linux-kernel - Re: [PATCH v2] fadvise: introduce POSIX_FADV_DONTNEED

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]

Date:	Wed, 27 Apr 2011 12:47:56 -0600
From:	Matthew Wilcox <matthew@....cx>
To:	Mike Frysinger <vapier@...too.org>
Cc:	Andrea Righi <andrea@...terlinux.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Chinner <david@...morbit.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, linux-fsdevel@...r.kernel.org,
	linux-api@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] fadvise: introduce POSIX_FADV_DONTNEED_FS

On Wed, Apr 27, 2011 at 02:39:53PM -0400, Mike Frysinger wrote:
> > Mmm ... what if I open /dev/sdxyz and call fadvise() on it? ??I think
> > you end up flushing /dev's page cache entries, instead of the filesystem
> > which is on /dev/sdxyz.
> 
> i was thinking of that, but was trying to come up with situations
> where there might not have a node to work on.  fs's in a file go
> through loop devs, dm/lvm have ones created, and flash fs's still have
> a mtd block.  how about network based fs's ?  how you going to signal
> dropping of pages for nfs or cifs or fuse ones ?

For a regular file, mapping->host->i_sb points to the superblock this
file is on.  For a device, mapping->host->i_sb points to the superblock
corresponding to this device.  So it's always what we want.

(hm, what about block devices not currently mounted?  do we need to check
whether mapping->host is NULL?)

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
--
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/