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[Qemu-block] [PATCH for-2.7 05/15] raw-posix: Implement .bdrv_lockf
From: |
Fam Zheng |
Subject: |
[Qemu-block] [PATCH for-2.7 05/15] raw-posix: Implement .bdrv_lockf |
Date: |
Wed, 13 Apr 2016 17:09:54 +0800 |
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,
+ };
+ 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(fd, F_SETLK, &fl);
+ return ret == -1 ? -errno : 0;
+}
+
+static char *raw_get_lock_file_name(BlockDriverState *bs)
+{
+ GChecksum *cksm;
+ const char *digest;
+ char *lock_file = NULL;
+ char *fullpath = g_malloc(PATH_MAX);
+
+ if (!realpath(bs->filename, fullpath)) {
+ pstrcpy(fullpath, PATH_MAX, bs->filename);
+ }
+ cksm = g_checksum_new(G_CHECKSUM_SHA1);
+ g_checksum_update(cksm, (const guchar *)fullpath, strlen(fullpath));
+ g_free(fullpath);
+ digest = g_checksum_get_string(cksm);
+ if (digest) {
+ lock_file = g_strdup_printf("/var/tmp/.qemu-%s.lock", digest);
+ }
+ g_checksum_free(cksm);
+ return lock_file;
+}
+
+static int raw_lockf(BlockDriverState *bs, BdrvLockfCmd cmd, Error **errp)
+{
+
+ BDRVRawState *s = bs->opaque;
+ int ret;
+
+ if ((cmd == BDRV_LOCKF_UNLOCK) == (!s->image_locked)) {
+ return 0;
+ }
+ if (s->lock_file_fd == -1) {
+ /* Create and open the lock file if necessary. */
+
+ assert(cmd != BDRV_LOCKF_UNLOCK);
+
+ s->lock_file_name = raw_get_lock_file_name(bs);
+
+ s->lock_file_fd = qemu_open(s->lock_file_name, O_RDWR | O_CREAT, 0644);
+ if (s->lock_file_fd == -1) {
+ error_setg_errno(errp, errno, "Failed to open file");
+ ret = -EIO;
+ goto out;
+ }
+ }
+
+ ret = raw_do_lockf(s->lock_file_fd, cmd);
+ if (ret) {
+ error_setg_errno(errp, errno,
+ "Failed to lock file: %s", s->lock_file_name);
+ } else {
+ s->image_locked = cmd != BDRV_LOCKF_UNLOCK;
+ }
+out:
+ return ret;
+}
+
#ifdef CONFIG_LINUX_AIO
static int raw_set_aio(void **aio_ctx, int *use_aio, int bdrv_flags)
{
@@ -585,6 +670,7 @@ static int raw_open(BlockDriverState *bs, QDict *options,
int flags,
int ret;
s->type = FTYPE_FILE;
+ s->lock_file_fd = -1;
ret = raw_open_common(bs, options, flags, 0, &local_err);
if (local_err) {
error_propagate(errp, local_err);
@@ -1393,6 +1479,15 @@ static void raw_close(BlockDriverState *bs)
raw_detach_aio_context(bs);
+ if (s->lock_file_fd != -1) {
+ qemu_close(s->lock_file_fd);
+ s->lock_file_fd = -1;
+ }
+ if (s->lock_file_name) {
+ unlink(s->lock_file_name);
+ g_free(s->lock_file_name);
+ s->lock_file_name = NULL;
+ }
#ifdef CONFIG_LINUX_AIO
if (s->use_aio) {
laio_cleanup(s->aio_ctx);
@@ -1960,6 +2055,8 @@ 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,
};
--
2.8.0
- [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 <=
- [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