From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 References: <1ec0a220-d5b0-1c27-e63b-c4d3f4ce9d77@torlan.ru> <20180803133102.GA3092@redhat.com> <20180803152034.GD32066@thunk.org> <20180803183932.GA3258@redhat.com> <20180803190617.GA4498@redhat.com> In-Reply-To: From: Linus Torvalds Date: Sat, 4 Aug 2018 10:04:47 -0700 Message-ID: Subject: Re: LVM snapshot broke between 4.14 and 4.16 To: wgh@torlan.ru Cc: Mike Snitzer , "Theodore Ts'o" , Jens Axboe , Sagi Grimberg , Linux Kernel Mailing List , linux-block , dm-devel@redhat.com, Ilya Dryomov , Zdenek Kabelac Content-Type: text/plain; charset="UTF-8" List-ID: On Sat, Aug 4, 2018 at 3:03 AM WGH wrote: > > > > The patch works for me. > > However, there's no text messsage in the kernel log, just a traceback. I > think that's because WARN_ONCE is supposed to take condition as a first > argument. Duh. It needs to be WARN_ONCE(1, ...); I obviously didn't test that patch, but I _did_ compile it. I wonder why I didn't get a compiler warning for it... [ Goes off and looks ] Oh, because the "bio_devname(bio, b)" argument ended up being interpreted as the format string, and since it was a dynamic string the compiler felt it was all fine. Just bad luck. Anyway, just out of curiosity, what was the traceback? I'm not entirely happy with that patch either (even after the obvious fix to add the "1" argument), but it does seem like the minimal temporary workaround for now. Linus From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: LVM snapshot broke between 4.14 and 4.16 Date: Sat, 4 Aug 2018 10:04:47 -0700 Message-ID: References: <1ec0a220-d5b0-1c27-e63b-c4d3f4ce9d77@torlan.ru> <20180803133102.GA3092@redhat.com> <20180803152034.GD32066@thunk.org> <20180803183932.GA3258@redhat.com> <20180803190617.GA4498@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: wgh@torlan.ru Cc: Jens Axboe , Theodore Ts'o , Sagi Grimberg , Mike Snitzer , Linux Kernel Mailing List , linux-block , dm-devel@redhat.com, Zdenek Kabelac , Ilya Dryomov List-Id: dm-devel.ids On Sat, Aug 4, 2018 at 3:03 AM WGH wrote: > > > > The patch works for me. > > However, there's no text messsage in the kernel log, just a traceback. I > think that's because WARN_ONCE is supposed to take condition as a first > argument. Duh. It needs to be WARN_ONCE(1, ...); I obviously didn't test that patch, but I _did_ compile it. I wonder why I didn't get a compiler warning for it... [ Goes off and looks ] Oh, because the "bio_devname(bio, b)" argument ended up being interpreted as the format string, and since it was a dynamic string the compiler felt it was all fine. Just bad luck. Anyway, just out of curiosity, what was the traceback? I'm not entirely happy with that patch either (even after the obvious fix to add the "1" argument), but it does seem like the minimal temporary workaround for now. Linus