kern/184677 / ZFS snapshot handling deadlocks
krichy at tvnetwork.hu
krichy at tvnetwork.hu
Tue Dec 24 20:35:37 UTC 2013
Dear all,
Now a user caused deadlock simply caused buildkernel to be blocked, so I
must correct myself in that this not only does a DoS for .zfs/snapshot
directories, but may for the whole system.
Regards,
P.S.: Merry Christmas!
Kojedzinszky Richard
Euronet Magyarorszag Informatikai Zrt.
On Tue, 24 Dec 2013, krichy at tvnetwork.hu wrote:
> Date: Tue, 24 Dec 2013 21:28:39 +0100 (CET)
> From: krichy at tvnetwork.hu
> To: Pawel Jakub Dawidek <pjd at FreeBSD.org>
> Cc: freebsd-fs at freebsd.org, avg at freebsd.org
> Subject: Re: kern/184677 / ZFS snapshot handling deadlocks
>
> Dear all,
>
> Unfortunately, this seems to be serious, as a plain user can deadlock zfs
> using the attached script, and can make a DoS against the mounted dataset's
> .zfs/snapshot directory.
>
> Regards,
>
> Kojedzinszky Richard
> Euronet Magyarorszag Informatikai Zrt.
>
> On Tue, 24 Dec 2013, krichy at tvnetwork.hu wrote:
>
>> Date: Tue, 24 Dec 2013 07:10:05 +0100 (CET)
>> From: krichy at tvnetwork.hu
>> To: Pawel Jakub Dawidek <pjd at FreeBSD.org>
>> Cc: freebsd-fs at freebsd.org, avg at freebsd.org
>> Subject: Re: kern/184677 / ZFS snapshot handling deadlocks
>>
>> Dear devs,
>>
>> A third one, again the snapshot dirs:
>>
>> # cd /tmp/test/.zfs/snapshot && yes .. | xargs stat > /dev/null &
>> # yes /tmp/test/.zfs/snapshot/snap | xargs umount > /dev/null
>>
>> Will deadlock in a few seconds.
>>
>> The first holds a lock on .zfs/snapshot vnode, when looking up .. it tries
>> to lock .zfs, while the other just tries to do this in reversed order.
>>
>> In a vop_lookup, why is the passed in vnode, and the returned vnode must be
>> locked? Why is not enough to have it held?
>>
>> Thanks in advance,
>> Kojedzinszky Richard
>> Euronet Magyarorszag Informatikai Zrt.
>>
>> On Mon, 23 Dec 2013, krichy at tvnetwork.hu wrote:
>>
>>> Date: Mon, 23 Dec 2013 17:55:08 +0100 (CET)
>>> From: krichy at tvnetwork.hu
>>> To: Pawel Jakub Dawidek <pjd at FreeBSD.org>
>>> Cc: freebsd-fs at freebsd.org, avg at freebsd.org
>>> Subject: Re: kern/184677 / ZFS snapshot handling deadlocks
>>>
>>> Dear Pawel,
>>>
>>> Thanks for your response. I hope someone will review my work.
>>>
>>> Secondly, I think I;ve found another deadlock scenario:
>>>
>>> When 'zfs send -R' finishes, in zfsdev_close() it has spa_namespace_lock
>>> held. Then it does an unmount of all snapshots, which in turn goes to
>>> zfsctl_snapshot_inactive(), in which sdp->sd_lock is being locked.
>>>
>>> Concurrently, a zfsctl_snapdir_lookup(), holding the same sdp->sd_lock
>>> does a snapshot mount, which somewhere tries to acquire
>>> spa_namespace_lock. So it deadlocks. Currently I dont know how to
>>> workaround this.
>>>
>>> Is spa_namespace_lock need to be held in zfsctl_snapshot_inactive()?
>>>
>>> What if we release it function enter, and re-acquire upon exit?
>>>
>>> Thanks in advance,
>>>
>>>
>>> Kojedzinszky Richard
>>> Euronet Magyarorszag Informatikai Zrt.
>>>
>>> On Fri, 20 Dec 2013, Pawel Jakub Dawidek wrote:
>>>
>>>> Date: Fri, 20 Dec 2013 14:44:05 +0100
>>>> From: Pawel Jakub Dawidek <pjd at FreeBSD.org>
>>>> To: krichy at tvnetwork.hu
>>>> Cc: freebsd-fs at freebsd.org
>>>> Subject: Re: kern/184677 / ZFS snapshot handling deadlocks
>>>>
>>>> On Thu, Dec 19, 2013 at 04:46:11PM +0100, krichy at tvnetwork.hu wrote:
>>>>> Dear devs,
>>>>>
>>>>> I am attaching a more clear patch/fix for my snapshot handling issues
>>>>> (0002), but I would be happy if some ZFS expert would comment it. I am
>>>>> trying to solve it at least for two weeks now, and an ACK or a NACK
>>>>> would
>>>>> be nice from someone. Also a commit is reverted since it also caused
>>>>> deadlocks. I've read its comments, which also eliminates deadlocks, but
>>>>> I
>>>>> did not find any reference how to produce that deadlock. In my view
>>>>> reverting that makes my issues disappear, but I dont know what new cases
>>>>> will it rise.
>>>>
>>>> Richard,
>>>>
>>>> I won't be able to analyse it myself anytime soon, because of other
>>>> obligations, but I forwarded you e-mail to the zfs-devel@ mailing list
>>>> (it is closed, but gathers FreeBSD ZFS devs). Hopefully someone from
>>>> there will be able to help you.
>>>>
>>>>> I've rewritten traverse() to make more like upstream, added two extra
>>>>> VN_HOLD()s to snapdir_lookup() when traverse returned the same vnode
>>>>> what
>>>>> was passed to it (I dont know even that upon creating a snapshot vnode
>>>>> why
>>>>> is that extra two holds needed for the vnode.) And unfortunately, due to
>>>>> FreeBSD calls vop_inactive callbacks with vnodes locked, that could also
>>>>> cause deadlocks, so zfsctl_snapshot_inactive() and
>>>>> zfsctl_snapshot_vptocnp() has been rewritten to work that around.
