Re: [PATCH -V14 04/11] vfs: Allow handle based open on symlinks

["Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>]

On Thu, 8 Jul 2010 01:23:03 +1000, Nick Piggin <npiggin@suse.de> wrote:
> On Tue, Jun 15, 2010 at 10:42:54PM +0530, Aneesh Kumar K.V wrote:
> > The patch update may_open to allow handle based open on symlinks.
> > The file handle based API use file descritor returned from open_by_handle_at
> > to do different file system operations. To find the link target name we
> > need to get a file descriptor on symlinks.
> 
> This is a pretty big change, isn't it?

Yes

> Have you looked through vfs to
> ensure this is actually OK? I was just looking at remount,ro code, for
> example, and it seems to assume only writable open files on ISREG
> files.

I verified that write and read returns an error on that descriptor. I
will look at rest of code to ensure the it doesn't break assumptions in
the rest of VFS.

> 
> Is this restricted to RDONLY? Really, it should be O_NONE...
> 
> 

we need the interface so that we can do fstat(lstat) and readlink using the
handle. If we are against the idea of allowing an fd on symlink, how about
adding stat_by_handle and readlink_by_handle syscall ? That way we can
drop "vfs: Support null pathname in readlink" patch 

-aneesh