[v2] NFSv4: Don't add a new lock on an interrupted wait for LOCK
diff mbox

Message ID cda7d9d6f145289d2855eb733a8d795938e67453.1501673116.git.bcodding@redhat.com
State New
Headers show

Commit Message

Benjamin Coddington Aug. 2, 2017, 11:27 a.m. UTC
If the wait for a LOCK operation is interrupted, and then the file is
closed, the locks cleanup code will assume that no new locks will be added
to the inode after it has completed.  We already have a mechanism to detect
if there was signal, so let's use that to avoid recreating the local lock
once the RPC completes.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
---
 fs/nfs/nfs4proc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Benjamin Coddington Aug. 23, 2017, 8:11 p.m. UTC | #1
Ping on this one as well -- it was buried in a thread:

Ben

On 2 Aug 2017, at 7:27, Benjamin Coddington wrote:

> If the wait for a LOCK operation is interrupted, and then the file is
> closed, the locks cleanup code will assume that no new locks will be 
> added
> to the inode after it has completed.  We already have a mechanism to 
> detect
> if there was signal, so let's use that to avoid recreating the local 
> lock
> once the RPC completes.
>
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> Reviewed-by: Jeff Layton <jlayton@redhat.com>
> ---
>  fs/nfs/nfs4proc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index dbfa18900e25..5256f429c268 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -6100,7 +6100,7 @@ static void nfs4_lock_done(struct rpc_task 
> *task, void *calldata)
>  	case 0:
>  		renew_lease(NFS_SERVER(d_inode(data->ctx->dentry)),
>  				data->timestamp);
> -		if (data->arg.new_lock) {
> +		if (data->arg.new_lock && !data->cancelled) {
>  			data->fl.fl_flags &= ~(FL_SLEEP | FL_ACCESS);
>  			if (locks_lock_inode_wait(lsp->ls_state->inode, &data->fl) < 0) {
>  				rpc_restart_call_prepare(task);
> -- 
> 2.9.3
>
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Trond Myklebust Aug. 23, 2017, 8:15 p.m. UTC | #2
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Benjamin Coddington Aug. 23, 2017, 8:25 p.m. UTC | #3
On 23 Aug 2017, at 16:15, Trond Myklebust wrote:

> On Wed, 2017-08-23 at 16:11 -0400, Benjamin Coddington wrote:
>> Ping on this one as well -- it was buried in a thread:
>>
>> Ben
>>
>> On 2 Aug 2017, at 7:27, Benjamin Coddington wrote:
>>
>>> If the wait for a LOCK operation is interrupted, and then the file
>>> is
>>> closed, the locks cleanup code will assume that no new locks will
>>> be
>>> added
>>> to the inode after it has completed.  We already have a mechanism
>>> to
>>> detect
>>> if there was signal, so let's use that to avoid recreating the
>>> local
>>> lock
>>> once the RPC completes.
>>>
>>> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
>>> Reviewed-by: Jeff Layton <jlayton@redhat.com>
>>> ---
>>>  fs/nfs/nfs4proc.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
>>> index dbfa18900e25..5256f429c268 100644
>>> --- a/fs/nfs/nfs4proc.c
>>> +++ b/fs/nfs/nfs4proc.c
>>> @@ -6100,7 +6100,7 @@ static void nfs4_lock_done(struct rpc_task
>>> *task, void *calldata)
>>>  	case 0:
>>>  		renew_lease(NFS_SERVER(d_inode(data->ctx-
>>>> dentry)),
>>>  				data->timestamp);
>>> -		if (data->arg.new_lock) {
>>> +		if (data->arg.new_lock && !data->cancelled) {
>>>  			data->fl.fl_flags &= ~(FL_SLEEP |
>>> FL_ACCESS);
>>>  			if (locks_lock_inode_wait(lsp->ls_state-
>>>> inode, &data->fl) < 0) {
>>>  				rpc_restart_call_prepare(task);
>>>
>
> Why do we want to special case '0'? Surely we don't want to restart the
> RPC call for any of the error cases if data->cancelled is set.

We don't want to add the local lock if data->cancelled is set.  It's
possible that the file has already been closed and the locks cleanup code
has removed all of the local locks, so if this races in and adds a lock we
end up with one left over.

I don't understand what you mean about restarting the RPC call - we'd only
restart the RPC call here if there was an error adding the local lock.

Ben
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Benjamin Coddington Aug. 23, 2017, 8:27 p.m. UTC | #4
On 23 Aug 2017, at 16:25, Benjamin Coddington wrote:

> On 23 Aug 2017, at 16:15, Trond Myklebust wrote:
>
>> On Wed, 2017-08-23 at 16:11 -0400, Benjamin Coddington wrote:
>>> Ping on this one as well -- it was buried in a thread:
>>>
>>> Ben
>>>
>>> On 2 Aug 2017, at 7:27, Benjamin Coddington wrote:
>>>
>>>> If the wait for a LOCK operation is interrupted, and then the file
>>>> is
>>>> closed, the locks cleanup code will assume that no new locks will
>>>> be
>>>> added
>>>> to the inode after it has completed.  We already have a mechanism
>>>> to
>>>> detect
>>>> if there was signal, so let's use that to avoid recreating the
>>>> local
>>>> lock
>>>> once the RPC completes.
>>>>
>>>> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
>>>> Reviewed-by: Jeff Layton <jlayton@redhat.com>
>>>> ---
>>>>  fs/nfs/nfs4proc.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
>>>> index dbfa18900e25..5256f429c268 100644
>>>> --- a/fs/nfs/nfs4proc.c
>>>> +++ b/fs/nfs/nfs4proc.c
>>>> @@ -6100,7 +6100,7 @@ static void nfs4_lock_done(struct rpc_task
>>>> *task, void *calldata)
>>>>  	case 0:
>>>>  		renew_lease(NFS_SERVER(d_inode(data->ctx-
>>>>> dentry)),
>>>>  				data->timestamp);
>>>> -		if (data->arg.new_lock) {
>>>> +		if (data->arg.new_lock && !data->cancelled) {
>>>>  			data->fl.fl_flags &= ~(FL_SLEEP |
>>>> FL_ACCESS);
>>>>  			if (locks_lock_inode_wait(lsp->ls_state-
>>>>> inode, &data->fl) < 0) {
>>>>  				rpc_restart_call_prepare(task);
>>>>
>>
>> Why do we want to special case '0'? Surely we don't want to restart the
>> RPC call for any of the error cases if data->cancelled is set.
>
> We don't want to add the local lock if data->cancelled is set.  It's
> possible that the file has already been closed and the locks cleanup code
> has removed all of the local locks, so if this races in and adds a lock we
> end up with one left over.
>
> I don't understand what you mean about restarting the RPC call - we'd only
> restart the RPC call here if there was an error adding the local lock.

Oh, I see what you mean.. we ought to bail out even if there is an error.
That makes sense, I can send this again.

Ben
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Patch
diff mbox

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index dbfa18900e25..5256f429c268 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6100,7 +6100,7 @@  static void nfs4_lock_done(struct rpc_task *task, void *calldata)
 	case 0:
 		renew_lease(NFS_SERVER(d_inode(data->ctx->dentry)),
 				data->timestamp);
-		if (data->arg.new_lock) {
+		if (data->arg.new_lock && !data->cancelled) {
 			data->fl.fl_flags &= ~(FL_SLEEP | FL_ACCESS);
 			if (locks_lock_inode_wait(lsp->ls_state->inode, &data->fl) < 0) {
 				rpc_restart_call_prepare(task);