[PATCH 11/11] dcache: d_splice_alias should detect loops

["J. Bruce Fields" <bfields@redhat.com>]

From: "J. Bruce Fields" <bfields@redhat.com>

I believe this can only happen in the case of a corrupted filesystem.
So -EIO looks like the appropriate error.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/dcache.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index 960a2e7..f6ab71b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2643,6 +2643,11 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
 				dput(new);
 				return ERR_PTR(-EIO);
 			}
+			if (d_ancestor(new, dentry)) {
+				spin_unlock(&inode->i_lock);
+				dput(new);
+				return ERR_PTR(-EIO);
+			}
 			write_seqlock(&rename_lock);
 			__d_materialise_dentry(dentry, new);
 			write_sequnlock(&rename_lock);
-- 
1.7.9.5