fs/9p: Attach writeback_fid on first open with WR flag

We don't need writeback fid if we are only doing O_RDONLY open

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>
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 0afbbb4..774a20a 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -652,7 +652,8 @@
 	if (nd && nd->flags & LOOKUP_OPEN) {
 		v9inode = V9FS_I(dentry->d_inode);
 		mutex_lock(&v9inode->v_mutex);
-		if (v9ses->cache && !v9inode->writeback_fid) {
+		if (v9ses->cache && !v9inode->writeback_fid &&
+		    ((flags & O_ACCMODE) != O_RDONLY)) {
 			/*
 			 * clone a fid and add it to writeback_fid
 			 * we do it during open time instead of