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
| ||
|
Date: Wed, 5 Apr 2017 14:03:58 -0700 From: Matthew Wilcox <willy@...radead.org> To: Jeff Layton <jlayton@...hat.com> Cc: NeilBrown <neilb@...e.com>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org, akpm@...ux-foundation.org, tytso@....edu, jack@...e.cz Subject: Re: [RFC PATCH 0/4] fs: introduce new writeback error tracking infrastructure and convert ext4 to use it On Wed, Apr 05, 2017 at 03:49:52PM -0400, Jeff Layton wrote: > > That only gives us 20 bits of counter, but I think that's enough. > > 2^20 is 1048576, which seems a little small to me. > > We may end up bumping the counter on every failed I/O. How fast can we > generate 1M failed I/Os? :) So there's a one-in-a-million chance of missing a failed I/O ... if we're generating lots of errors, the next time the app calls fsync(), it'll notice the other million times we've hit the problem :-) > Actually...we could put this field in the inode instead of the mapping. > I know we've traditionally tracked this in the mapping, but is that > required here? > > If we put this field in the inode then perhaps we can union it with > something and mitigate the cost of a larger counter...maybe in the > i_pipe union? I don't think S_ISREG inodes use anything in there, do > they? But writeback isn't just done on ISREG inodes, but also on S_ISBLK inodes, which use i_bdev (right?) Another possibility is to move this out of the address_space and into either the super_block or the backing_device_info. Errors don't tend to be constrained to a single file but affect the entire filesystem, or even multiple filesystems if you have a partitioned block device ...
Powered by blists - more mailing lists