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>

fs/9p/vfs_file.c

@@ -91,7 +91,8 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 
 	file->private_data = fid;
 	mutex_lock(&v9inode->v_mutex);
-	if (v9ses->cache && !v9inode->writeback_fid) {
+	if (v9ses->cache && !v9inode->writeback_fid &&
+	    ((file->f_flags & O_ACCMODE) != O_RDONLY)) {
 		/*
 		 * clone a fid and add it to writeback_fid
 		 * we do it during open time instead of

fs/9p/vfs_inode.c

@@ -652,7 +652,8 @@ v9fs_vfs_create(struct inode *dir, struct dentry *dentry, int mode,
 	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

fs/9p/vfs_inode_dotl.c

@@ -246,7 +246,8 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, int omode,
 
 	v9inode = V9FS_I(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