locks: protect most of the file_lock handling with i_lock

[linux-2.6-block.git] / Documentation / filesystems / Locking

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index f94a362f408e813a43727fdf73ed9a2209be7551..c2963a74fbc31290712df41d39a1dc101b7d0611 100644 (file)
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -342,7 +342,7 @@ prototypes:
 
 
 locking rules:
-                       file_lock_lock  may block
+                       inode->i_lock   may block
 fl_copy_lock:          yes             no
 fl_release_private:    maybe           no
 
@@ -355,12 +355,19 @@ prototypes:
        int (*lm_change)(struct file_lock **, int);
 
 locking rules:
-                       file_lock_lock  may block
-lm_compare_owner:      yes             no
-lm_notify:             yes             no
-lm_grant:              no              no
-lm_break:              yes             no
-lm_change              yes             no
+
+                       inode->i_lock   file_lock_lock  may block
+lm_compare_owner:      yes[1]          maybe           no
+lm_notify:             yes             yes             no
+lm_grant:              no              no              no
+lm_break:              yes             no              no
+lm_change              yes             no              no
+
+[1]:   ->lm_compare_owner is generally called with *an* inode->i_lock held. It
+may not be the i_lock of the inode for either file_lock being compared! This is
+the case with deadlock detection, since the code has to chase down the owners
+of locks that may be entirely unrelated to the one on which the lock is being
+acquired. When doing a search for deadlocks, the file_lock_lock is also held.
 
 --------------------------- buffer_head -----------------------------------
 prototypes: