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Commit c9bdbdc0 authored by Brian Foster's avatar Brian Foster Committed by Ben Myers
Browse files

xfs: push rounddown_pow_of_two() to after prealloc throttle 



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: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarBen Myers <bpm@sgi.com>
Reviewed-by: default avatarMark Tinguely <tinguely@sgi.com>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent 3c58b5f8

fs/xfs/xfs_iomap.c

+17 −2
Original line number Diff line number Diff line
@@ -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