* Re: [PATCH v2 1/2] nfsd: wake waiters blocked on file_lock before deleting it
[not found] ` <87wojl61s5.fsf@notabene.neil.brown.name>
@ 2019-04-24 13:58 ` J. Bruce Fields
2019-04-24 15:29 ` Steve Dickson
0 siblings, 1 reply; 4+ messages in thread
From: J. Bruce Fields @ 2019-04-24 13:58 UTC (permalink / raw)
To: NeilBrown; +Cc: Jeff Layton, slawek1211, linux-nfs, linux-cifs, Steve French
Steve, see Neil's comment, is there a cifs bug here?
--b.
On Tue, Apr 23, 2019 at 09:47:06AM +1000, NeilBrown wrote:
> On Mon, Apr 22 2019, Jeff Layton wrote:
>
> > After a blocked nfsd file_lock request is deleted, knfsd will send a
> > callback to the client and then free the request. Commit 16306a61d3b7
> > ("fs/locks: always delete_block after waiting.") changed it such that
> > locks_delete_block is always called on a request after it is awoken,
> > but that patch missed fixing up blocked nfsd request handling.
> >
> > Call locks_delete_block on the block to wake up any locks still blocked
> > on the nfsd lock request before freeing it. Some of its callers already
> > do this however, so just remove those calls.
> >
> > URL: https://bugzilla.kernel.org/show_bug.cgi?id=203363
> > Fixes: 16306a61d3b7 ("fs/locks: always delete_block after waiting.")
> > Reported-by: Slawomir Pryczek <slawek1211@gmail.com>
> > Cc: Neil Brown <neilb@suse.com>
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > ---
> > fs/nfsd/nfs4state.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 6a45fb00c5fc..e87e15df2044 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -265,6 +265,7 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
> > static void
> > free_blocked_lock(struct nfsd4_blocked_lock *nbl)
> > {
> > + locks_delete_block(&nbl->nbl_lock);
> > locks_release_private(&nbl->nbl_lock);
>
> Thanks for tracking this down.
>
> An implication of this bug and fix is that we need to be particularly
> careful to make sure locks_delete_block() is called on all relevant
> paths.
> Can we make that easier? My first thought was to include the call in
> locks_release_private, but lockd calls the two quite separately and it
> certainly seems appropriate that locks_delete_block should be called
> asap, but locks_release_private() can be delayed.
>
> Also cifs calls locks_delete_block, but never calls
> locks_release_private, so it wouldn't help there.
>
> Looking at cifs, I think there is a call missing there too.
> cifs_posix_lock_set() *doesn't* always call locks_delete_block() after
> waiting. In particular, if ->can_cache_brlcks becomes true while
> waiting then I don't think the behaviour is right.... though I'm not
> sure it is right for other reasons. It looks like the return value
> should be 1 in that case, but it'll be zero.
>
> But back to my question about making it easier, move the BUG_ON()
> calls from locks_free_lock() into locks_release_private().
>
> ??
>
> Thanks,
> NeilBrown
>
>
> > kfree(nbl);
> > }
> > @@ -293,7 +294,6 @@ remove_blocked_locks(struct nfs4_lockowner *lo)
> > nbl = list_first_entry(&reaplist, struct nfsd4_blocked_lock,
> > nbl_lru);
> > list_del_init(&nbl->nbl_lru);
> > - locks_delete_block(&nbl->nbl_lock);
> > free_blocked_lock(nbl);
> > }
> > }
> > @@ -4863,7 +4863,6 @@ nfs4_laundromat(struct nfsd_net *nn)
> > nbl = list_first_entry(&reaplist,
> > struct nfsd4_blocked_lock, nbl_lru);
> > list_del_init(&nbl->nbl_lru);
> > - locks_delete_block(&nbl->nbl_lock);
> > free_blocked_lock(nbl);
> > }
> > out:
> > --
> > 2.20.1
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 1/2] nfsd: wake waiters blocked on file_lock before deleting it
2019-04-24 13:58 ` [PATCH v2 1/2] nfsd: wake waiters blocked on file_lock before deleting it J. Bruce Fields
@ 2019-04-24 15:29 ` Steve Dickson
2019-04-24 15:47 ` J. Bruce Fields
0 siblings, 1 reply; 4+ messages in thread
From: Steve Dickson @ 2019-04-24 15:29 UTC (permalink / raw)
To: J. Bruce Fields, NeilBrown
Cc: Jeff Layton, slawek1211, linux-nfs, linux-cifs, Steve French
On 4/24/19 9:58 AM, J. Bruce Fields wrote:
> Steve, see Neil's comment, is there a cifs bug here?
Looking into it...
steved.
>
> --b.
