linux-kernel - Re: [PATCH 0/4] Properly invalidate data in the cleancache.

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Date:   Tue, 18 Apr 2017 11:24:11 -0400
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org,
        Eric Van Hensbergen <ericvh@...il.com>,
        Ron Minnich <rminnich@...dia.gov>,
        Latchesar Ionkov <lucho@...kov.net>,
        Steve French <sfrench@...ba.org>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Trond Myklebust <trond.myklebust@...marydata.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Jens Axboe <axboe@...nel.dk>,
        Johannes Weiner <hannes@...xchg.org>,
        Alexey Kuznetsov <kuznet@...tuozzo.com>,
        Christoph Hellwig <hch@....de>,
        v9fs-developer@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
        linux-nfs@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 0/4] Properly invalidate data in the cleancache.

On Fri, Apr 14, 2017 at 05:07:49PM +0300, Andrey Ryabinin wrote:
> We've noticed that after direct IO write, buffered read sometimes gets
> stale data which is coming from the cleancache.

That is not good.
> The reason for this is that some direct write hooks call call invalidate_inode_pages2[_range]()
> conditionally iff mapping->nrpages is not zero, so we may not invalidate
> data in the cleancache.
> 
> Another odd thing is that we check only for ->nrpages and don't check for ->nrexceptional,

Yikes.
> but invalidate_inode_pages2[_range] also invalidates exceptional entries as well.
> So we invalidate exceptional entries only if ->nrpages != 0? This doesn't feel right.
> 
>  - Patch 1 fixes direct IO writes by removing ->nrpages check.
>  - Patch 2 fixes similar case in invalidate_bdev(). 
>      Note: I only fixed conditional cleancache_invalidate_inode() here.
>        Do we also need to add ->nrexceptional check in into invalidate_bdev()?
>      
>  - Patches 3-4: some optimizations.

Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

Thanks!
> 
> Andrey Ryabinin (4):
>   fs: fix data invalidation in the cleancache during direct IO
>   fs/block_dev: always invalidate cleancache in invalidate_bdev()
>   mm/truncate: bail out early from invalidate_inode_pages2_range() if
>     mapping is empty
>   mm/truncate: avoid pointless cleancache_invalidate_inode() calls.
> 
>  fs/9p/vfs_file.c |  2 +-
>  fs/block_dev.c   | 11 +++++------
>  fs/cifs/inode.c  |  2 +-
>  fs/dax.c         |  2 +-
>  fs/iomap.c       | 16 +++++++---------
>  fs/nfs/direct.c  |  6 ++----
>  fs/nfs/inode.c   |  8 +++++---
>  mm/filemap.c     | 26 +++++++++++---------------
>  mm/truncate.c    | 13 +++++++++----
>  9 files changed, 42 insertions(+), 44 deletions(-)
> 
> -- 
> 2.10.2
>