[PATCH 1/3] xfs: lock rt summary inode on allocation

Dave Chinner
2016-02-02T00:39:33Z

From: Dave Chinner <dchinner@redhat.com>

RT allocation can fail on a debug kernel with:

XFS: Assertion failed: xfs_isilocked(ip, XFS_ILOCK_SHARED|XFS_ILOCK_EXCL), file: fs/xfs/libxfs/xfs_bmap.c, line: 4039

When modifying the summary inode during allocation. This occurs
because the summary inode is never locked, and xfs_bmapi_*
operations expect it to be locked. The summary inode is effectively
protected byt he lock on the bitmap inode, so this really is only a
debug kernel issue.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_bmap_util.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 7087756..fd7f51c 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -202,10 +202,12 @@ xfs_bmap_rtalloc(
ralen = MAXEXTLEN / mp->m_sb.sb_rextsize;

/*
- * Lock out other modifications to the RT bitmap inode.
+ * Lock out modifications to both the RT bitmap and summary inodes
*/
xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(ap->tp, mp->m_rbmip, XFS_ILOCK_EXCL);
+ xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(ap->tp, mp->m_rsumip, XFS_ILOCK_EXCL);

/*
* If it's an allocation to an empty file at offset 0,
--
2.5.0