Re: [PATCH -V18 04/13] vfs: Allow handle based open on symlinks

[Aneesh Kumar K. V]

On Sat, 21 Aug 2010 01:13:52 -0600, Andreas Dilger <andreas.dilger@xxxxxxxxxx> wrote:
> On 2010-08-20, at 18:09, Neil Brown <neilb@xxxxxxx> wrote:
> > How about a new AT flag:  AT_FILE_HANDLE
> > 
> > Meaning is that the 'dirfd' is used only to identify a filesystem (vfsmnt) and
> > the 'name' pointer actually points to a filehandle fragment interpreted in
> > that filesystem.
> > 
> > One problem is that there is no way to pass the length...
> > Options:
> >   fragment is at most 64 bytes nul padded at the end
> >   fragment is hex encoded and nul terminated
> >   ??
> > 
> > I think I prefer the hex encoding, but I'm hoping someone else has a better
> > idea.
> 
> That makes it ugly for the kernel to stringify and parse the file handles. 
> 
> How about for AT_FILE_HANDLE THE FIRST __u32 (maybe with an extra
> __u32 for alignment) is the length and the rest of the binary file
> handle follows this?  In fact, doesn't the handle itself already
> encode the length in the header?


struct file_handle already include length

-aneesh

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