On Wed, Jan 25, 2017 at 06:30:11PM +0100, Stanislav Brabec wrote:
> I got a report that TRIM is called many times on btrfs with subvolumes.
> I did a research and found that sys-utils/fstrim.c: uniq_fs_source_cmp()
> contains a code that compares not only file system sources (i. e.
> devices), but also roots.
>
> I doubt that it is needed in any situation. We just care about source,
> i. e. device node. I think that if it matches, it is always particular
> device duplicate.
>
> Root does not equal for btrfs subvolumes, but also it does not equal for
> bind mounts. And btrfs subvolumes remain duplicated after the whole
> de-duplication process.
Ah... I have probably thought the roots are really independent on the
device, but now when I think about it the idea does not make sense :-)
> The patch assumes that the root comparison is not needed here at all. If
> it is not true, I will prepare another patch ignoring root specifically
> for btrfs.
The patch makes more sense than the original code.
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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