reiserfs: fix xattr root locking/refcount bug
authorJeff Mahoney <jeffm@suse.com>
Mon, 23 Apr 2007 21:41:17 +0000 (14:41 -0700)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Tue, 24 Apr 2007 15:23:09 +0000 (08:23 -0700)
commit9b7f375505f5611efb562065b57814b28a81abc3
tree3f51e49ca5b70081bf15f4ce9d7ddbd289917932
parent1a641fceb6bb6b0930db1aadbda1aaf5711d65d6
reiserfs: fix xattr root locking/refcount bug

The listxattr() and getxattr() operations are only protected by a read
lock.  As a result, if either of these operations run in parallel, a race
condition exists where the xattr_root will end up being cached twice, which
results in the leaking of a reference and a BUG() on umount.

This patch refactors get_xa_root(), __get_xa_root(), and create_xa_root(),
into one get_xa_root() function that takes the appropriate locking around
the entire critical section.

Reported, diagnosed and tested by Andrea Righi <a.righi@cineca.it>

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Cc: Andrea Righi <a.righi@cineca.it>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Edward Shishkin <edward@namesys.com>
Cc: Alex Zarochentsev <zam@namesys.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/reiserfs/xattr.c