ovl: decode lower file handles of unlinked but open files

Lookup overlay inode in cache by origin inode, so we can decode a file
handle of an open file even if the index has a whiteout index entry to
mark this overlay inode was unlinked.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index bfd7c766b5cd..56ba015b9f5e 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -645,6 +645,22 @@ static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
 	return true;
 }
 
+struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *origin)
+{
+	struct inode *inode, *key = d_inode(origin);
+
+	inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
+	if (!inode)
+		return NULL;
+
+	if (!ovl_verify_inode(inode, origin, NULL)) {
+		iput(inode);
+		return ERR_PTR(-ESTALE);
+	}
+
+	return inode;
+}
+
 struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
 			    struct dentry *lowerdentry, struct dentry *index,
 			    unsigned int numlower)