From 55635ba76ef91f26b418702ace5e6287eb727f6a Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Wed, 3 May 2017 14:55:59 -0700 Subject: fs: fix data invalidation in the cleancache during direct IO 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: c515e1fd361c ("mm/fs: add hooks to support cleancache") Link: http://lkml.kernel.org/r/20170424164135.22350-2-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin Reviewed-by: Jan Kara Acked-by: Konrad Rzeszutek Wilk Cc: Alexander Viro Cc: Ross Zwisler Cc: Jens Axboe Cc: Johannes Weiner Cc: Alexey Kuznetsov Cc: Christoph Hellwig Cc: Nikolay Borisov Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/filemap.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-) (limited to 'mm/filemap.c') diff --git a/mm/filemap.c b/mm/filemap.c index 7f425f18c158..681da61080bc 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2720,18 +2720,16 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from) * about to write. We do this *before* the write so that we can return * without clobbering -EIOCBQUEUED from ->direct_IO(). */ - if (mapping->nrpages) { - written = invalidate_inode_pages2_range(mapping, + written = invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, end); - /* - * If a page can not be invalidated, return 0 to fall back - * to buffered write. - */ - if (written) { - if (written == -EBUSY) - return 0; - goto out; - } + /* + * If a page can not be invalidated, return 0 to fall back + * to buffered write. + */ + if (written) { + if (written == -EBUSY) + return 0; + goto out; } written = mapping->a_ops->direct_IO(iocb, from); @@ -2744,10 +2742,8 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from) * so we don't support it 100%. If this invalidation * fails, tough, the write still worked... */ - if (mapping->nrpages) { - invalidate_inode_pages2_range(mapping, - pos >> PAGE_SHIFT, end); - } + invalidate_inode_pages2_range(mapping, + pos >> PAGE_SHIFT, end); if (written > 0) { pos += written; -- cgit v1.2.3