Re: [RFC 1/9] block: add llseek(SEEK_HOLE/SEEK_DATA) support

Eric Blake
2024-03-28T23:50:33Z

On Thu, Mar 28, 2024 at 04:39:02PM -0400, Stefan Hajnoczi wrote:
> The SEEK_HOLE/SEEK_DATA interface is used by userspace applications to
> detect sparseness. This makes copying and backup applications faster and
> reduces space consumption because only ranges that do not contain data
> can be skipped.

s/only //

>
> Handle SEEK_HOLE/SEEK_DATA for block devices. No block drivers implement
> the new callback yet so the entire block device will appear to contain
> data. Later patches will add support to drivers so this actually becomes
> useful.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> include/linux/blkdev.h | 7 +++++++
> block/fops.c | 43 +++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 49 insertions(+), 1 deletion(-)
>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization: qemu.org | libguestfs.org