locks: allow ->lock() to return FILE_LOCK_DEFERRED

Allow filesystem's ->lock() method to call posix_lock_file() instead of
posix_lock_file_wait(), and return FILE_LOCK_DEFERRED.  This makes it
possible to implement a such a ->lock() function, that works with the lock
manager, which needs the call to be asynchronous.

Now the vfs_lock_file() helper can be used, so this is a cleanup as well.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: David Teigland <teigland@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 14 deletions

diff --git a/fs/locks.c b/fs/locks.c
index 6222e4b580e2..01490300f7cb 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1747,21 +1747,16 @@ static int do_lock_file_wait(struct file *filp, unsigned int cmd,
         if (error)
                 return error;
 
-        if (filp->f_op && filp->f_op->lock != NULL)
-                error = filp->f_op->lock(filp, cmd, fl);
-        else {
-                for (;;) {
-                        error = posix_lock_file(filp, fl, NULL);
-                        if (error != FILE_LOCK_DEFERRED)
-                                break;
-                        error = wait_event_interruptible(fl->fl_wait,
-                                                         !fl->fl_next);
-                        if (!error)
-                                continue;
-
-                        locks_delete_block(fl);
+        for (;;) {
+                error = vfs_lock_file(filp, cmd, fl, NULL);
+                if (error != FILE_LOCK_DEFERRED)
                         break;
-                }
+                error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
+                if (!error)
+                        continue;
+
+                locks_delete_block(fl);
+                break;
         }
 
         return error;