xfs: inode unlink does not set AGI buffer type

This leads to log recovery throwing errors like:

XFS (md0): Mounting V5 Filesystem
XFS (md0): Starting recovery (logdev: internal)
XFS (md0): Unknown buffer type 0!
XFS (md0): _xfs_buf_ioapply: no ops on block 0xaea8802/0x1
ffff8800ffc53800: 58 41 47 49 .....

Which is the AGI buffer magic number.

Ensure that we set the type appropriately in both unlink list
addition and removal.

cc: <stable@vger.kernel.org> # 3.10 to current
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_inode.c

@@ -1995,6 +1995,7 @@ xfs_iunlink(
 	agi->agi_unlinked[bucket_index] = cpu_to_be32(agino);
 	offset = offsetof(xfs_agi_t, agi_unlinked) +
 		(sizeof(xfs_agino_t) * bucket_index);
+	xfs_trans_buf_set_type(tp, agibp, XFS_BLFT_AGI_BUF);
 	xfs_trans_log_buf(tp, agibp, offset,
 			  (offset + sizeof(xfs_agino_t) - 1));
 	return 0;
@@ -2086,6 +2087,7 @@ xfs_iunlink_remove(
 		agi->agi_unlinked[bucket_index] = cpu_to_be32(next_agino);
 		offset = offsetof(xfs_agi_t, agi_unlinked) +
 			(sizeof(xfs_agino_t) * bucket_index);
+		xfs_trans_buf_set_type(tp, agibp, XFS_BLFT_AGI_BUF);
 		xfs_trans_log_buf(tp, agibp, offset,
 				  (offset + sizeof(xfs_agino_t) - 1));
 	} else {