>>>>>
>>>>> After this, one may also get a deadlock, when a simple access would call
>>>>> into zfsctl_snapshot_lookup(). The documentation says, that those vnodes
>>>>> should always be covered, but after some stress test, sometimes we hit
>>>>> that call, and that can cause again deadlocks. In our environment I've
>>>>> just uncommented that callback, which returns ENODIR on some calls, but
>>>>> at
>>>>> least not a deadlock.
>>>>>
>>>>> The attached script can be used to reproduce my cases (would one confirm
>>>>> that?), and after the patches applied, they disappear (confirm?).
>>>>>
>>>>> Thanks,
>>>>>
>>>>>
>>>>> Kojedzinszky Richard
>>>>> Euronet Magyarorszag Informatikai Zrt.
>>>>>
>>>>> On Tue, 17 Dec 2013, krichy at tvnetwork.hu wrote:
>>>>>
>>>>>> Date: Tue, 17 Dec 2013 14:50:16 +0100 (CET)
>>>>>> From: krichy at tvnetwork.hu
>>>>>> To: pjd at freebsd.org
>>>>>> Cc: freebsd-fs at freebsd.org
>>>>>> Subject: Re: kern/184677 (fwd)
>>>>>>
>>>>>> Dear devs,
>>>>>>
>>>>>> I will sum up my experience regarding the issue:
>>>>>>
>>>>>> The sympton is that a concurrent 'zfs send -R' and some activity on the
>>>>>> snapshot dir (or in the snapshot) may cause a deadlock.
>>>>>>
>>>>>> After investigating the problem, I found that zfs send umounts the
>>>>>> snapshots,
>>>>>> and that causes the deadlock, so later I tested only with concurrent
>>>>>> umount
>>>>>> and the "activity". More later I found that listing the snapshots in
>>>>>> .zfs/snapshot/ and unounting them can cause the found deadlock, so I
>>>>>> used
>>>>>> them for the tests. But for my surprise, instead of a deadlock, a
>>>>>> recursive
>>>>>> lock panic has arised.
>>>>>>
>>>>>> The vnode for the ".zfs/snapshot/" directory contains zfs's
>>>>>> zfsctl_snapdir_t
>>>>>> structure (sdp). This contains a tree of mounted snapshots, and each
>>>>>> entry
>>>>>> (sep) contains the vnode of entry on which the snapshot is mounted on
>>>>>> top
>>>>>> (se_root). The strange is that the se_root member does not hold a
>>>>>> reference
>>>>>> for the vnode, just a simple pointer to it.
>>>>>>
>>>>>> Upon entry lookup (zfsctl_snapdir_lookup()) the "snapshot" vnode is
>>>>>> locked,
>>>>>> the zfsctl_snapdir_t's tree is locked, and searched for the mount if it
>>>>>> exists already. If it founds no entry, does the mount. In the case of
>>>>>> an
>>>>>> entry was found, the se_root member contains the vnode which the
>>>>>> snapshot is
>>>>>> mounted on. Thus, a reference is taken for it, and the traverse() call
>>>>>> will
>>>>>> resolve to the real root vnode of the mounted snapshot, returning it as
>>>>>> locked. (Examining the traverse() code I've found that it did not
>>>>>> follow
>>>>>> FreeBSD's lock order recommendation described in sys/kern/vfs_subr.c.)
>>>>>>
>>>>>> On the other way, when an umount is issued, the se_root vnode looses
>>>>>> its last
>>>>>> reference (as only the mountpoint holds one for it), it goes through
>>>>>> the
>>>>>> vinactive() path, to zfsctl_snapshot_inactive(). In FreeBSD this is
>>>>>> called
>>>>>> with a locked vnode, so this is a deadlock race condition. While
>>>>>> zfsctl_snapdir_lookup() holds the mutex for the sdp tree, and
>>>>>> traverse()
>>>>>> tries to acquire the se_root, zfsctl_snapshot_inactive() holds the lock
>>>>>> on
>>>>>> se_root while tries to access the sdp lock.
>>>>>>
>>>>>> The zfsctl_snapshot_inactive() has an if statement checking the
>>>>>> v_usecount,
>>>>>> which is incremented in zfsctl_snapdir_lookup(), but in that context it
>>>>>> is
>>>>>> not covered by VI_LOCK. And it seems to me that FreeBSD's vinactive()
>>>>>> path
>>>>>> assumes that the vnode remains inactive (as opposed to illumos, at
>>>>>> least how
>>>>>> i read the code). So zfsctl_snapshot_inactive() must free resources
>>>>>> while in
>>>>>> a locked state. I was a bit confused, and probably that is why the
>>>>>> previously
>>>>>> posted patch is as is.
>>>>>>
>>>>>> Maybe if I had some clues on the directions of this problem, I could
>>>>>> have
>>>>>> worked more for a nicer, shorter solution.
>>>>>>
>>>>>> Please someone comment on my post.
>>>>>>
>>>>>> Regards,
>>>>>>
>>>>>>
>>>>>>
>>>>>> Kojedzinszky Richard
>>>>>> Euronet Magyarorszag Informatikai Zrt.
>>>>>>
>>>>>> On Mon, 16 Dec 2013, krichy at tvnetwork.hu wrote:
>>>>>>
>>>>>>> Date: Mon, 16 Dec 2013 16:52:16 +0100 (CET)
>>>>>>> From: krichy at tvnetwork.hu
>>>>>>> To: pjd at freebsd.org
>>>>>>> Cc: freebsd-fs at freebsd.org
>>>>>>> Subject: Re: kern/184677 (fwd)
>>>>>>>
>>>>>>> Dear PJD,
>>>>>>>
>>>>>>> I am a happy FreeBSD user, I am sure you've read my previous posts
>>>>>>> regarding some issues in ZFS. Please give some advice for me, where to
>>>>>>> look
>>>>>>> for solutions, or how could I help to resolve those issues.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Kojedzinszky Richard
>>>>>>> Euronet Magyarorszag Informatikai Zrt.
