Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-pd0-f169.google.com ([209.85.192.169]:55247 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754552AbaHUNRB (ORCPT ); Thu, 21 Aug 2014 09:17:01 -0400 Received: by mail-pd0-f169.google.com with SMTP id y10so13772883pdj.0 for ; Thu, 21 Aug 2014 06:17:00 -0700 (PDT) Message-ID: <53F5F12B.1020801@gmail.com> Date: Thu, 21 Aug 2014 21:16:27 +0800 From: Kinglong Mee MIME-Version: 1.0 To: Jeff Layton CC: "J. Bruce Fields" , Linux NFS Mailing List , Joe Perches , Kinglong Mee , eshel@almaden.ibm.com Subject: Re: [PATCH] lockd: Remove unused b_fl member from struct nlm_block References: <53F47357.7050608@gmail.com> <20140820065826.6def22d5@tlielax.poochiereds.net> <53F4904B.6080204@gmail.com> <20140820090412.309b7599@tlielax.poochiereds.net> In-Reply-To: <20140820090412.309b7599@tlielax.poochiereds.net> Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On 8/20/2014 21:04, Jeff Layton wrote: > On Wed, 20 Aug 2014 20:10:51 +0800 > Kinglong Mee wrote: > >> On 8/20/2014 18:58, Jeff Layton wrote: >>> On Wed, 20 Aug 2014 18:07:19 +0800 >>> Kinglong Mee wrote: >>> >>>> Fix left code by Joe Perches's patch, >>>> "locks: Remove unused conf argument from lm_grant" >>>> >>>> Signed-off-by: Kinglong Mee >>>> --- >>>> 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