linux-ext4 - Re: [PATCH 4/6] xstat: NFS: Return extended attributes

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Date:	Thu, 26 Apr 2012 14:52:40 +0100
From:	David Howells <dhowells@...hat.com>
To:	"Myklebust, Trond" <Trond.Myklebust@...app.com>
Cc:	dhowells@...hat.com,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
	"linux-cifs@...r.kernel.org" <linux-cifs@...r.kernel.org>,
	"samba-technical@...ts.samba.org" <samba-technical@...ts.samba.org>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	"wine-devel@...ehq.org" <wine-devel@...ehq.org>,
	"kfm-devel@....org" <kfm-devel@....org>,
	"nautilus-list@...me.org" <nautilus-list@...me.org>,
	"linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
	"libc-alpha@...rceware.org" <libc-alpha@...rceware.org>
Subject: Re: [PATCH 4/6] xstat: NFS: Return extended attributes

Myklebust, Trond <Trond.Myklebust@...app.com> wrote:

> Hmm... As far as I can see you are still doing an nfs_revalidate_inode()
> in the non-forced case. That will cause expired attributes to be
> retrieved from the server.

Revalidation is only done when you force it or explicitly ask for a basic stat
or the data version number:

-	if (need_atime)
-		err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
-	else
-		err = nfs_revalidate_inode(NFS_SERVER(inode), inode);
-	if (!err) {
-		generic_fillattr(inode, stat);
-		stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
+	if (force || stat->request_mask & (XSTAT_BASIC_STATS | XSTAT_VERSION)) {
+		if (force || need_atime)
+			err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
+		else
+			err = nfs_revalidate_inode(NFS_SERVER(inode), inode);
+		if (err)
+			goto out;

Unfortunately, I think I have to revalidate if any of XSTAT_BASIC_STATS are
requested to maintain compatibility with stat() so that stat() can be done
with xstat().  On the other hand, stat() could be done by userspace with
xstat() and AT_FORCE_ATTR_SYNC, I suppose.

David
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