xfs: add tracepoints and error injection for deferred extent freeing

Add a couple of tracepoints for the deferred extent free operation and
a site for injecting errors while finishing the operation.  This makes
it easier to debug deferred ops and test log redo.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/libxfs/xfs_alloc.c

@@ -2702,6 +2702,13 @@ xfs_free_extent(
 
 	ASSERT(len != 0);
 
+	trace_xfs_bmap_free_deferred(mp, agno, 0, agbno, len);
+
+	if (XFS_TEST_ERROR(false, mp,
+			XFS_ERRTAG_FREE_EXTENT,
+			XFS_RANDOM_FREE_EXTENT))
+		return -EIO;
+
 	error = xfs_free_extent_fix_freelist(tp, agno, &agbp);
 	if (error)
 		return error;

fs/xfs/libxfs/xfs_bmap.c

@@ -596,6 +596,8 @@ xfs_bmap_add_free(
 	new = kmem_zone_alloc(xfs_bmap_free_item_zone, KM_SLEEP);
 	new->xefi_startblock = bno;
 	new->xefi_blockcount = (xfs_extlen_t)len;
+	trace_xfs_bmap_free_defer(mp, XFS_FSB_TO_AGNO(mp, bno), 0,
+			XFS_FSB_TO_AGBNO(mp, bno), len);
 	xfs_defer_add(dfops, XFS_DEFER_OPS_TYPE_FREE, &new->xefi_list);
 }
 

fs/xfs/xfs_error.h

@@ -90,7 +90,8 @@ extern void xfs_verifier_error(struct xfs_buf *bp);
 #define XFS_ERRTAG_STRATCMPL_IOERR			19
 #define XFS_ERRTAG_DIOWRITE_IOERR			20
 #define XFS_ERRTAG_BMAPIFORMAT				21
-#define XFS_ERRTAG_MAX					22
+#define XFS_ERRTAG_FREE_EXTENT				22
+#define XFS_ERRTAG_MAX					23
 
 /*
  * Random factors for above tags, 1 means always, 2 means 1/2 time, etc.
@@ -117,6 +118,7 @@ extern void xfs_verifier_error(struct xfs_buf *bp);
 #define XFS_RANDOM_STRATCMPL_IOERR			(XFS_RANDOM_DEFAULT/10)
 #define XFS_RANDOM_DIOWRITE_IOERR			(XFS_RANDOM_DEFAULT/10)
 #define	XFS_RANDOM_BMAPIFORMAT				XFS_RANDOM_DEFAULT
+#define XFS_RANDOM_FREE_EXTENT				1
 
 #ifdef DEBUG
 extern int xfs_error_test_active;

fs/xfs/xfs_trace.h

@@ -2417,9 +2417,12 @@ DEFINE_DEFER_PENDING_EVENT(xfs_defer_pending_cancel);
 DEFINE_DEFER_PENDING_EVENT(xfs_defer_pending_finish);
 DEFINE_DEFER_PENDING_EVENT(xfs_defer_pending_abort);
 
-DEFINE_PHYS_EXTENT_DEFERRED_EVENT(xfs_defer_phys_extent);
 DEFINE_MAP_EXTENT_DEFERRED_EVENT(xfs_defer_map_extent);
 
+#define DEFINE_BMAP_FREE_DEFERRED_EVENT DEFINE_PHYS_EXTENT_DEFERRED_EVENT
+DEFINE_BMAP_FREE_DEFERRED_EVENT(xfs_bmap_free_defer);
+DEFINE_BMAP_FREE_DEFERRED_EVENT(xfs_bmap_free_deferred);
+
 #endif /* _TRACE_XFS_H */
 
 #undef TRACE_INCLUDE_PATH