Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-ig0-f178.google.com ([209.85.213.178]:64186 "EHLO mail-ig0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751959AbbBXAPB (ORCPT ); Mon, 23 Feb 2015 19:15:01 -0500 Received: by mail-ig0-f178.google.com with SMTP id hl2so22855306igb.5 for ; Mon, 23 Feb 2015 16:15:00 -0800 (PST) From: Trond Myklebust To: linux-nfs@vger.kernel.org Cc: Nix , Neil Brown Subject: [PATCH 1/3] NFS: Don't invalidate a submounted dentry in nfs_prime_dcache() Date: Mon, 23 Feb 2015 19:14:55 -0500 Message-Id: <1424736897-95767-1-git-send-email-trond.myklebust@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: If we're traversing a directory which contains a submounted filesystem, or one that has a referral, the NFS server that is processing the READDIR request will often return information for the underlying (mounted-on) directory. It may, or may not, also return filehandle information. If this happens, and the lookup in nfs_prime_dcache() returns the dentry for the submounted directory, the filehandle comparison will fail, and we call d_invalidate(). Post-commit 8ed936b5671bf ("vfs: Lazily remove mounts on unlinked files and directories."), this means the entire subtree is unmounted. The following minimal patch addresses this problem by punting on the invalidation if there is a submount. Kudos to Neil Brown for having tracked down this issue (see link). Reported-by: Nix Link: http://lkml.kernel.org/r/87iofju9ht.fsf@spindle.srvr.nix Cc: stable@vger.kernel.org # 3.18+ Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 9b0c55cb2a2e..0da617a61c0b 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -479,6 +479,10 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry) dentry = d_lookup(parent, &filename); if (dentry != NULL) { + /* Is there a mountpoint here? If so, just exit */ + if (!nfs_fsid_equal(&NFS_SB(dentry->d_sb)->fsid, + &entry->fattr->fsid)) + goto out; if (nfs_same_file(dentry, entry)) { nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); status = nfs_refresh_inode(dentry->d_inode, entry->fattr); -- 2.1.0