Re: [syzbot] [v9fs?] WARNING in v9fs_begin_writeback

[Edward Adam Davis]

debug

#syz test: upstream c0ecd6388360

diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index e0d34e4e9076..cb511d49e35a 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -218,8 +218,10 @@ int v9fs_dir_release(struct inode *inode, struct file *filp)
 		if ((S_ISREG(inode->i_mode)) && (filp->f_mode & FMODE_WRITE))
 			retval = filemap_fdatawrite(inode->i_mapping);
 
+		printk("fid: %p, %s\n", fid, __func__);
 		spin_lock(&inode->i_lock);
-		hlist_del(&fid->ilist);
+		if (refcount_read(&fid->count) == 1)
+			hlist_del(&fid->ilist);
 		spin_unlock(&inode->i_lock);
 		put_err = p9_fid_put(fid);
 		retval = retval < 0 ? retval : put_err;
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 348cc90bf9c5..129354d5b284 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -80,6 +80,8 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 
 		file->private_data = fid;
 	}
+	printk("fid: %p, %s\n", fid, __func__);
+	p9_fid_get(fid);
 
 #ifdef CONFIG_9P_FSCACHE
 	if (v9ses->cache & CACHE_FSCACHE)