>>>>>>>
>>>>>>> ---------- Forwarded message ----------
>>>>>>> Date: Mon, 16 Dec 2013 15:23:06 +0100 (CET)
>>>>>>> From: krichy at tvnetwork.hu
>>>>>>> To: freebsd-fs at freebsd.org
>>>>>>> Subject: Re: kern/184677
>>>>>>>
>>>>>>>
>>>>>>> Seems that pjd did a change which eliminated the zfsdev_state_lock on
>>>>>>> Fri
>>>>>>> Aug 12 07:04:16 2011 +0000, which might introduced a new deadlock
>>>>>>> situation. Any comments on this?
>>>>>>>
>>>>>>>
>>>>>>> Kojedzinszky Richard
>>>>>>> Euronet Magyarorszag Informatikai Zrt.
>>>>>>>
>>>>>>> On Mon, 16 Dec 2013, krichy at tvnetwork.hu wrote:
>>>>>>>
>>>>>>>> Date: Mon, 16 Dec 2013 11:08:11 +0100 (CET)
>>>>>>>> From: krichy at tvnetwork.hu
>>>>>>>> To: freebsd-fs at freebsd.org
>>>>>>>> Subject: kern/184677
>>>>>>>>
>>>>>>>> Dear devs,
>>>>>>>>
>>>>>>>> I've attached a patch, which makes the recursive lockmgr disappear,
>>>>>>>> and
>>>>>>>> makes the reported bug to disappear. I dont know if I followed any
>>>>>>>> guidelines well, or not, but at least it works for me. Please some
>>>>>>>> ZFS/FreeBSD fs expert review it, and fix it where it needed.
>>>>>>>>
>>>>>>>> But unfortunately, my original problem is still not solved, maybe the
>>>>>>>> same
>>>>>>>> as Ryan's:
>>>>>>>> http://lists.freebsd.org/pipermail/freebsd-fs/2013-December/018707.html
>>>>>>>>
>>>>>>>> Tracing the problem down is that zfsctl_snapdir_lookup() tries to
>>>>>>>> acquire
>>>>>>>> spa_namespace_lock while when finishing a zfs send -R does a
>>>>>>>> zfsdev_close(), and that also holds the same mutex. And this causes a
>>>>>>>> deadlock scenario. I looked at illumos's code, and for some reason
>>>>>>>> they
>>>>>>>> use another mutex on zfsdev_close(), which therefore may not deadlock
>>>>>>>> with
>>>>>>>> zfsctl_snapdir_lookup(). But I am still investigating the problem.
>>>>>>>>
>>>>>>>> I would like to help making ZFS more stable on freebsd also with its
>>>>>>>> whole
>>>>>>>> functionality. I would be very thankful if some expert would give
>>>>>>>> some
>>>>>>>> advice, how to solve these bugs. PJD, Steven, Xin?
>>>>>>>>
>>>>>>>> Thanks in advance,
>>>>>>>>
>>>>>>>>
>>>>>>>> Kojedzinszky Richard
>>>>>>>> Euronet Magyarorszag Informatikai Zrt.
>>>>>>> _______________________________________________
>>>>>>> freebsd-fs at freebsd.org mailing list
>>>>>>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs
>>>>>>> To unsubscribe, send any mail to "freebsd-fs-unsubscribe at freebsd.org"
>>>>>>>
>>>>>>
>>>>
>>>>
>>>>> From 39298da838d006ad225e41529d7b7f240fccfe73 Mon Sep 17 00:00:00 2001
>>>>> From: Richard Kojedzinszky <krichy at cflinux.hu>
>>>>> Date: Mon, 16 Dec 2013 15:39:11 +0100
>>>>> Subject: [PATCH 1/2] Revert "Eliminate the zfsdev_state_lock entirely
>>>>> and
>>>>> replace it with the"
>>>>>
>>>>> This reverts commit 1d8972b3f353f986eb5b85bc108b1c0d946d3218.
>>>>>
>>>>> Conflicts:
>>>>> sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>>>>> ---
>>>>> .../opensolaris/uts/common/fs/zfs/sys/zfs_ioctl.h | 1 +
>>>>> .../opensolaris/uts/common/fs/zfs/vdev_geom.c | 14 ++-
>>>>> .../opensolaris/uts/common/fs/zfs/zfs_ioctl.c | 16 +--
>>>>> .../contrib/opensolaris/uts/common/fs/zfs/zvol.c | 119
>>>>> +++++++++------------
>>>>> 4 files changed, 70 insertions(+), 80 deletions(-)
>>>>>
>>>>> diff --git
>>>>> a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_ioctl.h
>>>>> b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_ioctl.h
>>>>> index af2def2..8272c4d 100644
>>>>> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_ioctl.h
>>>>> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_ioctl.h
>>>>> @@ -383,6 +383,7 @@ extern void *zfsdev_get_soft_state(minor_t minor,
>>>>> extern minor_t zfsdev_minor_alloc(void);
>>>>>
>>>>> extern void *zfsdev_state;
>>>>> +extern kmutex_t zfsdev_state_lock;
>>>>>
>>>>> #endif /* _KERNEL */
>>>>>
>>>>> diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
>>>>> b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
>>>>> index 15685a5..5c3e9f3 100644
>>>>> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
>>>>> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
>>>>> @@ -581,7 +581,7 @@ vdev_geom_open(vdev_t *vd, uint64_t *psize, uint64_t
>>>>> *max_psize,
>>>>> struct g_provider *pp;
>>>>> struct g_consumer *cp;
>>>>> size_t bufsize;
>>>>> - int error;
>>>>> + int error, lock;
>>>>>
>>>>> /*
>>>>> * We must have a pathname, and it must be absolute.
