From: Valerie Aurora <vaurora@redhat.com>
To: Neil Brown <neilb@suse.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
Jan Blunck <jblunck@suse.de>,
David Woodhouse <dwmw2@infradead.org>,
linux-nfs@vger.kernel.org,
"J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: [PATCH 05/39] whiteout/NFSD: Don't return information about whiteouts to userspace
Date: Mon, 17 May 2010 15:51:45 -0400 [thread overview]
Message-ID: <20100517195145.GB18568@shell> (raw)
In-Reply-To: <20100507071808.20028458@notabene.brown>
On Fri, May 07, 2010 at 07:18:08AM +1000, Neil Brown wrote:
> On Thu, 6 May 2010 14:01:51 -0400
> Valerie Aurora <vaurora@redhat.com> wrote:
>
> > On Tue, May 04, 2010 at 09:37:31AM +1000, Neil Brown wrote:
> > > On Mon, 3 May 2010 16:12:04 -0700
> > > Valerie Aurora <vaurora@redhat.com> wrote:
> > >
> > > > From: Jan Blunck <jblunck@suse.de>
> > > >
> > > > Userspace isn't ready for handling another file type, so silently drop
> > > > whiteout directory entries before they leave the kernel.
> > >
> > > Feels very intrusive doesn't it....
> > >
> > > Have you considered something like the following?
> >
> > Hrm, I see how that could be more elegant, but I'd rather avoid yet
> > another layer of function pointer passing around. This code is
> > already hard enough to review...
>
> Yes, the extra indirection is a bit of a negative, but I don't think this
> patch is harder to review than the alternate.
> From a numerical perspective, with this patch you only need to look at the
> various places that ->readdir is called to be sure it is always correct.
> There are about 3. With the original you need to look at ever filldir
> function. Jan has found 9.
>
> And from a maintainability perspective, I think my approach is safer. Given
> that there are 9 filldir functions already, the chance that a need will be
> found for another seems good, and the chance that the coder will know to
> check for DT_WHT is a best even. Conversely if another call to ->readdir
> were added it is likely that nothing would need to be done.
>
> Of course just counting things doesn't give a completely picture but I think
> it can be indicative.
Okay, good points. Let me try it out after getting this next rewrite done.
Thanks,
-VAL
next prev parent reply other threads:[~2010-05-17 19:51 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-03 23:11 [RFC PATCH 00/39] Union mounts with xattrs Valerie Aurora
2010-05-03 23:12 ` [PATCH 01/39] VFS: Comment follow_mount() and friends Valerie Aurora
2010-05-03 23:12 ` [PATCH 02/39] VFS: Make lookup_hash() return a struct path Valerie Aurora
2010-05-03 23:12 ` [PATCH 03/39] VFS: Add read-only users count to superblock Valerie Aurora
2010-05-03 23:12 ` [PATCH 04/39] autofs4: Save autofs trigger's vfsmount in super block info Valerie Aurora
2010-05-03 23:12 ` [PATCH 05/39] whiteout/NFSD: Don't return information about whiteouts to userspace Valerie Aurora
2010-05-03 23:37 ` Neil Brown
2010-05-03 23:37 ` Neil Brown
2010-05-06 18:01 ` Valerie Aurora
2010-05-06 21:18 ` Neil Brown
2010-05-06 21:18 ` Neil Brown
2010-05-17 19:51 ` Valerie Aurora [this message]
2010-05-03 23:12 ` [PATCH 06/39] whiteout: Add vfs_whiteout() and whiteout inode operation Valerie Aurora
2010-05-03 23:12 ` [PATCH 07/39] whiteout: Set S_OPAQUE inode flag when creating directories Valerie Aurora
2010-05-03 23:12 ` [PATCH 08/39] whiteout: Allow removal of a directory with whiteouts Valerie Aurora
2010-05-03 23:12 ` [PATCH 09/39] whiteout: tmpfs whiteout support Valerie Aurora
