svn commit: r318942 - vendor-sys/illumos/dist/uts/common/fs/zfs

[Andriy Gapon]

Author: avg
Date: Fri May 26 12:02:51 2017
New Revision: 318942
URL: https://svnweb.freebsd.org/changeset/base/318942

Log:
  8166 zpool scrub thinks it repaired offline device
  
  illumos/illumos-gate at 2d2f193a21231a58c583466dc23ba71f1a25f424
  https://github.com/illumos/illumos-gate/commit/2d2f193a21231a58c583466dc23ba71f1a25f424
  
  https://www.illumos.org/issues/8166
    If we do a scrub while a leaf device is offline (via "zpool offline"),
    we will inadvertently clear the DTL (dirty time log) of the offline
    device, even though it is still damaged. When the device comes back
    online, we will incompletely resilver it, thinking that the scrub
    repaired blocks written before the scrub was started. The incomplete
    resilver can lead to data loss if there is a subsequent failure of a
    different leaf device.
    The fix is to never clear the DTL of offline devices. Note that if a
    device is onlined while a scrub is in progress, the scrub will be
    restarted.
    The problem can be worked around by running "zpool scrub" after
    "zpool online".
    See also https://github.com/zfsonlinux/zfs/issues/5806
  
  Reviewed by: George Wilson george.wilson at delphix.com
  Reviewed by: Brad Lewis <brad.lewis at delphix.com>
  Approved by: Richard Lowe <richlowe at richlowe.net>
  Author: Matthew Ahrens <mahrens at delphix.com>

Modified:
  vendor-sys/illumos/dist/uts/common/fs/zfs/vdev.c

Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/vdev.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/zfs/vdev.c	Fri May 26 12:02:14 2017	(r318941)
+++ vendor-sys/illumos/dist/uts/common/fs/zfs/vdev.c	Fri May 26 12:02:51 2017	(r318942)
@@ -1788,6 +1788,9 @@ vdev_dtl_should_excise(vdev_t *vd)
 	ASSERT0(scn->scn_phys.scn_errors);
 	ASSERT0(vd->vdev_children);
 
+	if (vd->vdev_state < VDEV_STATE_DEGRADED)
+		return (B_FALSE);
+
 	if (vd->vdev_resilver_txg == 0 ||
 	    range_tree_space(vd->vdev_dtl[DTL_MISSING]) == 0)
 		return (B_TRUE);