>>>>> @@ -593,6 +593,12 @@ vdev_geom_open(vdev_t *vd, uint64_t *psize,
>>>>> uint64_t *max_psize,
>>>>>
>>>>> vd->vdev_tsd = NULL;
>>>>>
>>>>> + if (mutex_owned(&spa_namespace_lock)) {
>>>>> + mutex_exit(&spa_namespace_lock);
>>>>> + lock = 1;
>>>>> + } else {
>>>>> + lock = 0;
>>>>> + }
>>>>> DROP_GIANT();
>>>>> g_topology_lock();
>>>>> error = 0;
>>>>> @@ -624,7 +630,11 @@ vdev_geom_open(vdev_t *vd, uint64_t *psize,
>>>>> uint64_t *max_psize,
>>>>> !ISP2(cp->provider->sectorsize)) {
>>>>> ZFS_LOG(1, "Provider %s has unsupported sectorsize.",
>>>>> vd->vdev_path);
>>>>> +
>>>>> + g_topology_lock();
>>>>> vdev_geom_detach(cp, 0);
>>>>> + g_topology_unlock();
>>>>> +
>>>>> error = EINVAL;
>>>>> cp = NULL;
>>>>> } else if (cp->acw == 0 && (spa_mode(vd->vdev_spa) & FWRITE) != 0) {
>>>>> @@ -647,6 +657,8 @@ vdev_geom_open(vdev_t *vd, uint64_t *psize, uint64_t
>>>>> *max_psize,
>>>>> }
>>>>> g_topology_unlock();
>>>>> PICKUP_GIANT();
>>>>> + if (lock)
>>>>> + mutex_enter(&spa_namespace_lock);
>>>>> if (cp == NULL) {
>>>>> vd->vdev_stat.vs_aux = VDEV_AUX_OPEN_FAILED;
>>>>> return (error);
>>>>> diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
>>>>> b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
>>>>> index e9fba26..91becde 100644
>>>>> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
>>>>> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
>>>>> @@ -5635,7 +5635,7 @@ zfsdev_minor_alloc(void)
>>>>> static minor_t last_minor;
>>>>> minor_t m;
>>>>>
>>>>> - ASSERT(MUTEX_HELD(&spa_namespace_lock));
>>>>> + ASSERT(MUTEX_HELD(&zfsdev_state_lock));
>>>>>
>>>>> for (m = last_minor + 1; m != last_minor; m++) {
>>>>> if (m > ZFSDEV_MAX_MINOR)
>>>>> @@ -5655,7 +5655,7 @@ zfs_ctldev_init(struct cdev *devp)
>>>>> minor_t minor;
>>>>> zfs_soft_state_t *zs;
>>>>>
>>>>> - ASSERT(MUTEX_HELD(&spa_namespace_lock));
>>>>> + ASSERT(MUTEX_HELD(&zfsdev_state_lock));
>>>>>
>>>>> minor = zfsdev_minor_alloc();
>>>>> if (minor == 0)
>>>>> @@ -5676,7 +5676,7 @@ zfs_ctldev_init(struct cdev *devp)
>>>>> static void
>>>>> zfs_ctldev_destroy(zfs_onexit_t *zo, minor_t minor)
>>>>> {
>>>>> - ASSERT(MUTEX_HELD(&spa_namespace_lock));
>>>>> + ASSERT(MUTEX_HELD(&zfsdev_state_lock));
>>>>>
>>>>> zfs_onexit_destroy(zo);
>>>>> ddi_soft_state_free(zfsdev_state, minor);
>>>>> @@ -5706,9 +5706,9 @@ zfsdev_open(struct cdev *devp, int flag, int mode,
>>>>> struct thread *td)
>>>>>
>>>>> /* This is the control device. Allocate a new minor if requested. */
>>>>> if (flag & FEXCL) {
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>> error = zfs_ctldev_init(devp);
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> }
>>>>>
>>>>> return (error);
>>>>> @@ -5723,14 +5723,14 @@ zfsdev_close(void *data)
>>>>> if (minor == 0)
>>>>> return;
>>>>>
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>> zo = zfsdev_get_soft_state(minor, ZSST_CTLDEV);
>>>>> if (zo == NULL) {
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return;
>>>>> }
>>>>> zfs_ctldev_destroy(zo, minor);
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> }
>>>>>
>>>>> static int
>>>>> diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>>>>> b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>>>>> index 72d4502..aec5219 100644
>>>>> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>>>>> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>>>>> @@ -104,11 +104,12 @@ static char *zvol_tag = "zvol_tag";
>>>>> #define ZVOL_DUMPSIZE "dumpsize"
>>>>>
>>>>> /*
>>>>> - * The spa_namespace_lock protects the zfsdev_state structure from
>>>>> being
>>>>> - * modified while it's being used, e.g. an open that comes in before a
>>>>> - * create finishes. It also protects temporary opens of the dataset so
>>>>> that,
>>>>> + * This lock protects the zfsdev_state structure from being modified
>>>>> + * while it's being used, e.g. an open that comes in before a create
>>>>> + * finishes. It also protects temporary opens of the dataset so that,
>>>>> * e.g., an open doesn't get a spurious EBUSY.
