Re: [PATCH 00/11 v2] Push file_update_time() into .page_mkwrite

[Jan Kara <jack@suse.cz>]

  Bah, the subject should have been 0/9... Sorry.

								Honza
On Thu 01-03-12 12:41:34, Jan Kara wrote:
>   Hello,
> 
>   to provide reliable support for filesystem freezing, filesystems need to have
> complete control over when metadata is changed. In particular,
> file_update_time() calls from page fault code make it impossible for
> filesystems to prevent inodes from being dirtied while the filesystem is
> frozen.
> 
> To fix the issue, this patch set changes page fault code to call
> file_update_time() only when ->page_mkwrite() callback is not provided. If the
> callback is provided, it is the responsibility of the filesystem to perform
> update of i_mtime / i_ctime if needed. We also push file_update_time() call
> to all existing ->page_mkwrite() implementations if the time update does not
> obviously happen by other means. If you know your filesystem does not need
> update of modification times in ->page_mkwrite() handler, please speak up and
> I'll drop the patch for your filesystem.
> 
> As a side note, an alternative would be to remove call of file_update_time()
> from page fault code altogether and require all filesystems needing it to do
> that in their ->page_mkwrite() implementation. That is certainly possible
> although maybe slightly inefficient and would require auditting 100+
> vm_operations_structs *shiver*.
> 
> Changes since v1:
> * Dropped patches for filesystems which don't need them
> * Added some acks
> * Improved sysfs patch by Alex Elder's suggestion
> 
> Andrew, would you be willing to merge these patches via your tree?
> 
> 								Honza
> 
> CC: Jaya Kumar <jayalk@intworks.biz>
> CC: Sage Weil <sage@newdream.net>
> CC: ceph-devel@vger.kernel.org
> CC: Steve French <sfrench@samba.org>
> CC: linux-cifs@vger.kernel.org
> CC: Eric Van Hensbergen <ericvh@gmail.com>
> CC: Ron Minnich <rminnich@sandia.gov>
> CC: Latchesar Ionkov <lucho@ionkov.net>
> CC: v9fs-developer@lists.sourceforge.net
> CC: Miklos Szeredi <miklos@szeredi.hu>
> CC: fuse-devel@lists.sourceforge.net
> CC: Steven Whitehouse <swhiteho@redhat.com>
> CC: cluster-devel@redhat.com
> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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