Patch "ovl: fix false positive ESTALE on lookup" has been added to the 4.13-stable tree

This is a note to let you know that I've just added the patch titled

ovl: fix false positive ESTALE on lookup

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ovl-fix-false-positive-estale-on-lookup.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Amir Goldstein <[email protected]>
Date: Mon, 11 Sep 2017 16:30:15 +0300
Subject: ovl: fix false positive ESTALE on lookup

From: Amir Goldstein <[email protected]>

commit 939ae4efd51c627da270af74ef069db5124cb5b0 upstream.

Commit b9ac5c274b8c ("ovl: hash overlay non-dir inodes by copy up origin") verifies that the origin lower inode stored in the overlayfs inode matched the inode of a copy up origin dentry found by lookup.

There is a false positive result in that check when lower fs does not support file handles and copy up origin cannot be followed by file handle at lookup time.

The false negative happens when finding an overlay inode in cache on a copied up overlay dentry lookup. The overlay inode still 'remembers' the copy up origin inode, but the copy up origin dentry is not available for verification.

Relax the check in case copy up origin dentry is not available.

---
 fs/overlayfs/inode.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

@@ -576,10 +576,13 @@ static int ovl_inode_set(struct inode *i
 static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
 			     struct dentry *upperdentry)
 {
-	struct inode *lowerinode = lowerdentry ? d_inode(lowerdentry) : NULL;
-
-	/* Lower (origin) inode must match, even if NULL */
-	if (ovl_inode_lower(inode) != lowerinode)
+	/*
+	 * Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL.
+	 * This happens when finding a copied up overlay inode for a renamed
+	 * or hardlinked overlay dentry and lower dentry cannot be followed
+	 * by origin because lower fs does not support file handles.
+	 */
+	if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry))
 		return false;
 
 	/*

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/ovl-fix-false-positive-estale-on-lookup.patch