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> Reviewed-by: Ben Myers <bpm@xxxxxxx> --- fs/xfs/xfs_iomap.c | 19 +++++++++++++++++-- 1 files changed, 17 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index d914419..daa08f6 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -389,8 +389,15 @@ xfs_iomap_prealloc_size( if (!alloc_blocks) goto check_writeio; - alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN, - rounddown_pow_of_two(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. + */ + alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN), + alloc_blocks); xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT); freesp = mp->m_sb.sb_fdblocks; @@ -407,6 +414,14 @@ 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; /* * If we are still trying to allocate more space than is -- 1.7.7.6 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
