This patch addresses this issue:
When accessing a volume on an NFS filesystem without supporting the file lock,
tools, like qemu-img, will complain "Failed to lock byte 100".
Add a new function 'qemu_has_file_lock' to detect if the filesystem supports
locks
or not.
And when the drive is auto mode, use the 'qemu_has_file_lock' to set the toggle.
Signed-off-by: Li Feng <fen...@smartx.com>
---
v3: don't call the qemu_has_ofd_lock, use a new function instead.
v2: remove the refactoring.
---
block/file-posix.c | 30 +++++++++++++++++-------------
include/qemu/osdep.h | 1 +
util/osdep.c | 29 +++++++++++++++++++++++++++++
3 files changed, 47 insertions(+), 13 deletions(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index 806764f7e3..48f9a32de2 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -606,7 +606,7 @@ static int raw_open_common(BlockDriverState *bs, QDict
*options,
s->use_lock = false;
break;
case ON_OFF_AUTO_AUTO:
- s->use_lock = qemu_has_ofd_lock();
+ s->use_lock = qemu_has_file_lock(filename);
break;
default:
abort();
@@ -2388,6 +2388,7 @@ raw_co_create(BlockdevCreateOptions *options, Error
**errp)
int fd;
uint64_t perm, shared;
int result = 0;
+ bool use_lock;
/* Validate options and set default values */
assert(options->driver == BLOCKDEV_DRIVER_FILE);
@@ -2428,19 +2429,22 @@ raw_co_create(BlockdevCreateOptions *options, Error
**errp)
perm = BLK_PERM_WRITE | BLK_PERM_RESIZE;
shared = BLK_PERM_ALL & ~BLK_PERM_RESIZE;
- /* Step one: Take locks */
- result = raw_apply_lock_bytes(NULL, fd, perm, ~shared, false, errp);
- if (result < 0) {
- goto out_close;
- }
+ use_lock = qemu_has_file_lock(file_opts->filename);
+ if (use_lock) {
+ /* Step one: Take locks */
+ result = raw_apply_lock_bytes(NULL, fd, perm, ~shared, false, errp);
+ if (result < 0) {
+ goto out_close;
+ }
- /* Step two: Check that nobody else has taken conflicting locks */
- result = raw_check_lock_bytes(fd, perm, shared, errp);
- if (result < 0) {
- error_append_hint(errp,
- "Is another process using the image [%s]?\n",
- file_opts->filename);
- goto out_unlock;
+ /* Step two: Check that nobody else has taken conflicting locks */
+ result = raw_check_lock_bytes(fd, perm, shared, errp);
+ if (result < 0) {
+ error_append_hint(errp,
+ "Is another process using the image [%s]?\n",
+ file_opts->filename);
+ goto out_unlock;
+ }
}
/* Clear the file by truncating it to 0 */
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index f9ec8c84e9..593ae0f4d2 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -513,6 +513,7 @@ int qemu_lock_fd(int fd, int64_t start, int64_t len, bool
exclusive);
int qemu_unlock_fd(int fd, int64_t start, int64_t len);
int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
bool qemu_has_ofd_lock(void);
+bool qemu_has_file_lock(const char *filename);
#endif
#if defined(__HAIKU__) && defined(__i386__)
diff --git a/util/osdep.c b/util/osdep.c
index 66d01b9160..5d9961d261 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -225,6 +225,35 @@ static void qemu_probe_lock_ops(void)
}
}
+bool qemu_has_file_lock(const char *filename)
+{
+#ifdef F_OFD_SETLK
+ int cmd = F_OFD_GETLK;
+#else
+ int cmd = F_GETLK;
+#endif
+ int fd;
+ int ret;
+ struct flock fl = {
+ .l_whence = SEEK_SET,
+ .l_start = 0,
+ .l_len = 0,
+ .l_type = F_WRLCK,
+ };
+
+ fd = open(filename, O_RDWR);
+ if (fd < 0) {
+ fprintf(stderr,
+ "Failed to open %s for OFD lock probing: %s\n",
+ filename,
+ strerror(errno));
+ return false;
+ }
+ ret = fcntl(fd, cmd, &fl);
+ close(fd);
+ return ret == 0;
+}
+
bool qemu_has_ofd_lock(void)
{
qemu_probe_lock_ops();
--
2.24.3
