linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Theodore Ts'o <tytso@mit.edu>
To: Matthew Wilcox <matthew@wil.cx>
Cc: Dave Chinner <david@fromorbit.com>,
	Matthew Wilcox <matthew.r.wilcox@intel.com>,
	linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v3 0/3] Add XIP support to ext4
Date: Wed, 18 Dec 2013 21:07:59 -0500	[thread overview]
Message-ID: <20131219020759.GA27469@thunk.org> (raw)
In-Reply-To: <20131218142749.GA9207@parisc-linux.org>

On Wed, Dec 18, 2013 at 07:27:49AM -0700, Matthew Wilcox wrote:
> 
> I think there is a callback in xip_file_write(), and it's get_xip_mem().
> From what you're saying, it sounds like it's just not doing enough.

The problem is that git_xip_mem() is called before we write to the
memory, right?

We need to convert the uninit extents to be marked as initialized in
*after* the write has been sent to the storage medium.

> Could you take pity on me and tell me what flags I need to check in the
> buffer_head to determine this state of affairs?

The buffer head flag is BH_Unwritten, but note that how BH_Delay and
BH_Boundary are handled is very file system specific.  There is no
guarantee that all file systems will use these flags, nor will use
them in the same way.  (I've been considering changing ext4 to not
attach buffer heads to the pages at all -- except for DIO, which
requires them today -- because iterating over all of the buffer heads
attached to the pages is a pain in the tuckus, and ext4 now has an
extent status tree which we could use to get this information without
needing to lock the pages.)

It's much better to give a way for the file system to attach a
callback to the XIP request object.

Cheers,

						- Ted

  reply	other threads:[~2013-12-19  2:08 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-17 19:18 [PATCH v3 0/3] Add XIP support to ext4 Matthew Wilcox
2013-12-17 19:18 ` [PATCH v3 1/3] Fix XIP fault vs truncate race Matthew Wilcox
2013-12-17 19:18 ` [PATCH v3 2/3] xip: Add xip_zero_page_range Matthew Wilcox
2013-12-17 19:18 ` [PATCH v3 3/3] ext4: Add XIP functionality Matthew Wilcox
2013-12-17 22:30 ` [PATCH v3 0/3] Add XIP support to ext4 Dave Chinner
2013-12-18  2:31   ` Matthew Wilcox
2013-12-18  5:01     ` Theodore Ts'o
2013-12-18 14:27       ` Matthew Wilcox
2013-12-19  2:07         ` Theodore Ts'o [this message]
2013-12-19  4:12           ` Matthew Wilcox
2013-12-19  4:37             ` Dave Chinner
2013-12-19  5:43             ` Theodore Ts'o
2013-12-19 15:20               ` Matthew Wilcox
2013-12-19 16:17                 ` Theodore Ts'o
2013-12-19 17:12                   ` Matthew Wilcox
2013-12-19 17:18                     ` Theodore Ts'o
2013-12-20 18:17                       ` Matthew Wilcox
2013-12-20 19:34                         ` Theodore Ts'o
2013-12-20 20:11                           ` Matthew Wilcox
2013-12-23  3:36                             ` Dave Chinner
2013-12-23  3:45                               ` Matthew Wilcox
2013-12-23  4:32                                 ` Dave Chinner
2013-12-23  6:56                                 ` Dave Chinner
2013-12-23 14:51                                   ` Theodore Ts'o
2013-12-23  3:16                         ` Dave Chinner
2013-12-24 16:27                           ` Matthew Wilcox
2013-12-18 12:33     ` Dave Chinner
2013-12-18 15:22       ` Matthew Wilcox
2013-12-19  0:48         ` Dave Chinner
2013-12-19  1:05           ` Matthew Wilcox
2013-12-19  1:58             ` Dave Chinner
2013-12-19 15:32               ` Matthew Wilcox
2013-12-19 23:46                 ` Dave Chinner
2013-12-20 16:45                   ` Matthew Wilcox
2013-12-23  4:14                     ` Dave Chinner
2013-12-18 18:13   ` Eric Sandeen

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=20131219020759.GA27469@thunk.org \
    --to=tytso@mit.edu \
    --cc=david@fromorbit.com \
    --cc=linux-ext4@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=matthew.r.wilcox@intel.com \
    --cc=matthew@wil.cx \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).