This patch updates the existing documentation regarding recent changes to vfs_lock_file() and lm_grant() is set. In case of lm_grant() is set we only handle FILE_LOCK_DEFERRED in case of FL_SLEEP in fl_flags is not set. This is the case of an blocking lock request. Non-blocking lock requests, when FL_SLEEP is not set, are handled in a synchronized way. Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx> --- fs/locks.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index df8b26a42524..a8e51f462b43 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -2255,21 +2255,21 @@ int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock) * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX * locks, the ->lock() interface may return asynchronously, before the lock has * been granted or denied by the underlying filesystem, if (and only if) - * lm_grant is set. Callers expecting ->lock() to return asynchronously - * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if) - * the request is for a blocking lock. When ->lock() does return asynchronously, - * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock - * request completes. - * If the request is for non-blocking lock the file system should return - * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine - * with the result. If the request timed out the callback routine will return a + * lm_grant and FL_SLEEP in fl_flags is set. Callers expecting ->lock() to return + * asynchronously will only use F_SETLK, not F_SETLKW; When ->lock() does return + * asynchronously, it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when + * the lock request completes. The lm_grant() callback must be called in a + * sleepable context. + * + * If the request timed out the ->lm_grant() callback routine will return a * nonzero return code and the file system should release the lock. The file - * system is also responsible to keep a corresponding posix lock when it - * grants a lock so the VFS can find out which locks are locally held and do - * the correct lock cleanup when required. - * The underlying filesystem must not drop the kernel lock or call - * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED - * return code. + * system is also responsible to keep a corresponding posix lock when it grants + * a lock so the VFS can find out which locks are locally held and do the correct + * lock cleanup when required. + * + * If the request is for non-blocking lock (when F_SETLK and FL_SLEEP in fl_flags is not set) + * the file system should return -EAGAIN if failed to acquire or zero if acquiring was + * successfully without calling the ->lm_grant() callback routine. */ int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf) { -- 2.31.1