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

["NAGABHUSHAN BS" <bsn.0007@gmail.com>]

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