[PATCH 3/5] xfs: use xfs_ilock_map_shared in xfs_qm_dqiterate

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

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@xxxxxx>

Index: xfs/fs/xfs/xfs_qm.c
===================================================================
--- xfs.orig/fs/xfs/xfs_qm.c    2013-11-18 14:39:01.967589998 +0100
+++ xfs/fs/xfs/xfs_qm.c 2013-12-05 12:32:36.623617997 +0100
@@ -1193,16 +1193,18 @@ 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_map_shared(qip);
                error = xfs_bmapi_read(qip, lblkno, maxlblkcnt - lblkno,
                                       map, &nmaps, 0);
-               xfs_iunlock(qip, XFS_ILOCK_SHARED);
+               xfs_iunlock_map_shared(qip, lock_mode);
                if (error)
                        break;