || (count & target->bt_smask))
 639                return -XFS_ERROR(EINVAL);
 640
 641        if ((pos & mp->m_blockmask) || ((pos + count) & mp->m_blockmask))
 642                unaligned_io = 1;
 643
 644        /*
 645         * We don't need to take an exclusive lock unless there page cache needs
 646         * to be invalidated or unaligned IO is being executed. We don't need to
 647         * consider the EOF extension case here because
 648         * xfs_file_aio_write_checks() will relock the inode as necessary for
 649         * EOF zeroing cases and fill out the new inode size as appropriate.
 650         */
 651        if (unaligned_io || mapping->nrpages)
 652                iolock = XFS_IOLOCK_EXCL;
 653        else
 654                iolock = XFS_IOLOCK_SHARED;
 655        xfs_rw_ilock(ip, iolock);
 656
 657        /*
 658         * Recheck if there are cached pages that need invalidate after we got
 659         * the iolock to protect against other threads adding new pages while
 660         * we were waiting for the iolock.
 661         */
 662        if (mapping->nrpages && iolock == XFS_IOLOCK_SHARED) {
 663                xfs_rw_iunlock(ip, iolock);
 664                iolock = XFS_IOLOCK_EXCL;
 665                xfs_rw_ilock(ip, iolock);
 666        }
 667
 668        ret = xfs_file_aio_write_checks(file, &pos, &count, &iolock);
 669        if (ret)
 670                goto out;
 671
 672        if (mapping->nrpages) {
 673                ret = -xfs_flushinval_pages(ip, (pos & PAGE_CACHE_MASK), -1,
 674                                                        FI_REMAPF_LOCKED);
 675                if (ret)
 676                        goto out;
 677        }
 678
 679        /*
 680         * If we are doing unaligned IO, wait for all other IO to drain,
 681         * otherwise demote the lock if we had to flush cached pages
 682         */
 683        if (unaligned_io)
 684                inode_dio_wait(inode);
 685        else if (iolock == XFS_IOLOCK_EXCL) {
 686                xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
 687                iolock = XFS_IOLOCK_SHARED;
 688        }
 689
 690        trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);
 691        ret = generic_file_direct_write(iocb, iovp,
 692                        &nr_segs, pos, &iocb->ki_pos, count, ocount);
 693
 694out:
 695        xfs_rw_iunlock(ip, iolock);
 696
 697        /* No fallback to buffered IO on errors for XFS. */
 698        ASSERT(ret < 0 || ret == count);
 699        return ret;
 700}
 701
 702STATIC ssize_t
 703xfs_file_buffered_aio_write(
 704        struct kiocb            *iocb,
 705        const struct iovec      *iovp,
 706        unsigned long           nr_segs,
 707        loff_t                  pos,
 708        size_t                  ocount)
 709{
 710        struct file             *file = iocb->ki_filp;
 711        struct address_space    *mapping = file->f_mapping;
 712        struct inode            *inode = mapping->host;
 713        struct xfs_inode        *ip = XFS_I(inode);
 714        ssize_t                 ret;
 715        int                     enospc = 0;
 716        int                     iolock = XFS_IOLOCK_EXCL;
 717        size_t                  count = ocount;
 718
 719        xfs_rw_ilock(ip, iolock);
 720
 721        ret = xfs_file_aio_write_checks(file, &pos, &count, &iolock);
 722        if (ret)
 723                goto out;
 724
 725        /* We can write back this queue in page reclaim */
 726        current->backing_dev_info = mapping->backing_dev_info;
 727
 728write_retry:
 729        trace_xfs_file_buffered_write(ip, count, iocb->ki_pos, 0);
 730        ret = generic_file_buffered_write(iocb, iovp, nr_segs,
 731                        pos, &iocb->ki_pos, count, ret);
 732        /*
 733         * if we just got an ENOSPC, flush the inode now we aren't holding any
 734         * page locks and retry *once*
 735         */
 736        if (ret == -ENOSPC && !enospc) {
 737                enospc = 1;
 738                ret = -xfs_flush_pages(ip, 0, -1, 0, FI_NONE);
 739                if (!ret)
 740                        goto write_retry;
 741        }
 742
 743        current->backing_dev_info = NULL;
 744out:
 745        xfs_rw_iunlock(ip, iolock);
 746        return ret;
 747}
 748
 749STATIC ssize_t
 750xfs_file_aio_write(
 751        struct kiocb            *iocb,
