fix inode leaks on d_splice_alias() failure exits

d_splice_alias() callers expect it to either stash the inode reference
into a new alias, or drop the inode reference.  That makes it possible
to just return d_splice_alias() result from ->lookup() instance, without
any extra housekeeping required.

Unfortunately, that should include the failure exits.  If d_splice_alias()
returns an error, it leaves the dentry it has been given negative and
thus it *must* drop the inode reference.  Easily fixed, but it goes way
back and will need backporting.

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index d5a23fd0da90..3ffef7f4e5cd 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2673,11 +2673,13 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
                         if (!IS_ROOT(new)) {
                                 spin_unlock(&inode->i_lock);
                                 dput(new);
+                                iput(inode);
                                 return ERR_PTR(-EIO);
                         }
                         if (d_ancestor(new, dentry)) {
                                 spin_unlock(&inode->i_lock);
                                 dput(new);
+                                iput(inode);
                                 return ERR_PTR(-EIO);
                         }
                         write_seqlock(&rename_lock);