linux-kernel - Re: [PATCH v6 1/7] fs: pass the request_mask to generic

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Message-ID: <e1c4a6d5001d029548542a1f10425c5639ce28e4.camel@kernel.org>
Date:   Tue, 29 Aug 2023 18:58:47 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Eric Van Hensbergen <ericvh@...nel.org>,
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Subject: Re: [PATCH v6 1/7] fs: pass the request_mask to generic_fillattr

On Tue, 2023-08-29 at 23:44 +0100, Al Viro wrote:
> On Tue, Jul 25, 2023 at 10:58:14AM -0400, Jeff Layton wrote:
> > generic_fillattr just fills in the entire stat struct indiscriminately
> > today, copying data from the inode. There is at least one attribute
> > (STATX_CHANGE_COOKIE) that can have side effects when it is reported,
> > and we're looking at adding more with the addition of multigrain
> > timestamps.
> > 
> > Add a request_mask argument to generic_fillattr and have most callers
> > just pass in the value that is passed to getattr. Have other callers
> > (e.g. ksmbd) just pass in STATX_BASIC_STATS. Also move the setting of
> > STATX_CHANGE_COOKIE into generic_fillattr.
> 
> Out of curiosity - how much PITA would it be to put request_mask into
> kstat?  Set it in vfs_getattr_nosec() (and those get_file_..._info()
> on smbd side) and don't bother with that kind of propagation boilerplate
> - just have generic_fillattr() pick it there...
> 
> Reduces the patchset size quite a bit...

It could be done. To do that right, I think we'd want to drop
request_mask from the ->getattr prototype as well and just have
everything use the mask in the kstat.

I don't think it'd reduce the size of the patchset in any meaningful
way, but it might make for a more sensible API over the long haul.
-- 
Jeff Layton <jlayton@...nel.org>