From: David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Andreas Gruenbacher
<agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Alexander Viro
<viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
Cc: dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
"Theodore Ts'o" <tytso-3s7WtUTddSA@public.gmane.org>,
Andreas Dilger
<adilger.kernel-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>,
"J. Bruce Fields"
<bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>,
Trond Myklebust
<trond.myklebust-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>,
Anna Schumaker
<anna.schumaker-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org>,
Dave Chinner <david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org>,
linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
xfs-VZNHf3L845pBDgjK7y7TUQ@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH v23 13/22] vfs: Cache richacl in struct inode
Date: Thu, 07 Jul 2016 15:14:13 +0100 [thread overview]
Message-ID: <1689.1467900853@warthog.procyon.org.uk> (raw)
In-Reply-To: <1467831425.2908.16.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> > + if (cmpxchg(&inode->i_acl, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
> > + /* fall through */ ;
> > +
>
> So you do the same thing regardless of the outcome of the above? Why
> bother with the if at all here? Just do the cmpxchg and toss out the
> result.
gcc might complain if you don't check the result.
However, this does look like it's subject to a thundering herd problem. If
30000 processes all look at the ACL at the same time on a network fs, could
that cause 30000 RPC calls to be transmitted for the same thing?
David
WARNING: multiple messages have this Message-ID (diff)
From: David Howells <dhowells@redhat.com>
To: Jeff Layton <jlayton@redhat.com>,
Andreas Gruenbacher <agruenba@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>
Cc: dhowells@redhat.com, Christoph Hellwig <hch@infradead.org>,
"Theodore Ts'o" <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
"J. Bruce Fields" <bfields@fieldses.org>,
Trond Myklebust <trond.myklebust@primarydata.com>,
Anna Schumaker <anna.schumaker@netapp.com>,
Dave Chinner <david@fromorbit.com>,
linux-ext4@vger.kernel.org, xfs@oss.sgi.com,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org,
linux-api@vger.kernel.org
Subject: Re: [PATCH v23 13/22] vfs: Cache richacl in struct inode
Date: Thu, 07 Jul 2016 15:14:13 +0100 [thread overview]
Message-ID: <1689.1467900853@warthog.procyon.org.uk> (raw)
In-Reply-To: <1467831425.2908.16.camel@redhat.com>
Jeff Layton <jlayton@redhat.com> wrote:
> > + if (cmpxchg(&inode->i_acl, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
> > + /* fall through */ ;
> > +
>
> So you do the same thing regardless of the outcome of the above? Why
> bother with the if at all here? Just do the cmpxchg and toss out the
> result.
gcc might complain if you don't check the result.
However, this does look like it's subject to a thundering herd problem. If
30000 processes all look at the ACL at the same time on a network fs, could
that cause 30000 RPC calls to be transmitted for the same thing?
David
WARNING: multiple messages have this Message-ID (diff)
From: David Howells <dhowells@redhat.com>
To: Jeff Layton <jlayton@redhat.com>,
Andreas Gruenbacher <agruenba@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-nfs@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>,
linux-cifs@vger.kernel.org, linux-api@vger.kernel.org,
Trond Myklebust <trond.myklebust@primarydata.com>,
linux-kernel@vger.kernel.org, xfs@oss.sgi.com,
dhowells@redhat.com, Andreas Dilger <adilger.kernel@dilger.ca>,
"J. Bruce Fields" <bfields@fieldses.org>,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
Anna Schumaker <anna.schumaker@netapp.com>
Subject: Re: [PATCH v23 13/22] vfs: Cache richacl in struct inode
Date: Thu, 07 Jul 2016 15:14:13 +0100 [thread overview]
Message-ID: <1689.1467900853@warthog.procyon.org.uk> (raw)
In-Reply-To: <1467831425.2908.16.camel@redhat.com>
Jeff Layton <jlayton@redhat.com> wrote:
> > + if (cmpxchg(&inode->i_acl, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
> > + /* fall through */ ;
> > +
>
> So you do the same thing regardless of the outcome of the above? Why
> bother with the if at all here? Just do the cmpxchg and toss out the
> result.
gcc might complain if you don't check the result.
