From: Andreas Dilger <adilger@clusterfs.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: How can I force a read to hit the disk?
Date: Fri, 5 Sep 2003 12:15:22 -0600 [thread overview]
Message-ID: <20030905121522.B30448@schatzie.adilger.int> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0309051331230.678-100000@ida.rowland.org>; from stern@rowland.harvard.edu on Fri, Sep 05, 2003 at 01:46:22PM -0400
On Sep 05, 2003 13:46 -0400, Alan Stern wrote:
> My kernel module for Linux-2.6 needs to be able to verify that the media
> on which a file resides actually is readable. How can I do that?
>
> It would certainly suffice to use the normal VFS read routines, if there
> was some way to force the system to actually read from the device rather
> than just returning data already in the cache. So I guess it would be
> enough to perform an fdatasync for the file and then invalidate the file's
> cache entries. How does one invalidate a file's cache entries? Does
> filemap_flush() perform both these operations for you?
If you open the file with O_DIRECT, it should read/write directly on the
disk, and it will also invalidate any existing cache for the read/written
area.
Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/
next prev parent reply other threads:[~2003-09-05 18:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-05 17:46 Alan Stern
2003-09-05 18:15 ` Andreas Dilger [this message]
2003-09-05 18:49 ` Alan Stern
2003-09-05 19:09 ` Jörn Engel
2003-09-05 19:56 ` Alan Stern
2003-09-05 20:12 ` Alan Stern
2003-09-08 19:22 ` Alan Stern
2003-09-08 19:42 ` Richard B. Johnson
2003-09-08 20:36 ` Alan Stern
2003-09-09 12:13 ` Richard B. Johnson
2003-09-09 13:56 ` Alan Stern
2003-09-09 14:51 ` Richard B. Johnson
2003-09-09 20:16 ` Alan Stern
2003-09-05 18:42 ` Richard B. Johnson
2003-09-05 19:16 ` Alan Stern
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