From: Christoph Hellwig <hch@lst.de>
To: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>,
Chris Mason <chris.mason@oracle.com>,
Cesar Eduardo Barros <cesarb@cesarb.net>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Jens Axboe <jaxboe@fusionio.com>,
linux-btrfs@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, stable@kernel.org,
Jens Axboe <axboe@kernel.dk>,
Micha?? Piotrowski <mkkp4x4@gmail.com>,
Chuck Ebbert <cebbert@redhat.com>,
kernel@lists.fedoraproject.org, linux-mtd@lists.infradead.org,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: Dirtiable inode bdi default != sb bdi btrfs
Date: Thu, 30 Sep 2010 02:06:41 +0200 [thread overview]
Message-ID: <20100930000641.GA27865@lst.de> (raw)
In-Reply-To: <20100929233806.GB12707@quack.suse.cz>
On Thu, Sep 30, 2010 at 01:38:07AM +0200, Jan Kara wrote:
> > No. For one thing we don't need any exception for correctnes alone -
> > even the block device variant would work fine with the default case.
> Here I don't agree. If you don't have some kind of exception, sb->s_bdi
> for both "block" and "mtd_inodefs" filesystems points to
> noop_backing_dev_info and you get no writeback for that one. So it isn't
> just a performance issue but also a correctness one.
Indeed - for internal filesystems that require writeback the change
causes trouble if they haven't registered a s_bdi. But for all user
visible filesystems that doesn't happen as we require s_bdi for
sync or even unmounts to work.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>,
kernel@lists.fedoraproject.org, Jens Axboe <jaxboe@fusionio.com>,
linux-kernel@vger.kernel.org, stable@kernel.org,
Micha?? Piotrowski <mkkp4x4@gmail.com>,
linux-mtd@lists.infradead.org,
Cesar Eduardo Barros <cesarb@cesarb.net>,
Chuck Ebbert <cebbert@redhat.com>,
linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linux-btrfs@vger.kernel.org,
David Woodhouse <dwmw2@infradead.org>,
Christoph Hellwig <hch@lst.de>,
Chris Mason <chris.mason@oracle.com>,
Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: Dirtiable inode bdi default != sb bdi btrfs
Date: Thu, 30 Sep 2010 02:06:41 +0200 [thread overview]
Message-ID: <20100930000641.GA27865@lst.de> (raw)
In-Reply-To: <20100929233806.GB12707@quack.suse.cz>
On Thu, Sep 30, 2010 at 01:38:07AM +0200, Jan Kara wrote:
> > No. For one thing we don't need any exception for correctnes alone -
> > even the block device variant would work fine with the default case.
> Here I don't agree. If you don't have some kind of exception, sb->s_bdi
> for both "block" and "mtd_inodefs" filesystems points to
> noop_backing_dev_info and you get no writeback for that one. So it isn't
> just a performance issue but also a correctness one.
Indeed - for internal filesystems that require writeback the change
causes trouble if they haven't registered a s_bdi. But for all user
visible filesystems that doesn't happen as we require s_bdi for
sync or even unmounts to work.
next prev parent reply other threads:[~2010-09-30 0:06 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-23 0:54 Dirtiable inode bdi default != sb bdi btrfs Cesar Eduardo Barros
2010-09-23 19:38 ` Andrew Morton
2010-09-23 19:40 ` Chris Mason
2010-09-23 19:40 ` Jens Axboe
2010-09-23 20:53 ` [stable] " Greg KH
2010-09-24 18:39 ` Jens Axboe
2010-09-27 0:15 ` Greg KH
2010-09-27 22:25 ` Jan Kara
2010-09-27 22:54 ` Chris Mason
2010-09-27 23:51 ` Jan Kara
2010-09-27 23:51 ` Jan Kara
2010-09-28 7:05 ` Artem Bityutskiy
2010-09-28 7:05 ` Artem Bityutskiy
2010-09-29 13:00 ` Jan Kara
2010-09-29 13:40 ` Artem Bityutskiy
2010-09-29 13:40 ` Artem Bityutskiy
2010-09-29 13:40 ` Artem Bityutskiy
2010-09-29 8:19 ` Christoph Hellwig
2010-09-29 8:19 ` Christoph Hellwig
2010-09-29 8:19 ` Christoph Hellwig
2010-09-29 12:18 ` Jan Kara
2010-09-29 12:18 ` Jan Kara
2010-09-29 14:10 ` Christoph Hellwig
2010-09-29 23:38 ` Jan Kara
2010-09-29 23:38 ` Jan Kara
2010-09-30 0:06 ` Christoph Hellwig [this message]
2010-09-30 0:06 ` Christoph Hellwig
2010-09-27 23:55 ` Cesar Eduardo Barros
2010-09-29 13:01 ` Jan Kara
2010-09-29 13:01 ` Jan Kara
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