From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josef Bacik Subject: Re: [PATCH] dm-log-writes: fix bug with too large bios Date: Fri, 27 May 2016 11:36:34 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Mikulas Patocka , "Alasdair G. Kergon" , Mike Snitzer Cc: dm-devel@redhat.com, James Johnston , 'Eric Wheeler' , 'Tim Small' , 'Kent Overstreet' , linux-bcache@vger.kernel.org, dm-crypt@saout.de, 'Neil Brown' , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 05/27/2016 10:51 AM, Mikulas Patocka wrote: > bio_alloc can allocate a bio with at most BIO_MAX_PAGES (256) vector > entries. However, the incoming bio may have more vector entries if it was > allocated by other means. For example, bcache submits bios with more than > BIO_MAX_PAGES entries. This results in bio_alloc failure. > > To avoid the failure, change the code so that it allocates bio with at > most BIO_MAX_PAGES entries. If the incoming bio has more entries, > bio_add_page will fail and a new bio will be allocated - the code that > handles bio_add_page failure already exists in the dm-log-writes target. > > Also, move atomic_inc(&lc->io_blocks) before bio_alloc to fix a bug that > the target hangs if bio_alloc fails. The error path does put_io_block(lc), > so we must do atomic_inc(&lc->io_blocks) before invoking the error path to > avoid underflow of lc->io_blocks. > > Signed-off-by: Mikulas Patocka > Cc: stable@vger.kernel.org # v4.1+ Reviewed-by: Josef Bacik Thanks, Josef