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_dir2_format.h"
  35#include "xfs_dir2_priv.h"
  36#include "xfs_ioctl.h"
  37#include "xfs_trace.h"
  38
  39#include <linux/dcache.h>
  40#include <linux/falloc.h>
  41#include <linux/pagevec.h>
  42
  43static const struct vm_operations_struct xfs_file_vm_ops;
  44
  45/*
  46 * Locking primitives for read and write IO paths to ensure we consistently use
  47 * and order the inode->i_mutex, ip->i_lock and ip->i_iolock.
  48 */
  49static inline void
  50xfs_rw_ilock(
  51        struct xfs_inode        *ip,
  52        int                     type)
  53{
  54        if (type & XFS_IOLOCK_EXCL)
  55                mutex_lock(&VFS_I(ip)->i_mutex);
  56        xfs_ilock(ip, type);
  57}
  58
  59static inline void
  60xfs_rw_iunlock(
  61        struct xfs_inode        *ip,
  62        int                     type)
  63{
  64        xfs_iunlock(ip, type);
  65        if (type & XFS_IOLOCK_EXCL)
  66                mutex_unlock(&VFS_I(ip)->i_mutex);
  67}
  68
  69static inline void
  70xfs_rw_ilock_demote(
  71        struct xfs_inode        *ip,
  72        int                     type)
  73{
  74        xfs_ilock_demote(ip, type);
  75        if (type & XFS_IOLOCK_EXCL)
  76                mutex_unlock(&VFS_I(ip)->i_mutex);
  77}
  78
  79/*
  80 *      xfs_iozero
  81 *
  82 *      xfs_iozero clears the specified range of buffer supplied,
  83 *      and marks all the affected blocks as valid and modified.  If
  84 *      an affected block is not allocated, it will be allocated.  If
  85 *      an affected block is not completely overwritten, and is not
  86 *      valid before the operation, it will be read from disk before
  87 *      being partially zeroed.
  88 */
  89int
  90xfs_iozero(
  91        struct xfs_inode        *ip,    /* inode                        */
  92        loff_t                  pos,    /* offset in file               */
  93        size_t                  count)  /* size of data to zero         */
  94{
  95        struct page             *page;
  96        struct address_space    *mapping;
  97        int                     status;
  98
  99        mapping = VFS_I(ip)->i_mapping;
 100        do {
 101                unsigned offset, bytes;
 102                void *fsdata;
 103
 104                offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
 105                bytes = PAGE_CACHE_SIZE - offset;
 106                if (bytes > count)
 107                        bytes = count;
 108
 109                status = pagecache_write_begin(NULL, mapping, pos, bytes,
 110                                        AOP_FLAG_UNINTERRUPTIBLE,
 111                                        &page, &fsdata);
 112                if (status)
 113                        break;
 114
 115                zero_user(page, offset, bytes);
 116
 117                status = pagecache_write_end(NULL, mapping, pos, bytes, bytes,
 118                                        page, fsdata);
 119                WARN_ON(status <= 0); /* can't return less than zero! */
 120                pos += bytes;
 121                count -= bytes;
 122                status = 0;
 123        } while (count);
 124
 125        return (-status);
 126}
 127
 128/*
 129 * Fsync operations on directories are much simpler than on regular files,
 130 * as there is no file data to flush, and thus also no need for explicit
 131 * cache flush operations, and there are no non-transaction metadata updates
 132 * on directories either.
 133 */
 134STATIC int
 135xfs_dir_fsync(
 136        struct file             *file,
 137        loff_t                  start,
 138        loff_t                  end,
 139        int                     datasync)
 140{
 141        struct xfs_inode        *ip = XFS_I(file->f_mapping->host);
 142        struct xfs_mount        *mp = ip->i_mount;
 143        xfs_lsn_t               lsn = 0;
 144
 145        trace_xfs_dir_fsync(ip);
 146
 147        xfs_ilock(ip, XFS_ILOCK_SHARED);
 148        if (xfs_ipincount(ip))
 149                lsn = ip->i_itemp->ili_last_lsn;
 150        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 151
 152        if (!lsn)
 153                return 0;
 154        return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 155}
 156
 157STATIC int
 158xfs_file_fsync(
 159        struct file             *file,
 160        loff_t                  start,
 161        loff_t                  end,
 162        int                     datasync)
 163{
 164        struct inode            *inode = file->f_mapping->host;
 165        struct xfs_inode        *ip = XFS_I(inode);
 166        struct xfs_mount        *mp = ip->i_mount;
 167        int                     error = 0;
 168        int                     log_flushed = 0;
 169        xfs_lsn_t               lsn = 0;
 170
 171        trace_xfs_file_fsync(ip);
 172
 173        error = filemap_write_and_wait_range(inode->i_mapping, start, end);
 174        if (error)
 175                return error;
 176
 177        if (XFS_FORCED_SHUTDOWN(mp))
 178                return -XFS_ERROR(EIO);
 179
 180        xfs_iflags_clear(ip, XFS_ITRUNCATED);
 181
 182        if (mp->m_flags & XFS_MOUNT_BARRIER) {
 183                /*
 184                 * If we have an RT and/or log subvolume we need to make sure
 185                 * to flush the write cache the device used for file data
 186                 * first.  This is to ensure newly written file data make
 187                 * it to disk before logging the new inode size in case of
 188                 * an extending write.
 189                 */
 190                if (XFS_IS_REALTIME_INODE(ip))
 191                        xfs_blkdev_issue_flush(mp->m_rtdev_targp);
 192                else if (mp->m_logdev_targp != mp->m_ddev_targp)
 193                        xfs_blkdev_issue_flush(mp->m_ddev_targp);
 194        }
 195
 196        /*
 197         * All metadata updates are logged, which means that we just have
 198         * to flush the log up to the latest LSN that touched the inode.
 199         */
 200        xfs_ilock(ip, XFS_ILOCK_SHARED);
 201        if (xfs_ipincount(ip)) {
 202                if (!datasync ||
 203                    (ip->i_itemp->ili_fields & ~XFS_ILOG_TIMESTAMP))
 204                        lsn = ip->i_itemp->ili_last_lsn;
 205        }
 206        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 207
 208        if (lsn)
 209                error = _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, &log_flushed);
 210
 211        /*
 212         * If we only have a single device, and the log force about was
 213         * a no-op we might have to flush the data device cache here.
