Re: [PATCH 2/3] nfsd: move change attribute generation to filesystem

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Jan 20, 2021 at 08:46:38AM +0000, Christoph Hellwig wrote:
> On Tue, Jan 19, 2021 at 02:24:56PM -0500, J. Bruce Fields wrote:
> > From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
> > 
> > After this, only filesystems lacking change attribute support will leave
> > the fetch_iversion export op NULL.
> > 
> > This seems cleaner to me, and will allow some minor optimizations in the
> > nfsd code.
> 
> Another indirect call just to fetch the change attribute (which happens
> a lot IIRC) does not seem very optimal to me.

In the next patch we're removing an fh_getattr (vfs_getattr) in the case
we call the new op, so that's typically a net decrease in indirect
calls.

Though maybe we could use a flag here and do without either.

> And the fact that we need three duplicate implementations also is not
> very nice.

Ext4 and xfs are identical, btrfs is a little different since it doesn't
consult I_VERSION.  (And then there's nfs, which uses the origin
server's i_version if it can.)

I also have a vague idea that some filesystem-specific improvements
might be possible.  (E.g., if a filesystem had some kind of boot count
in the superblock, maybe that would be a better way to prevent the
change attribute from going backwards on reboot than the thing
generic_fetch_iversion is currently doing with ctime.  But I have no
concrete plan there, maybe I'm dreaming.)

--b.




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux