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FreeBSD: Fix spurious failure in zvol_geom_open 

In zvol_geom_open on first open we need to guarantee
that the namespace lock is held to avoid spurious
failures in zvol_first_open.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <freqlabs@FreeBSD.org>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #10841
This commit is contained in:
Matthew Macy 2020-08-30 14:11:33 -07:00 committed by Brian Behlendorf
parent 8639ca86da
commit f4c8e9c69b
1 changed files with 20 additions and 0 deletions
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20
module/os/freebsd/zfs/zvol_os.c
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@ -210,6 +210,7 @@ zvol_geom_open(struct g_provider *pp, int flag, int count)
zvol_state_t *zv;
int err = 0;
boolean_t drop_suspend = B_TRUE;
boolean_t drop_namespace = B_FALSE;
if (!zpool_on_zvol && tsd_get(zfs_geom_probe_vdev_key) != NULL) {
/*
@ -223,13 +224,28 @@ zvol_geom_open(struct g_provider *pp, int flag, int count)
return (SET_ERROR(EOPNOTSUPP));
}
retry:
rw_enter(&zvol_state_lock, ZVOL_RW_READER);
zv = pp->private;
if (zv == NULL) {
if (drop_namespace)
mutex_exit(&spa_namespace_lock);
rw_exit(&zvol_state_lock);
return (SET_ERROR(ENXIO));
}
if (zv->zv_open_count == 0 && !mutex_owned(&spa_namespace_lock)) {
/*
* We need to guarantee that the namespace lock is held
* to avoid spurious failures in zvol_first_open
*/
drop_namespace = B_TRUE;
if (!mutex_tryenter(&spa_namespace_lock)) {
rw_exit(&zvol_state_lock);
mutex_enter(&spa_namespace_lock);
goto retry;
}
}
mutex_enter(&zv->zv_state_lock);
ASSERT(zv->zv_zso->zso_volmode == ZFS_VOLMODE_GEOM);
@ -291,6 +307,8 @@ zvol_geom_open(struct g_provider *pp, int flag, int count)
#endif
zv->zv_open_count += count;
if (drop_namespace)
mutex_exit(&spa_namespace_lock);
mutex_exit(&zv->zv_state_lock);
if (drop_suspend)
rw_exit(&zv->zv_suspend_lock);
@ -300,6 +318,8 @@ out_open_count:
if (zv->zv_open_count == 0)
zvol_last_close(zv);
out_mutex:
if (drop_namespace)
mutex_exit(&spa_namespace_lock);
mutex_exit(&zv->zv_state_lock);
if (drop_suspend)
rw_exit(&zv->zv_suspend_lock);