 752        const struct iovec      *iovp,
 753        unsigned long           nr_segs,
 754        loff_t                  pos)
 755{
 756        struct file             *file = iocb->ki_filp;
 757        struct address_space    *mapping = file->f_mapping;
 758        struct inode            *inode = mapping->host;
 759        struct xfs_inode        *ip = XFS_I(inode);
 760        ssize_t                 ret;
 761        size_t                  ocount = 0;
 762
 763        XFS_STATS_INC(xs_write_calls);
 764
 765        BUG_ON(iocb->ki_pos != pos);
 766
 767        ret = generic_segment_checks(iovp, &nr_segs, &ocount, VERIFY_READ);
 768        if (ret)
 769                return ret;
 770
 771        if (ocount == 0)
 772                return 0;
 773
 774        sb_start_write(inode->i_sb);
 775
 776        if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
 777                ret = -EIO;
 778                goto out;
 779        }
 780
 781        if (unlikely(file->f_flags & O_DIRECT))
 782                ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos, ocount);
 783        else
 784                ret = xfs_file_buffered_aio_write(iocb, iovp, nr_segs, pos,
 785                                                  ocount);
 786
 787        if (ret > 0) {
 788                ssize_t err;
 789
 790                XFS_STATS_ADD(xs_write_bytes, ret);
 791
 792                /* Handle various SYNC-type writes */
 793                err = generic_write_sync(file, pos, ret);
 794                if (err < 0)
 795                        ret = err;
 796        }
 797
 798out:
 799        sb_end_write(inode->i_sb);
 800        return ret;
 801}
 802
 803STATIC long
 804xfs_file_fallocate(
 805        struct file     *file,
 806        int             mode,
 807        loff_t          offset,
 808        loff_t          len)
 809{
 810        struct inode    *inode = file->f_path.dentry->d_inode;
 811        long            error;
 812        loff_t          new_size = 0;
 813        xfs_flock64_t   bf;
 814        xfs_inode_t     *ip = XFS_I(inode);
 815        int             cmd = XFS_IOC_RESVSP;
 816        int             attr_flags = XFS_ATTR_NOLOCK;
 817
 818        if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
 819                return -EOPNOTSUPP;
 820
 821        bf.l_whence = 0;
 822        bf.l_start = offset;
 823        bf.l_len = len;
 824
 825        xfs_ilock(ip, XFS_IOLOCK_EXCL);
 826
 827        if (mode & FALLOC_FL_PUNCH_HOLE)
 828                cmd = XFS_IOC_UNRESVSP;
 829
 830        /* check the new inode size is valid before allocating */
 831        if (!(mode & FALLOC_FL_KEEP_SIZE) &&
 832            offset + len > i_size_read(inode)) {
 833                new_size = offset + len;
 834                error = inode_newsize_ok(inode, new_size);
 835                if (error)
 836                        goto out_unlock;
 837        }
 838
 839        if (file->f_flags & O_DSYNC)
 840                attr_flags |= XFS_ATTR_SYNC;
 841
 842        error = -xfs_change_file_space(ip, cmd, &bf, 0, attr_flags);
 843        if (error)
 844                goto out_unlock;
 845
 846        /* Change file size if needed */
 847        if (new_size) {
 848                struct iattr iattr;
 849
 850                iattr.ia_valid = ATTR_SIZE;
 851                iattr.ia_size = new_size;
 852                error = -xfs_setattr_size(ip, &iattr, XFS_ATTR_NOLOCK);
 853        }
 854
 855out_unlock:
 856        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 857        return error;
 858}
 859
 860
 861STATIC int
 862xfs_file_open(
 863        struct inode    *inode,
 864        struct file     *file)
 865{
 866        if (!(file->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
 867                return -EFBIG;
 868        if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
 869                return -EIO;
 870        return 0;
 871}
 872
 873STATIC int
 874xfs_dir_open(
 875        struct inode    *inode,
 876        struct file     *file)
 877{
 878        struct xfs_inode *ip = XFS_I(inode);
 879        int             mode;
 880        int             error;
 881
 882        error = xfs_file_open(inode, file);
 883        if (error)
 884                return error;
 885
 886        /*
 887         * If there are any blocks, read-ahead block 0 as we're almost
 888         * certain to have the next operation be a read there.
