linux-kernel - Re: [RFD] BIO_RW_BARRIER - what it means for devices, filesystems, and dm/md.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <18010.47701.751118.336431@gargle.gargle.HOWL>
Date:	Mon, 28 May 2007 15:17:41 +0400
From:	Nikita Danilov <nikita@...sterfs.com>
To:	device-mapper development <dm-devel@...hat.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-raid@...r.kernel.org,
	David Chinner <dgc@....com>, linux-kernel@...r.kernel.org,
	Jens Axboe <jens.axboe@...cle.com>
Subject: Re: [RFD] BIO_RW_BARRIER - what it means for devices,
	filesystems, and dm/md.

Neil Brown writes:
 > 

[...]

 > Thus the general sequence might be:
 > 
 >   a/ issue all "preceding writes".
 >   b/ issue the commit write with BIO_RW_BARRIER
 >   c/ wait for the commit to complete.
 >          If it was successful - done.
 >          If it failed other than with EOPNOTSUPP, abort
 >          else continue
 >   d/ wait for all 'preceding writes' to complete
 >   e/ call blkdev_issue_flush
 >   f/ issue commit write without BIO_RW_BARRIER
 >   g/ wait for commit write to complete
 >        if it failed, abort
 >   h/ call blkdev_issue
 >   DONE
 > 
 > steps b and c can be left out if it is known that the device does not
 > support barriers.  The only way to discover this to try and see if it
 > fails.
 > 
 > I don't think any filesystem follows all these steps.

It seems that steps b/ -- h/ are quite generic, and can be implemented
once in a generic code (with some synchronization mechanism like
wait-queue at d/).

Nikita.

[...]

 > 
 > Thank you for your attention.
 > 
 > NeilBrown
 > 

Nikita.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/