2010-05-03 23:12 ` Valerie Aurora
2010-05-03 23:12 ` [PATCH 10/39] whiteout: Split of ext2_append_link() from ext2_add_link() Valerie Aurora
2010-05-03 23:12 ` [PATCH 11/39] whiteout: ext2 whiteout support Valerie Aurora
2010-05-03 23:12 ` [PATCH 12/39] whiteout: jffs2 " Valerie Aurora
2010-05-03 23:12 ` Valerie Aurora
2010-05-03 23:12 ` Valerie Aurora
2010-05-03 23:12 ` [PATCH 13/39] fallthru: Basic fallthru definitions Valerie Aurora
2010-05-03 23:12 ` [PATCH 14/39] fallthru: ext2 fallthru support Valerie Aurora
2010-05-03 23:12 ` [PATCH 15/39] fallthru: jffs2 " Valerie Aurora
2010-05-03 23:12 ` Valerie Aurora
2010-05-03 23:12 ` Valerie Aurora
2010-05-03 23:12 ` [PATCH 16/39] fallthru: tmpfs " Valerie Aurora
2010-05-03 23:12 ` [PATCH 17/39] union-mount: Union mounts documentation Valerie Aurora
2010-05-04 1:54 ` Valdis.Kletnieks
2010-05-05 13:06 ` Valerie Aurora
2010-05-04 21:12 ` Jamie Lokier
2010-05-05 13:19 ` Valerie Aurora
2010-05-03 23:12 ` [PATCH 18/39] union-mount: Introduce MNT_UNION and MS_UNION flags Valerie Aurora
2010-05-03 23:12 ` [PATCH 19/39] union-mount: Introduce union_mount structure and basic operations Valerie Aurora
2010-05-03 23:12 ` [PATCH 20/39] union-mount: Drive the union cache via dcache Valerie Aurora
2010-05-03 23:12 ` [PATCH 21/39] union-mount: Implement union lookup Valerie Aurora
2010-05-03 23:12 ` [PATCH 22/39] union-mount: Support for mounting union mount file systems Valerie Aurora
2010-05-03 23:12 ` [PATCH 23/39] union-mount: Call do_whiteout() on unlink and rmdir in unions Valerie Aurora
2010-05-03 23:12 ` [PATCH 24/39] union-mount: Copy up directory entries on first readdir() Valerie Aurora
2010-05-03 23:12 ` [PATCH 25/39] VFS: Split inode_permission() and create path_permission() Valerie Aurora
2010-05-03 23:12 ` [PATCH 26/39] VFS: Create user_path_nd() to lookup both parent and target Valerie Aurora
2010-05-03 23:12 ` [PATCH 27/39] union-mount: In-kernel copyup routines Valerie Aurora
2010-05-04 1:40 ` Valdis.Kletnieks
2010-05-07 14:45 ` Valerie Aurora
2010-05-03 23:12 ` [PATCH 28/39] union-mount: In-kernel copyup of xattrs Valerie Aurora
2010-05-03 23:12 ` [PATCH 29/39] union-mount: Implement union-aware access()/faccessat() Valerie Aurora
2010-05-03 23:12 ` [PATCH 30/39] union-mount: Implement union-aware link() Valerie Aurora
2010-05-03 23:12 ` [PATCH 31/39] union-mount: Implement union-aware rename() Valerie Aurora
2010-05-03 23:12 ` [PATCH 32/39] union-mount: Implement union-aware writable open() Valerie Aurora
2010-05-03 23:12 ` [PATCH 33/39] union-mount: Implement union-aware chown() Valerie Aurora
2010-05-03 23:12 ` [PATCH 34/39] union-mount: Implement union-aware truncate() Valerie Aurora
2010-05-03 23:12 ` [PATCH 35/39] union-mount: Implement union-aware chmod()/fchmodat() Valerie Aurora
2010-05-03 23:12 ` [PATCH 36/39] union-mount: Implement union-aware lchown() Valerie Aurora
2010-05-03 23:12 ` [PATCH 37/39] union-mount: Implement union-aware utimensat() Valerie Aurora
2010-05-03 23:12 ` [PATCH 38/39] union-mount: Implement union-aware setxattr() Valerie Aurora
2010-05-03 23:12 ` [PATCH 39/39] union-mount: Implement union-aware lsetxattr() Valerie Aurora
-- strict thread matches above, loose matches on Subject: below --
2010-08-08 15:52 [PATCH 00/39] Union mounts - return d_ino from lower fs Valerie Aurora
2010-08-08 15:52 ` [PATCH 05/39] whiteout/NFSD: Don't return information about whiteouts to userspace Valerie Aurora
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