1 files changed, 10 insertions, 3 deletions

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 78bcb97c3425..ffed55817f0c 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -90,7 +90,9 @@ int v9fs_file_open(struct inode *inode, struct file *file)
         }
 
         file->private_data = fid;
-        if (v9ses->cache && !v9inode->writeback_fid) {
+        mutex_lock(&v9inode->v_mutex);
+        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
@@ -101,10 +103,12 @@ int v9fs_file_open(struct inode *inode, struct file *file)
                 fid = v9fs_writeback_fid(file->f_path.dentry);
                 if (IS_ERR(fid)) {
                         err = PTR_ERR(fid);
+                        mutex_unlock(&v9inode->v_mutex);
                         goto out_error;
                 }
                 v9inode->writeback_fid = (void *) fid;
         }
+        mutex_unlock(&v9inode->v_mutex);
 #ifdef CONFIG_9P_FSCACHE
         if (v9ses->cache)
                 v9fs_cache_inode_set_cookie(inode, file);
@@ -504,9 +508,12 @@ v9fs_file_write(struct file *filp, const char __user * data,
         if (!count)
                 goto out;
 
-        return v9fs_file_write_internal(filp->f_path.dentry->d_inode,
+        retval = v9fs_file_write_internal(filp->f_path.dentry->d_inode,
                                         filp->private_data,
-                                        data, count, offset, 1);
+                                        data, count, &origin, 1);
+        /* update offset on successful write */
+        if (retval > 0)
+                *offset = origin;
 out:
         return retval;
 }