On Mon, Apr 25, 2022 at 10:38:02AM -0500, Eric Sandeen wrote:
> On 4/25/22 8:43 AM, Karel Zak wrote:
> >
> > Thanks Andrey,
> >
> > the code looks good.
> >
> > On Thu, Apr 21, 2022 at 03:09:44PM +0200, Andrey Albershteyn wrote:
> >> I had a look into other fs, like ext4 and btrfs, to implement FSSIZE
> >> for them, but I think I don't have enough expertize to do that as
> >> they have not so trivial metadata overhead calculation :)
> >
> > But it would be nice to have ext4 and btrfs too. Maybe Eric can help
> > you :-)
> >
> > Karel
>
> For ext4 something like e2fsprogs does is probably ok:
>
> static __u64 e2p_free_blocks_count(struct ext2_super_block *super)
> {
> return super->s_free_blocks_count |
> (ext2fs_has_feature_64bit(super) ?
> (__u64) super->s_free_blocks_hi << 32 : 0);
> }
>
> though I wonder if a little documentation on the intent of the flag is
> in order; ext4 can return "df" in different ways (see the minixdf and
> bsddf mount options.)
>
> I think best effort seems fine here, and reporting the same number
> as the ext4 utilities do should be fine.
Yes, that's good enough.
> As for btrfs - I'm really not sure what this should return on a
> multi-device filesystem?
Hmm ... good point. I guess the right answer is return nothing,
because we really don't want any complicated fs-specific logic in
libblkid.
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
