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FreeBSD: Simplify zvol_geom_open and zvol_cdev_open 

We can consolidate the unlocking procedure into one place by starting
with drop_suspend set to B_FALSE and moving the open count check up.

While here, a little code cleanup. Match the out labels between
zvol_geom_open and zvol_cdev_open, and add a missing period in some
comments.

Reviewed-by: Matt Macy <mmacy@FreeBSD.org>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #11175
This commit is contained in:
Ryan Moeller 2020-11-06 13:56:58 -05:00 committed by Brian Behlendorf
parent 2186ed33f1
commit 7b42f09049
1 changed files with 16 additions and 36 deletions
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52
module/os/freebsd/zfs/zvol_os.c
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@ -209,7 +209,7 @@ zvol_geom_open(struct g_provider *pp, int flag, int count)
{ {
zvol_state_t *zv; zvol_state_t *zv;
int err = 0; int err = 0;
boolean_t drop_suspend = B_TRUE; boolean_t drop_suspend = B_FALSE;
boolean_t drop_namespace = B_FALSE; boolean_t drop_namespace = B_FALSE;
if (!zpool_on_zvol && tsd_get(zfs_geom_probe_vdev_key) != NULL) { if (!zpool_on_zvol && tsd_get(zfs_geom_probe_vdev_key) != NULL) {
@ -228,16 +228,14 @@ retry:
rw_enter(&zvol_state_lock, ZVOL_RW_READER); rw_enter(&zvol_state_lock, ZVOL_RW_READER);
zv = pp->private; zv = pp->private;
if (zv == NULL) { if (zv == NULL) {
if (drop_namespace) err = SET_ERROR(ENXIO);
mutex_exit(&spa_namespace_lock); goto out_locked;
rw_exit(&zvol_state_lock);
return (SET_ERROR(ENXIO));
} }
if (zv->zv_open_count == 0 && !mutex_owned(&spa_namespace_lock)) { if (zv->zv_open_count == 0 && !mutex_owned(&spa_namespace_lock)) {
/* /*
* We need to guarantee that the namespace lock is held * We need to guarantee that the namespace lock is held
* to avoid spurious failures in zvol_first_open * to avoid spurious failures in zvol_first_open.
*/ */
drop_namespace = B_TRUE; drop_namespace = B_TRUE;
if (!mutex_tryenter(&spa_namespace_lock)) { if (!mutex_tryenter(&spa_namespace_lock)) {
@ -256,6 +254,7 @@ retry:
* ordering - zv_suspend_lock before zv_state_lock * ordering - zv_suspend_lock before zv_state_lock
*/ */
if (zv->zv_open_count == 0) { if (zv->zv_open_count == 0) {
drop_suspend = B_TRUE;
if (!rw_tryenter(&zv->zv_suspend_lock, ZVOL_RW_READER)) { if (!rw_tryenter(&zv->zv_suspend_lock, ZVOL_RW_READER)) {
mutex_exit(&zv->zv_state_lock); mutex_exit(&zv->zv_state_lock);
rw_enter(&zv->zv_suspend_lock, ZVOL_RW_READER); rw_enter(&zv->zv_suspend_lock, ZVOL_RW_READER);
@ -266,8 +265,6 @@ retry:
drop_suspend = B_FALSE; drop_suspend = B_FALSE;
} }
} }
} else {
drop_suspend = B_FALSE;
} }
rw_exit(&zvol_state_lock); rw_exit(&zvol_state_lock);
@ -277,7 +274,7 @@ retry:
ASSERT(ZVOL_RW_READ_HELD(&zv->zv_suspend_lock)); ASSERT(ZVOL_RW_READ_HELD(&zv->zv_suspend_lock));
err = zvol_first_open(zv, !(flag & FWRITE)); err = zvol_first_open(zv, !(flag & FWRITE));
if (err) if (err)
goto out_mutex; goto out_locked;
pp->mediasize = zv->zv_volsize; pp->mediasize = zv->zv_volsize;
pp->stripeoffset = 0; pp->stripeoffset = 0;
pp->stripesize = zv->zv_volblocksize; pp->stripesize = zv->zv_volblocksize;
@ -290,34 +287,27 @@ retry:
if ((flag & FWRITE) && ((zv->zv_flags & ZVOL_RDONLY) || if ((flag & FWRITE) && ((zv->zv_flags & ZVOL_RDONLY) ||
dmu_objset_incompatible_encryption_version(zv->zv_objset))) { dmu_objset_incompatible_encryption_version(zv->zv_objset))) {