 889         */
 890        mode = xfs_ilock_map_shared(ip);
 891        if (ip->i_d.di_nextents > 0)
 892                xfs_da_reada_buf(NULL, ip, 0, XFS_DATA_FORK);
 893        xfs_iunlock(ip, mode);
 894        return 0;
 895}
 896
 897STATIC int
 898xfs_file_release(
 899        struct inode    *inode,
 900        struct file     *filp)
 901{
 902        return -xfs_release(XFS_I(inode));
 903}
 904
 905STATIC int
 906xfs_file_readdir(
 907        struct file     *filp,
 908        void            *dirent,
 909        filldir_t       filldir)
 910{
 911        struct inode    *inode = filp->f_path.dentry->d_inode;
 912        xfs_inode_t     *ip = XFS_I(inode);
 913        int             error;
 914        size_t          bufsize;
 915
 916        /*
 917         * The Linux API doesn't pass down the total size of the buffer
 918         * we read into down to the filesystem.  With the filldir concept
 919         * it's not needed for correct information, but the XFS dir2 leaf
 920         * code wants an estimate of the buffer size to calculate it's
 921         * readahead window and size the buffers used for mapping to
 922         * physical blocks.
 923         *
 924         * Try to give it an estimate that's good enough, maybe at some
 925         * point we can change the ->readdir prototype to include the
 926         * buffer size.  For now we use the current glibc buffer size.
 927         */
 928        bufsize = (size_t)min_t(loff_t, 32768, ip->i_d.di_size);
 929
 930        error = xfs_readdir(ip, dirent, bufsize,
 931                                (xfs_off_t *)&filp->f_pos, filldir);
 932        if (error)
 933                return -error;
 934        return 0;
 935}
 936
 937STATIC int
 938xfs_file_mmap(
 939        struct file     *filp,
 940        struct vm_area_struct *vma)
 941{
 942        vma->vm_ops = &xfs_file_vm_ops;
 943
 944        file_accessed(filp);
 945        return 0;
 946}
 947
 948/*
 949 * mmap()d file has taken write protection fault and is being made
 950 * writable. We can set the page state up correctly for a writable
 951 * page, which means we can do correct delalloc accounting (ENOSPC
 952 * checking!) and unwritten extent mapping.
 953 */
 954STATIC int
 955xfs_vm_page_mkwrite(
 956        struct vm_area_struct   *vma,
 957        struct vm_fault         *vmf)
 958{
 959        return block_page_mkwrite(vma, vmf, xfs_get_blocks);
 960}
 961
 962/*
 963 * This type is designed to indicate the type of offset we would like
 964 * to search from page cache for either xfs_seek_data() or xfs_seek_hole().
 965 */
 966enum {
 967        HOLE_OFF = 0,
 968        DATA_OFF,
 969};
 970
 971/*
 972 * Lookup the desired type of offset from the given page.
 973 *
 974 * On success, return true and the offset argument will point to the
 975 * start of the region that was found.  Otherwise this function will
 976 * return false and keep the offset argument unchanged.