>>>>> */
>>>>> +kmutex_t zfsdev_state_lock;
>>>>> static uint32_t zvol_minors;
>>>>>
>>>>> typedef struct zvol_extent {
>>>>> @@ -249,7 +250,7 @@ zvol_minor_lookup(const char *name)
>>>>> struct g_geom *gp;
>>>>> zvol_state_t *zv = NULL;
>>>>>
>>>>> - ASSERT(MUTEX_HELD(&spa_namespace_lock));
>>>>> + ASSERT(MUTEX_HELD(&zfsdev_state_lock));
>>>>>
>>>>> g_topology_lock();
>>>>> LIST_FOREACH(gp, &zfs_zvol_class.geom, geom) {
>>>>> @@ -465,11 +466,11 @@ zvol_name2minor(const char *name, minor_t *minor)
>>>>> {
>>>>> zvol_state_t *zv;
>>>>>
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>> zv = zvol_minor_lookup(name);
>>>>> if (minor && zv)
>>>>> *minor = zv->zv_minor;
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (zv ? 0 : -1);
>>>>> }
>>>>> #endif /* sun */
>>>>> @@ -489,10 +490,10 @@ zvol_create_minor(const char *name)
>>>>>
>>>>> ZFS_LOG(1, "Creating ZVOL %s...", name);
>>>>>
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>>
>>>>> if (zvol_minor_lookup(name) != NULL) {
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(EEXIST));
>>>>> }
>>>>>
>>>>> @@ -500,20 +501,20 @@ zvol_create_minor(const char *name)
>>>>> error = dmu_objset_own(name, DMU_OST_ZVOL, B_TRUE, FTAG, &os);
>>>>>
>>>>> if (error) {
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (error);
>>>>> }
>>>>>
>>>>> #ifdef sun
>>>>> if ((minor = zfsdev_minor_alloc()) == 0) {
>>>>> dmu_objset_disown(os, FTAG);
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(ENXIO));
>>>>> }
>>>>>
>>>>> if (ddi_soft_state_zalloc(zfsdev_state, minor) != DDI_SUCCESS) {
>>>>> dmu_objset_disown(os, FTAG);
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(EAGAIN));
>>>>> }
>>>>> (void) ddi_prop_update_string(minor, zfs_dip, ZVOL_PROP_NAME,
>>>>> @@ -525,7 +526,7 @@ zvol_create_minor(const char *name)
>>>>> minor, DDI_PSEUDO, 0) == DDI_FAILURE) {
>>>>> ddi_soft_state_free(zfsdev_state, minor);
>>>>> dmu_objset_disown(os, FTAG);
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(EAGAIN));
>>>>> }
>>>>>
>>>>> @@ -536,7 +537,7 @@ zvol_create_minor(const char *name)
>>>>> ddi_remove_minor_node(zfs_dip, chrbuf);
>>>>> ddi_soft_state_free(zfsdev_state, minor);
>>>>> dmu_objset_disown(os, FTAG);
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(EAGAIN));
>>>>> }
>>>>>
>>>>> @@ -587,7 +588,7 @@ zvol_create_minor(const char *name)
>>>>>
>>>>> zvol_minors++;
>>>>>
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>>
>>>>> zvol_geom_run(zv);
>>>>>
>>>>> @@ -609,7 +610,7 @@ zvol_remove_zv(zvol_state_t *zv)
>>>>> minor_t minor = zv->zv_minor;
>>>>> #endif
>>>>>
>>>>> - ASSERT(MUTEX_HELD(&spa_namespace_lock));
>>>>> + ASSERT(MUTEX_HELD(&zfsdev_state_lock));
>>>>> if (zv->zv_total_opens != 0)
>>>>> return (SET_ERROR(EBUSY));
>>>>>
>>>>> @@ -635,15 +636,15 @@ zvol_remove_minor(const char *name)
>>>>> zvol_state_t *zv;
>>>>> int rc;
>>>>>
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>> if ((zv = zvol_minor_lookup(name)) == NULL) {
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(ENXIO));
>>>>> }
>>>>> g_topology_lock();
>>>>> rc = zvol_remove_zv(zv);
>>>>> g_topology_unlock();
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (rc);
>>>>> }
>>>>>
>>>>> @@ -755,7 +756,7 @@ zvol_update_volsize(objset_t *os, uint64_t volsize)
>>>>> dmu_tx_t *tx;
>>>>> int error;
>>>>>
>>>>> - ASSERT(MUTEX_HELD(&spa_namespace_lock));
>>>>> + ASSERT(MUTEX_HELD(&zfsdev_state_lock));
>>>>>
>>>>> tx = dmu_tx_create(os);
>>>>> dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
>>>>> @@ -786,7 +787,7 @@ zvol_remove_minors(const char *name)
>>>>> namelen = strlen(name);
>>>>>
>>>>> DROP_GIANT();
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>> g_topology_lock();
>>>>>
>>>>> LIST_FOREACH_SAFE(gp, &zfs_zvol_class.geom, geom, gptmp) {
>>>>> @@ -804,7 +805,7 @@ zvol_remove_minors(const char *name)
>>>>> }
>>>>>
>>>>> g_topology_unlock();
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> PICKUP_GIANT();
>>>>> }
>>>>>
>>>>> @@ -818,10 +819,10 @@ zvol_set_volsize(const char *name, major_t maj,
>>>>> uint64_t volsize)
>>>>> uint64_t old_volsize = 0ULL;
>>>>> uint64_t readonly;
>>>>>
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>> zv = zvol_minor_lookup(name);
>>>>> if ((error = dmu_objset_hold(name, FTAG, &os)) != 0) {
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (error);
>>>>> }
>>>>>
>>>>> @@ -888,7 +889,7 @@ zvol_set_volsize(const char *name, major_t maj,
>>>>> uint64_t volsize)
>>>>> out:
>>>>> dmu_objset_rele(os, FTAG);
>>>>>
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>>
>>>>> return (error);
>>>>> }
>>>>> @@ -899,36 +900,19 @@ zvol_open(struct g_provider *pp, int flag, int
>>>>> count)
>>>>> {
>>>>> zvol_state_t *zv;
>>>>> int err = 0;
>>>>> - boolean_t locked = B_FALSE;
>>>>>
>>>>> - /*
>>>>> - * Protect against recursively entering spa_namespace_lock
>>>>> - * when spa_open() is used for a pool on a (local) ZVOL(s).
