From: Andrew Burford <aburford@cs.stonybrook.edu>
Date: Sun, 15 May 2022 01:02:19 +0000 (-0400)
Subject: add self-stack patch that removes check preventing self-stacking
X-Git-Url: https://git.fsl.cs.sunysb.edu/?a=commitdiff_plain;h=ce482587aaef9823bf5821635dd94dbfed97fca6;p=wrapfs-mgmt.git

add self-stack patch that removes check preventing self-stacking
---

diff --git a/bug-fixes/andrew-fix-self-stack2.patch b/bug-fixes/andrew-fix-self-stack2.patch
new file mode 100644
index 0000000..87cd6f5
--- /dev/null
+++ b/bug-fixes/andrew-fix-self-stack2.patch
@@ -0,0 +1,39 @@
+diff --git a/fs/wrapfs/lookup.c b/fs/wrapfs/lookup.c
+index 7c78d5a4a30f..b166c0e50b98 100644
+--- a/fs/wrapfs/lookup.c
++++ b/fs/wrapfs/lookup.c
+@@ -260,7 +260,14 @@ static struct dentry *__wrapfs_lookup(struct dentry *dentry,
+ 		err = -ENOMEM;
+ 		goto out;
+ 	}
+-	d_add(lower_dentry, NULL); /* instantiate and hash */
++
++	/*
++	 * Calling ->lookup instead of d_add will give the lower fs a chance
++	 * to allocate the d_fsdata field but will still instantiate and hash the
++	 * lower_dentry. Without this, wrapfs could not stack on top of itself.
++	 */
++	d_inode(lower_dir_dentry)
++		->i_op->lookup(d_inode(lower_dir_dentry), lower_dentry, flags);
+ 
+ setup_lower:
+ 	lower_path.dentry = lower_dentry;
+diff --git a/fs/wrapfs/main.c b/fs/wrapfs/main.c
+index 15c97a78d765..b5d7c178324c 100644
+--- a/fs/wrapfs/main.c
++++ b/fs/wrapfs/main.c
+@@ -39,14 +39,6 @@ static int wrapfs_read_super(struct super_block *sb, void *raw_data, int silent)
+ 		goto out;
+ 	}
+ 
+-        if (lower_path.dentry->d_sb->s_type == &wrapfs_fs_type) {
+-		err = -EINVAL;
+-		printk(KERN_ERR "Mount on filesystem of type "
+-		       "wrapfs explicitly disallowed due to "
+-		       "known incompatibilities\n");
+-		goto out_pput;
+-	}
+-
+ 	if (mnt_user_ns(lower_path.mnt) != &init_user_ns) {
+ 		err = -EINVAL;
+ 		printk(KERN_ERR "Mounting on idmapped mounts currently "