Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757616AbYFYMlk (ORCPT ); Wed, 25 Jun 2008 08:41:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755518AbYFYMl1 (ORCPT ); Wed, 25 Jun 2008 08:41:27 -0400 Received: from fxip-0047f.externet.hu ([88.209.222.127]:34462 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755196AbYFYMl0 (ORCPT ); Wed, 25 Jun 2008 08:41:26 -0400 Message-Id: <20080625124121.839734708@szeredi.hu> References: <20080625124038.103406301@szeredi.hu> User-Agent: quilt/0.45-1 Date: Wed, 25 Jun 2008 14:40:39 +0200 From: Miklos Szeredi To: jens.axboe@oracle.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, hugh@veritas.com, nickpiggin@yahoo.com.au Subject: [patch 1/2] mm: dont clear PG_uptodate in invalidate_complete_page2() Content-Disposition: inline; filename=splice_page_cache_pipe_buf_confirm_fix.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1903 Lines: 47 From: Miklos Szeredi Clearing the uptodate page flag will cause page_cache_pipe_buf_confirm() to return -ENODATA if that page was in the buffer. This in turn will cause splice() to return a short or zero count. This manifested itself in rare I/O errors seen on nfs exported fuse filesystems. This is because nfsd uses splice_direct_to_actor() to read files, and fuse uses invalidate_inode_pages2() to invalidate stale data on open. Fix this by not clearing PG_uptodate on page invalidation. This will result in the old, invalid page contents being copied. But that's OK, the contents were valid at splice-in time (which is when the the "copy" was conceptually done). I haven't done an audit of all code that checks the PG_uptodate flags, but I suspect, that this change won't have any harmful effects. Most code checks page->mapping to see if the page was truncated or invalidated, before using it, and retries the find/read on the page if it wasn't. The page_cache_pipe_buf_confirm() code is an exception in this regard. Signed-off-by: Miklos Szeredi --- mm/truncate.c | 1 - 1 file changed, 1 deletion(-) Index: linux-2.6/mm/truncate.c =================================================================== --- linux-2.6.orig/mm/truncate.c 2008-06-24 20:49:25.000000000 +0200 +++ linux-2.6/mm/truncate.c 2008-06-24 23:28:32.000000000 +0200 @@ -356,7 +356,6 @@ invalidate_complete_page2(struct address BUG_ON(PagePrivate(page)); __remove_from_page_cache(page); write_unlock_irq(&mapping->tree_lock); - ClearPageUptodate(page); page_cache_release(page); /* pagecache ref */ return 1; failed: -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/