 977 */
 978STATIC bool
 979xfs_lookup_buffer_offset(
 980        struct page             *page,
 981        loff_t                  *offset,
 982        unsigned int            type)
 983{
 984        loff_t                  lastoff = page_offset(page);
 985        bool                    found = false;
 986        struct buffer_head      *bh, *head;
 987
 988        bh = head = page_buffers(page);
 989        do {
 990                /*
 991                 * Unwritten extents that have data in the page
 992                 * cache covering them can be identified by the
 993                 * BH_Unwritten state flag.  Pages with multiple
 994                 * buffers might have a mix of holes, data and
 995                 * unwritten extents - any buffer with valid
 996                 * data in it should have BH_Uptodate flag set
 997                 * on it.
 998                 */
 999                if (buffer_unwritten(bh) ||
1000                    buffer_uptodate(bh)) {
1001                        if (type == DATA_OFF)
1002                                found = true;
1003                } else {
1004                        if (type == HOLE_OFF)
1005                                found = true;
1006                }
1007
1008                if (found) {
1009                        *offset = lastoff;
1010                        break;
1011                }
1012                lastoff += bh->b_size;
1013        } while ((bh = bh->b_this_page) != head);
1014
1015        return found;
1016}
1017
1018/*
1019 * This routine is called to find out and return a data or hole offset
1020 * from the page cache for unwritten extents according to the desired
1021 * type for xfs_seek_data() or xfs_seek_hole().
1022 *
1023 * The argument offset is used to tell where we start to search from the
1024 * page cache.  Map is used to figure out the end points of the range to
1025 * lookup pages.
1026 *
1027 * Return true if the desired type of offset was found, and the argument
1028 * offset is filled with that address.  Otherwise, return false and keep
1029 * offset unchanged.
1030 */
1031STATIC bool
1032xfs_find_get_desired_pgoff(
1033        struct inode            *inode,
1034        struct xfs_bmbt_irec    *map,
1035        unsigned int            type,
1036        loff_t                  *offset)
1037{
1038        struct xfs_inode        *ip = XFS_I(inode);
1039        struct xfs_mount        *mp = ip->i_mount;
1040        struct pagevec          pvec;
1041        pgoff_t                 index;
1042        pgoff_t                 end;
1043        loff_t                  endoff;
1044        loff_t                  startoff = *offset;
1045        loff_t                  lastoff = startoff;
1046        bool                    found = false;
1047
1048        pagevec_init(&pvec, 0);
1049
1050        index = startoff >> PAGE_CACHE_SHIFT;
1051        endoff = XFS_FSB_TO_B(mp, map->br_startoff + map->br_blockcount);
1052        end = endoff >> PAGE_CACHE_SHIFT;
1053        do {
1054                int             want;
1055                unsigned        nr_pages;
1056                unsigned int    i;
1057
1058                want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
1059                nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
1060                                          want);
1061                /*
1062                 * No page mapped into given range.  If we are searching holes
1063                 * and if this is the first time we got into the loop, it means
1064                 * that the given offset is landed in a hole, return it.
1065                 *
1066                 * If we have already stepped through some block buffers to find
1067                 * holes but they all contains data.  In this case, the last
1068                 * offset is already updated and pointed to the end of the last
1069                 * mapped page, if it does not reach the endpoint to search,
1070                 * that means there should be a hole between them.
1071                 */
1072                if (nr_pages == 0) {
1073                        /* Data search found nothing */
1074                        if (type == DATA_OFF)
1075                                break;
1076
1077                        ASSERT(type == HOLE_OFF);
1078                        if (lastoff == startoff || lastoff < endoff) {
1079                                found = true;
1080                                *offset = lastoff;
1081                        }
1082                        break;
1083                }
1084
1085                /*
1086                 * At lease we found one page.  If this is the first time we
1087                 * step into the loop, and if the first page index offset is
1088                 * greater than the given search offset, a hole was found.
