Re: [PATCH 1/2] fs: add SEEK_HOLE and SEEK_DATA flags

[Christoph Hellwig <hch@infradead.org>]

[Eric: please don't drop the Cc list, thanks!]

On Thu, Apr 21, 2011 at 09:22:55PM -0400, Josef Bacik wrote:
> > since all files have a virtual hole at the end, but leaves the position
> > unchanged). ??I'd have to write a test program on Solaris to see whether that
> > definition is actually true, or if it is a bug in the Solaris man page.
> >
> 
> lseek's purpose is to reposition the file position, so I'd imagine
> this is just a bug in the man page.

I would be surprised if the bug is around for such a long time, but
otherwise I concur.

> Except you can have blocks allocated past i_size, so returning i_size
> isn't necessarily correct.  Obviously the idea is to have most of the
> filesystems doing the correct thing, but for my first go around I just
> was going to do one since I expect quite a bit of repainting for this
> bikeshed is yet to be done.  But I guess if you have data past i_size
> doing this would encourage the various fs people to fix it.

Trying to be smart about our semantics is not helpful here.  The
interface has been out in Solaris for a while, and we'll have to either
stick to it or use different names for the interface.  And staying
compatible is far more useful for userspace programmers.