>
> On Tue, Apr 23, 2019 at 09:47:06AM +1000, NeilBrown wrote:
>> On Mon, Apr 22 2019, Jeff Layton wrote:
>>
>>> After a blocked nfsd file_lock request is deleted, knfsd will send a
>>> callback to the client and then free the request. Commit 16306a61d3b7
>>> ("fs/locks: always delete_block after waiting.") changed it such that
>>> locks_delete_block is always called on a request after it is awoken,
>>> but that patch missed fixing up blocked nfsd request handling.
>>>
>>> Call locks_delete_block on the block to wake up any locks still blocked
>>> on the nfsd lock request before freeing it. Some of its callers already
>>> do this however, so just remove those calls.
>>>
>>> URL: https://bugzilla.kernel.org/show_bug.cgi?id=203363
>>> Fixes: 16306a61d3b7 ("fs/locks: always delete_block after waiting.")
>>> Reported-by: Slawomir Pryczek <slawek1211@gmail.com>
>>> Cc: Neil Brown <neilb@suse.com>
>>> Cc: stable@vger.kernel.org
>>> Signed-off-by: Jeff Layton <jlayton@kernel.org>
>>> ---
>>> fs/nfsd/nfs4state.c | 3 +--
>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>> index 6a45fb00c5fc..e87e15df2044 100644
>>> --- a/fs/nfsd/nfs4state.c
>>> +++ b/fs/nfsd/nfs4state.c
>>> @@ -265,6 +265,7 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
>>> static void
>>> free_blocked_lock(struct nfsd4_blocked_lock *nbl)
>>> {
>>> + locks_delete_block(&nbl->nbl_lock);
>>> locks_release_private(&nbl->nbl_lock);
>>
>> Thanks for tracking this down.
>>
>> An implication of this bug and fix is that we need to be particularly
>> careful to make sure locks_delete_block() is called on all relevant
>> paths.
>> Can we make that easier? My first thought was to include the call in
>> locks_release_private, but lockd calls the two quite separately and it
>> certainly seems appropriate that locks_delete_block should be called
>> asap, but locks_release_private() can be delayed.
>>
>> Also cifs calls locks_delete_block, but never calls
>> locks_release_private, so it wouldn't help there.
>>
>> Looking at cifs, I think there is a call missing there too.
>> cifs_posix_lock_set() *doesn't* always call locks_delete_block() after
>> waiting. In particular, if ->can_cache_brlcks becomes true while
>> waiting then I don't think the behaviour is right.... though I'm not
>> sure it is right for other reasons. It looks like the return value
>> should be 1 in that case, but it'll be zero.
>>
>> But back to my question about making it easier, move the BUG_ON()
>> calls from locks_free_lock() into locks_release_private().
>>
>> ??
>>
>> Thanks,
>> NeilBrown
>>
>>
>>> kfree(nbl);
>>> }
>>> @@ -293,7 +294,6 @@ remove_blocked_locks(struct nfs4_lockowner *lo)
>>> nbl = list_first_entry(&reaplist, struct nfsd4_blocked_lock,
>>> nbl_lru);
>>> list_del_init(&nbl->nbl_lru);
>>> - locks_delete_block(&nbl->nbl_lock);
>>> free_blocked_lock(nbl);
>>> }
>>> }
>>> @@ -4863,7 +4863,6 @@ nfs4_laundromat(struct nfsd_net *nn)
>>> nbl = list_first_entry(&reaplist,
>>> struct nfsd4_blocked_lock, nbl_lru);
>>> list_del_init(&nbl->nbl_lru);
>>> - locks_delete_block(&nbl->nbl_lock);
>>> free_blocked_lock(nbl);
>>> }
>>> out:
>>> --
>>> 2.20.1
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 1/2] nfsd: wake waiters blocked on file_lock before deleting it
2019-04-24 15:29 ` Steve Dickson
@ 2019-04-24 15:47 ` J. Bruce Fields
2019-04-24 19:09 ` Pavel Shilovsky
0 siblings, 1 reply; 4+ messages in thread
From: J. Bruce Fields @ 2019-04-24 15:47 UTC (permalink / raw)
To: Steve Dickson
Cc: NeilBrown, Jeff Layton, slawek1211, linux-nfs, linux-cifs, Steve French
On Wed, Apr 24, 2019 at 11:29:59AM -0400, Steve Dickson wrote:
>
>
> On 4/24/19 9:58 AM, J. Bruce Fields wrote:
> > Steve, see Neil's comment, is there a cifs bug here?
> Looking into it...
I was thinking Steve French, though I'm sure he wouldn't mind if you
fixed cifs bugs. Too many Steves!
--b.
>
> steved.
> >
> > --b.
