Enable the head_errlog feature to remove errors

In case check_filesystem() does not error out and does not report
an error, remove that error block from error lists and logs
without requiring a scrub. This can happen when the original file and
all snapshots/clones referencing it have been removed.

Otherwise zpool status will still report that "Permanent errors have
been detected..." without actually reporting any of them.

To implement this change the functions introduced in corrective
receive were modified to take into account the head_errlog feature.

Before this change:
=============================
pool: test
 state: ONLINE
status: One or more devices has experienced an error resulting in data
        corruption.  Applications may be affected.
action: Restore the file in question if possible.  Otherwise restore the
        entire pool from backup.
   see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-8A
config:

        NAME                   STATE     READ WRITE CKSUM
        test                   ONLINE       0     0     0
          /home/user/vdev_a    ONLINE       0     0     2

errors: Permanent errors have been detected in the following files:

=============================

After this change:
=============================
  pool: test
 state: ONLINE
status: One or more devices has experienced an unrecoverable error.  An
        attempt was made to correct the error.  Applications are
unaffected.
action: Determine if the device needs to be replaced, and clear the
errors
        using 'zpool clear' or replace the device with 'zpool replace'.
   see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-9P
config:

        NAME                   STATE     READ WRITE CKSUM
        test                   ONLINE       0     0     0
          /home/user/vdev_a    ONLINE       0     0     2

errors: No known data errors
=============================

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Brian Atkinson <[email protected]>
Signed-off-by: George Amanakis <[email protected]>
Closes #14813 

1 files changed, 3 insertions, 0 deletions

diff --git a/man/man8/zpool-status.8 b/man/man8/zpool-status.8
index ed572e29f..8f9580cf0 100644
--- a/man/man8/zpool-status.8
+++ b/man/man8/zpool-status.8
@@ -119,6 +119,9 @@ See
 .It Fl v
 Displays verbose data error information, printing out a complete list of all
 data errors since the last complete pool scrub.
+If the head_errlog feature is enabled and files containing errors have been
+removed then the respective filenames will not be reported in subsequent runs
+of this command.
 .It Fl x
 Only display status for pools that are exhibiting errors or are otherwise
 unavailable.