1089                 */
1090                if (type == HOLE_OFF && lastoff == startoff &&
1091                    lastoff < page_offset(pvec.pages[0])) {
1092                        found = true;
1093                        break;
1094                }
1095
1096                for (i = 0; i < nr_pages; i++) {
1097                        struct page     *page = pvec.pages[i];
1098                        loff_t          b_offset;
1099
1100                        /*
1101                         * At this point, the page may be truncated or
1102                         * invalidated (changing page->mapping to NULL),
1103                         * or even swizzled back from swapper_space to tmpfs
1104                         * file mapping. However, page->index will not change
1105                         * because we have a reference on the page.
1106                         *
1107                         * Searching done if the page index is out of range.
1108                         * If the current offset is not reaches the end of
1109                         * the specified search range, there should be a hole
1110                         * between them.
1111                         */
1112                        if (page->index > end) {
1113                                if (type == HOLE_OFF && lastoff < endoff) {
1114                                        *offset = lastoff;
1115                                        found = true;
1116                                }
1117                                goto out;
1118                        }
1119
1120                        lock_page(page);
1121                        /*
1122                         * Page truncated or invalidated(page->mapping == NULL).
1123                         * We can freely skip it and proceed to check the next
1124                         * page.
1125                         */
1126                        if (unlikely(page->mapping != inode->i_mapping)) {
1127                                unlock_page(page);
1128                                continue;
1129                        }
1130
1131                        if (!page_has_buffers(page)) {
1132                                unlock_page(page);
1133                                continue;
1134                        }
1135
1136                        found = xfs_lookup_buffer_offset(page, &b_offset, type);
1137                        if (found) {
1138                                /*
1139                                 * The found offset may be less than the start
1140                                 * point to search if this is the first time to
1141                                 * come here.
1142                                 */
1143                                *offset = max_t(loff_t, startoff, b_offset);
1144                                unlock_page(page);
1145                                goto out;
1146                        }
1147
1148                        /*
1149                         * We either searching data but nothing was found, or
1150                         * searching hole but found a data buffer.  In either
1151                         * case, probably the next page contains the desired
1152                         * things, update the last offset to it so.
1153                         */
1154                        lastoff = page_offset(page) + PAGE_SIZE;
1155                        unlock_page(page);
1156                }
1157
1158                /*
1159                 * The number of returned pages less than our desired, search
1160                 * done.  In this case, nothing was found for searching data,
1161                 * but we found a hole behind the last offset.
1162                 */
1163                if (nr_pages < want) {
1164                        if (type == HOLE_OFF) {
1165                                *offset = lastoff;
1166                                found = true;
1167                        }
1168                        break;
1169                }
1170
1171                index = pvec.pages[i - 1]->index + 1;
1172                pagevec_release(&pvec);
1173        } while (index <= end);
1174
1175out:
1176        pagevec_release(&pvec);
1177        return found;
1178}
1179
1180STATIC loff_t
1181xfs_seek_data(
1182        struct file             *file,
1183        loff_t                  start)
1184{
1185        struct inode            *inode = file->f_mapping->host;
1186        struct xfs_inode        *ip = XFS_I(inode);
1187        struct xfs_mount        *mp = ip->i_mount;
1188        loff_t                  uninitialized_var(offset);
1189        xfs_fsize_t             isize;
1190        xfs_fileoff_t           fsbno;
1191        xfs_filblks_t           end;
1192        uint                    lock;
1193        int                     error;
1194
1195        lock = xfs_ilock_map_shared(ip);
1196
1197        isize = i_size_read(inode);
1198        if (start >= isize) {
1199                error = ENXIO;
1200                goto out_unlock;
1201        }
1202
1203        /*
1204         * Try to read extents from the first block indicated
1205         * by fsbno to the end block of the file.
