The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b688741cb06695312f18b730653d6611e1bad28d Mon Sep 17 00:00:00 2001
From: NeilBrown neilb@suse.com Date: Fri, 25 Aug 2017 17:34:41 +1000 Subject: [PATCH] NFS: revalidate "." etc correctly on "open".
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
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index db482d4c15d5..c583093a066b 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1241,8 +1241,7 @@ static int nfs_weak_revalidate(struct dentry *dentry, unsigned int flags) return 0; }
- if (nfs_mapping_need_revalidate_inode(inode)) - 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; @@ -1393,6 +1392,7 @@ static int nfs4_lookup_revalidate(struct dentry *, unsigned int);
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,