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

NFS: revalidate "." etc correctly on "open".

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: nfs-revalidate-.-etc-correctly-on-open.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From b688741cb06695312f18b730653d6611e1bad28d Mon Sep 17 00:00:00 2001

From: NeilBrown neilb@suse.com Date: Fri, 25 Aug 2017 17:34:41 +1000 Subject: NFS: revalidate "." etc correctly on "open".

From: NeilBrown neilb@suse.com

commit b688741cb06695312f18b730653d6611e1bad28d upstream.

For correct close-to-open semantics, NFS must validate the change attribute of a directory (or file) on open.

Since commit ecf3d1f1aa74 ("vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op"), open() of "." or a path ending ".." is not revalidated reliably (except when that direct is a mount point).

Prior to that commit, "." was revalidated using nfs_lookup_revalidate() which checks the LOOKUP_OPEN flag and forces revalidation if the flag is set. Since that commit, nfs_weak_revalidate() is used for NFSv3 (which ignores the flags) and nothing is used for NFSv4.

This is fixed by using nfs_lookup_verify_inode() in nfs_weak_revalidate(). This does the revalidation exactly when needed. Also, add a definition of .d_weak_revalidate for NFSv4.

The incorrect behavior is easily demonstrated by running "echo *" in some non-mountpoint NFS directory while watching network traffic. Without this patch, "echo *" sometimes doesn't produce any traffic. With the patch it always does.

Fixes: ecf3d1f1aa74 ("vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op") cc: stable@vger.kernel.org (3.9+) Signed-off-by: NeilBrown neilb@suse.com Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- fs/nfs/dir.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1292,7 +1292,7 @@ static int nfs_weak_revalidate(struct de return 0; }

- error = nfs_revalidate_inode(NFS_SERVER(inode), inode); + error = nfs_lookup_verify_inode(inode, flags); dfprintk(LOOKUPCACHE, "NFS: %s: inode %lu is %s\n", __func__, inode->i_ino, error ? "invalid" : "valid"); return !error; @@ -1443,6 +1443,7 @@ static int nfs4_lookup_revalidate(struct

const struct dentry_operations nfs4_dentry_operations = { .d_revalidate = nfs4_lookup_revalidate, + .d_weak_revalidate = nfs_weak_revalidate, .d_delete = nfs_dentry_delete, .d_iput = nfs_dentry_iput, .d_automount = nfs_d_automount,

Patches currently in stable-queue which might be from neilb@suse.com are

queue-4.9/nfs-revalidate-.-etc-correctly-on-open.patch