err = SET_ERROR(EROFS); err = SET_ERROR(EROFS);
goto out_open_count; goto out_opened;
} }
if (zv->zv_flags & ZVOL_EXCL) { if (zv->zv_flags & ZVOL_EXCL) {
err = SET_ERROR(EBUSY); err = SET_ERROR(EBUSY);
goto out_open_count; goto out_opened;
} }
#ifdef FEXCL #ifdef FEXCL
if (flag & FEXCL) { if (flag & FEXCL) {
if (zv->zv_open_count != 0) { if (zv->zv_open_count != 0) {
err = SET_ERROR(EBUSY); err = SET_ERROR(EBUSY);
goto out_open_count; goto out_opened;
} }
zv->zv_flags |= ZVOL_EXCL; zv->zv_flags |= ZVOL_EXCL;
} }
#endif #endif
zv->zv_open_count += count; zv->zv_open_count += count;
if (drop_namespace) out_opened:
mutex_exit(&spa_namespace_lock);
mutex_exit(&zv->zv_state_lock);
if (drop_suspend)
rw_exit(&zv->zv_suspend_lock);
return (0);
out_open_count:
if (zv->zv_open_count == 0) if (zv->zv_open_count == 0)
zvol_last_close(zv); zvol_last_close(zv);
out_mutex: out_locked:
if (drop_namespace) if (drop_namespace)
mutex_exit(&spa_namespace_lock); mutex_exit(&spa_namespace_lock);
mutex_exit(&zv->zv_state_lock); mutex_exit(&zv->zv_state_lock);
@ -826,23 +816,21 @@ zvol_cdev_open(struct cdev *dev, int flags, int fmt, struct thread *td)
zvol_state_t *zv; zvol_state_t *zv;
struct zvol_state_dev *zsd; struct zvol_state_dev *zsd;
int err = 0; int err = 0;
boolean_t drop_suspend = B_TRUE; boolean_t drop_suspend = B_FALSE;
boolean_t drop_namespace = B_FALSE; boolean_t drop_namespace = B_FALSE;
retry: retry:
rw_enter(&zvol_state_lock, ZVOL_RW_READER); rw_enter(&zvol_state_lock, ZVOL_RW_READER);
zv = dev->si_drv2; zv = dev->si_drv2;
if (zv == NULL) { if (zv == NULL) {
if (drop_namespace) err = SET_ERROR(ENXIO);
mutex_exit(&spa_namespace_lock); goto out_locked;
rw_exit(&zvol_state_lock);
return (SET_ERROR(ENXIO));
} }
if (zv->zv_open_count == 0 && !mutex_owned(&spa_namespace_lock)) { if (zv->zv_open_count == 0 && !mutex_owned(&spa_namespace_lock)) {
/* /*
* We need to guarantee that the namespace lock is held * We need to guarantee that the namespace lock is held
* to avoid spurious failures in zvol_first_open * to avoid spurious failures in zvol_first_open.
*/ */
drop_namespace = B_TRUE; drop_namespace = B_TRUE;
if (!mutex_tryenter(&spa_namespace_lock)) { if (!mutex_tryenter(&spa_namespace_lock)) {
@ -861,6 +849,7 @@ retry:
* ordering - zv_suspend_lock before zv_state_lock * ordering - zv_suspend_lock before zv_state_lock
*/ */
if (zv->zv_open_count == 0) { if (zv->zv_open_count == 0) {
drop_suspend = B_TRUE;
if (!rw_tryenter(&zv->zv_suspend_lock, ZVOL_RW_READER)) { if (!rw_tryenter(&zv->zv_suspend_lock, ZVOL_RW_READER)) {
mutex_exit(&zv->zv_state_lock); mutex_exit(&zv->zv_state_lock);
rw_enter(&zv->zv_suspend_lock, ZVOL_RW_READER); rw_enter(&zv->zv_suspend_lock, ZVOL_RW_READER);
@ -871,8 +860,6 @@ retry:
drop_suspend = B_FALSE; drop_suspend = B_FALSE;
} }
} }
} else {
drop_suspend = B_FALSE;
} }
rw_exit(&zvol_state_lock); rw_exit(&zvol_state_lock);
@ -911,13 +898,6 @@ retry:
(zv->zv_flags & ZVOL_WRITTEN_TO) != 0) (zv->zv_flags & ZVOL_WRITTEN_TO) != 0)
zil_async_to_sync(zv->zv_zilog, ZVOL_OBJ); zil_async_to_sync(zv->zv_zilog, ZVOL_OBJ);
} }
if (drop_namespace)
mutex_exit(&spa_namespace_lock);
mutex_exit(&zv->zv_state_lock);
if (drop_suspend)
rw_exit(&zv->zv_suspend_lock);
return (0);
out_opened: out_opened:
if (zv->zv_open_count == 0) if (zv->zv_open_count == 0)
zvol_last_close(zv); zvol_last_close(zv);