xfs: assert that we don't enter agfl freeing with a non-permanent transaction

Block allocation requires a permanent transaction for deferred AGFL
frees.  Add an assert in the block allocation path to make explicit and
obvious to future callers the requirement of a transaction with a
permanent reservation.

Reported-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
[darrick: split this out from the previous patch per hch request]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 857a53e58b94..a9ff3cf82cce 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2243,6 +2243,9 @@ xfs_alloc_fix_freelist(
         xfs_extlen_t            need;   /* total blocks needed in freelist */
         int                     error = 0;
 
+        /* deferred ops (AGFL block frees) require permanent transactions */
+        ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
+
         if (!pag->pagf_init) {
                 error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
                 if (error)