• Andrey Ryabinin's avatar
    fs: fix data invalidation in the cleancache during direct IO · 60146286
    Andrey Ryabinin authored
    commit 55635ba7 upstream.
    
    Patch series "Properly invalidate data in the cleancache", v2.
    
    We've noticed that after direct IO write, buffered read sometimes gets
    stale data which is coming from the cleancache.  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, 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.
    
    This patch (of 4):
    
    Some direct IO write fs hooks call invalidate_inode_pages2[_range]()
    conditionally iff mapping->nrpages is not zero.  This can't be right,
    because invalidate_inode_pages2[_range]() also invalidate data in the
    cleancache via cleancache_invalidate_inode() call.  So if page cache is
    empty but there is some data in the cleancache, buffered read after
    direct IO write would get stale data from the cleancache.
    
    Also it doesn't feel right to check only for ->nrpages because
    invalidate_inode_pages2[_range] invalidates exceptional entries as well.
    
    Fix this by calling invalidate_inode_pages2[_range]() regardless of
    nrpages state.
    
    Note: nfs,cifs,9p doesn't need similar fix because the never call
    cleancache_get_page() (nor directly, nor via mpage_readpage[s]()), so
    they are not affected by this bug.
    
    Fixes: c515e1fd ("mm/fs: add hooks to support cleancache")
    Link: http://lkml.kernel.org/r/20170424164135.22350-2-aryabinin@virtuozzo.comSigned-off-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
    Reviewed-by: default avatarJan Kara <jack@suse.cz>
    Acked-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Cc: Alexander Viro <viro@zeniv.linux.org.uk>
    Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Alexey Kuznetsov <kuznet@virtuozzo.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Nikolay Borisov <n.borisov.lkml@gmail.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    60146286
filemap.c 79.9 KB