Commit f7d3daca authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
Browse files

ovl: relax same fs constrain for ovl_check_origin() 



For the case of all layers not on the same fs, try to decode the copy up
origin file handle on any of the lower layers.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 2cac0c00

fs/overlayfs/namei.c

+24 −18
Original line number Diff line number Diff line
@@ -272,29 +272,25 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, 
static int ovl_check_origin(struct dentry *dentry, struct dentry *upperdentry,

			    struct path **stackp, unsigned int *ctrp)

{

	struct super_block *same_sb = ovl_same_sb(dentry->d_sb);

	struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;

	struct vfsmount *mnt;

	struct dentry *origin;



	if (!same_sb || !roe->numlower)

		return 0;

	struct dentry *origin = NULL;

	int i;



       /*

	* Since all layers are on the same fs, we use the first layer for

	* decoding the file handle.  We may get a disconnected dentry,

	* which is fine, because we only need to hold the origin inode in

	* cache and use its inode number.  We may even get a connected dentry,

	* that is not under the first layer's root.  That is also fine for

	* using it's inode number - it's the same as if we held a reference

	* to a dentry in first layer that was moved under us.

	*/

	mnt = roe->lowerstack[0].mnt;



	for (i = 0; i < roe->numlower; i++) {

		mnt = roe->lowerstack[i].mnt;

		origin = ovl_get_origin(upperdentry, mnt);

	if (IS_ERR_OR_NULL(origin))

		if (IS_ERR(origin))

			return PTR_ERR(origin);



		if (origin)

			break;

	}



	if (!origin)

		return 0;



	BUG_ON(*stackp || *ctrp);

	*stackp = kmalloc(sizeof(struct path), GFP_TEMPORARY);

	if (!*stackp) {
@@ -371,6 +367,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
		}

		if (upperdentry && !d.is_dir) {

			BUG_ON(!d.stop || d.redirect);

			/*

			 * Lookup copy up origin by decoding origin file handle.

			 * We may get a disconnected dentry, which is fine,

			 * because we only need to hold the origin inode in

			 * cache and use its inode number.  We may even get a

			 * connected dentry, that is not under any of the lower

			 * layers root.  That is also fine for using it's inode

			 * number - it's the same as if we held a reference

			 * to a dentry in lower layer that was moved under us.

			 */

			err = ovl_check_origin(dentry, upperdentry,

					       &stack, &ctr);

			if (err)