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Re: [Qemu-block] [PATCH for-2.7 05/15] raw-posix: Implement .bdrv_lockf
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-block] [PATCH for-2.7 05/15] raw-posix: Implement .bdrv_lockf |
Date: |
Wed, 13 Apr 2016 10:21:06 +0100 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Wed, Apr 13, 2016 at 05:09:54PM +0800, Fam Zheng wrote:
> Because virtlockd in libvirt already uses the fcntl lock on the image file, we
> have to workaround this by locking a digest-mapped temporary file.
>
> Signed-off-by: Fam Zheng <address@hidden>
> ---
> block/raw-posix.c | 97
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 97 insertions(+)
>
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index 906d5c9..277f20d 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -35,6 +35,7 @@
> #include "raw-aio.h"
> #include "qapi/util.h"
> #include "qapi/qmp/qstring.h"
> +#include "glib.h"
>
> #if defined(__APPLE__) && (__MACH__)
> #include <paths.h>
> @@ -149,6 +150,9 @@ typedef struct BDRVRawState {
> bool discard_zeroes:1;
> bool has_fallocate;
> bool needs_alignment;
> + bool image_locked;
> + int lock_file_fd;
> + char *lock_file_name;
> } BDRVRawState;
>
> typedef struct BDRVRawReopenState {
> @@ -397,6 +401,87 @@ static void raw_attach_aio_context(BlockDriverState *bs,
> #endif
> }
>
> +static int raw_do_lockf(int fd, BdrvLockfCmd cmd)
> +{
> + int ret;
> + struct flock fl = (struct flock) {
> + .l_start = 0,
> + .l_whence = SEEK_SET,
> + .l_len = 0,
> + };
If you change this to
.l_start = 1,
.l_len = 1,
then you would be telling a selective lock at byte 1 which would
not interfere with anything virtlockd currently does, and also
leave the other bytes unlocked for future use by QEMU or libvirt
as needed.
Regards,
Daniel
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- [Qemu-block] [PATCH for-2.7 00/15] block: Lock images when opening, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 01/15] block: Add BDRV_O_NO_LOCK, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 02/15] qapi: Add lock-image in blockdev-add options, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 03/15] blockdev: Add and parse "lock-image" option for block devices, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 04/15] block: Introduce image file locking interface, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 05/15] raw-posix: Implement .bdrv_lockf, Fam Zheng, 2016/04/13
- Re: [Qemu-block] [PATCH for-2.7 05/15] raw-posix: Implement .bdrv_lockf,
Daniel P. Berrange <=
- [Qemu-block] [PATCH for-2.7 07/15] qemu-io: Add "-L" option for BDRV_O_NO_LOCK, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 06/15] gluster: Implement .bdrv_lockf, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 08/15] qemu-iotests: 140: Disable image lock for qemu-io access, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 09/15] qemu-iotests: 046: Move version detection out from verify_io, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 11/15] qemu-iotests: Disable image lock when checking test image, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 10/15] qemu-iotests: Fix lock-image for shared disk in test case 091, Fam Zheng, 2016/04/13
- [Qemu-block] [PATCH for-2.7 13/15] ahci-test: Specify "lock-image=off" in CLI, Fam Zheng, 2016/04/13