/**
* lock a file on disk for the process.
*
* @param[in] lf the struct VLockFile representing the file to lock
* @param[in] offset the offset in the file to lock
* @param[in] locktype READ_LOCK or WRITE_LOCK
* @param[in] nonblock 0 to wait for conflicting locks to clear before
* obtaining the lock; 1 to fail immediately if a
* conflicting lock is held by someone else
*
* @return operation status
* @retval 0 success
* @retval EBUSY someone else is holding a conflicting lock and nonblock=1 was
* specified
* @retval EIO error acquiring file lock
*
* @note DAFS only
*
* @note do not try to lock/unlock the same offset in the same file from
* different threads; use VGetDiskLock to protect threads from each other in
* addition to other processes
*/
int
VLockFileLock(struct VLockFile *lf, afs_uint32 offset, int locktype, int nonblock)
{
int code;
opr_Assert(locktype == READ_LOCK || locktype == WRITE_LOCK);
opr_mutex_enter(&lf->mutex);
if (lf->fd == INVALID_FD) {
lf->fd = _VOpenPath(lf->path);
if (lf->fd == INVALID_FD) {
opr_mutex_exit(&lf->mutex);
return EIO;
}
}
lf->refcount++;
opr_mutex_exit(&lf->mutex);
code = _VLockFd(lf->fd, offset, locktype, nonblock);
if (code) {
opr_mutex_enter(&lf->mutex);
if (--lf->refcount < 1) {
_VCloseFd(lf->fd);
lf->fd = INVALID_FD;
}
opr_mutex_exit(&lf->mutex);
}
return code;
}
/**
* lock a file on disk for the process.
*
* @param[in] lf the struct VLockFile representing the file to lock
* @param[in] offset the offset in the file to lock
* @param[in] locktype READ_LOCK or WRITE_LOCK
* @param[in] nonblock 0 to wait for conflicting locks to clear before
* obtaining the lock; 1 to fail immediately if a
* conflicting lock is held by someone else
*
* @return operation status
* @retval 0 success
* @retval EBUSY someone else is holding a conflicting lock and nonblock=1 was
* specified
* @retval EIO error acquiring file lock
*
* @note DAFS only
*
* @note do not try to lock/unlock the same offset in the same file from
* different threads; use VGetDiskLock to protect threads from each other in
* addition to other processes
*/
int
VLockFileLock(struct VLockFile *lf, afs_uint32 offset, int locktype, int nonblock)
{
int code;
assert(locktype == READ_LOCK || locktype == WRITE_LOCK);
AFS_LF_LOCK(lf);
if (lf->fd == INVALID_FD) {
lf->fd = _VOpenPath(lf->path);
if (lf->fd == INVALID_FD) {
AFS_LF_UNLOCK(lf);
return EIO;
}
}
lf->refcount++;
AFS_LF_UNLOCK(lf);
code = _VLockFd(lf->fd, offset, locktype, nonblock);
if (code) {
AFS_LF_LOCK(lf);
if (--lf->refcount < 1) {
_VCloseFd(lf->fd);
lf->fd = INVALID_FD;
}
AFS_LF_UNLOCK(lf);
}
return code;
}
