From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51581) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XuLbg-0003Zy-RA for qemu-devel@nongnu.org; Fri, 28 Nov 2014 08:29:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XuLbX-0004wU-Og for qemu-devel@nongnu.org; Fri, 28 Nov 2014 08:29:08 -0500 Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:45372) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XuLbX-0004wM-Fl for qemu-devel@nongnu.org; Fri, 28 Nov 2014 08:28:59 -0500 Received: from /spool/local by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 28 Nov 2014 13:28:57 -0000 Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id 4524117D8056 for ; Fri, 28 Nov 2014 13:29:12 +0000 (GMT) Received: from d06av04.portsmouth.uk.ibm.com (d06av04.portsmouth.uk.ibm.com [9.149.37.216]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id sASDStXb20316246 for ; Fri, 28 Nov 2014 13:28:55 GMT Received: from d06av04.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av04.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id sASDSs7e015097 for ; Fri, 28 Nov 2014 06:28:55 -0700 Message-ID: <54787894.4000604@linux.vnet.ibm.com> Date: Fri, 28 Nov 2014 16:28:52 +0300 From: Ekaterina Tumanova MIME-Version: 1.0 References: <1416392276-10408-1-git-send-email-tumanova@linux.vnet.ibm.com> <1416392276-10408-3-git-send-email-tumanova@linux.vnet.ibm.com> <874mtkczhu.fsf@blackfin.pond.sub.org> <54785544.5020904@linux.vnet.ibm.com> <87sih35vx3.fsf@blackfin.pond.sub.org> In-Reply-To: <87sih35vx3.fsf@blackfin.pond.sub.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 2/6] geometry: Detect blocksize via ioctls in separate static functions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: kwolf@redhat.com, dahi@linux.vnet.ibm.com, Public KVM Mailing List , mihajlov@linux.vnet.ibm.com, borntraeger@de.ibm.com, stefanha@redhat.com, cornelia.huck@de.ibm.com, pbonzini@redhat.com On 11/28/2014 03:52 PM, Markus Armbruster wrote: > Ekaterina Tumanova writes: > >>> >>> Suggest function comment >>> >>> /** >>> * Return logical block size, or zero if we can't figure it out >>> */ >>> >>>> { >>>> - BDRVRawState *s = bs->opaque; >>>> - char *buf; >>>> - unsigned int sector_size; >>>> - >>>> - /* For /dev/sg devices the alignment is not really used. >>>> - With buffered I/O, we don't have any restrictions. */ >>>> - if (bs->sg || !s->needs_alignment) { >>>> - bs->request_alignment = 1; >>>> - s->buf_align = 1; >>>> - return; >>>> - } >>>> + unsigned int sector_size = 0; >>> >>> Pointless initialization. >> >> If I do not initialize the sector_size, and the ioctl fails, >> I will return garbage as a blocksize to the caller. > > Where? As far as I can see, we return it only after ioctl() succeeded. > Sorry, you're absolutely right. I kept seeing and thinking that I always returned sector_size variable. ::facepalm:: >>>> >>>> /* Try a few ioctls to get the right size */ >>>> - bs->request_alignment = 0; >>>> - s->buf_align = 0; >>>> - >>>> #ifdef BLKSSZGET >>>> if (ioctl(fd, BLKSSZGET, §or_size) >= 0) { >>>> - bs->request_alignment = sector_size; >>>> + return sector_size; >>>> } >>>> #endif >>>> #ifdef DKIOCGETBLOCKSIZE >>>> if (ioctl(fd, DKIOCGETBLOCKSIZE, §or_size) >= 0) { >>>> - bs->request_alignment = sector_size; >>>> + return sector_size; >>>> } >>>> #endif >>>> #ifdef DIOCGSECTORSIZE >>>> if (ioctl(fd, DIOCGSECTORSIZE, §or_size) >= 0) { >>>> - bs->request_alignment = sector_size; >>>> + return sector_size; >>>> } >>>> #endif >>>> #ifdef CONFIG_XFS >>>> if (s->is_xfs) { >>>> struct dioattr da; >>>> if (xfsctl(NULL, fd, XFS_IOC_DIOINFO, &da) >= 0) { >>>> - bs->request_alignment = da.d_miniosz; >>>> + sector_size = da.d_miniosz; >>>> /* The kernel returns wrong information for d_mem */ >>>> /* s->buf_align = da.d_mem; */ >>> >>> Since you keep the enabled assignments to s->buf_align out of this >>> function, you should keep out this disabled one, too. >>> >>>> + return sector_size; >>>> } >>>> } >>>> #endif >>>> >>>> + return 0; >>>> +} >>>> + >>>> +static unsigned int probe_physical_blocksize(BlockDriverState *bs, int fd) >>> >>> Parameter bs is unused, let's drop it. >>> >>>> +{ >>>> + unsigned int blk_size = 0; >>> >>> Pointless initialization. >> >> Same here. > > Again, we return it only after ioctl() succeeded. > >>>> +#ifdef BLKPBSZGET >>>> + if (ioctl(fd, BLKPBSZGET, &blk_size) >= 0) { >>>> + return blk_size; >>>> + } >>>> +#endif >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) >>>> +{ >>>> + BDRVRawState *s = bs->opaque; >>>> + char *buf; >>>> + >>>> + /* For /dev/sg devices the alignment is not really used. >>>> + With buffered I/O, we don't have any restrictions. */ >>>> + if (bs->sg || !s->needs_alignment) { >>>> + bs->request_alignment = 1; >>>> + s->buf_align = 1; >>>> + return; >>>> + } >>>> + >>>> + s->buf_align = 0; >>>> + /* Let's try to use the logical blocksize for the alignment. */ >>>> + bs->request_alignment = probe_logical_blocksize(bs, fd); >>>> + >>>> /* If we could not get the sizes so far, we can only guess them */ >>>> if (!s->buf_align) { >>>> size_t align; >>> >