On 8/20/2014 21:04, Jeff Layton wrote:
> On Wed, 20 Aug 2014 20:10:51 +0800
> Kinglong Mee <kinglongmee@xxxxxxxxx> wrote:
>
>> On 8/20/2014 18:58, Jeff Layton wrote:
>>> On Wed, 20 Aug 2014 18:07:19 +0800
>>> Kinglong Mee <kinglongmee@xxxxxxxxx> wrote:
>>>
>>>> Fix left code by Joe Perches's patch,
>>>> "locks: Remove unused conf argument from lm_grant"
>>>>
>>>> Signed-off-by: Kinglong Mee <kinglongmee@xxxxxxxxx>
>>>> ---
>>>> fs/lockd/svclock.c | 26 +++++---------------------
>>>> include/linux/lockd/lockd.h | 1 -
>>>> 2 files changed, 5 insertions(+), 22 deletions(-)
>>>>
>>>> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
>>>> index 2a61701..796e63b 100644
>>>> --- a/fs/lockd/svclock.c
>>>> +++ b/fs/lockd/svclock.c
>>>> @@ -245,7 +245,6 @@ nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
>>>> block->b_daemon = rqstp->rq_server;
>>>> block->b_host = host;
>>>> block->b_file = file;
>>>> - block->b_fl = NULL;
>>>> file->f_count++;
>>>>
>>>> /* Add to file's list of blocks */
>>>> @@ -295,7 +294,6 @@ static void nlmsvc_free_block(struct kref *kref)
>>>> nlmsvc_freegrantargs(block->b_call);
>>>> nlmsvc_release_call(block->b_call);
>>>> nlm_release_file(block->b_file);
>>>> - kfree(block->b_fl);
>>>> kfree(block);
>>>> }
>>>>
>>>> @@ -523,20 +521,13 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
>>>> block = nlmsvc_lookup_block(file, lock);
>>>>
>>>> if (block == NULL) {
>>>> - struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
>>>> -
>>>> - if (conf == NULL)
>>>> - return nlm_granted;
>>>> block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
>>>> - if (block == NULL) {
>>>> - kfree(conf);
>>>> + if (block == NULL)
>>>> return nlm_granted;
>>>> - }
>>>> - block->b_fl = conf;
>>>
>>> NAK. The b_fl member is not unused, as is evidenced by the assignment
>>> above.
>>
>> Sorry for my bad title, Maybe I should use a good name, sorry!
>>
>>>
>>> Joe's patch removed the conflock from the lm_grant callback since the
>>> filesystem never set that parameter in the lm_grant callback. This call
>>> however has nothing to do with lm_grant. It's done when the client
>>> issues a NLM_TEST operation.
>>>
>>>> }
>>>> if (block->b_flags & B_QUEUED) {
>>>> - dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
>>>> - block, block->b_flags, block->b_fl);
>>>> + dprintk("lockd: nlmsvc_testlock deferred block %p flags %d\n",
>>>> + block, block->b_flags);
>>>> if (block->b_flags & B_TIMED_OUT) {
>>>> nlmsvc_unlink_block(block);
>>>> ret = nlm_lck_denied;
>>>> @@ -544,14 +535,8 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
>>>> }
>>>> if (block->b_flags & B_GOT_CALLBACK) {
>>>> nlmsvc_unlink_block(block);
>>>> - if (block->b_fl != NULL
>>>> - && block->b_fl->fl_type != F_UNLCK) {
>>>> - lock->fl = *block->b_fl;
>>>> - goto conf_lock;
>>
>> block->b_fl = conf just set an all-zero filed structure to block above,
>> and never be updated later.
>> If lockd enter here, lock->fl will contains all filed with zero,
>> I don't know whether is it OK.
>>
>> thanks,
>> Kinglong Mee
>>
>
> Not quite....You can end up getting back FILE_LOCK_DEFERRED from an
> initial vfs_test_lock request. At that point, a block will be queued
> and we'll end up retrying that until the fs comes back. The result of
> those retries will end up in b_fl and that's what will end up being
> copied to lock->fl.
Yes, that's right.
What I care is that block->b_fl contains with all zero for all field,
block->b_fl->fl_type == 0 == F_RDLCK.
For block with b_flags & B_GOT_CALLBACK, block->b_fl will always be non-NULL,
and block->b_fl->fl_type always be F_RDLCK (Cannot be updated after initial),
so that, nlmsvc_testlock will return nlm_lck_denied,
but I think should return nlm_granted.
So, I think commit 5ea0d75037b9 (lockd: handle test_lock deferrals)
introduces the bug. After Joe's patch, we should remove b_fl in struct block.
Cc Marc Eshel
506 __be32
507 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
508 struct nlm_host *host, struct nlm_lock *lock,
509 struct nlm_lock *conflock, struct nlm_cookie *cookie)
510 {
511 struct nlm_block *block = NULL;
... ...
536 }
537 if (block->b_flags & B_QUEUED) {
538 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
539 block, block->b_flags, block->b_fl);
540 if (block->b_flags & B_TIMED_OUT) {
541 nlmsvc_unlink_block(block);
542 ret = nlm_lck_denied;
543 goto out;
544 }
545 if (block->b_flags & B_GOT_CALLBACK) {
546 nlmsvc_unlink_block(block);
547 if (block->b_fl != NULL
548 && block->b_fl->fl_type != F_UNLCK) {
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
549 lock->fl = *block->b_fl;
550 goto conf_lock;
551 } else {
552 ret = nlm_granted;
553 goto out;
554 }
555 }
thanks,
Kinglong Mee
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