On 04/15/2016 06:27 AM, Fam Zheng wrote:
virtlockd in libvirt locks the first byte, we lock byte 1 to avoid
the intervene.
Suggested-by: "Daniel P. Berrange" <berra...@redhat.com>
Signed-off-by: Fam Zheng <f...@redhat.com>
---
block/raw-posix.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 906d5c9..3a2c17f 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>
@@ -397,6 +398,38 @@ static void raw_attach_aio_context(BlockDriverState *bs,
#endif
}
+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;
+ default:
+ abort();
+ }
+ ret = fcntl(s->fd, F_SETLK, &fl);
+ if (ret) {
+ ret = -errno;
+ }
+ return ret;
+}
+
#ifdef CONFIG_LINUX_AIO
static int raw_set_aio(void **aio_ctx, int *use_aio, int bdrv_flags)
{
@@ -1960,6 +1993,8 @@ BlockDriver bdrv_file = {
.bdrv_detach_aio_context = raw_detach_aio_context,
.bdrv_attach_aio_context = raw_attach_aio_context,
+ .bdrv_lockf = raw_lockf,
+
.create_opts = &raw_create_opts,
};
would it be better to use
int flock(int fd, int operation);
DESCRIPTION
Apply or remove an advisory lock on the open file specified by
fd. The
argument operation is one of the following:
LOCK_SH Place a shared lock. More than one process may
hold a
shared lock for a given file at a given time.
LOCK_EX Place an exclusive lock. Only one process may
hold an
exclusive lock for a given file at a given time.
LOCK_UN Remove an existing lock held by this process.
for this purpose?
Sorry that missed this point in the initial review...
We will not intersect with libvirt for the case.
Den
