On Wed, 2023-08-23 at 17:33 -0400, Alexander Aring wrote: > This patch adds a note to enable EXPORT_OP_SAFE_ASYNC_LOCK for > asynchronous lock request handling. > > Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx> > --- > fs/locks.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/fs/locks.c b/fs/locks.c > index df8b26a42524..edee02d1ca93 100644 > --- a/fs/locks.c > +++ b/fs/locks.c > @@ -2255,11 +2255,13 @@ 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. > + * lm_grant is set. Additionally EXPORT_OP_SAFE_ASYNC_LOCK in export_operations > + * flags need to be 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 Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
