linux-kernel - [PATCH 4.2.y-ckt 77/98] jffs2: reduce the breakage on recovery from halfway failed rename()

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Message-Id: <1458084692-23100-78-git-send-email-kamal@canonical.com>
Date:	Tue, 15 Mar 2016 16:31:11 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Al Viro <viro@...iv.linux.org.uk>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 77/98] jffs2: reduce the breakage on recovery from halfway failed rename()

4.2.8-ckt6 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Al Viro <viro@...iv.linux.org.uk>

commit f93812846f31381d35c04c6c577d724254355e7f upstream.

d_instantiate(new_dentry, old_inode) is absolutely wrong thing to
do - it will oops if new_dentry used to be positive, for starters.
What we need is d_invalidate() the target and be done with that.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 fs/jffs2/dir.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c
index 8118002..da37f2e 100644
--- a/fs/jffs2/dir.c
+++ b/fs/jffs2/dir.c
@@ -846,9 +846,14 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 
 		pr_notice("%s(): Link succeeded, unlink failed (err %d). You now have a hard link\n",
 			  __func__, ret);
-		/* Might as well let the VFS know */
-		d_instantiate(new_dentry, d_inode(old_dentry));
-		ihold(d_inode(old_dentry));
+		/*
+		 * We can't keep the target in dcache after that.
+		 * For one thing, we can't afford dentry aliases for directories.
+		 * For another, if there was a victim, we _can't_ set new inode
+		 * for that sucker and we have to trigger mount eviction - the
+		 * caller won't do it on its own since we are returning an error.
+		 */
+		d_invalidate(new_dentry);
 		new_dir_i->i_mtime = new_dir_i->i_ctime = ITIME(now);
 		return ret;
 	}
-- 
2.7.0