Commit 19957a18 authored Mar 06, 2018 by Vratislav Bendel Committed by Darrick J. Wong Mar 11, 2018

xfs: Correctly invert xfs_buftarg LRU isolation logic



Due to an inverted logic mistake in xfs_buftarg_isolate()
the xfs_buffers with zero b_lru_ref will take another trip
around LRU, while isolating buffers with non-zero b_lru_ref.

Additionally those isolated buffers end up right back on the LRU
once they are released, because b_lru_ref remains elevated.

Fix that circuitous route by leaving them on the LRU
as originally intended.

Signed-off-by: Vratislav Bendel <vbendel@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

parent 4df0f7f1

fs/xfs/xfs_buf.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1708,7 +1708,7 @@ xfs_buftarg_isolate(
		* zero. If the value is already zero, we need to reclaim the
		* buffer, otherwise it gets another trip through the LRU.
		*/
		if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
		if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
		spin_unlock(&bp->b_lock);
		return LRU_ROTATE;
		}