[PATCH] 9p: fix segfault caused by race condition in meta-data operations

Running dbench multithreaded exposed a race condition where fid structures
were removed while in use.  This patch adds semaphores to meta-data operations
to protect the fid structure.  Some cleanup of error-case handling in the
inode operations is also included.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/9p/fid.h b/fs/9p/fid.h
index aa974d6875c3..48fc170c26c8 100644
--- a/fs/9p/fid.h
+++ b/fs/9p/fid.h
@@ -30,6 +30,8 @@ struct v9fs_fid {
         struct list_head list;   /* list of fids associated with a dentry */
         struct list_head active; /* XXX - debug */
 
+        struct semaphore lock;
+
         u32 fid;
         unsigned char fidopen;    /* set when fid is opened */
         unsigned char fidclunked; /* set when fid has already been clunked */
@@ -55,3 +57,6 @@ struct v9fs_fid *v9fs_fid_get_created(struct dentry *);
 void v9fs_fid_destroy(struct v9fs_fid *fid);
 struct v9fs_fid *v9fs_fid_create(struct v9fs_session_info *, int fid);
 int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry);
+struct v9fs_fid *v9fs_fid_clone(struct dentry *dentry);
+void v9fs_fid_clunk(struct v9fs_session_info *v9ses, struct v9fs_fid *fid);
+