xfs: add error injection to test file mapping exchange recovery

Add an errortag so that we can test recovery of exchmaps log items.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_errortag.h

@@ -63,7 +63,8 @@
 #define XFS_ERRTAG_ATTR_LEAF_TO_NODE			41
 #define XFS_ERRTAG_WB_DELAY_MS				42
 #define XFS_ERRTAG_WRITE_DELAY_MS			43
-#define XFS_ERRTAG_MAX					44
+#define XFS_ERRTAG_EXCHMAPS_FINISH_ONE			44
+#define XFS_ERRTAG_MAX					45
 
 /*
  * Random factors for above tags, 1 means always, 2 means 1/2 time, etc.
@@ -111,5 +112,6 @@
 #define XFS_RANDOM_ATTR_LEAF_TO_NODE			1
 #define XFS_RANDOM_WB_DELAY_MS				3000
 #define XFS_RANDOM_WRITE_DELAY_MS			3000
+#define XFS_RANDOM_EXCHMAPS_FINISH_ONE			1
 
 #endif /* __XFS_ERRORTAG_H_ */

fs/xfs/libxfs/xfs_exchmaps.c

@@ -437,6 +437,9 @@ xfs_exchmaps_finish_one(
 			return error;
 	}
 
+	if (XFS_TEST_ERROR(false, tp->t_mountp, XFS_ERRTAG_EXCHMAPS_FINISH_ONE))
+		return -EIO;
+
 	/* If we still have work to do, ask for a new transaction. */
 	if (xmi_has_more_exchange_work(xmi) || xmi_has_postop_work(xmi)) {
 		trace_xfs_exchmaps_defer(tp->t_mountp, xmi);

fs/xfs/xfs_error.c

@@ -62,6 +62,7 @@ static unsigned int xfs_errortag_random_default[] = {
 	XFS_RANDOM_ATTR_LEAF_TO_NODE,
 	XFS_RANDOM_WB_DELAY_MS,
 	XFS_RANDOM_WRITE_DELAY_MS,
+	XFS_RANDOM_EXCHMAPS_FINISH_ONE,
 };
 
 struct xfs_errortag_attr {
@@ -179,6 +180,7 @@ XFS_ERRORTAG_ATTR_RW(da_leaf_split,	XFS_ERRTAG_DA_LEAF_SPLIT);
 XFS_ERRORTAG_ATTR_RW(attr_leaf_to_node,	XFS_ERRTAG_ATTR_LEAF_TO_NODE);
 XFS_ERRORTAG_ATTR_RW(wb_delay_ms,	XFS_ERRTAG_WB_DELAY_MS);
 XFS_ERRORTAG_ATTR_RW(write_delay_ms,	XFS_ERRTAG_WRITE_DELAY_MS);
+XFS_ERRORTAG_ATTR_RW(exchmaps_finish_one, XFS_ERRTAG_EXCHMAPS_FINISH_ONE);
 
 static struct attribute *xfs_errortag_attrs[] = {
 	XFS_ERRORTAG_ATTR_LIST(noerror),
@@ -224,6 +226,7 @@ static struct attribute *xfs_errortag_attrs[] = {
 	XFS_ERRORTAG_ATTR_LIST(attr_leaf_to_node),
 	XFS_ERRORTAG_ATTR_LIST(wb_delay_ms),
 	XFS_ERRORTAG_ATTR_LIST(write_delay_ms),
+	XFS_ERRORTAG_ATTR_LIST(exchmaps_finish_one),
 	NULL,
 };
 ATTRIBUTE_GROUPS(xfs_errortag);