 214         * This can only happen for fdatasync/O_DSYNC if we were overwriting
 215         * an already allocated file and thus do not have any metadata to
 216         * commit.
 217         */
 218        if ((mp->m_flags & XFS_MOUNT_BARRIER) &&
 219            mp->m_logdev_targp == mp->m_ddev_targp &&
 220            !XFS_IS_REALTIME_INODE(ip) &&
 221            !log_flushed)
 222                xfs_blkdev_issue_flush(mp->m_ddev_targp);
 223
 224        return -error;
 225}
 226
 227STATIC ssize_t
 228xfs_file_aio_read(
 229        struct kiocb            *iocb,
 230        const struct iovec      *iovp,
 231        unsigned long           nr_segs,
 232        loff_t                  pos)
 233{
 234        struct file             *file = iocb->ki_filp;
 235        struct inode            *inode = file->f_mapping->host;
 236        struct xfs_inode        *ip = XFS_I(inode);
 237        struct xfs_mount        *mp = ip->i_mount;
 238        size_t                  size = 0;
 239        ssize_t                 ret = 0;
 240        int                     ioflags = 0;
 241        xfs_fsize_t             n;
 242
 243        XFS_STATS_INC(xs_read_calls);
 244
 245        BUG_ON(iocb->ki_pos != pos);
 246
 247        if (unlikely(file->f_flags & O_DIRECT))
 248                ioflags |= IO_ISDIRECT;
 249        if (file->f_mode & FMODE_NOCMTIME)
 250                ioflags |= IO_INVIS;
 251
 252        ret = generic_segment_checks(iovp, &nr_segs, &size, VERIFY_WRITE);
 253        if (ret < 0)
 254                return ret;
 255
 256        if (unlikely(ioflags & IO_ISDIRECT)) {
 257                xfs_buftarg_t   *target =
 258                        XFS_IS_REALTIME_INODE(ip) ?
 259                                mp->m_rtdev_targp : mp->m_ddev_targp;
 260                if ((pos & target->bt_smask) || (size & target->bt_smask)) {
 261                        if (pos == i_size_read(inode))
 262                                return 0;
 263                        return -XFS_ERROR(EINVAL);
 264                }
 265        }
 266
 267        n = mp->m_super->s_maxbytes - pos;
 268        if (n <= 0 || size == 0)
 269                return 0;
 270
 271        if (n < size)
 272                size = n;
 273
 274        if (XFS_FORCED_SHUTDOWN(mp))
 275                return -EIO;
 276
 277        /*
 278         * Locking is a bit tricky here. If we take an exclusive lock
 279         * for direct IO, we effectively serialise all new concurrent
 280         * read IO to this file and block it behind IO that is currently in
 281         * progress because IO in progress holds the IO lock shared. We only
 282         * need to hold the lock exclusive to blow away the page cache, so
 283         * only take lock exclusively if the page cache needs invalidation.
 284         * This allows the normal direct IO case of no page cache pages to
 285         * proceeed concurrently without serialisation.
 286         */
 287        xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
 288        if ((ioflags & IO_ISDIRECT) && inode->i_mapping->nrpages) {
 289                xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
 290                xfs_rw_ilock(ip, XFS_IOLOCK_EXCL);
 291
 292                if (inode->i_mapping->nrpages) {
 293                        ret = -filemap_write_and_wait_range(
 294                                                        VFS_I(ip)->i_mapping,
 295                                                        pos, -1);
 296                        if (ret) {
 297                                xfs_rw_iunlock(ip, XFS_IOLOCK_EXCL);
 298                                return ret;
 299                        }
 300                        truncate_pagecache_range(VFS_I(ip), pos, -1);
 301                }
 302                xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
 303        }
 304
 305        trace_xfs_file_read(ip, size, pos, ioflags);
 306
 307        ret = generic_file_aio_read(iocb, iovp, nr_segs, pos);
 308        if (ret > 0)
 309                XFS_STATS_ADD(xs_read_bytes, ret);
 310
 311        xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
 312        return ret;
 313}
 314
 315STATIC ssize_t
 316xfs_file_splice_read(
 317        struct file             *infilp,
 318        loff_t                  *ppos,
 319        struct pipe_inode_info  *pipe,
 320        size_t                  count,
 321        unsigned int            flags)
 322{
 323        struct xfs_inode        *ip = XFS_I(infilp->f_mapping->host);
 324        int                     ioflags = 0;
 325        ssize_t                 ret;
 326
 327        XFS_STATS_INC(xs_read_calls);
 328
 329        if (infilp->f_mode & FMODE_NOCMTIME)
 330                ioflags |= IO_INVIS;
 331
 332        if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 333                return -EIO;
 334
 335        xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
 336
 337        trace_xfs_file_splice_read(ip, count, *ppos, ioflags);
 338
 339        ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
 340        if (ret > 0)
 341                XFS_STATS_ADD(xs_read_bytes, ret);
 342
 343        xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
 344        return ret;
 345}
 346
 347/*
 348 * xfs_file_splice_write() does not use xfs_rw_ilock() because
 349 * generic_file_splice_write() takes the i_mutex itself. This, in theory,
 350 * couuld cause lock inversions between the aio_write path and the splice path
 351 * if someone is doing concurrent splice(2) based writes and write(2) based
 352 * writes to the same inode. The only real way to fix this is to re-implement
 353 * the generic code here with correct locking orders.
 354 */
 355STATIC ssize_t
 356xfs_file_splice_write(
 357        struct pipe_inode_info  *pipe,
 358        struct file             *outfilp,
 359        loff_t                  *ppos,
 360        size_t                  count,
 361        unsigned int            flags)
 362{
 363        struct inode            *inode = outfilp->f_mapping->host;
 364        struct xfs_inode        *ip = XFS_I(inode);
 365        int                     ioflags = 0;
 366        ssize_t                 ret;
 367
 368        XFS_STATS_INC(xs_write_calls);
 369
 370        if (outfilp->f_mode & FMODE_NOCMTIME)
 371                ioflags |= IO_INVIS;
 372
 373        if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 374                return -EIO;
 375
 376        xfs_ilock(ip, XFS_IOLOCK_EXCL);
 377
 378        trace_xfs_file_splice_write(ip, count, *ppos, ioflags);
 379
 380        ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
 381        if (ret > 0)
 382                XFS_STATS_ADD(xs_write_bytes, ret);
 383
 384        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 385        return ret;
 386}
 387
 388/*
 389 * This routine is called to handle zeroing any space in the last block of the
 390 * file that is beyond the EOF.  We do this since the size is being increased
 391 * without writing anything to that block and we don't want to read the
 392 * garbage on the disk.
