From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52392) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z2G4f-0005bw-36 for qemu-devel@nongnu.org; Tue, 09 Jun 2015 05:44:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z2G4e-0007sh-2f for qemu-devel@nongnu.org; Tue, 09 Jun 2015 05:44:00 -0400 Message-ID: <5576B638.8000907@cn.fujitsu.com> Date: Tue, 9 Jun 2015 17:47:36 +0800 From: Wen Congyang MIME-Version: 1.0 References: <1433840108-9996-1-git-send-email-kwolf@redhat.com> In-Reply-To: <1433840108-9996-1-git-send-email-kwolf@redhat.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] raw-posix: Fix .bdrv_co_get_block_status() for unaligned image size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf , qemu-block@nongnu.org Cc: pbonzini@redhat.com, crobinso@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, eharney@redhat.com On 06/09/2015 04:55 PM, Kevin Wolf wrote: > Image files with an unaligned image size have a final hole that starts > at EOF, i.e. in the middle of a sector. Currently, *pnum == 0 is > returned when checking the status of this sector. In qemu-img, this > triggers an assertion failure. > > In order to fix this, one type for the sector that contains EOF must be > found. Treating a hole as data is safe, so this patch rounds the > calculated number of data sectors up, so that a partial sector at EOF is > treated as a full data sector. > > This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1229394 > > Signed-off-by: Kevin Wolf > --- > block/raw-posix.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/block/raw-posix.c b/block/raw-posix.c > index 2990e95..44ade8c 100644 > --- a/block/raw-posix.c > +++ b/block/raw-posix.c > @@ -1848,8 +1848,9 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs, > *pnum = nb_sectors; > ret = BDRV_BLOCK_DATA; > } else if (data == start) { > - /* On a data extent, compute sectors to the end of the extent. */ > - *pnum = MIN(nb_sectors, (hole - start) / BDRV_SECTOR_SIZE); > + /* On a data extent, compute sectors to the end of the extent, > + * possibly including a partial sector at EOF. */ Not only for EOF. If the hole and start are in the same sector, (hole - start) / BDRV_SECTOR_SIZE will be 0 > + *pnum = MIN(nb_sectors, DIV_ROUND_UP(hole - start, BDRV_SECTOR_SIZE)); > ret = BDRV_BLOCK_DATA; > } else { > /* On a hole, compute sectors to the beginning of the next extent. */ > So, if start is hole, data and start are in the same sector, (data - start) / BDRV_SECTOR_SIZE will be 0, you also need to fix it here. Thanks Wen Congyang