jffs2: Fix page lock / f->sem deadlock
With this fix, all code paths should now be obtaining the page lock before
f->sem.
Reported-by: Szabó Tamás <sztomi89@gmail.com>
Tested-by: Thomas Betker <thomas.betker@rohde-schwarz.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@vger.kernel.org
diff --git a/fs/jffs2/README.Locking b/fs/jffs2/README.Locking
index 3ea3655..8918ac9 100644
--- a/fs/jffs2/README.Locking
+++ b/fs/jffs2/README.Locking
@@ -2,10 +2,6 @@
JFFS2 LOCKING DOCUMENTATION
---------------------------
-At least theoretically, JFFS2 does not require the Big Kernel Lock
-(BKL), which was always helpfully obtained for it by Linux 2.4 VFS
-code. It has its own locking, as described below.
-
This document attempts to describe the existing locking rules for
JFFS2. It is not expected to remain perfectly up to date, but ought to
be fairly close.
@@ -69,6 +65,7 @@
any f->sem held.
2. Never attempt to lock two file mutexes in one thread.
No ordering rules have been made for doing so.
+ 3. Never lock a page cache page with f->sem held.
erase_completion_lock spinlock