Re: [Bug-tar] [PATCH] Re: Detection of sparse files is broken on btrfs

[Pavel Raiskup]

On Tuesday, January 9, 2018 11:15:56 AM CET Joerg Schilling wrote:
> Pavel Raiskup <address@hidden> wrote:
> 
> > On Tuesday, January 9, 2018 8:59:06 AM CET Paul Eggert wrote:
> > > Pavel Raiskup wrote:
> > > > So what about special casing that filesystem, where we can lseek() for
> > > > holes anyway?
> > > 
> > > If we can lseek for holes, then why not just do that?
> >
> > Checking whether lseek() actually works costs some additional syscalls _per
> > sparse_ file;  checking for ST_NBLOCKS() is without this penalty.
> 
> Well, star does this since a long time and the penalty is a few microseconds.

It would be interesting to see how network filesystems are affected.

Pavel