Re: BIG files & file systems

[Nikita Danilov]

Trond Myklebust writes:
 > >>>>> " " == Nikita Danilov <[e-mail]> writes:
 > 
 >      > But there still is a problem with applications (if any) calling
 >      > seekdir/telldir directly...
 > 
 > Agreed. Note however that the semantics for seekdir/telldir as
 > specified by SUSv2 are much weaker than those in our current
 > getdents()+lseek().
 > 
 > >From the Opengroup documentation for seekdir, it states that:
 > 
 >   On systems that conform to the Single UNIX Specification, Version 2,
 >   a subsequent call to readdir() may not be at the desired position if
 >   the value of loc was not obtained from an earlier call to telldir(),
 >   or if a call to rewinddir() occurred between the call to telldir()
 >   and the call to seekdir().
 > 
 > IOW assigning a unique offset to each and every entry in the directory
 > is overkill (unless the user is calling telldir() for all those
 > entries).

Are you implying some kind of ->telldir() file operation that notifies
file-system that user has intention to later restart readdir from the
"current" position and changing glibc to call sys_telldir/sys_seekdir in
stead of lseek? This will allow file-systems like reiser4 that cannot
restart readdir from 32bitsful of data to, at least, allocate something
in kernel on call to ->telldir() and free in ->release().

 > 
 > Cheers,
 >   Trond

Nikita.