Add zfs_scan_ignore_errors tunable

When it's set, a DTL range will be cleared even if its scan/scrub had
errors.  This allows to work around resilver/scrub upon import when the
pool has errors.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Tim Chase <[email protected]>
Closes #7293 

1 files changed, 16 insertions, 0 deletions

diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c
index 172485f6e..8ab996434 100644
--- a/module/zfs/vdev.c
+++ b/module/zfs/vdev.c
@@ -67,6 +67,12 @@ unsigned int zfs_delays_per_second = 20;
 unsigned int zfs_checksums_per_second = 20;
 
 /*
+ * Ignore errors during scrub/resilver.  Allows to work around resilver
+ * upon import when there are pool errors.
+ */
+int zfs_scan_ignore_errors = 0;
+
+/*
  * Virtual device management.
  */
 
@@ -1964,6 +1970,12 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
 		mutex_enter(&vd->vdev_dtl_lock);
 
 		/*
+		 * If requested, pretend the scan completed cleanly.
+		 */
+		if (zfs_scan_ignore_errors && scn)
+			scn->scn_phys.scn_errors = 0;
+
+		/*
 		 * If we've completed a scan cleanly then determine
 		 * if this vdev should remove any DTLs. We only want to
 		 * excise regions on vdevs that were available during
@@ -3777,5 +3789,9 @@ module_param(zfs_checksums_per_second, uint, 0644);
 	MODULE_PARM_DESC(zfs_checksums_per_second, "Rate limit checksum events "
 	"to this many checksum errors per second (do not set below zed"
 	"threshold).");
+
+module_param(zfs_scan_ignore_errors, int, 0644);
+MODULE_PARM_DESC(zfs_scan_ignore_errors,
+	"Ignore errors during resilver/scrub");
 /* END CSTYLED */
 #endif