xfs: restore old agirotor behavior

Prior to the removal of xfs_ialloc_next_ag, we would increment the agi
rotor and return the *old* value.  atomic_inc_return returns the new
value, which causes mkfs to allocate the root directory in AG 1.  Put
back the old behavior (at least for mkfs) by subtracting 1 here.

Fixes: 20a5eab49d35 ("xfs: convert xfs_ialloc_next_ag() to an atomic")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 82ea6aa..7ee292a 100644 (file)
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -1729,7 +1729,8 @@ xfs_dialloc(
         * an AG has enough space for file creation.
         */
        if (S_ISDIR(mode))
-               start_agno = atomic_inc_return(&mp->m_agirotor) % mp->m_maxagi;
+               start_agno = (atomic_inc_return(&mp->m_agirotor) - 1) %
+                               mp->m_maxagi;
        else {
                start_agno = XFS_INO_TO_AGNO(mp, parent);
                if (start_agno >= mp->m_maxagi)