>>>>> - * This is needed since we replaced upstream zfsdev_state_lock
>>>>> - * with spa_namespace_lock in the ZVOL code.
>>>>> - * We are using the same trick as spa_open().
>>>>> - * Note that calls in zvol_first_open which need to resolve
>>>>> - * pool name to a spa object will enter spa_open()
>>>>> - * recursively, but that function already has all the
>>>>> - * necessary protection.
>>>>> - */
>>>>> - if (!MUTEX_HELD(&spa_namespace_lock)) {
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> - locked = B_TRUE;
>>>>> - }
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>>
>>>>> zv = pp->private;
>>>>> if (zv == NULL) {
>>>>> - if (locked)
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(ENXIO));
>>>>> }
>>>>>
>>>>> if (zv->zv_total_opens == 0)
>>>>> err = zvol_first_open(zv);
>>>>> if (err) {
>>>>> - if (locked)
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (err);
>>>>> }
>>>>> if ((flag & FWRITE) && (zv->zv_flags & ZVOL_RDONLY)) {
>>>>> @@ -950,15 +934,13 @@ zvol_open(struct g_provider *pp, int flag, int
>>>>> count)
>>>>> #endif
>>>>>
>>>>> zv->zv_total_opens += count;
>>>>> - if (locked)
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>>
>>>>> return (err);
>>>>> out:
>>>>> if (zv->zv_total_opens == 0)
>>>>> zvol_last_close(zv);
>>>>> - if (locked)
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (err);
>>>>> }
>>>>>
>>>>> @@ -968,18 +950,12 @@ zvol_close(struct g_provider *pp, int flag, int
>>>>> count)
>>>>> {
>>>>> zvol_state_t *zv;
>>>>> int error = 0;
>>>>> - boolean_t locked = B_FALSE;
>>>>>
>>>>> - /* See comment in zvol_open(). */
>>>>> - if (!MUTEX_HELD(&spa_namespace_lock)) {
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> - locked = B_TRUE;
>>>>> - }
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>>
>>>>> zv = pp->private;
>>>>> if (zv == NULL) {
>>>>> - if (locked)
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(ENXIO));
>>>>> }
>>>>>
>>>>> @@ -1002,8 +978,7 @@ zvol_close(struct g_provider *pp, int flag, int
>>>>> count)
>>>>> if (zv->zv_total_opens == 0)
>>>>> zvol_last_close(zv);
>>>>>
>>>>> - if (locked)
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (error);
>>>>> }
>>>>>
>>>>> @@ -1658,12 +1633,12 @@ zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int
>>>>> flag, cred_t *cr, int *rvalp)
>>>>> int error = 0;
>>>>> rl_t *rl;
>>>>>
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>>
>>>>> zv = zfsdev_get_soft_state(getminor(dev), ZSST_ZVOL);
>>>>>
>>>>> if (zv == NULL) {
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (SET_ERROR(ENXIO));
>>>>> }
>>>>> ASSERT(zv->zv_total_opens > 0);
>>>>> @@ -1677,7 +1652,7 @@ zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int
>>>>> flag, cred_t *cr, int *rvalp)
>>>>> dki.dki_ctype = DKC_UNKNOWN;
>>>>> dki.dki_unit = getminor(dev);
>>>>> dki.dki_maxtransfer = 1 << (SPA_MAXBLOCKSHIFT -
>>>>> zv->zv_min_bs);
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> if (ddi_copyout(&dki, (void *)arg, sizeof (dki), flag))
>>>>> error = SET_ERROR(EFAULT);
>>>>> return (error);
>>>>> @@ -1687,7 +1662,7 @@ zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int
>>>>> flag, cred_t *cr, int *rvalp)
>>>>> dkm.dki_lbsize = 1U << zv->zv_min_bs;
>>>>> dkm.dki_capacity = zv->zv_volsize >> zv->zv_min_bs;
>>>>> dkm.dki_media_type = DK_UNKNOWN;
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> if (ddi_copyout(&dkm, (void *)arg, sizeof (dkm), flag))
>>>>> error = SET_ERROR(EFAULT);
>>>>> return (error);
>>>>> @@ -1697,14 +1672,14 @@ zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int
>>>>> flag, cred_t *cr, int *rvalp)
>>>>> uint64_t vs = zv->zv_volsize;
>>>>> uint8_t bs = zv->zv_min_bs;
>>>>>
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> error = zvol_getefi((void *)arg, flag, vs, bs);
>>>>> return (error);
>>>>> }
>>>>>
>>>>> case DKIOCFLUSHWRITECACHE:
>>>>> dkc = (struct dk_callback *)arg;
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> zil_commit(zv->zv_zilog, ZVOL_OBJ);
>>>>> if ((flag & FKIOCTL) && dkc != NULL && dkc->dkc_callback) {
>>>>> (*dkc->dkc_callback)(dkc->dkc_cookie, error);
>>>>> @@ -1730,10 +1705,10 @@ zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int
>>>>> flag, cred_t *cr, int *rvalp)
>>>>> }
>>>>> if (wce) {
>>>>> zv->zv_flags |= ZVOL_WCE;
