From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752093Ab2LUV2l (ORCPT ); Fri, 21 Dec 2012 16:28:41 -0500 Received: from mail-da0-f54.google.com ([209.85.210.54]:57024 "EHLO mail-da0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751814Ab2LUV2i (ORCPT ); Fri, 21 Dec 2012 16:28:38 -0500 X-Greylist: delayed 79824 seconds by postgrey-1.27 at vger.kernel.org; Fri, 21 Dec 2012 16:28:38 EST From: Andy Lutomirski To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linux FS Devel Cc: Dave Chinner , Jan Kara , Al Viro , Andy Lutomirski Subject: [PATCH v2 0/3] Rework mtime and ctime updates on mmaped writes Date: Fri, 21 Dec 2012 13:28:25 -0800 Message-Id: X-Mailer: git-send-email 1.7.11.7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Writes via mmap currently update mtime and ctime in ->page_mkwrite. This is unfortunate from a performance and a correctness point of view. The file times should be updated after writes, not before (so that every write eventually results in a fresh timestamp). This is needed for POSIX compliance. More importantly (for me), ->page_mkwrite is called periodically even on mlocked pages, and some filesystems can sleep in mark_inode_dirty. This patchset attempts to fix both issues at once. It adds a new address_space flag AS_CMTIME that is set atomically whenever the system transfers a pte dirty bit to a struct page backed by the address_space. This can happen with various locks held and when low on memory. Later on, whenever syncing an inode (which happens indirectly in msync) or whenever a vma is torn down, if AS_CMTIME is set, then the file times are updated. This happens in a context from which (I think) it's safe to dirty inodes. One nice property of this approach is that it requires no fs-specific work. It's actually quite a bit simpler than I expected. I've tested this, and mtime and ctime are updated on munmap, exit, MS_SYNC, and fsync after writing via mmap. The times are also updated 30 seconds after writing, all by themselves :) xfstest #215 also passes.Lockdep has no complaints. Changes from v1: - inode_update_time_writable now locks against the fs freezer - Minor cleanups - Major changelog improvements Andy Lutomirski (3): mm: Explicitly track when the page dirty bit is transferred from a pte mm: Update file times when inodes are written after mmaped writes Remove file_update_time from all mkwrite paths fs/9p/vfs_file.c | 3 --- fs/btrfs/inode.c | 4 +-- fs/buffer.c | 6 ----- fs/ceph/addr.c | 3 --- fs/ext4/inode.c | 1 - fs/gfs2/file.c | 3 --- fs/inode.c | 72 ++++++++++++++++++++++++++++++++++++++----------- fs/nilfs2/file.c | 1 - fs/sysfs/bin.c | 2 -- include/linux/fs.h | 1 + include/linux/mm.h | 1 + include/linux/pagemap.h | 3 +++ mm/filemap.c | 1 - mm/memory-failure.c | 4 +-- mm/memory.c | 5 +--- mm/mmap.c | 4 +++ mm/page-writeback.c | 42 +++++++++++++++++++++++++++-- mm/rmap.c | 9 ++++--- 18 files changed, 115 insertions(+), 50 deletions(-) -- 1.7.11.7