 393 */
 394STATIC int                              /* error (positive) */
 395xfs_zero_last_block(
 396        struct xfs_inode        *ip,
 397        xfs_fsize_t             offset,
 398        xfs_fsize_t             isize)
 399{
 400        struct xfs_mount        *mp = ip->i_mount;
 401        xfs_fileoff_t           last_fsb = XFS_B_TO_FSBT(mp, isize);
 402        int                     zero_offset = XFS_B_FSB_OFFSET(mp, isize);
 403        int                     zero_len;
 404        int                     nimaps = 1;
 405        int                     error = 0;
 406        struct xfs_bmbt_irec    imap;
 407
 408        xfs_ilock(ip, XFS_ILOCK_EXCL);
 409        error = xfs_bmapi_read(ip, last_fsb, 1, &imap, &nimaps, 0);
 410        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 411        if (error)
 412                return error;
 413
 414        ASSERT(nimaps > 0);
 415
 416        /*
 417         * If the block underlying isize is just a hole, then there
 418         * is nothing to zero.
 419         */
 420        if (imap.br_startblock == HOLESTARTBLOCK)
 421                return 0;
 422
 423        zero_len = mp->m_sb.sb_blocksize - zero_offset;
 424        if (isize + zero_len > offset)
 425                zero_len = offset - isize;
 426        return xfs_iozero(ip, isize, zero_len);
 427}
 428
 429/*
 430 * Zero any on disk space between the current EOF and the new, larger EOF.
 431 *
 432 * This handles the normal case of zeroing the remainder of the last block in
 433 * the file and the unusual case of zeroing blocks out beyond the size of the
 434 * file.  This second case only happens with fixed size extents and when the
 435 * system crashes before the inode size was updated but after blocks were
 436 * allocated.
 437 *
 438 * Expects the iolock to be held exclusive, and will take the ilock internally.
 439 */
 440int                                     /* error (positive) */
 441xfs_zero_eof(
 442        struct xfs_inode        *ip,
 443        xfs_off_t               offset,         /* starting I/O offset */
 444        xfs_fsize_t             isize)          /* current inode size */
 445{
 446        struct xfs_mount        *mp = ip->i_mount;
 447        xfs_fileoff_t           start_zero_fsb;
 448        xfs_fileoff_t           end_zero_fsb;
 449        xfs_fileoff_t           zero_count_fsb;
 450        xfs_fileoff_t           last_fsb;
 451        xfs_fileoff_t           zero_off;
 452        xfs_fsize_t             zero_len;
 453        int                     nimaps;
 454        int                     error = 0;
 455        struct xfs_bmbt_irec    imap;
 456
 457        ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
 458        ASSERT(offset > isize);
 459
 460        /*
 461         * First handle zeroing the block on which isize resides.
 462         *
 463         * We only zero a part of that block so it is handled specially.
 464         */
 465        if (XFS_B_FSB_OFFSET(mp, isize) != 0) {
 466                error = xfs_zero_last_block(ip, offset, isize);
 467                if (error)
 468                        return error;
 469        }
 470
 471        /*
 472         * Calculate the range between the new size and the old where blocks
 473         * needing to be zeroed may exist.
 474         *
 475         * To get the block where the last byte in the file currently resides,
 476         * we need to subtract one from the size and truncate back to a block
 477         * boundary.  We subtract 1 in case the size is exactly on a block
 478         * boundary.
 479         */
 480        last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
 481        start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
 482        end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
 483        ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
 484        if (last_fsb == end_zero_fsb) {
 485                /*
 486                 * The size was only incremented on its last block.
 487                 * We took care of that above, so just return.
 488                 */
 489                return 0;
 490        }
 491
 492        ASSERT(start_zero_fsb <= end_zero_fsb);
 493        while (start_zero_fsb <= end_zero_fsb) {
 494                nimaps = 1;
 495                zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
 496
 497                xfs_ilock(ip, XFS_ILOCK_EXCL);
 498                error = xfs_bmapi_read(ip, start_zero_fsb, zero_count_fsb,
 499                                          &imap, &nimaps, 0);
 500                xfs_iunlock(ip, XFS_ILOCK_EXCL);
 501                if (error)
 502                        return error;
 503
 504                ASSERT(nimaps > 0);
 505
 506                if (imap.br_state == XFS_EXT_UNWRITTEN ||
 507                    imap.br_startblock == HOLESTARTBLOCK) {
 508                        start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 509                        ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 510                        continue;
 511                }
 512
 513                /*
 514                 * There are blocks we need to zero.
 515                 */
 516                zero_off = XFS_FSB_TO_B(mp, start_zero_fsb);
 517                zero_len = XFS_FSB_TO_B(mp, imap.br_blockcount);
 518
 519                if ((zero_off + zero_len) > offset)
 520                        zero_len = offset - zero_off;
 521
 522                error = xfs_iozero(ip, zero_off, zero_len);
 523                if (error)
 524                        return error;
 525
 526                start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 527                ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 528        }
 529
 530        return 0;
 531}
 532
 533/*
 534 * Common pre-write limit and setup checks.
 535 *
 536 * Called with the iolocked held either shared and exclusive according to
 537 * @iolock, and returns with it held.  Might upgrade the iolock to exclusive
 538 * if called for a direct write beyond i_size.
 539 */
 540STATIC ssize_t
 541xfs_file_aio_write_checks(
 542        struct file             *file,
 543        loff_t                  *pos,
 544        size_t                  *count,
 545        int                     *iolock)
 546{
 547        struct inode            *inode = file->f_mapping->host;
 548        struct xfs_inode        *ip = XFS_I(inode);
 549        int                     error = 0;
 550
 551restart:
 552        error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode));
 553        if (error)
 554                return error;
 555
 556        /*
 557         * If the offset is beyond the size of the file, we need to zero any
 558         * blocks that fall between the existing EOF and the start of this
 559         * write.  If zeroing is needed and we are currently holding the
 560         * iolock shared, we need to update it to exclusive which implies
 561         * having to redo all checks before.
