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Add parameter to wait for lock in file locking APIs

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Our current pidfile acquire APis (virPidFileAcquire) simply return -1 upon
failure to acquire a lock. This patch adds a parameter 'bool waitForLock'
which instructs the APIs if we want to make it block and wait for the lock
or not.
This commit is contained in:
Nehal J Wani 2014-03-17 19:47:36 +05:30 committed by Eric Blake
parent cb873e9d15
commit 2250a2b5d2
7 changed files with 22 additions and 14 deletions
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2
daemon/libvirtd.c
View File

@ -1369,7 +1369,7 @@ int main(int argc, char **argv) {
umask(old_umask);
/* Try to claim the pidfile, exiting if we can't */
if ((pid_file_fd = virPidFileAcquirePath(pid_file, getpid())) < 0) {
if ((pid_file_fd = virPidFileAcquirePath(pid_file, false, getpid())) < 0) {
ret = VIR_DAEMON_ERR_PIDFILE;
goto cleanup;
}

4
src/locking/lock_daemon.c
View File

@ -1020,7 +1020,7 @@ virLockDaemonPostExecRestart(const char *state_file,
/* Re-claim PID file now as we will not be daemonizing */
if (pid_file &&
(*pid_file_fd = virPidFileAcquirePath(pid_file, getpid())) < 0)
(*pid_file_fd = virPidFileAcquirePath(pid_file, false, getpid())) < 0)
goto cleanup;
if (!(lockDaemon = virLockDaemonNewPostExecRestart(object, privileged)))
@ -1382,7 +1382,7 @@ int main(int argc, char **argv) {
}
/* If we have a pidfile set, claim it now, exiting if already taken */
if ((pid_file_fd = virPidFileAcquirePath(pid_file, getpid())) < 0) {
if ((pid_file_fd = virPidFileAcquirePath(pid_file, false, getpid())) < 0) {
ret = VIR_LOCK_DAEMON_ERR_PIDFILE;
goto cleanup;
}

14
src/util/virfile.c
View File

@ -339,13 +339,14 @@ virFileWrapperFdFree(virFileWrapperFdPtr wfd)
* @shared: type of lock to acquire
* @start: byte offset to start lock
* @len: length of lock (0 to acquire entire remaining file from @start)
* @waitForLock: wait for previously held lock or not
*
* Attempt to acquire a lock on the file @fd. If @shared
* is true, then a shared lock will be acquired,
* otherwise an exclusive lock will be acquired. If
* the lock cannot be acquired, an error will be
* returned. This will not wait to acquire the lock if
* another process already holds it.
* returned. If @waitForLock is true, this will wait
* for the lock if another process has already acquired it.
*
* The lock will be released when @fd is closed. The lock
* will also be released if *any* other open file descriptor
@ -356,7 +357,7 @@ virFileWrapperFdFree(virFileWrapperFdPtr wfd)
*
* Returns 0 on success, or -errno otherwise
*/
int virFileLock(int fd, bool shared, off_t start, off_t len)
int virFileLock(int fd, bool shared, off_t start, off_t len, bool waitForLock)
{
struct flock fl = {
.l_type = shared ? F_RDLCK : F_WRLCK,
@ -365,7 +366,9 @@ int virFileLock(int fd, bool shared, off_t start, off_t len)
.l_len = len,
};
if (fcntl(fd, F_SETLK, &fl) < 0)
int cmd = waitForLock ? F_SETLKW : F_SETLK;
if (fcntl(fd, cmd, &fl) < 0)
return -errno;
return 0;
@ -402,7 +405,8 @@ int virFileUnlock(int fd, off_t start, off_t len)
int virFileLock(int fd ATTRIBUTE_UNUSED,
bool shared ATTRIBUTE_UNUSED,
off_t start ATTRIBUTE_UNUSED,
off_t len ATTRIBUTE_UNUSED)
off_t len ATTRIBUTE_UNUSED,
bool waitForLock ATTRIBUTE_UNUSED)
{
return -ENOSYS;
}

2
src/util/virfile.h
View File

@ -97,7 +97,7 @@ int virFileWrapperFdClose(virFileWrapperFdPtr dfd);
void virFileWrapperFdFree(virFileWrapperFdPtr dfd);
int virFileLock(int fd, bool shared, off_t start, off_t len);
int virFileLock(int fd, bool shared, off_t start, off_t len, bool waitForLock);
int virFileUnlock(int fd, off_t start, off_t len);
typedef int (*virFileRewriteFunc)(int fd, void *opaque);

6
src/util/virlockspace.c
View File

@ -82,7 +82,7 @@ static void virLockSpaceResourceFree(virLockSpaceResourcePtr res)
if (res->flags & VIR_LOCK_SPACE_ACQUIRE_SHARED) {
/* We must upgrade to an exclusive lock to ensure
* no one else still has it before trying to delete */
if (virFileLock(res->fd, false, 0, 1) < 0) {
if (virFileLock(res->fd, false, 0, 1, false) < 0) {
VIR_DEBUG("Could not upgrade shared lease to exclusive, not deleting");
} else {
if (unlink(res->path) < 0 &&
@ -155,7 +155,7 @@ virLockSpaceResourceNew(virLockSpacePtr lockspace,
goto error;
}
if (virFileLock(res->fd, shared, 0, 1) < 0) {
if (virFileLock(res->fd, shared, 0, 1, false) < 0) {
if (errno == EACCES || errno == EAGAIN) {
virReportError(VIR_ERR_RESOURCE_BUSY,
_("Lockspace resource '%s' is locked"),
@ -202,7 +202,7 @@ virLockSpaceResourceNew(virLockSpacePtr lockspace,
goto error;
}
if (virFileLock(res->fd, shared, 0, 1) < 0) {
if (virFileLock(res->fd, shared, 0, 1, false) < 0) {
if (errno == EACCES || errno == EAGAIN) {
virReportError(VIR_ERR_RESOURCE_BUSY,
_("Lockspace resource '%s' is locked"),

6
src/util/virpidfile.c
View File

@ -372,6 +372,7 @@ cleanup:
}
int virPidFileAcquirePath(const char *path,
bool waitForLock,
pid_t pid)
{
int fd = -1;
@ -405,7 +406,7 @@ int virPidFileAcquirePath(const char *path,
return -1;
}
if (virFileLock(fd, false, 0, 1) < 0) {
if (virFileLock(fd, false, 0, 1, waitForLock) < 0) {
virReportSystemError(errno,
_("Failed to acquire pid file '%s'"),
path);
@ -448,6 +449,7 @@ int virPidFileAcquirePath(const char *path,
int virPidFileAcquire(const char *dir,
const char *name,
bool waitForLock,
pid_t pid)
{
int rc = 0;
@ -463,7 +465,7 @@ int virPidFileAcquire(const char *dir,
goto cleanup;
}
rc = virPidFileAcquirePath(pidfile, pid);
rc = virPidFileAcquirePath(pidfile, waitForLock, pid);
cleanup:
VIR_FREE(pidfile);

2
src/util/virpidfile.h
View File

@ -56,9 +56,11 @@ int virPidFileDelete(const char *dir,
int virPidFileAcquirePath(const char *path,
bool waitForLock,
pid_t pid) ATTRIBUTE_RETURN_CHECK;
int virPidFileAcquire(const char *dir,
const char *name,
bool waitForLock,
pid_t pid) ATTRIBUTE_RETURN_CHECK;
int virPidFileReleasePath(const char *path,