Re: Reiser4 + seekdir()

[Hans Reiser <reiser@namesys.com>]

Artem B. Bityuckiy wrote:

>> Location within a directory in reiser4 is logical number of entry within
>> the directory.
>
> Yes, I know. It does not absolutely correctly handle the way when
> dirents were deleted before and after the saved position.
>
> Well, Nikita kindly answered my questions in IRC (unfortunately there
> are few Namesys people there).
> According to him, seekdir() doesn't have to work correctly if the
> previous N direntries were deleted (it only tries). Indeed, even
> classical FSes (where directory is a file with the plain list of
> direntries) may shrink directories. I thought Reiser4 pretends to work
> correctly even in case of deletions.
>
>> fs/reiser4/plugin/dir/dir.c:seek_dir()
>>
>> You may also want to read a comment before
>> fs/reiser4/plugin/dir/dir.c:readdir_common and comment named  "STATELESS
>> READDIR" in the fs/reiser4/plugin/dir/dir.c.
>
> Yes, I read it of course. It is really confusing. What it should
> mention is that
>
>> we can not return entry key to telldir, on seekdir we have to be able to
>> position within a directory by off_t - therefore, we need adjust_dir_pos
>> anyway.
>
> Yes, thanks, I've realized this as well.
>
> Could you please explain the real difference between
> SEEKABLE_HASHED_DIR_PLUGIN_ID and LAST_DIR_ID plugins. Both seems to
> support seeks. Both seems to call adjust_dir_pos(). Only key
> assignment is simpler in case of SEEKABLE_HASHED_DIR_PLUGIN_ID. This
> confused me very much.
>
> Thanks.
>
We do accept patch contributions consisting of comments only.;-)  
Thanks for your patience.

Hans