However, this does look like it's subject to a thundering herd problem. If
30000 processes all look at the ACL at the same time on a network fs, could
that cause 30000 RPC calls to be transmitted for the same thing?
David
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next prev parent reply other threads:[~2016-07-07 14:14 UTC|newest]
Thread overview: 133+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-30 13:46 [PATCH v23 00/22] Richacls (Core and Ext4) Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
2016-06-30 13:46 ` [PATCH v23 01/22] vfs: Add IS_ACL() and IS_RICHACL() tests Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
2016-07-05 11:00 ` Jeff Layton
2016-07-05 11:00 ` Jeff Layton
2016-06-30 13:46 ` [PATCH v23 02/22] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-3-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-05 11:02 ` Jeff Layton
2016-07-05 11:02 ` Jeff Layton
2016-07-05 11:02 ` Jeff Layton
2016-06-30 13:46 ` [PATCH v23 03/22] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD " Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-4-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-05 11:07 ` Jeff Layton
2016-07-05 11:07 ` Jeff Layton
2016-07-05 11:07 ` Jeff Layton
2016-06-30 13:46 ` [PATCH v23 04/22] vfs: Make the inode passed to inode_change_ok non-const Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-5-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-05 11:12 ` Jeff Layton
2016-07-05 11:12 ` Jeff Layton
2016-07-05 11:12 ` Jeff Layton
2016-06-30 13:46 ` [PATCH v23 05/22] vfs: Add permission flags for setting file attributes Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
2016-07-05 11:18 ` Jeff Layton
2016-07-05 11:18 ` Jeff Layton
2016-06-30 13:46 ` [PATCH v23 06/22] richacl: In-memory representation and helper functions Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
2016-07-05 11:34 ` Jeff Layton
2016-07-05 11:34 ` Jeff Layton
2016-07-05 11:34 ` Jeff Layton
[not found] ` <1467718448.3800.16.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-11 10:11 ` Andreas Gruenbacher
2016-07-11 10:11 ` Andreas Gruenbacher
2016-07-11 10:11 ` Andreas Gruenbacher
2016-06-30 13:46 ` [PATCH v23 07/22] richacl: Permission mapping functions Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
2016-07-05 13:39 ` Jeff Layton
2016-07-05 13:39 ` Jeff Layton
2016-07-05 13:39 ` Jeff Layton
2016-07-11 13:26 ` Andreas Gruenbacher
2016-07-11 13:26 ` Andreas Gruenbacher
2016-06-30 13:46 ` [PATCH v23 08/22] richacl: Compute maximum file masks from an acl Andreas Gruenbacher
2016-06-30 13:46 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-9-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-05 14:22 ` Jeff Layton
2016-07-05 14:22 ` Jeff Layton
2016-07-05 14:22 ` Jeff Layton
2016-07-05 17:08 ` Frank Filz
2016-07-05 17:08 ` Frank Filz
2016-07-05 17:08 ` Frank Filz
2016-07-13 12:34 ` Andreas Gruenbacher
2016-07-13 12:34 ` Andreas Gruenbacher
2016-07-13 19:38 ` Frank Filz
2016-07-13 19:38 ` Frank Filz
2016-07-13 19:38 ` Frank Filz
2016-06-30 13:47 ` [PATCH v23 09/22] richacl: Permission check algorithm Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-07-05 14:59 ` Jeff Layton
2016-07-05 14:59 ` Jeff Layton
2016-07-11 13:28 ` Andreas Gruenbacher
2016-07-11 13:28 ` Andreas Gruenbacher
2016-06-30 13:47 ` [PATCH v23 10/22] posix_acl: Improve xattr fixup code Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-11-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-05 15:38 ` Jeff Layton
2016-07-05 15:38 ` Jeff Layton
2016-07-05 15:38 ` Jeff Layton
