From: ebiederm@xmission.com (Eric W. Biederman)
To: Jan Kara <jack@suse.cz>
Cc: Alex Elder <elder@dreamhost.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Eric Sandeen <sandeen@redhat.com>,
Dave Chinner <david@fromorbit.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH 09/11] sysfs: Push file_update_time() into bin_page_mkwrite()
Date: Wed, 29 Feb 2012 09:46:40 -0800 [thread overview]
Message-ID: <m1vcmp8rcv.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <20120220110006.GA6799@quack.suse.cz> (Jan Kara's message of "Mon, 20 Feb 2012 12:00:06 +0100")
Jan Kara <jack@suse.cz> writes:
> On Thu 16-02-12 13:04:44, Alex Elder wrote:
>> On Thu, 2012-02-16 at 14:46 +0100, Jan Kara wrote:
>> > CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> > Signed-off-by: Jan Kara <jack@suse.cz>
>> > ---
>> > fs/sysfs/bin.c | 2 ++
>> > 1 files changed, 2 insertions(+), 0 deletions(-)
>> >
>> > diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
>> > index a475983..6ceb16f 100644
>> > --- a/fs/sysfs/bin.c
>> > +++ b/fs/sysfs/bin.c
>> > @@ -225,6 +225,8 @@ static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
>> > if (!sysfs_get_active(attr_sd))
>> > return VM_FAULT_SIGBUS;
>> >
>> > + file_update_time(file);
>> > +
>> > ret = 0;
>> > if (bb->vm_ops->page_mkwrite)
>> > ret = bb->vm_ops->page_mkwrite(vma, vmf);
>>
>> If the filesystem's page_mkwrite() function is responsible
>> for updating the time, can't the call to file_update_time()
>> here be conditional?
>>
>> I.e:
>> ret = 0;
>> if (bb->vm_ops->page_mkwrite)
>> ret = bb->vm_ops->page_mkwrite(vma, vmf);
>> else
>> file_update_time(file);
> Hmm, I didn't look previously where do we get bb->vm_ops. It seems they
> are inherited from vma->vm_ops so what you suggest should be safe without
> any further changes. So I can do that if someone who understands the sysfs
> code likes it more.
I do. Essentially sysfs is being a stackable filesystem here, because
sysfs needs the ability to remove a file mapping.
In practice we could probably get away without a single
file_update_time(file) here because there are mmio mappings. Normally
for pci resources, but we might as well use good form since we can.
Eric
next prev parent reply other threads:[~2012-02-29 17:43 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-16 13:46 [PATCH 00/11] Push file_update_time() into .page_mkwrite Jan Kara
2012-02-16 13:46 ` [PATCH 01/11] perf: Push file_update_time() into perf_mmap_fault() Jan Kara
2012-02-16 13:50 ` Peter Zijlstra
2012-02-20 22:33 ` Jan Kara
2012-02-16 13:46 ` [PATCH 02/11] fb_defio: Push file_update_time() into fb_deferred_io_mkwrite() Jan Kara
2012-02-16 13:46 ` [PATCH 03/11] fs: Push file_update_time() into __block_page_mkwrite() Jan Kara
2012-02-16 13:46 ` [PATCH 04/11] ceph: Push file_update_time() into ceph_page_mkwrite() Jan Kara
2012-02-16 19:04 ` Alex Elder
2012-02-16 19:13 ` Sage Weil
2012-02-20 22:42 ` Jan Kara
2012-02-20 22:57 ` Sage Weil
2012-02-20 11:06 ` Jan Kara
2012-02-16 13:46 ` [PATCH 05/11] cifs: Push file_update_time() into cifs_page_mkwrite() Jan Kara
2012-02-16 13:46 ` [PATCH 06/11] 9p: Push file_update_time() into v9fs_vm_page_mkwrite() Jan Kara
2012-02-16 13:46 ` [PATCH 07/11] fuse: Push file_update_time() into fuse_page_mkwrite() Jan Kara
2012-02-16 13:46 ` [PATCH 08/11] gfs2: Push file_update_time() into gfs2_page_mkwrite() Jan Kara
2012-02-16 16:47 ` Steven Whitehouse
2012-02-16 13:46 ` [PATCH 09/11] sysfs: Push file_update_time() into bin_page_mkwrite() Jan Kara
2012-02-16 16:24 ` Greg Kroah-Hartman
2012-02-16 19:04 ` Alex Elder
2012-02-20 11:00 ` Jan Kara
2012-02-29 17:46 ` Eric W. Biederman [this message]
2012-02-16 13:46 ` [PATCH 10/11] nfs: Push file_update_time() into nfs_vm_page_mkwrite() Jan Kara
2012-02-16 13:50 ` Myklebust, Trond
2012-02-20 22:32 ` Jan Kara
2012-02-16 13:46 ` [PATCH 11/11] mm: Update file times from fault path only if .page_mkwrite is not set Jan Kara
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