Re: [PATCH 4/4] copyfile: copyfile

[Jörn Engel]

On Tue, 7 September 2004 07:06:00 -0700, Linus Torvalds wrote:
> 
> Then you could (and should) make a "generic_file_copy()" function that
> takes that pathname format, and then uses sendfile() to do the copy for
> regular disk-based filesystems.

Does that mean that you're ok with the first three patches?

> I think you should be able to copy the "sys_link()" code for almost all of 
> the top-level stuff. The only real difference being
> 
> -	error = dir->i_op->link(old_dentry, dir, new_dentry);
> +	error = dir->i_op->copy(old_dentry, dir, new_dentry);
> 
> or something.

ok.

> And no, I don't know how to handle interruptability.

How about the loop in 3/4?

> I think the right
> answer may be that filesystems that don't support this as a "native op"  
> and can't do it quickly should just return an error, and then users can
> copy their multi-gigabyte files by hand, like they used to.
> 
> So if we do this, we do this _right_. We also make sure that we error out 
> "too much" rather than "too little", so that people don't start depending 
> on behaviour that we don't want them to depend on. 

Makes sense, as long as any disk filesystem can decide to add a
one-liner like
	.copy = generic_file_copy;
to their operations and explicitly allow this.  Cowlinks remain my pet
project, even if I get distracted by Real Work sometimes.  Without
some form of in-kernel copy, they'd be dead in the water.

Jörn

-- 
Fantasy is more important than knowledge. Knowledge is limited,
while fantasy embraces the whole world.
-- Albert Einstein
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