1206         */
1207        fsbno = XFS_B_TO_FSBT(mp, start);
1208        end = XFS_B_TO_FSB(mp, isize);
1209        for (;;) {
1210                struct xfs_bmbt_irec    map[2];
1211                int                     nmap = 2;
1212                unsigned int            i;
1213
1214                error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
1215                                       XFS_BMAPI_ENTIRE);
1216                if (error)
1217                        goto out_unlock;
1218
1219                /* No extents at given offset, must be beyond EOF */
1220                if (nmap == 0) {
1221                        error = ENXIO;
1222                        goto out_unlock;
1223                }
1224
1225                for (i = 0; i < nmap; i++) {
1226                        offset = max_t(loff_t, start,
1227                                       XFS_FSB_TO_B(mp, map[i].br_startoff));
1228
1229                        /* Landed in a data extent */
1230                        if (map[i].br_startblock == DELAYSTARTBLOCK ||
1231                            (map[i].br_state == XFS_EXT_NORM &&
1232                             !isnullstartblock(map[i].br_startblock)))
1233                                goto out;
1234
1235                        /*
1236                         * Landed in an unwritten extent, try to search data
1237                         * from page cache.
1238                         */
1239                        if (map[i].br_state == XFS_EXT_UNWRITTEN) {
1240                                if (xfs_find_get_desired_pgoff(inode, &map[i],
1241                                                        DATA_OFF, &offset))
1242                                        goto out;
1243                        }
1244                }
1245
1246                /*
1247                 * map[0] is hole or its an unwritten extent but
1248                 * without data in page cache.  Probably means that
1249                 * we are reading after EOF if nothing in map[1].
1250                 */
1251                if (nmap == 1) {
1252                        error = ENXIO;
1253                        goto out_unlock;
1254                }
1255
1256                ASSERT(i > 1);
1257
1258                /*
1259                 * Nothing was found, proceed to the next round of search
1260                 * if reading offset not beyond or hit EOF.
1261                 */
1262                fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
1263                start = XFS_FSB_TO_B(mp, fsbno);
1264                if (start >= isize) {
1265                        error = ENXIO;
1266                        goto out_unlock;
1267                }
1268        }
1269
1270out:
1271        if (offset != file->f_pos)
1272                file->f_pos = offset;
1273
1274out_unlock:
1275        xfs_iunlock_map_shared(ip, lock);
1276
1277        if (error)
1278                return -error;
1279        return offset;
1280}
1281
1282STATIC loff_t
1283xfs_seek_hole(
1284        struct file             *file,
1285        loff_t                  start)
1286{
1287        struct inode            *inode = file->f_mapping->host;
1288        struct xfs_inode        *ip = XFS_I(inode);
1289        struct xfs_mount        *mp = ip->i_mount;
1290        loff_t                  uninitialized_var(offset);
1291        xfs_fsize_t             isize;
1292        xfs_fileoff_t           fsbno;
1293        xfs_filblks_t           end;
1294        uint                    lock;
1295        int                     error;
1296
1297        if (XFS_FORCED_SHUTDOWN(mp))
1298                return -XFS_ERROR(EIO);
1299
1300        lock = xfs_ilock_map_shared(ip);
1301
1302        isize = i_size_read(inode);
1303        if (start >= isize) {
1304                error = ENXIO;
1305                goto out_unlock;
1306        }
1307
1308        fsbno = XFS_B_TO_FSBT(mp, start);
1309        end = XFS_B_TO_FSB(mp, isize);
1310
1311        for (;;) {
1312                struct xfs_bmbt_irec    map[2];
1313                int                     nmap = 2;
1314                unsigned int            i;
1315
1316                error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
1317                                       XFS_BMAPI_ENTIRE);
1318                if (error)
1319                        goto out_unlock;
1320
1321                /* No extents at given offset, must be beyond EOF */
1322                if (nmap == 0) {
1323                        error = ENXIO;
1324                        goto out_unlock;
1325                }
1326
1327                for (i = 0; i < nmap; i++) {
1328                        offset = max_t(loff_t, start,
1329                                       XFS_FSB_TO_B(mp, map[i].br_startoff));
1330
1331                        /* Landed in a hole */
1332                        if (map[i].br_startblock == HOLESTARTBLOCK)
1333                                goto out;
1334
1335                        /*
1336                         * Landed in an unwritten extent, try to search hole
1337                         * from page cache.
