From: Bruce Allen <ballen@gravity.phys.uwm.edu>
To: Andrew Morton <akpm@osdl.org>
Cc: Andy Isaacson <adi@hexapodia.org>,
bug-coreutils@gnu.org, linux-kernel@vger.kernel.org
Subject: Re: dd PATCH: add conv=direct
Date: Wed, 7 Apr 2004 11:21:40 -0500 (CDT) [thread overview]
Message-ID: <Pine.GSO.4.21.0404071119120.903-100000@dirac.phys.uwm.edu> (raw)
In-Reply-To: <20040406173326.0fbb9d7a.akpm@osdl.org>
> > On modern Linux, apparently the correct way to bypass the buffer cache
> > when writing to a block device is to open the block device with
> > O_DIRECT. This enables, for example, the user to more easily force a
> > reallocation of a single sector of an IDE disk with a media error
> > (without overwriting anything but the 1k "sector pair" containing the
> > error). dd(1) is convenient for this purpose, but is lacking a method
> > to force O_DIRECT. The enclosed patch adds a "conv=direct" flag to
> > enable this usage.
>
> This would be rather nice to have. You'll need to ensure that the data
> is page-aligned in memory.
>
> While you're there, please add an fsync-before-closing option.
Andrew, am I right that this is NOT needed for the proposed O_DIRECT
option, since open(2) says:
"The I/O is synchronous, i.e., at the completion of the read(2) or
write(2) system call, data is guaranteed to have been transferred."
so the write will block until data is physically on the disk.
Cheers,
Bruce
next prev parent reply other threads:[~2004-04-07 16:21 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-06 22:03 dd PATCH: add conv=direct Andy Isaacson
2004-04-07 0:33 ` Andrew Morton
2004-04-07 16:21 ` Bruce Allen [this message]
2004-04-07 16:42 ` Andrew Morton
2004-04-07 17:31 ` Andy Isaacson
2004-04-07 18:18 ` Andrew Morton
2004-04-07 19:24 ` Andy Isaacson
2004-04-07 19:34 ` Andrew Morton
2004-04-07 19:47 ` Andy Isaacson
2004-04-07 20:03 ` Andrew Morton
2004-04-07 20:43 ` Andy Isaacson
2004-04-07 21:00 ` Valdis.Kletnieks
2004-04-07 21:35 ` Bruce Allen
2004-04-08 6:56 ` Paul Eggert
2004-04-08 11:07 ` Jim Meyering
2004-04-08 19:32 ` Paul Eggert
2004-04-08 19:51 ` Paul Jarc
2004-04-08 21:34 ` Jim Meyering
2004-04-08 16:23 ` Philippe Troin
2004-04-08 20:20 ` dd patch to remove noctty Paul Eggert
2004-04-08 21:40 ` Jim Meyering
2004-04-09 0:37 ` dd PATCH: add conv=direct Anton Blanchard
2004-04-09 1:42 ` Wim Coekaerts
2004-04-10 21:28 ` Jim Meyering
2004-04-07 20:46 ` Paul Eggert
2004-04-07 21:06 ` Andrew Morton
2004-04-07 21:09 ` Andy Isaacson
2004-04-07 19:12 ` Miquel van Smoorenburg
2004-04-07 20:14 ` Andy Isaacson
2004-04-07 22:02 ` Nathan Straz
2004-04-07 22:09 ` Andy Isaacson
2004-04-08 11:44 ` Miquel van Smoorenburg
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=Pine.GSO.4.21.0404071119120.903-100000@dirac.phys.uwm.edu \
--to=ballen@gravity.phys.uwm.edu \
--cc=adi@hexapodia.org \
--cc=akpm@osdl.org \
--cc=bug-coreutils@gnu.org \
--cc=linux-kernel@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 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).