From: Theodore Ts'o <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] ext4: optimize ext4 direct I/O locking for reading
Date: Thu, 22 Sep 2016 09:30:31 -0400 [thread overview]
Message-ID: <20160922133031.zjiyudqwthqp742g@thunk.org> (raw)
In-Reply-To: <20160922123143.GO2834@quack2.suse.cz>
On Thu, Sep 22, 2016 at 02:31:43PM +0200, Jan Kara wrote:
>
> So I think what Christoph meant in this case is something like attached
> patch. That achieves more than your dirty hack in a much cleaner way.
> Beware, the patch is only compile-tested.
Your patch also disables dioread_nolock (which is what I think
Christoph was asking about because it's the rest of the dioread nolock
support code which causes the eye-bleeding complexity on the write
path).
> Then there is the case of unlocked direct IO overwrites which we allow to
> run without inode_lock in dioread_nolock mode as well and that is more
> difficult to resolve (there lay the problems with blocksize < pagesize you
> speak about).
Right, by disabling dioread_nolock, it means we lose the feature that
dioread_nolock doesn't require blocking versus _any_ direct I/O writes
(because of the post-write uninit->init conversion) --- not just DIO
overwrites.
But we should be able to support dioread_nolock as well as by only
taking inode_lock_shared() in the non-dioread_nolock case, I think.
Thanks for the prototype patch; I agree it's a cleaner way to go.
- Ted
next prev parent reply other threads:[~2016-09-22 13:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 5:27 [PATCH] ext4: optimize ext4 direct I/O locking for reading Theodore Ts'o
2016-09-21 13:26 ` Christoph Hellwig
2016-09-21 14:37 ` Theodore Ts'o
2016-09-22 12:31 ` Jan Kara
2016-09-22 13:18 ` Christoph Hellwig
2016-09-22 13:30 ` Theodore Ts'o [this message]
2016-09-30 5:22 ` Theodore Ts'o
2016-10-03 7:41 ` Jan Kara
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160922133031.zjiyudqwthqp742g@thunk.org \
--to=tytso@mit.edu \
--cc=hch@infradead.org \
--cc=jack@suse.cz \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.