Re: [RFC PATCH 0/2] Union Mount: Directory listing in glibc

NAGABHUSHAN BS
2008-04-30T06:07:28Z

On Tue, Apr 29, 2008 at 9:19 PM, Erez Zadok <ezk@cs.sunysb.edu> wrote:
> In message <20080429133201.GA9938@localhost.localdomain>, bsn.0007@gmail.com writes:
> > Hi,
> >
> > I went through Bharata's RFC post on glibc based Union Mount readdir solution
> > (http://lkml.org/lkml/2008/3/11/34) and have come up with patches
> > against glibc to implement the same.
> [...]
>
> The last set of discussions on glibc support ended, as I understood it, with
> the glibc people objecting to such "special-purpose" code in glibc. See
> <http://lkml.org/lkml/2008/3/11/66>. So has anything changed behind the
> scenes, or is this idea unlikely to be merged into glibc any time soon, if
> ever. (Personally I'd love to rip out the readdir-related code from unionfs
> if glibc supported the same.)
>
>
> > Patch 1. readdir support for union mounted directories.
> > I am caching the dirent names in a list to aid duplicate elimination.
> > And this cache is stored in DIRP. For duplicate elimination I am using
> > strcmp(). I am not sure if this works universally with different types
> > of filesystems. Any suggestions here would be welcome.
> [...]
>
> You might consider using a hash table instead of a list; it'll be faster in
> case where there are a lot of whiteouts/duplicates to process.
>

Yes, hash table was one of the things i had considered to use as a
cache. But i am not completely sure how this would support seekdir.
Any suggestions are greatly welcome.

Regards Nagabhushan