> >
> > On Tue, Apr 23, 2019 at 09:47:06AM +1000, NeilBrown wrote:
> >> On Mon, Apr 22 2019, Jeff Layton wrote:
> >>
> >>> After a blocked nfsd file_lock request is deleted, knfsd will send a
> >>> callback to the client and then free the request. Commit 16306a61d3b7
> >>> ("fs/locks: always delete_block after waiting.") changed it such that
> >>> locks_delete_block is always called on a request after it is awoken,
> >>> but that patch missed fixing up blocked nfsd request handling.
> >>>
> >>> Call locks_delete_block on the block to wake up any locks still blocked
> >>> on the nfsd lock request before freeing it. Some of its callers already
> >>> do this however, so just remove those calls.
> >>>
> >>> URL: https://bugzilla.kernel.org/show_bug.cgi?id=203363
> >>> Fixes: 16306a61d3b7 ("fs/locks: always delete_block after waiting.")
> >>> Reported-by: Slawomir Pryczek <slawek1211@gmail.com>
> >>> Cc: Neil Brown <neilb@suse.com>
> >>> Cc: stable@vger.kernel.org
> >>> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> >>> ---
> >>> fs/nfsd/nfs4state.c | 3 +--
> >>> 1 file changed, 1 insertion(+), 2 deletions(-)
> >>>
> >>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> >>> index 6a45fb00c5fc..e87e15df2044 100644
> >>> --- a/fs/nfsd/nfs4state.c
> >>> +++ b/fs/nfsd/nfs4state.c
> >>> @@ -265,6 +265,7 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
> >>> static void
> >>> free_blocked_lock(struct nfsd4_blocked_lock *nbl)
> >>> {
> >>> + locks_delete_block(&nbl->nbl_lock);
> >>> locks_release_private(&nbl->nbl_lock);
> >>
> >> Thanks for tracking this down.
> >>
> >> An implication of this bug and fix is that we need to be particularly
> >> careful to make sure locks_delete_block() is called on all relevant
> >> paths.
> >> Can we make that easier? My first thought was to include the call in
> >> locks_release_private, but lockd calls the two quite separately and it
> >> certainly seems appropriate that locks_delete_block should be called
> >> asap, but locks_release_private() can be delayed.
> >>
> >> Also cifs calls locks_delete_block, but never calls
> >> locks_release_private, so it wouldn't help there.
> >>
> >> Looking at cifs, I think there is a call missing there too.
> >> cifs_posix_lock_set() *doesn't* always call locks_delete_block() after
> >> waiting. In particular, if ->can_cache_brlcks becomes true while
> >> waiting then I don't think the behaviour is right.... though I'm not
> >> sure it is right for other reasons. It looks like the return value
> >> should be 1 in that case, but it'll be zero.
> >>
> >> But back to my question about making it easier, move the BUG_ON()
> >> calls from locks_free_lock() into locks_release_private().
> >>
> >> ??
> >>
> >> Thanks,
> >> NeilBrown
> >>
> >>
> >>> kfree(nbl);
> >>> }
> >>> @@ -293,7 +294,6 @@ remove_blocked_locks(struct nfs4_lockowner *lo)
> >>> nbl = list_first_entry(&reaplist, struct nfsd4_blocked_lock,
> >>> nbl_lru);
> >>> list_del_init(&nbl->nbl_lru);
> >>> - locks_delete_block(&nbl->nbl_lock);
> >>> free_blocked_lock(nbl);
> >>> }
> >>> }
> >>> @@ -4863,7 +4863,6 @@ nfs4_laundromat(struct nfsd_net *nn)
> >>> nbl = list_first_entry(&reaplist,
> >>> struct nfsd4_blocked_lock, nbl_lru);
> >>> list_del_init(&nbl->nbl_lru);
> >>> - locks_delete_block(&nbl->nbl_lock);
> >>> free_blocked_lock(nbl);
> >>> }
> >>> out:
> >>> --
> >>> 2.20.1
> >
> >
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 1/2] nfsd: wake waiters blocked on file_lock before deleting it
2019-04-24 15:47 ` J. Bruce Fields
@ 2019-04-24 19:09 ` Pavel Shilovsky
0 siblings, 0 replies; 4+ messages in thread
From: Pavel Shilovsky @ 2019-04-24 19:09 UTC (permalink / raw)
To: J. Bruce Fields
Cc: Steve Dickson, NeilBrown, Jeff Layton, slawek1211,
Linux NFS Mailing list, linux-cifs, Steve French,
Ronnie Sahlberg
Yes, I think there is a bug here, thanks!
If cinode->can_cache_brlcks is false we should return 1 but the code
will return 0 if coming from the "try_again" label. We also need to
call locks_delete_block unconditionally at the end of the function.
--
Best regards,
Pavel Shilovsky
ср, 24 апр. 2019 г. в 08:48, J. Bruce Fields <bfields@fieldses.org>:
>
> On Wed, Apr 24, 2019 at 11:29:59AM -0400, Steve Dickson wrote:
> >
> >
> > On 4/24/19 9:58 AM, J. Bruce Fields wrote:
> > > Steve, see Neil's comment, is there a cifs bug here?
