diff options
| -rw-r--r-- | fs/xfs/xfs_iomap.c | 77 |
1 files changed, 67 insertions, 10 deletions
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 364818eef40..912d83d8860 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -311,6 +311,62 @@ xfs_iomap_eof_want_preallocate( } /* + * 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 preceeding data extent as the basis for the + * preallocation size. If the size of the extent 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. + */ +STATIC int +xfs_iomap_eof_prealloc_initial_size( + struct xfs_mount *mp, + struct xfs_inode *ip, + xfs_off_t offset, + xfs_bmbt_irec_t *imap, + int nimaps) +{ + xfs_fileoff_t start_fsb; + int imaps = 1; + int error; + + ASSERT(nimaps >= imaps); + + /* if we are using a specific prealloc size, return now */ + if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) + return 0; + + /* + * As we write multiple pages, the offset will always align to the + * start of a page and hence point to a hole at EOF. i.e. if the size is + * 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096) + * will return FSB 1. Hence if there are blocks in the file, we want to + * point to the block prior to the EOF block and not the hole that maps + * directly at @offset. + */ + start_fsb = XFS_B_TO_FSB(mp, offset); + if (start_fsb) + start_fsb--; + error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE); + if (error) + return 0; + + ASSERT(imaps == 1); + if (imap[0].br_startblock == HOLESTARTBLOCK) + return 0; + if (imap[0].br_blockcount <= (MAXEXTLEN >> 1)) + return imap[0].br_blockcount; + return XFS_B_TO_FSB(mp, offset); +} + +/* * 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 @@ -319,20 +375,19 @@ xfs_iomap_eof_want_preallocate( STATIC xfs_fsblock_t xfs_iomap_prealloc_size( struct xfs_mount *mp, - struct xfs_inode *ip) + struct xfs_inode *ip, + xfs_off_t offset, + struct xfs_bmbt_irec *imap, + int nimaps) { xfs_fsblock_t alloc_blocks = 0; - if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) { + alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset, + imap, nimaps); + if (alloc_blocks > 0) { int shift = 0; int64_t freesp; - /* - * rounddown_pow_of_two() returns an undefined result - * if we pass in alloc_blocks = 0. Hence the "+ 1" to - * ensure we always pass in a non-zero value. - */ - alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1; alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN, rounddown_pow_of_two(alloc_blocks)); @@ -399,7 +454,6 @@ xfs_iomap_write_delay( extsz = xfs_get_extsz_hint(ip); offset_fsb = XFS_B_TO_FSBT(mp, offset); - error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count, imap, XFS_WRITE_IMAPS, &prealloc); if (error) @@ -407,7 +461,10 @@ xfs_iomap_write_delay( retry: if (prealloc) { - xfs_fsblock_t alloc_blocks = xfs_iomap_prealloc_size(mp, ip); + xfs_fsblock_t alloc_blocks; + + alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap, + XFS_WRITE_IMAPS); aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1)); ioalign = XFS_B_TO_FSBT(mp, aligned_offset); |