 562         */
 563        if (*pos > i_size_read(inode)) {
 564                if (*iolock == XFS_IOLOCK_SHARED) {
 565                        xfs_rw_iunlock(ip, *iolock);
 566                        *iolock = XFS_IOLOCK_EXCL;
 567                        xfs_rw_ilock(ip, *iolock);
 568                        goto restart;
 569                }
 570                error = -xfs_zero_eof(ip, *pos, i_size_read(inode));
 571                if (error)
 572                        return error;
 573        }
 574
 575        /*
 576         * Updating the timestamps will grab the ilock again from
 577         * xfs_fs_dirty_inode, so we have to call it after dropping the
 578         * lock above.  Eventually we should look into a way to avoid
 579         * the pointless lock roundtrip.
 580         */
 581        if (likely(!(file->f_mode & FMODE_NOCMTIME))) {
 582                error = file_update_time(file);
 583                if (error)
 584                        return error;
 585        }
 586
 587        /*
 588         * If we're writing the file then make sure to clear the setuid and
 589         * setgid bits if the process is not being run by root.  This keeps
 590         * people from modifying setuid and setgid binaries.
 591         */
 592        return file_remove_suid(file);
 593}
 594
 595/*
 596 * xfs_file_dio_aio_write - handle direct IO writes
 597 *
 598 * Lock the inode appropriately to prepare for and issue a direct IO write.
 599 * By separating it from the buffered write path we remove all the tricky to
 600 * follow locking changes and looping.
 601 *
 602 * If there are cached pages or we're extending the file, we need IOLOCK_EXCL
 603 * until we're sure the bytes at the new EOF have been zeroed and/or the cached
 604 * pages are flushed out.
 605 *
 606 * In most cases the direct IO writes will be done holding IOLOCK_SHARED
 607 * allowing them to be done in parallel with reads and other direct IO writes.
 608 * However, if the IO is not aligned to filesystem blocks, the direct IO layer
 609 * needs to do sub-block zeroing and that requires serialisation against other
 610 * direct IOs to the same block. In this case we need to serialise the
 611 * submission of the unaligned IOs so that we don't get racing block zeroing in
 612 * the dio layer.  To avoid the problem with aio, we also need to wait for
 613 * outstanding IOs to complete so that unwritten extent conversion is completed
 614 * before we try to map the overlapping block. This is currently implemented by
 615 * hitting it with a big hammer (i.e. inode_dio_wait()).
 616 *
 617 * Returns with locks held indicated by @iolock and errors indicated by
 618 * negative return values.
 619 */
 620STATIC ssize_t
 621xfs_file_dio_aio_write(
 622        struct kiocb            *iocb,
 623        const struct iovec      *iovp,
 624        unsigned long           nr_segs,
 625        loff_t                  pos,
 626        size_t                  ocount)
 627{
 628        struct file             *file = iocb->ki_filp;
 629        struct address_space    *mapping = file->f_mapping;
 630        struct inode            *inode = mapping->host;
 631        struct xfs_inode        *ip = XFS_I(inode);
 632        struct xfs_mount        *mp = ip->i_mount;
 633        ssize_t                 ret = 0;
 634        size_t                  count = ocount;
 635        int                     unaligned_io = 0;
 636        int                     iolock;
 637        struct xfs_buftarg      *target = XFS_IS_REALTIME_INODE(ip) ?
 638                                        mp->m_rtdev_targp : mp->m_ddev_targp;
 639
 640        if ((pos & target->bt_smask) || (count & target->bt_smask))
 641                return -XFS_ERROR(EINVAL);
 642
 643        if ((pos & mp->m_blockmask) || ((pos + count) & mp->m_blockmask))
 644                unaligned_io = 1;
 645
 646        /*
 647         * We don't need to take an exclusive lock unless there page cache needs
 648         * to be invalidated or unaligned IO is being executed. We don't need to
 649         * consider the EOF extension case here because
 650         * xfs_file_aio_write_checks() will relock the inode as necessary for
 651         * EOF zeroing cases and fill out the new inode size as appropriate.
 652         */
 653        if (unaligned_io || mapping->nrpages)
 654                iolock = XFS_IOLOCK_EXCL;
 655        else
 656                iolock = XFS_IOLOCK_SHARED;
 657        xfs_rw_ilock(ip, iolock);
 658
 659        /*
 660         * Recheck if there are cached pages that need invalidate after we got
 661         * the iolock to protect against other threads adding new pages while
 662         * we were waiting for the iolock.