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> } else {
>>>>> zv->zv_flags &= ~ZVOL_WCE;
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> zil_commit(zv->zv_zilog, ZVOL_OBJ);
>>>>> }
>>>>> return (0);
>>>>> @@ -1828,7 +1803,7 @@ zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int
>>>>> flag, cred_t *cr, int *rvalp)
>>>>> break;
>>>>>
>>>>> }
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> return (error);
>>>>> }
>>>>> #endif /* sun */
>>>>> @@ -1844,12 +1819,14 @@ zvol_init(void)
>>>>> {
>>>>> VERIFY(ddi_soft_state_init(&zfsdev_state, sizeof (zfs_soft_state_t),
>>>>> 1) == 0);
>>>>> + mutex_init(&zfsdev_state_lock, NULL, MUTEX_DEFAULT, NULL);
>>>>> ZFS_LOG(1, "ZVOL Initialized.");
>>>>> }
>>>>>
>>>>> void
>>>>> zvol_fini(void)
>>>>> {
>>>>> + mutex_destroy(&zfsdev_state_lock);
>>>>> ddi_soft_state_fini(&zfsdev_state);
>>>>> ZFS_LOG(1, "ZVOL Deinitialized.");
>>>>> }
>>>>> @@ -1889,7 +1866,7 @@ zvol_dump_init(zvol_state_t *zv, boolean_t resize)
>>>>> uint64_t version = spa_version(spa);
>>>>> enum zio_checksum checksum;
>>>>>
>>>>> - ASSERT(MUTEX_HELD(&spa_namespace_lock));
>>>>> + ASSERT(MUTEX_HELD(&zfsdev_state_lock));
>>>>> ASSERT(vd->vdev_ops == &vdev_root_ops);
>>>>>
>>>>> error = dmu_free_long_range(zv->zv_objset, ZVOL_OBJ, 0,
>>>>> @@ -2437,7 +2414,7 @@ zvol_rename_minor(struct g_geom *gp, const char
>>>>> *newname)
>>>>> struct g_provider *pp;
>>>>> zvol_state_t *zv;
>>>>>
>>>>> - ASSERT(MUTEX_HELD(&spa_namespace_lock));
>>>>> + ASSERT(MUTEX_HELD(&zfsdev_state_lock));
>>>>> g_topology_assert();
>>>>>
>>>>> pp = LIST_FIRST(&gp->provider);
>>>>> @@ -2471,7 +2448,7 @@ zvol_rename_minors(const char *oldname, const char
>>>>> *newname)
>>>>> newnamelen = strlen(newname);
>>>>>
>>>>> DROP_GIANT();
>>>>> - mutex_enter(&spa_namespace_lock);
>>>>> + mutex_enter(&zfsdev_state_lock);
>>>>> g_topology_lock();
>>>>>
>>>>> LIST_FOREACH(gp, &zfs_zvol_class.geom, geom) {
>>>>> @@ -2494,6 +2471,6 @@ zvol_rename_minors(const char *oldname, const char
>>>>> *newname)
>>>>> }
>>>>>
>>>>> g_topology_unlock();
>>>>> - mutex_exit(&spa_namespace_lock);
>>>>> + mutex_exit(&zfsdev_state_lock);
>>>>> PICKUP_GIANT();
>>>>> }
>>>>> --
>>>>> 1.8.4.2
>>>>>
>>>>
>>>>> From 57d5a383b585c32c77af54e8cdacaddf8ce7584f Mon Sep 17 00:00:00 2001
>>>>> From: Richard Kojedzinszky <krichy at cflinux.hu>
>>>>> Date: Wed, 18 Dec 2013 22:11:21 +0100
>>>>> Subject: [PATCH 2/2] ZFS snapshot handling fix
>>>>>
>>>>> ---
>>>>> .../compat/opensolaris/kern/opensolaris_lookup.c | 13 +++---
>>>>> .../opensolaris/uts/common/fs/zfs/zfs_ctldir.c | 53
>>>>> +++++++++++++++-------
>>>>> 2 files changed, 42 insertions(+), 24 deletions(-)
>>>>>
>>>>> diff --git a/sys/cddl/compat/opensolaris/kern/opensolaris_lookup.c
>>>>> b/sys/cddl/compat/opensolaris/kern/opensolaris_lookup.c
>>>>> index 94383d6..4cac053 100644
>>>>> --- a/sys/cddl/compat/opensolaris/kern/opensolaris_lookup.c
>>>>> +++ b/sys/cddl/compat/opensolaris/kern/opensolaris_lookup.c
>>>>> @@ -81,6 +81,8 @@ traverse(vnode_t **cvpp, int lktype)
>>>>> * progress on this vnode.
>>>>> */
>>>>>
>>>>> + vn_lock(cvp, lktype);
>>>>> +
>>>>> for (;;) {
>>>>> /*
>>>>> * Reached the end of the mount chain?
>>>>> @@ -89,13 +91,7 @@ traverse(vnode_t **cvpp, int lktype)
>>>>> if (vfsp == NULL)
>>>>> break;
>>>>> error = vfs_busy(vfsp, 0);
>>>>> - /*
>>>>> - * tvp is NULL for *cvpp vnode, which we can't unlock.
>>>>> - */
>>>>> - if (tvp != NULL)
>>>>> - vput(cvp);
>>>>> - else
>>>>> - vrele(cvp);
>>>>> + VOP_UNLOCK(cvp, 0);
>>>>> if (error)
>>>>> return (error);
>>>>>
>>>>> @@ -107,6 +103,9 @@ traverse(vnode_t **cvpp, int lktype)
>>>>> vfs_unbusy(vfsp);
>>>>> if (error != 0)
>>>>> return (error);
>>>>> +
>>>>> + VN_RELE(cvp);
>>>>> +
>>>>> cvp = tvp;
>>>>> }
>>>>>
>>>>> diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c
>>>>> b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c
>>>>> index 28ab1fa..d3464b4 100644
>>>>> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c
>>>>> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c
>>>>> @@ -112,6 +112,25 @@ snapentry_compare(const void *a, const void *b)
>>>>> return (0);
>>>>> }
>>>>>
>>>>> +/* Return the zfsctl_snapdir_t object from current vnode, following
>>>>> + * the lock orders in zfsctl_snapdir_lookup() to avoid deadlocks.