> > Looking into it...
>
> I was thinking Steve French, though I'm sure he wouldn't mind if you
> fixed cifs bugs. Too many Steves!
>
> --b.
>
> >
> > steved.
> > >
> > > --b.
> > >
> > > On Tue, Apr 23, 2019 at 09:47:06AM +1000, NeilBrown wrote:
> > >> On Mon, Apr 22 2019, Jeff Layton wrote:
> > >>
> > >>> After a blocked nfsd file_lock request is deleted, knfsd will send a
> > >>> callback to the client and then free the request. Commit 16306a61d3b7
> > >>> ("fs/locks: always delete_block after waiting.") changed it such that
> > >>> locks_delete_block is always called on a request after it is awoken,
> > >>> but that patch missed fixing up blocked nfsd request handling.
> > >>>
> > >>> Call locks_delete_block on the block to wake up any locks still blocked
> > >>> on the nfsd lock request before freeing it. Some of its callers already
> > >>> do this however, so just remove those calls.
> > >>>
> > >>> URL: https://bugzilla.kernel.org/show_bug.cgi?id=203363
> > >>> Fixes: 16306a61d3b7 ("fs/locks: always delete_block after waiting.")
> > >>> Reported-by: Slawomir Pryczek <slawek1211@gmail.com>
> > >>> Cc: Neil Brown <neilb@suse.com>
> > >>> Cc: stable@vger.kernel.org
> > >>> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > >>> ---
> > >>> fs/nfsd/nfs4state.c | 3 +--
> > >>> 1 file changed, 1 insertion(+), 2 deletions(-)
> > >>>
> > >>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > >>> index 6a45fb00c5fc..e87e15df2044 100644
> > >>> --- a/fs/nfsd/nfs4state.c
> > >>> +++ b/fs/nfsd/nfs4state.c
> > >>> @@ -265,6 +265,7 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
> > >>> static void
> > >>> free_blocked_lock(struct nfsd4_blocked_lock *nbl)
> > >>> {
> > >>> + locks_delete_block(&nbl->nbl_lock);
> > >>> locks_release_private(&nbl->nbl_lock);
> > >>
> > >> Thanks for tracking this down.
> > >>
> > >> An implication of this bug and fix is that we need to be particularly
> > >> careful to make sure locks_delete_block() is called on all relevant
> > >> paths.
> > >> Can we make that easier? My first thought was to include the call in
> > >> locks_release_private, but lockd calls the two quite separately and it
> > >> certainly seems appropriate that locks_delete_block should be called
> > >> asap, but locks_release_private() can be delayed.
> > >>
> > >> Also cifs calls locks_delete_block, but never calls
> > >> locks_release_private, so it wouldn't help there.
> > >>
> > >> Looking at cifs, I think there is a call missing there too.
> > >> cifs_posix_lock_set() *doesn't* always call locks_delete_block() after
> > >> waiting. In particular, if ->can_cache_brlcks becomes true while
> > >> waiting then I don't think the behaviour is right.... though I'm not
> > >> sure it is right for other reasons. It looks like the return value
> > >> should be 1 in that case, but it'll be zero.
> > >>
> > >> But back to my question about making it easier, move the BUG_ON()
> > >> calls from locks_free_lock() into locks_release_private().
> > >>
> > >> ??
> > >>
> > >> Thanks,
> > >> NeilBrown
> > >>
> > >>
> > >>> kfree(nbl);
> > >>> }
> > >>> @@ -293,7 +294,6 @@ remove_blocked_locks(struct nfs4_lockowner *lo)
> > >>> nbl = list_first_entry(&reaplist, struct nfsd4_blocked_lock,
> > >>> nbl_lru);
> > >>> list_del_init(&nbl->nbl_lru);
> > >>> - locks_delete_block(&nbl->nbl_lock);
> > >>> free_blocked_lock(nbl);
> > >>> }
> > >>> }
> > >>> @@ -4863,7 +4863,6 @@ nfs4_laundromat(struct nfsd_net *nn)
> > >>> nbl = list_first_entry(&reaplist,
> > >>> struct nfsd4_blocked_lock, nbl_lru);
> > >>> list_del_init(&nbl->nbl_lru);
> > >>> - locks_delete_block(&nbl->nbl_lock);
> > >>> free_blocked_lock(nbl);
> > >>> }
> > >>> out:
> > >>> --
> > >>> 2.20.1
> > >
> > >
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-04-24 13:58 ` [PATCH v2 1/2] nfsd: wake waiters blocked on file_lock before deleting it J. Bruce Fields
2019-04-24 15:29 ` Steve Dickson
2019-04-24 15:47 ` J. Bruce Fields
2019-04-24 19:09 ` Pavel Shilovsky
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