 663         */
 664        if (mapping->nrpages && iolock == XFS_IOLOCK_SHARED) {
 665                xfs_rw_iunlock(ip, iolock);
 666                iolock = XFS_IOLOCK_EXCL;
 667                xfs_rw_ilock(ip, iolock);
 668        }
 669
 670        ret = xfs_file_aio_write_checks(file, &pos, &count, &iolock);
 671        if (ret)
 672                goto out;
 673
 674        if (mapping->nrpages) {
 675                ret = -filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
 676                                                    pos, -1);
 677                if (ret)
 678                        goto out;
 679                truncate_pagecache_range(VFS_I(ip), pos, -1);
 680        }
 681
 682        /*
 683         * If we are doing unaligned IO, wait for all other IO to drain,
 684         * otherwise demote the lock if we had to flush cached pages
 685         */
 686        if (unaligned_io)
 687                inode_dio_wait(inode);
 688        else if (iolock == XFS_IOLOCK_EXCL) {
 689                xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
 690                iolock = XFS_IOLOCK_SHARED;
 691        }
 692
 693        trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);
 694        ret = generic_file_direct_write(iocb, iovp,
 695                        &nr_segs, pos, &iocb->ki_pos, count, ocount);
 696
 697out:
 698        xfs_rw_iunlock(ip, iolock);
 699
 700        /* No fallback to buffered IO on errors for XFS. */
 701        ASSERT(ret < 0 || ret == count);
 702        return ret;
 703}
 704
 705STATIC ssize_t
 706xfs_file_buffered_aio_write(
 707        struct kiocb            *iocb,
 708        const struct iovec      *iovp,
 709        unsigned long           nr_segs,
 710        loff_t                  pos,
 711        size_t                  ocount)
 712{
 713        struct file             *file = iocb->ki_filp;
 714        struct address_space    *mapping = file->f_mapping;
 715        struct inode            *inode = mapping->host;
 716        struct xfs_inode        *ip = XFS_I(inode);
 717        ssize_t                 ret;
 718        int                     enospc = 0;
 719        int                     iolock = XFS_IOLOCK_EXCL;
 720        size_t                  count = ocount;
 721
 722        xfs_rw_ilock(ip, iolock);
 723
 724        ret = xfs_file_aio_write_checks(file, &pos, &count, &iolock);
 725        if (ret)
 726                goto out;
 727
 728        /* We can write back this queue in page reclaim */
 729        current->backing_dev_info = mapping->backing_dev_info;
 730
 731write_retry:
 732        trace_xfs_file_buffered_write(ip, count, iocb->ki_pos, 0);
 733        ret = generic_file_buffered_write(iocb, iovp, nr_segs,
 734                        pos, &iocb->ki_pos, count, 0);
 735
 736        /*
 737         * If we just got an ENOSPC, try to write back all dirty inodes to
 738         * convert delalloc space to free up some of the excess reserved
 739         * metadata space.
 740         */
 741        if (ret == -ENOSPC && !enospc) {
 742                enospc = 1;
 743                xfs_flush_inodes(ip->i_mount);
 744                goto write_retry;
 745        }
 746
 747        current->backing_dev_info = NULL;
 748out:
 749        xfs_rw_iunlock(ip, iolock);
 750        return ret;
 751}
 752
 753STATIC ssize_t
 754xfs_file_aio_write(
 755        struct kiocb            *iocb,
 756        const struct iovec      *iovp,
 757        unsigned long           nr_segs,
 758        loff_t                  pos)
 759{
 760        struct file             *file = iocb->ki_filp;
 761        struct address_space    *mapping = file->f_mapping;
 762        struct inode            *inode = mapping->host;
 763        struct xfs_inode        *ip = XFS_I(inode);
 764        ssize_t                 ret;
 765        size_t                  ocount = 0;
 766
 767        XFS_STATS_INC(xs_write_calls);
 768
 769        BUG_ON(iocb->ki_pos != pos);
 770
 771        ret = generic_segment_checks(iovp, &nr_segs, &ocount, VERIFY_READ);
 772        if (ret)
 773                return ret;
 774
 775        if (ocount == 0)
 776                return 0;
 777
 778        sb_start_write(inode->i_sb);
 779
 780        if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
 781                ret = -EIO;
 782                goto out;
 783        }
 784
 785        if (unlikely(file->f_flags & O_DIRECT))
 786                ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos, ocount);
 787        else
 788                ret = xfs_file_buffered_aio_write(iocb, iovp, nr_segs, pos,
 789                                                  ocount);
 790
 791        if (ret > 0) {
 792                ssize_t err;
 793
 794                XFS_STATS_ADD(xs_write_bytes, ret);
 795
 796                /* Handle various SYNC-type writes */
 797                err = generic_write_sync(file, pos, ret);
 798                if (err < 0)
 799                        ret = err;
 800        }
 801
 802out:
 803        sb_end_write(inode->i_sb);
 804        return ret;
 805}
 806
 807STATIC long
 808xfs_file_fallocate(
 809        struct file     *file,
 810        int             mode,
 811        loff_t          offset,
 812        loff_t          len)
 813{
 814        struct inode    *inode = file->f_path.dentry->d_inode;
 815        long            error;
 816        loff_t          new_size = 0;
 817        xfs_flock64_t   bf;
 818        xfs_inode_t     *ip = XFS_I(inode);
 819        int             cmd = XFS_IOC_RESVSP;
 820        int             attr_flags = XFS_ATTR_NOLOCK;
 821
 822        if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
 823                return -EOPNOTSUPP;
 824
 825        bf.l_whence = 0;
 826        bf.l_start = offset;
 827        bf.l_len = len;
 828
 829        xfs_ilock(ip, XFS_IOLOCK_EXCL);
 830
 831        if (mode & FALLOC_FL_PUNCH_HOLE)
 832                cmd = XFS_IOC_UNRESVSP;
 833
 834        /* check the new inode size is valid before allocating */
 835        if (!(mode & FALLOC_FL_KEEP_SIZE) &&
 836            offset + len > i_size_read(inode)) {
 837                new_size = offset + len;
 838                error = inode_newsize_ok(inode, new_size);
 839                if (error)
 840                        goto out_unlock;
 841        }
 842
 843        if (file->f_flags & O_DSYNC)
 844                attr_flags |= XFS_ATTR_SYNC;
 845
 846        error = -xfs_change_file_space(ip, cmd, &bf, 0, attr_flags);
 847        if (error)
 848                goto out_unlock;
 849
 850        /* Change file size if needed */
 851        if (new_size) {
 852                struct iattr iattr;
 853
 854                iattr.ia_valid = ATTR_SIZE;
 855                iattr.ia_size = new_size;
 856                error = -xfs_setattr_size(ip, &iattr, XFS_ATTR_NOLOCK);
 857        }
 858
 859out_unlock:
 860        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 861        return error;
 862}
 863
 864
 865STATIC int
 866xfs_file_open(
 867        struct inode    *inode,
 868        struct file     *file)
 869{
 870        if (!(file->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
 871                return -EFBIG;
 872        if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
 873                return -EIO;
 874        return 0;
 875}
 876
 877STATIC int
 878xfs_dir_open(
 879        struct inode    *inode,
 880        struct file     *file)
 881{
 882        struct xfs_inode *ip = XFS_I(inode);
 883        int             mode;
 884        int             error;
 885
 886        error = xfs_file_open(inode, file);
 887        if (error)
 888                return error;
 889
 890        /*
 891         * If there are any blocks, read-ahead block 0 as we're almost
 892         * certain to have the next operation be a read there.
