The round down occurs towards the beginning of the function. Push it down after throttling has occurred. This is to support adding further transformations to 'alloc_blocks' that might not preserve power-of-two alignment (and thus could lead to rounding down multiple times). Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx> --- fs/xfs/xfs_iomap.c | 21 +++++++++++++++------ 1 files changed, 15 insertions(+), 6 deletions(-) diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index bd7c060..b2002a5 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -329,13 +329,14 @@ xfs_iomap_prealloc_size( goto check_writeio; /* - * 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. + * 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. */ - alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1; - alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN, - rounddown_pow_of_two(alloc_blocks)); + alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN), + XFS_B_TO_FSB(mp, XFS_ISIZE(ip))); xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT); freesp = mp->m_sb.sb_fdblocks; @@ -352,6 +353,14 @@ xfs_iomap_prealloc_size( } if (shift) alloc_blocks >>= shift; + /* + * rounddown_pow_of_two() returns an undefined result if we pass in + * alloc_blocks = 0. + */ + if (alloc_blocks) + alloc_blocks = rounddown_pow_of_two(alloc_blocks); + if (alloc_blocks > MAXEXTLEN) + alloc_blocks = MAXEXTLEN; check_writeio: if (alloc_blocks < mp->m_writeio_blocks) -- 1.7.7.6 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
