fs/9p: Fix race in initializing writeback fid

When two process open the same file we can end up with both of them
allocating the writeback_fid. Add a new mutex which can be used
for synchronizing v9fs_inode member values.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index bd8496db135b..89657e865162 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -130,6 +130,7 @@ struct v9fs_inode {
 #endif
         unsigned int cache_validity;
         struct p9_fid *writeback_fid;
+        struct mutex v_mutex;
         struct inode vfs_inode;
 };