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Re: [Qemu-devel] [PATCH 3/7] block: raw-posix image file reopen
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH 3/7] block: raw-posix image file reopen |
Date: |
Fri, 31 Aug 2012 16:49:50 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 |
Am 31.08.2012 16:42, schrieb Jeff Cody:
> On 08/30/2012 06:15 PM, Eric Blake wrote:
>> On 08/30/2012 11:47 AM, Jeff Cody wrote:
>>> This is derived from the Supriya Kannery's reopen patches.
>>>
>>> This contains the raw-posix driver changes for the bdrv_reopen_*
>>> functions. All changes are staged into a temporary scratch buffer
>>> during the prepare() stage, and copied over to the live structure
>>> during commit(). Upon abort(), all changes are abandoned, and the
>>> live structures are unmodified.
>>>
>>> The _prepare() will create an extra fd - either by means of a dup,
>>> if possible, or opening a new fd if not (for instance, access
>>> control changes). Upon _commit(), the original fd is closed and
>>> the new fd is used. Upon _abort(), the duplicate/new fd is closed.
>>>
>>
>>> + if ((raw_s->open_flags & ~fcntl_flags) == (s->open_flags &
>>> ~fcntl_flags)) {
>>> + /* dup the original fd */
>>> + /* TODO: use qemu fcntl wrapper */
>>> + raw_s->fd = fcntl(s->fd, F_DUPFD_CLOEXEC, 0);
>>
>> I assume this TODO has to be fixed to allow compilation on systems that
>> lack F_DUPFD_CLOEXEC.
>
> Yes, either that or add the logic here.
Would qemu_dup_flags() from osdep.c be the right thing here? It was
introduces with Corey's fd passing series.
>>> + if (raw_s->fd == -1) {
>>> + ret = -1;
>>> + goto error;
>>> + }
>>> + ret = fcntl_setfl(raw_s->fd, raw_s->open_flags);
>>> + } else {
>>> + raw_s->fd = qemu_open(state->bs->filename, raw_s->open_flags,
>>> 0644);
>>
>> Is raw_s->open_flags every going to contain O_CREAT, or is the 0644 mode
>> argument spurious?
>
> Thanks, you are right, it is spurious. The raw_s->open_flags are
> explicitly set via raw_parse_flags(), so we know it will never contain
> O_CREAT.
We can probably assert it.
Kevin
- [Qemu-devel] [PATCH 0/7] block: bdrv_reopen() patches, Jeff Cody, 2012/08/30
- [Qemu-devel] [PATCH 1/7] block: correctly set the keep_read_only flag, Jeff Cody, 2012/08/30
- [Qemu-devel] [PATCH 2/7] block: Framework for reopening files safely, Jeff Cody, 2012/08/30
- [Qemu-devel] [PATCH 4/7] block: raw image file reopen, Jeff Cody, 2012/08/30
- [Qemu-devel] [PATCH 5/7] block: qed image file reopen, Jeff Cody, 2012/08/30
- [Qemu-devel] [PATCH 3/7] block: raw-posix image file reopen, Jeff Cody, 2012/08/30
[Qemu-devel] [PATCH 6/7] block: qcow2 image file reopen, Jeff Cody, 2012/08/30
[Qemu-devel] [PATCH 7/7] block: qcow image file reopen, Jeff Cody, 2012/08/30