 893         */
 894        mode = xfs_ilock_map_shared(ip);
 895        if (ip->i_d.di_nextents > 0)
 896                xfs_dir2_data_readahead(NULL, ip, 0, -1);
 897        xfs_iunlock(ip, mode);
 898        return 0;
 899}
 900
 901STATIC int
 902xfs_file_release(
 903        struct inode    *inode,
 904        struct file     *filp)
 905{
 906        return -xfs_release(XFS_I(inode));
 907}
 908
 909STATIC int
 910xfs_file_readdir(
 911        struct file     *filp,
 912        void            *dirent,
 913        filldir_t       filldir)
 914{
 915        struct inode    *inode = filp->f_path.dentry->d_inode;
 916        xfs_inode_t     *ip = XFS_I(inode);
 917        int             error;
 918        size_t          bufsize;
 919
 920        /*
 921         * The Linux API doesn't pass down the total size of the buffer
 922         * we read into down to the filesystem.  With the filldir concept
 923         * it's not needed for correct information, but the XFS dir2 leaf
 924         * code wants an estimate of the buffer size to calculate it's
 925         * readahead window and size the buffers used for mapping to
 926         * physical blocks.
 927         *
 928         * Try to give it an estimate that's good enough, maybe at some
 929         * point we can change the ->readdir prototype to include the
 930         * buffer size.  For now we use the current glibc buffer size.
 931         */
 932        bufsize = (size_t)min_t(loff_t, 32768, ip->i_d.di_size);
 933
 934        error = xfs_readdir(ip, dirent, bufsize,
 935                                (xfs_off_t *)&filp->f_pos, filldir);
 936        if (error)
 937                return -error;
 938        return 0;
 939}
 940
 941STATIC int
 942xfs_file_mmap(
 943        struct file     *filp,
 944        struct vm_area_struct *vma)
 945{
 946        vma->vm_ops = &xfs_file_vm_ops;
 947
 948        file_accessed(filp);
 949        return 0;
 950}
 951
 952/*
 953 * mmap()d file has taken write protection fault and is being made
 954 * writable. We can set the page state up correctly for a writable
 955 * page, which means we can do correct delalloc accounting (ENOSPC
 956 * checking!) and unwritten extent mapping.
 957 */
 958STATIC int
 959xfs_vm_page_mkwrite(
 960        struct vm_area_struct   *vma,
 961        struct vm_fault         *vmf)
 962{
 963        return block_page_mkwrite(vma, vmf, xfs_get_blocks);
 964}
 965
 966/*
 967 * This type is designed to indicate the type of offset we would like
 968 * to search from page cache for either xfs_seek_data() or xfs_seek_hole().
 969 */
 970enum {
 971        HOLE_OFF = 0,
 972        DATA_OFF,
 973};
 974
 975/*
 976 * Lookup the desired type of offset from the given page.
 977 *
 978 * On success, return true and the offset argument will point to the
 979 * start of the region that was found.  Otherwise this function will
 980 * return false and keep the offset argument unchanged.
 981 */
 982STATIC bool
 983xfs_lookup_buffer_offset(
 984        struct page             *page,
 985        loff_t                  *offset,
 986        unsigned int            type)
 987{
 988        loff_t                  lastoff = page_offset(page);
 989        bool                    found = false;
 990        struct buffer_head      *bh, *head;
 991
 992        bh = head = page_buffers(page);
 993        do {
 994                /*
 995                 * Unwritten extents that have data in the page
 996                 * cache covering them can be identified by the
 997                 * BH_Unwritten state flag.  Pages with multiple
 998                 * buffers might have a mix of holes, data and
 999                 * unwritten extents - any buffer with valid
1000                 * data in it should have BH_Uptodate flag set
1001                 * on it.
1002                 */
1003                if (buffer_unwritten(bh) ||
1004                    buffer_uptodate(bh)) {
1005                        if (type == DATA_OFF)
1006                                found = true;
1007                } else {
1008                        if (type == HOLE_OFF)
1009                                found = true;
1010                }
1011
1012                if (found) {
1013                        *offset = lastoff;
1014                        break;
1015                }
1016                lastoff += bh->b_size;
1017        } while ((bh = bh->b_this_page) != head);
1018
1019        return found;
1020}
1021
1022/*
1023 * This routine is called to find out and return a data or hole offset
1024 * from the page cache for unwritten extents according to the desired
1025 * type for xfs_seek_data() or xfs_seek_hole().
1026 *
1027 * The argument offset is used to tell where we start to search from the
1028 * page cache.  Map is used to figure out the end points of the range to
1029 * lookup pages.
1030 *
1031 * Return true if the desired type of offset was found, and the argument
1032 * offset is filled with that address.  Otherwise, return false and keep
1033 * offset unchanged.
1034 */
1035STATIC bool
1036xfs_find_get_desired_pgoff(
1037        struct inode            *inode,
1038        struct xfs_bmbt_irec    *map,
1039        unsigned int            type,
1040        loff_t                  *offset)
1041{
1042        struct xfs_inode        *ip = XFS_I(inode);
1043        struct xfs_mount        *mp = ip->i_mount;
1044        struct pagevec          pvec;
1045        pgoff_t                 index;
1046        pgoff_t                 end;
1047        loff_t                  endoff;
1048        loff_t                  startoff = *offset;
1049        loff_t                  lastoff = startoff;
1050        bool                    found = false;
1051
1052        pagevec_init(&pvec, 0);
1053
1054        index = startoff >> PAGE_CACHE_SHIFT;
1055        endoff = XFS_FSB_TO_B(mp, map->br_startoff + map->br_blockcount);
1056        end = endoff >> PAGE_CACHE_SHIFT;
1057        do {
1058                int             want;
1059                unsigned        nr_pages;
1060                unsigned int    i;
1061
1062                want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
1063                nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
1064                                          want);
1065                /*
1066                 * No page mapped into given range.  If we are searching holes
1067                 * and if this is the first time we got into the loop, it means
1068                 * that the given offset is landed in a hole, return it.
1069                 *
1070                 * If we have already stepped through some block buffers to find
1071                 * holes but they all contains data.  In this case, the last
1072                 * offset is already updated and pointed to the end of the last
1073                 * mapped page, if it does not reach the endpoint to search,
1074                 * that means there should be a hole between them.
