| From 19957a181608d25c8f4136652d0ea00b3738972d Mon Sep 17 00:00:00 2001 |
| From: Vratislav Bendel <vbendel@redhat.com> |
| Date: Tue, 6 Mar 2018 17:07:44 -0800 |
| Subject: xfs: Correctly invert xfs_buftarg LRU isolation logic |
| |
| 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 |
| @@ -1702,7 +1702,7 @@ 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; |
| } |
