From 2beb6614f5e36c6165b704c167d82ef3e4ceaa0c Mon Sep 17 00:00:00 2001 From: Marc Eshel Date: Tue, 5 Dec 2006 23:31:28 -0500 Subject: locks: add fl_grant callback for asynchronous lock return Acquiring a lock on a cluster filesystem may require communication with remote hosts, and to avoid blocking lockd or nfsd threads during such communication, we allow the results to be returned asynchronously. When a ->lock() call needs to block, the file system will return -EINPROGRESS, and then later return the results with a call to the routine in the fl_grant field of the lock_manager_operations struct. This differs from the case when ->lock returns -EAGAIN to a blocking lock request; in that case, the filesystem calls fl_notify when the lock is granted, and the caller retries the original lock. So while fl_notify is merely a hint to the caller that it should retry, fl_grant actually communicates the final result of the lock operation (with the lock already acquired in the succesful case). Therefore fl_grant takes a lock, a status and, for the test lock case, a conflicting lock. We also allow fl_grant to return an error to the filesystem, to handle the case where the fl_grant requests arrives after the lock manager has already given up waiting for it. Signed-off-by: Marc Eshel Signed-off-by: J. Bruce Fields --- include/linux/fs.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/fs.h') diff --git a/include/linux/fs.h b/include/linux/fs.h index 64b8ae205309..b22991d5f16b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -785,6 +785,7 @@ struct file_lock_operations { struct lock_manager_operations { int (*fl_compare_owner)(struct file_lock *, struct file_lock *); void (*fl_notify)(struct file_lock *); /* unblock callback */ + int (*fl_grant)(struct file_lock *, struct file_lock *, int); void (*fl_copy_lock)(struct file_lock *, struct file_lock *); void (*fl_release_private)(struct file_lock *); void (*fl_break)(struct file_lock *); -- cgit v1.2.3-59-g8ed1b