1338                         */
1339                        if (map[i].br_state == XFS_EXT_UNWRITTEN) {
1340                                if (xfs_find_get_desired_pgoff(inode, &map[i],
1341                                                        HOLE_OFF, &offset))
1342                                        goto out;
1343                        }
1344                }
1345
1346                /*
1347                 * map[0] contains data or its unwritten but contains
1348                 * data in page cache, probably means that we are
1349                 * reading after EOF.  We should fix offset to point
1350                 * to the end of the file(i.e., there is an implicit
1351                 * hole at the end of any file).
1352                 */
1353                if (nmap == 1) {
1354                        offset = isize;
1355                        break;
1356                }
1357
1358                ASSERT(i > 1);
1359
1360                /*
1361                 * Both mappings contains data, proceed to the next round of
1362                 * search if the current reading offset not beyond or hit EOF.
1363                 */
1364                fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
1365                start = XFS_FSB_TO_B(mp, fsbno);
1366                if (start >= isize) {
1367                        offset = isize;
1368                        break;
1369                }
1370        }
1371
1372out:
1373        /*
1374         * At this point, we must have found a hole.  However, the returned
1375         * offset may be bigger than the file size as it may be aligned to
1376         * page boundary for unwritten extents, we need to deal with this
1377         * situation in particular.
1378         */
1379        offset = min_t(loff_t, offset, isize);
1380        if (offset != file->f_pos)
1381                file->f_pos = offset;
1382
1383out_unlock:
1384        xfs_iunlock_map_shared(ip, lock);
1385
1386        if (error)
1387                return -error;
1388        return offset;
1389}
1390
1391STATIC loff_t
1392xfs_file_llseek(
1393        struct file     *file,
1394        loff_t          offset,
1395        int             origin)
1396{
1397        switch (origin) {
1398        case SEEK_END:
1399        case SEEK_CUR:
1400        case SEEK_SET:
1401                return generic_file_llseek(file, offset, origin);
1402        case SEEK_DATA:
1403                return xfs_seek_data(file, offset);
1404        case SEEK_HOLE:
1405                return xfs_seek_hole(file, offset);
1406        default:
1407                return -EINVAL;
1408        }
1409}
1410
1411const struct file_operations xfs_file_operations = {
1412        .llseek         = xfs_file_llseek,
1413        .read           = do_sync_read,
1414        .write          = do_sync_write,
1415        .aio_read       = xfs_file_aio_read,
1416        .aio_write      = xfs_file_aio_write,
1417        .splice_read    = xfs_file_splice_read,
1418        .splice_write   = xfs_file_splice_write,
1419        .unlocked_ioctl = xfs_file_ioctl,
1420#ifdef CONFIG_COMPAT
1421        .compat_ioctl   = xfs_file_compat_ioctl,
1422#endif
1423        .mmap           = xfs_file_mmap,
1424        .open           = xfs_file_open,
1425        .release        = xfs_file_release,
1426        .fsync          = xfs_file_fsync,
1427        .fallocate      = xfs_file_fallocate,
1428};
1429
1430const struct file_operations xfs_dir_file_operations = {
1431        .open           = xfs_dir_open,
1432        .read           = generic_read_dir,
1433        .readdir        = xfs_file_readdir,
1434        .llseek         = generic_file_llseek,
1435        .unlocked_ioctl = xfs_file_ioctl,
1436#ifdef CONFIG_COMPAT
1437        .compat_ioctl   = xfs_file_compat_ioctl,
1438#endif
1439        .fsync          = xfs_dir_fsync,
1440};
1441
1442static const struct vm_operations_struct xfs_file_vm_ops = {
1443        .fault          = filemap_fault,
1444        .page_mkwrite   = xfs_vm_page_mkwrite,
1445        .remap_pages    = generic_file_remap_pages,
1446};
1447
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