2016-06-30 13:47 ` [PATCH v23 11/22] vfs: Cache base_acl objects in inodes Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-12-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-05 15:56 ` Jeff Layton
2016-07-05 15:56 ` Jeff Layton
2016-07-05 15:56 ` Jeff Layton
2016-06-30 13:47 ` [PATCH v23 12/22] vfs: Add get_richacl and set_richacl inode operations Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-13-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-06 18:31 ` Jeff Layton
2016-07-06 18:31 ` Jeff Layton
2016-07-06 18:31 ` Jeff Layton
2016-06-30 13:47 ` [PATCH v23 13/22] vfs: Cache richacl in struct inode Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-14-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-06 18:57 ` Jeff Layton
2016-07-06 18:57 ` Jeff Layton
2016-07-06 18:57 ` Jeff Layton
2016-07-14 20:02 ` Andreas Gruenbacher
2016-07-14 20:02 ` Andreas Gruenbacher
[not found] ` <1467831425.2908.16.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-07 14:14 ` David Howells [this message]
2016-07-07 14:14 ` David Howells
2016-07-07 14:14 ` David Howells
2016-06-30 13:47 ` [PATCH v23 14/22] richacl: Update the file masks in chmod() Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
[not found] ` <1467294433-3222-15-git-send-email-agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-12 11:36 ` Jeff Layton
2016-07-12 11:36 ` Jeff Layton
2016-07-12 11:36 ` Jeff Layton
2016-06-30 13:47 ` [PATCH v23 15/22] richacl: Check if an acl is equivalent to a file mode Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-07-12 11:39 ` Jeff Layton
2016-07-12 11:39 ` Jeff Layton
2016-07-12 11:39 ` Jeff Layton
2016-06-30 13:47 ` [PATCH v23 16/22] richacl: Create-time inheritance Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-07-12 11:41 ` Jeff Layton
2016-07-12 11:41 ` Jeff Layton
2016-06-30 13:47 ` [PATCH v23 17/22] richacl: Automatic Inheritance Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-07-12 11:56 ` Jeff Layton
2016-07-12 11:56 ` Jeff Layton
2016-07-12 11:56 ` Jeff Layton
[not found] ` <1468324560.7798.14.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-12 19:11 ` J. Bruce Fields
2016-07-12 19:11 ` J. Bruce Fields
2016-07-12 19:11 ` J. Bruce Fields
[not found] ` <20160712191142.GE449-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>
2016-07-12 20:28 ` Andreas Gruenbacher
2016-07-12 20:28 ` Andreas Gruenbacher
2016-07-12 20:28 ` Andreas Gruenbacher
2016-06-30 13:47 ` [PATCH v23 18/22] richacl: xattr mapping functions Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-07-12 12:02 ` Jeff Layton
2016-07-12 12:02 ` Jeff Layton
2016-07-14 20:33 ` Andreas Gruenbacher
2016-07-14 20:33 ` Andreas Gruenbacher
2016-06-30 13:47 ` [PATCH v23 19/22] richacl: Add richacl xattr handler Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-07-12 12:13 ` Jeff Layton
2016-07-12 12:13 ` Jeff Layton
2016-06-30 13:47 ` [PATCH v23 20/22] vfs: Add richacl permission checking Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-07-12 12:13 ` Jeff Layton
2016-07-12 12:13 ` Jeff Layton
2016-07-12 12:13 ` Jeff Layton
[not found] ` <1468325634.7798.24.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-07-14 20:59 ` Andreas Gruenbacher
2016-07-14 20:59 ` Andreas Gruenbacher
2016-07-14 20:59 ` Andreas Gruenbacher
2016-06-30 13:47 ` [PATCH v23 21/22] ext4: Add richacl support Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-06-30 13:47 ` [PATCH v23 22/22] ext4: Add richacl feature flag Andreas Gruenbacher
2016-06-30 13:47 ` Andreas Gruenbacher
2016-06-30 14:11 ` [PATCH v23 00/22] Richacls (Core and Ext4) Volker Lendecke
2016-06-30 14:11 ` Volker Lendecke
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