[PATCH] xfs: lock bitmap/summary inodes in xfs_rtbuf_get()

[Eric Sandeen]

Commit eef334e added an ASSERT that the inode was locked in
some way in xfs_bmapi_read(), but on realtime paths through
xfs_rtbuf_get() this isn't the case; fix that.

Reported-by: Ross Zwisler <ross.zwisler at linux.intel.com>
Signed-off-by: Eric Sandeen <sandeen at redhat.com>
---

I think we need the data_map_shared gyrations here, but not certain...

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
index 9b59ffa..e6da0b2 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.c
+++ b/fs/xfs/libxfs/xfs_rtbitmap.c
@@ -57,11 +57,14 @@ xfs_rtbuf_get(
 	xfs_inode_t	*ip;		/* bitmap or summary inode */
 	xfs_bmbt_irec_t	map;
 	int		nmap = 1;
+	int		lock_mode;
 	int		error;		/* error value */
 
 	ip = issum ? mp->m_rsumip : mp->m_rbmip;
 
+	lock_mode = xfs_ilock_data_map_shared(ip);
 	error = xfs_bmapi_read(ip, block, 1, &map, &nmap, XFS_DATA_FORK);
+	xfs_iunlock(ip, lock_mode);
 	if (error)
 		return error;