[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implem
From: |
Fam Zheng |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf |
Date: |
Mon, 18 Apr 2016 09:10:36 +0800 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Sun, 04/17 20:27, Richard W.M. Jones wrote:
> On Fri, Apr 15, 2016 at 11:27:55AM +0800, Fam Zheng wrote:
> > virtlockd in libvirt locks the first byte, we lock byte 1 to avoid
> > the intervene.
> > +static int raw_lockf(BlockDriverState *bs, BdrvLockfCmd cmd)
> > +{
> > +
> > + BDRVRawState *s = bs->opaque;
> > + int ret;
> > + struct flock fl = (struct flock) {
> > + .l_whence = SEEK_SET,
> > + /* Locking byte 1 avoids interfereing with virtlockd. */
> > + .l_start = 1,
> > + .l_len = 1,
> > + };
> > +
> > + switch (cmd) {
> > + case BDRV_LOCKF_RWLOCK:
> > + fl.l_type = F_WRLCK;
> > + break;
> > + case BDRV_LOCKF_ROLOCK:
> > + fl.l_type = F_RDLCK;
> > + break;
> > + case BDRV_LOCKF_UNLOCK:
> > + fl.l_type = F_UNLCK;
> > + break;
>
> My understanding is this prevents libguestfs from working on live disk
> images -- we want to be able to read live disk images (using a
> writable overlay and the real disk image as a read-only backing file).
Do you lock the live image or the backing file? If not, you can just read/write
as before, as what the -L option does in this series. Otherwise, you should use
an RO lock on the backing image, which still works.
Fam
- Re: [Qemu-block] [PATCH for-2.7 v2 04/17] block: Introduce image file locking, (continued)
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Richard W.M. Jones, 2016/04/17
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf,
Fam Zheng <=
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Richard W.M. Jones, 2016/04/18
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Fam Zheng, 2016/04/19
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Richard W.M. Jones, 2016/04/19
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Fam Zheng, 2016/04/19
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Richard W.M. Jones, 2016/04/19
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Daniel P. Berrange, 2016/04/19
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Daniel P. Berrange, 2016/04/19
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.7 v2 05/17] raw-posix: Implement .bdrv_lockf, Richard W.M. Jones, 2016/04/19
[Qemu-block] [PATCH for-2.7 v2 07/17] rbd: Implement image locking, Fam Zheng, 2016/04/14