1075                 */
1076                if (nr_pages == 0) {
1077                        /* Data search found nothing */
1078                        if (type == DATA_OFF)
1079                                break;
1080
1081                        ASSERT(type == HOLE_OFF);
1082                        if (lastoff == startoff || lastoff < endoff) {
1083                                found = true;
1084                                *offset = lastoff;
1085                        }
1086                        break;
1087                }
1088
1089                /*
1090                 * At lease we found one page.  If this is the first time we
1091                 * step into the loop, and if the first page index offset is
1092                 * greater than the given search offset, a hole was found.
1093                 */
1094                if (type == HOLE_OFF && lastoff == startoff &&
1095                    lastoff < page_offset(pvec.pages[0])) {
1096                        found = true;
1097                        break;
1098                }
1099
1100                for (i = 0; i < nr_pages; i++) {
1101                        struct page     *page = pvec.pages[i];
1102                        loff_t          b_offset;
1103
1104                        /*
1105                         * At this point, the page may be truncated or
1106                         * invalidated (changing page->mapping to NULL),
1107                         * or even swizzled back from swapper_space to tmpfs
1108                         * file mapping. However, page->index will not change
1109                         * because we have a reference on the page.
1110                         *
1111                         * Searching done if the page index is out of range.
1112                         * If the current offset is not reaches the end of
1113                         * the specified search range, there should be a hole
1114                         * between them.
1115                         */
1116                        if (page->index > end) {
1117                                if (type == HOLE_OFF && lastoff < endoff) {
1118                                        *offset = lastoff;
1119                                        found = true;
1120                                }
1121                                goto out;
1122                        }
1123
1124                        lock_page(page);
1125                        /*
1126                         * Page truncated or invalidated(page->mapping == NULL).
1127                         * We can freely skip it and proceed to check the next
1128                         * page.
1129                         */
1130                        if (unlikely(page->mapping != inode->i_mapping)) {
1131                                unlock_page(page);
1132                                continue;
1133                        }
1134
1135                        if (!page_has_buffers(page)) {
1136                                unlock_page(page);
1137                                continue;
1138                        }
1139
1140                        found = xfs_lookup_buffer_offset(page, &b_offset, type);
1141                        if (found) {
1142                                /*
1143                                 * The found offset may be less than the start
1144                                 * point to search if this is the first time to
1145                                 * come here.
1146                                 */
1147                                *offset = max_t(loff_t, startoff, b_offset);
1148                                unlock_page(page);
1149                                goto out;
1150                        }
1151
1152                        /*
1153                         * We either searching data but nothing was found, or
1154                         * searching hole but found a data buffer.  In either
1155                         * case, probably the next page contains the desired
1156                         * things, update the last offset to it so.
1157                         */
1158                        lastoff = page_offset(page) + PAGE_SIZE;
1159                        unlock_page(page);
1160                }
1161
1162                /*
1163                 * The number of returned pages less than our desired, search
1164                 * done.  In this case, nothing was found for searching data,
1165                 * but we found a hole behind the last offset.
1166                 */
1167                if (nr_pages < want) {
1168                        if (type == HOLE_OFF) {
1169                                *offset = lastoff;
1170                                found = true;
1171                        }
1172                        break;
1173                }
1174
1175                index = pvec.pages[i - 1]->index + 1;
1176                pagevec_release(&pvec);
1177        } while (index <= end);
1178
1179out:
1180        pagevec_release(&pvec);
1181        return found;
1182}
1183
1184STATIC loff_t
1185xfs_seek_data(
1186        struct file             *file,
1187        loff_t                  start)
1188{
1189        struct inode            *inode = file->f_mapping->host;
1190        struct xfs_inode        *ip = XFS_I(inode);
1191        struct xfs_mount        *mp = ip->i_mount;
1192        loff_t                  uninitialized_var(offset);
1193        xfs_fsize_t             isize;
1194        xfs_fileoff_t           fsbno;
1195        xfs_filblks_t           end;
1196        uint                    lock;
1197        int                     error;
1198
1199        lock = xfs_ilock_map_shared(ip);
1200
1201        isize = i_size_read(inode);
1202        if (start >= isize) {
1203                error = ENXIO;
1204                goto out_unlock;
1205        }
1206
1207        /*
1208         * Try to read extents from the first block indicated
1209         * by fsbno to the end block of the file.
1210         */
1211        fsbno = XFS_B_TO_FSBT(mp, start);
1212        end = XFS_B_TO_FSB(mp, isize);
1213        for (;;) {
1214                struct xfs_bmbt_irec    map[2];
1215                int                     nmap = 2;
1216                unsigned int            i;
1217
1218                error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
1219                                       XFS_BMAPI_ENTIRE);
1220                if (error)
1221                        goto out_unlock;
1222
1223                /* No extents at given offset, must be beyond EOF */
1224                if (nmap == 0) {
1225                        error = ENXIO;
1226                        goto out_unlock;
1227                }
1228
1229                for (i = 0; i < nmap; i++) {
1230                        offset = max_t(loff_t, start,
1231                                       XFS_FSB_TO_B(mp, map[i].br_startoff));
1232
1233                        /* Landed in a data extent */
1234                        if (map[i].br_startblock == DELAYSTARTBLOCK ||
1235                            (map[i].br_state == XFS_EXT_NORM &&
1236                             !isnullstartblock(map[i].br_startblock)))
1237                                goto out;
1238
1239                        /*
1240                         * Landed in an unwritten extent, try to search data
1241                         * from page cache.
1242                         */
1243                        if (map[i].br_state == XFS_EXT_UNWRITTEN) {
1244                                if (xfs_find_get_desired_pgoff(inode, &map[i],
1245                                                        DATA_OFF, &offset))
1246                                        goto out;
1247                        }
1248                }
1249
1250                /*
1251                 * map[0] is hole or its an unwritten extent but
1252                 * without data in page cache.  Probably means that
1253                 * we are reading after EOF if nothing in map[1].
1254                 */
1255                if (nmap == 1) {
1256                        error = ENXIO;
1257                        goto out_unlock;
1258                }
1259
1260                ASSERT(i > 1);
1261
1262                /*
1263                 * Nothing was found, proceed to the next round of search
1264                 * if reading offset not beyond or hit EOF.
