diff options
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/xfs_iomap.c | 83 |
1 files changed, 35 insertions, 48 deletions
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index e74a8c2c94ce..b9a8c3798e08 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -352,22 +352,10 @@ xfs_quota_calc_throttle( } /* - * If we are doing a write at the end of the file and there are no allocations - * past this one, then extend the allocation out to the file system's write - * iosize. - * * If we don't have a user specified preallocation size, dynamically increase * the preallocation size as the size of the file grows. Cap the maximum size * at a single extent or less if the filesystem is near full. The closer the - * filesystem is to full, the smaller the maximum prealocation. - * - * As an exception we don't do any preallocation at all if the file is smaller - * than the minimum preallocation and we are using the default dynamic - * preallocation scheme, as it is likely this is the only write to the file that - * is going to be done. - * - * We clean up any extra space left over when the file is closed in - * xfs_inactive(). + * filesystem is to being full, the smaller the maximum preallocation. */ STATIC xfs_fsblock_t xfs_iomap_prealloc_size( @@ -389,41 +377,28 @@ xfs_iomap_prealloc_size( int shift = 0; int qshift = 0; - if (offset + count <= XFS_ISIZE(ip)) - return 0; - - if (!(mp->m_flags & XFS_MOUNT_ALLOCSIZE) && - (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_allocsize_blocks))) + /* + * As an exception we don't do any preallocation at all if the file is + * smaller than the minimum preallocation and we are using the default + * dynamic preallocation scheme, as it is likely this is the only write + * to the file that is going to be done. + */ + if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_allocsize_blocks)) return 0; /* - * If an explicit allocsize is set, the file is small, or we - * are writing behind a hole, then use the minimum prealloc: + * Use the minimum preallocation size for small files or if we are + * writing right after a hole. */ - if ((mp->m_flags & XFS_MOUNT_ALLOCSIZE) || - XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) || + if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) || !xfs_iext_prev_extent(ifp, &ncur, &prev) || prev.br_startoff + prev.br_blockcount < offset_fsb) return mp->m_allocsize_blocks; /* - * Determine the initial size of the preallocation. We are beyond the - * current EOF here, but we need to take into account whether this is - * a sparse write or an extending write when determining the - * preallocation size. Hence we need to look up the extent that ends - * at the current write offset and use the result to determine the - * preallocation size. - * - * If the extent is a hole, then preallocation is essentially disabled. - * Otherwise we take the size of the preceding data extents as the basis - * for the preallocation size. Note that we don't care if the previous - * extents are written or not. - * - * If the size of the extents is greater than half the maximum extent - * length, then use the current offset as the basis. This ensures that - * for large files the preallocation size always extends to MAXEXTLEN - * rather than falling short due to things like stripe unit/width - * alignment of real extents. + * Take the size of the preceding data extents as the basis for the + * preallocation size. Note that we don't care if the previous extents + * are written or not. */ plen = prev.br_blockcount; while (xfs_iext_prev_extent(ifp, &ncur, &got)) { @@ -435,19 +410,25 @@ xfs_iomap_prealloc_size( plen += got.br_blockcount; prev = got; } + + /* + * If the size of the extents is greater than half the maximum extent + * length, then use the current offset as the basis. This ensures that + * for large files the preallocation size always extends to MAXEXTLEN + * rather than falling short due to things like stripe unit/width + * alignment of real extents. + */ alloc_blocks = plen * 2; if (alloc_blocks > MAXEXTLEN) alloc_blocks = XFS_B_TO_FSB(mp, offset); - if (!alloc_blocks) - goto check_writeio; qblocks = alloc_blocks; /* * MAXEXTLEN is not a power of two value but we round the prealloc down * to the nearest power of two value after throttling. To prevent the - * round down from unconditionally reducing the maximum supported prealloc - * size, we round up first, apply appropriate throttling, round down and - * cap the value to MAXEXTLEN. + * round down from unconditionally reducing the maximum supported + * prealloc size, we round up first, apply appropriate throttling, + * round down and cap the value to MAXEXTLEN. */ alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN), alloc_blocks); @@ -508,7 +489,6 @@ xfs_iomap_prealloc_size( */ while (alloc_blocks && alloc_blocks >= freesp) alloc_blocks >>= 4; -check_writeio: if (alloc_blocks < mp->m_allocsize_blocks) alloc_blocks = mp->m_allocsize_blocks; trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift, @@ -975,9 +955,16 @@ xfs_buffered_write_iomap_begin( if (error) goto out_unlock; - if (eof) { - prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork, offset, - count, &icur); + if (eof && offset + count > XFS_ISIZE(ip)) { + /* + * Determine the initial size of the preallocation. + * We clean up any extra preallocation when the file is closed. + */ + if (mp->m_flags & XFS_MOUNT_ALLOCSIZE) + prealloc_blocks = mp->m_allocsize_blocks; + else + prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork, + offset, count, &icur); if (prealloc_blocks) { xfs_extlen_t align; xfs_off_t end_offset; |