From: Vratislav Bendel vbendel@redhat.com
commit 19957a181608d25c8f4136652d0ea00b3738972d upstream.
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 Signed-off-by: Alex Lyakas alex@zadara.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/xfs/xfs_buf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -1584,7 +1584,7 @@ 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; }