1265                 */
1266                fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
1267                start = XFS_FSB_TO_B(mp, fsbno);
1268                if (start >= isize) {
1269                        error = ENXIO;
1270                        goto out_unlock;
1271                }
1272        }
1273
1274out:
1275        if (offset != file->f_pos)
1276                file->f_pos = offset;
1277
1278out_unlock:
1279        xfs_iunlock_map_shared(ip, lock);
1280
1281        if (error)
1282                return -error;
1283        return offset;
1284}
1285
1286STATIC loff_t
1287xfs_seek_hole(
1288        struct file             *file,
1289        loff_t                  start)
1290{
1291        struct inode            *inode = file->f_mapping->host;
1292        struct xfs_inode        *ip = XFS_I(inode);
1293        struct xfs_mount        *mp = ip->i_mount;
1294        loff_t                  uninitialized_var(offset);
1295        xfs_fsize_t             isize;
1296        xfs_fileoff_t           fsbno;
1297        xfs_filblks_t           end;
1298        uint                    lock;
1299        int                     error;
1300
1301        if (XFS_FORCED_SHUTDOWN(mp))
1302                return -XFS_ERROR(EIO);
1303
1304        lock = xfs_ilock_map_shared(ip);
1305
1306        isize = i_size_read(inode);
1307        if (start >= isize) {
1308                error = ENXIO;
1309                goto out_unlock;
1310        }
1311
1312        fsbno = XFS_B_TO_FSBT(mp, start);
1313        end = XFS_B_TO_FSB(mp, isize);
1314
1315        for (;;) {
1316                struct xfs_bmbt_irec    map[2];
1317                int                     nmap = 2;
1318                unsigned int            i;
1319
1320                error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
1321                                       XFS_BMAPI_ENTIRE);
1322                if (error)
1323                        goto out_unlock;
1324
1325                /* No extents at given offset, must be beyond EOF */
1326                if (nmap == 0) {
1327                        error = ENXIO;
1328                        goto out_unlock;
1329                }
1330
1331                for (i = 0; i < nmap; i++) {
1332                        offset = max_t(loff_t, start,
1333                                       XFS_FSB_TO_B(mp, map[i].br_startoff));
1334
1335                        /* Landed in a hole */
1336                        if (map[i].br_startblock == HOLESTARTBLOCK)
1337                                goto out;
1338
1339                        /*
1340                         * Landed in an unwritten extent, try to search hole
1341                         * from page cache.
1342                         */
1343                        if (map[i].br_state == XFS_EXT_UNWRITTEN) {
1344                                if (xfs_find_get_desired_pgoff(inode, &map[i],
1345                                                        HOLE_OFF, &offset))
1346                                        goto out;
1347                        }
1348                }
1349
1350                /*
1351                 * map[0] contains data or its unwritten but contains
1352                 * data in page cache, probably means that we are
1353                 * reading after EOF.  We should fix offset to point
1354                 * to the end of the file(i.e., there is an implicit
1355                 * hole at the end of any file).
1356                 */
1357                if (nmap == 1) {
1358                        offset = isize;
1359                        break;
1360                }
1361
1362                ASSERT(i > 1);
1363
1364                /*
1365                 * Both mappings contains data, proceed to the next round of
1366                 * search if the current reading offset not beyond or hit EOF.
1367                 */
1368                fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
1369                start = XFS_FSB_TO_B(mp, fsbno);
1370                if (start >= isize) {
1371                        offset = isize;
1372                        break;
1373                }
1374        }
1375
1376out:
1377        /*
1378         * At this point, we must have found a hole.  However, the returned
1379         * offset may be bigger than the file size as it may be aligned to
1380         * page boundary for unwritten extents, we need to deal with this
1381         * situation in particular.
1382         */
1383        offset = min_t(loff_t, offset, isize);
1384        if (offset != file->f_pos)
1385                file->f_pos = offset;
1386
1387out_unlock:
1388        xfs_iunlock_map_shared(ip, lock);
1389
1390        if (error)
1391                return -error;
1392        return offset;
1393}
1394
1395STATIC loff_t
1396xfs_file_llseek(
1397        struct file     *file,
1398        loff_t          offset,
1399        int             origin)
1400{
1401        switch (origin) {
1402        case SEEK_END:
1403        case SEEK_CUR:
1404        case SEEK_SET:
1405                return generic_file_llseek(file, offset, origin);
1406        case SEEK_DATA:
1407                return xfs_seek_data(file, offset);
1408        case SEEK_HOLE:
1409                return xfs_seek_hole(file, offset);
1410        default:
1411                return -EINVAL;
1412        }
1413}
1414
1415const struct file_operations xfs_file_operations = {
1416        .llseek         = xfs_file_llseek,
1417        .read           = do_sync_read,
1418        .write          = do_sync_write,
1419        .aio_read       = xfs_file_aio_read,
1420        .aio_write      = xfs_file_aio_write,
1421        .splice_read    = xfs_file_splice_read,
1422        .splice_write   = xfs_file_splice_write,
1423        .unlocked_ioctl = xfs_file_ioctl,
1424#ifdef CONFIG_COMPAT
1425        .compat_ioctl   = xfs_file_compat_ioctl,
1426#endif
1427        .mmap           = xfs_file_mmap,
1428        .open           = xfs_file_open,
1429        .release        = xfs_file_release,
1430        .fsync          = xfs_file_fsync,
1431        .fallocate      = xfs_file_fallocate,
1432};
1433
1434const struct file_operations xfs_dir_file_operations = {
1435        .open           = xfs_dir_open,
1436        .read           = generic_read_dir,
1437        .readdir        = xfs_file_readdir,
1438        .llseek         = generic_file_llseek,
1439        .unlocked_ioctl = xfs_file_ioctl,
1440#ifdef CONFIG_COMPAT
1441        .compat_ioctl   = xfs_file_compat_ioctl,
1442#endif
1443        .fsync          = xfs_dir_fsync,
1444};
1445
1446static const struct vm_operations_struct xfs_file_vm_ops = {
1447        .fault          = filemap_fault,
1448        .page_mkwrite   = xfs_vm_page_mkwrite,
1449        .remap_pages    = generic_file_remap_pages,
1450};
1451
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