OpenZFS 9189 - Add debug to vdev_label_read_config when txg check fails

These changes were added to help debug issue #9187.

Essentially, in the original bug, vdev_validate() seems to fails in
vdev_label_read_config() and prints "failed reading config". This could
happen because either:
1. The labels are actually corrupt and zio_wait() fails for all of them
2. The labels were discarded because they didn't pass the txg check.

Beyond 9187, having debug info when case 2 happens could be useful in
other scenarios, such as zpool import.

Authored by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Prashanth Sreenivasa <pks@delphix.com>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Approved by: Matt Ahrens <mahrens@delphix.com>
Ported-by:  Brian Behlendorf <behlendorf1@llnl.gov>

OpenZFS-issue: https://illumos.org/issues/9189
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/f6af1b7
Closes #7533
This commit is contained in:
Pavel Zakharov 2016-09-14 11:01:40 -04:00 committed by Brian Behlendorf
parent db7d07e14b
commit 38a19edd34
2 changed files with 12 additions and 3 deletions

View File

@ -1704,7 +1704,8 @@ vdev_validate(vdev_t *vd)
if ((label = vdev_label_read_config(vd, txg)) == NULL) {
vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
VDEV_AUX_BAD_LABEL);
vdev_dbgmsg(vd, "vdev_validate: failed reading config");
vdev_dbgmsg(vd, "vdev_validate: failed reading config for "
"txg %llu", (u_longlong_t)txg);
return (0);
}

View File

@ -673,6 +673,7 @@ vdev_label_read_config(vdev_t *vd, uint64_t txg)
abd_t *vp_abd;
zio_t *zio;
uint64_t best_txg = 0;
uint64_t label_txg = 0;
int error = 0;
int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
ZIO_FLAG_SPECULATIVE;
@ -698,8 +699,6 @@ retry:
if (zio_wait(zio) == 0 &&
nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
&label, 0) == 0) {
uint64_t label_txg = 0;
/*
* Auxiliary vdevs won't have txg values in their
* labels and newly added vdevs may not have been
@ -730,6 +729,15 @@ retry:
goto retry;
}
/*
* We found a valid label but it didn't pass txg restrictions.
*/
if (config == NULL && label_txg != 0) {
vdev_dbgmsg(vd, "label discarded as txg is too large "
"(%llu > %llu)", (u_longlong_t)label_txg,
(u_longlong_t)txg);
}
abd_free(vp_abd);
return (config);