xfs: use xfs_ilock_data_map_shared in xfs_qm_dqiterate

We might not have read in the extent list at this point, so make sure we
take the ilock exclusively if we have to do so.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index dd88f0e27bd8..348e4d2ed6e6 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -1222,16 +1222,18 @@ xfs_qm_dqiterate(
         lblkno = 0;
         maxlblkcnt = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
         do {
+                uint            lock_mode;
+
                 nmaps = XFS_DQITER_MAP_SIZE;
                 /*
                  * We aren't changing the inode itself. Just changing
                  * some of its data. No new blocks are added here, and
                  * the inode is never added to the transaction.
                  */
-                xfs_ilock(qip, XFS_ILOCK_SHARED);
+                lock_mode = xfs_ilock_data_map_shared(qip);
                 error = xfs_bmapi_read(qip, lblkno, maxlblkcnt - lblkno,
                                        map, &nmaps, 0);
-                xfs_iunlock(qip, XFS_ILOCK_SHARED);
+                xfs_iunlock(qip, lock_mode);
                 if (error)
                         break;