From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:35831) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T9FMA-00081U-Dh for qemu-devel@nongnu.org; Wed, 05 Sep 2012 09:09:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T9FM0-00054O-Ph for qemu-devel@nongnu.org; Wed, 05 Sep 2012 09:09:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1507) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T9FM0-00052t-H2 for qemu-devel@nongnu.org; Wed, 05 Sep 2012 09:09:12 -0400 Message-ID: <50474EDC.1090204@redhat.com> Date: Wed, 05 Sep 2012 09:08:44 -0400 From: Jeff Cody MIME-Version: 1.0 References: <431ff7f85fb9c83b5300360273322e6a0c76aee2.1346352124.git.jcody@redhat.com> <504749EE.20903@redhat.com> In-Reply-To: <504749EE.20903@redhat.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/7] block: correctly set the keep_read_only flag Reply-To: jcody@redhat.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: supriyak@linux.vnet.ibm.com, pbonzini@redhat.com, eblake@redhat.com, qemu-devel@nongnu.org, stefanha@gmail.com On 09/05/2012 08:47 AM, Kevin Wolf wrote: > Am 30.08.2012 20:47, schrieb Jeff Cody: >> I believe the bs->keep_read_only flag is supposed to reflect >> the initial open state of the device. If the device is initially >> opened R/O, then commit operations, or reopen operations changing >> to R/W, are prohibited. >> >> Currently, the keep_read_only flag is only accurate for the active >> layer, and its backing file. Subsequent images end up always having >> the keep_read_only flag set. >> >> For instance, what happens now: >> >> [ base ] kro = 1, ro = 1 >> | >> v >> [ snap-1 ] kro = 1, ro = 1 >> | >> v >> [ snap-2 ] kro = 0, ro = 1 >> | >> v >> [ active ] kro = 0, ro = 0 >> >> What we want: >> >> [ base ] kro = 0, ro = 1 >> | >> v >> [ snap-1 ] kro = 0, ro = 1 >> | >> v >> [ snap-2 ] kro = 0, ro = 1 >> | >> v >> [ active ] kro = 0, ro = 0 >> >> Signed-off-by: Jeff Cody >> --- >> block.c | 16 +++++++--------- >> block.h | 1 + >> 2 files changed, 8 insertions(+), 9 deletions(-) >> >> diff --git a/block.c b/block.c >> index 470bdcc..e31b76f 100644 >> --- a/block.c >> +++ b/block.c >> @@ -655,7 +655,7 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename, >> * Clear flags that are internal to the block layer before opening the >> * image. >> */ >> - open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING); >> + open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_ALLOW_RDWR); >> >> /* >> * Snapshots should be writable. >> @@ -664,8 +664,6 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename, >> open_flags |= BDRV_O_RDWR; >> } >> >> - bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR); >> - >> /* Open the image, either directly or using a protocol */ >> if (drv->bdrv_file_open) { >> ret = drv->bdrv_file_open(bs, filename, open_flags); >> @@ -804,6 +802,12 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags, >> goto unlink_and_fail; >> } >> >> + if (flags & BDRV_O_RDWR) { >> + flags |= BDRV_O_ALLOW_RDWR; >> + } >> + >> + bs->keep_read_only = !(flags & BDRV_O_ALLOW_RDWR); > > Do we still need bs->keep_read_only or is it duplicated in > bs->open_flags now? We can convert all users in a follow-up patch. > I think we can ditch keep_read_only, and just use BDRV_O_ALLOW_RDWR. The only other user of keep_read_only is the original bdrv_commit(), in block.c. And, the natural way to convert that function would be to have it use bdrv_reopen(), to change from r/o->r/w.