>>>>> + * On return the passed in vp is unlocked */
>>>>> +static zfsctl_snapdir_t *
>>>>> +zfsctl_snapshot_get_snapdir(vnode_t *vp, vnode_t **dvpp)
>>>>> +{
>>>>> + gfs_dir_t *dp = vp->v_data;
>>>>> + *dvpp = dp->gfsd_file.gfs_parent;
>>>>> + zfsctl_snapdir_t *sdp;
>>>>> +
>>>>> + VN_HOLD(*dvpp);
>>>>> + VOP_UNLOCK(vp, 0);
>>>>> + vn_lock(*dvpp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
>>>>> + sdp = (*dvpp)->v_data;
>>>>> + VOP_UNLOCK(*dvpp, 0);
>>>>> +
>>>>> + return (sdp);
>>>>> +}
>>>>> +
>>>>> #ifdef sun
>>>>> vnodeops_t *zfsctl_ops_root;
>>>>> vnodeops_t *zfsctl_ops_snapdir;
>>>>> @@ -1013,6 +1032,8 @@ zfsctl_snapdir_lookup(ap)
>>>>> * The snapshot was unmounted behind our backs,
>>>>> * try to remount it.
>>>>> */
>>>>> + VOP_UNLOCK(*vpp, 0);
>>>>> + VN_HOLD(*vpp);
>>>>> VERIFY(zfsctl_snapshot_zname(dvp, nm, MAXNAMELEN,
>>>>> snapname) == 0);
>>>>> goto domount;
>>>>> } else {
>>>>> @@ -1064,7 +1085,6 @@ zfsctl_snapdir_lookup(ap)
>>>>> sep->se_name = kmem_alloc(strlen(nm) + 1, KM_SLEEP);
>>>>> (void) strcpy(sep->se_name, nm);
>>>>> *vpp = sep->se_root = zfsctl_snapshot_mknode(dvp,
>>>>> dmu_objset_id(snap));
>>>>> - VN_HOLD(*vpp);
>>>>> avl_insert(&sdp->sd_snaps, sep, where);
>>>>>
>>>>> dmu_objset_rele(snap, FTAG);
>>>>> @@ -1075,6 +1095,7 @@ domount:
>>>>> (void) snprintf(mountpoint, mountpoint_len,
>>>>> "%s/" ZFS_CTLDIR_NAME "/snapshot/%s",
>>>>> dvp->v_vfsp->mnt_stat.f_mntonname, nm);
>>>>> + VN_HOLD(*vpp);
>>>>> err = mount_snapshot(curthread, vpp, "zfs", mountpoint, snapname, 0);
>>>>> kmem_free(mountpoint, mountpoint_len);
>>>>> if (err == 0) {
>>>>> @@ -1464,16 +1485,18 @@ zfsctl_snapshot_inactive(ap)
>>>>> int locked;
>>>>> vnode_t *dvp;
>>>>>
>>>>> - if (vp->v_count > 0)
>>>>> - goto end;
>>>>> -
>>>>> - VERIFY(gfs_dir_lookup(vp, "..", &dvp, cr, 0, NULL, NULL) == 0);
>>>>> - sdp = dvp->v_data;
>>>>> - VOP_UNLOCK(dvp, 0);
>>>>> + sdp = zfsctl_snapshot_get_snapdir(vp, &dvp);
>>>>>
>>>>> if (!(locked = MUTEX_HELD(&sdp->sd_lock)))
>>>>> mutex_enter(&sdp->sd_lock);
>>>>>
>>>>> + vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
>>>>> +
>>>>> + if (vp->v_count > 0) {
>>>>> + mutex_exit(&sdp->sd_lock);
>>>>> + return (0);
>>>>> + }
>>>>> +
>>>>> ASSERT(!vn_ismntpt(vp));
>>>>>
>>>>> sep = avl_first(&sdp->sd_snaps);
>>>>> @@ -1494,7 +1517,6 @@ zfsctl_snapshot_inactive(ap)
>>>>> mutex_exit(&sdp->sd_lock);
>>>>> VN_RELE(dvp);
>>>>>
>>>>> -end:
>>>>> /*
>>>>> * Dispose of the vnode for the snapshot mount point.
>>>>> * This is safe to do because once this entry has been removed
>>>>> @@ -1595,20 +1617,17 @@ zfsctl_snapshot_lookup(ap)
>>>>> static int
>>>>> zfsctl_snapshot_vptocnp(struct vop_vptocnp_args *ap)
>>>>> {
>>>>> - zfsvfs_t *zfsvfs = ap->a_vp->v_vfsp->vfs_data;
>>>>> - vnode_t *dvp, *vp;
>>>>> + vnode_t *dvp, *vp = ap->a_vp;
>>>>> zfsctl_snapdir_t *sdp;
>>>>> zfs_snapentry_t *sep;
>>>>> - int error;
>>>>> + int error = 0;
>>>>>
>>>>> - ASSERT(zfsvfs->z_ctldir != NULL);
>>>>> - error = zfsctl_root_lookup(zfsvfs->z_ctldir, "snapshot", &dvp,
>>>>> - NULL, 0, NULL, kcred, NULL, NULL, NULL);
>>>>> - if (error != 0)
>>>>> - return (error);
>>>>> - sdp = dvp->v_data;
>>>>> + sdp = zfsctl_snapshot_get_snapdir(vp, &dvp);
>>>>>
>>>>> mutex_enter(&sdp->sd_lock);
>>>>> +
>>>>> + vn_lock(vp, LK_SHARED | LK_RETRY);
>>>>> +
>>>>> sep = avl_first(&sdp->sd_snaps);
>>>>> while (sep != NULL) {
>>>>> vp = sep->se_root;
>>>>> --
>>>>> 1.8.4.2
>>>>>
>>>>
>>>> --
>>>> Pawel Jakub Dawidek http://www.wheelsystems.com
>>>> FreeBSD committer http://www.FreeBSD.org
>>>> Am I Evil? Yes, I Am! http://mobter.com
>>>>
>>> _______________________________________________
>>> freebsd-fs at freebsd.org mailing list
>>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs
>>> To unsubscribe, send any mail to "freebsd-fs-unsubscribe at freebsd.org"
>>>
>
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