KDE Ending Out June With Many Bug Fixes, Finally Supporting Btrfs Copy-On-Write

[phoronix]

Phoronix: KDE Ending Out June With Many Bug Fixes, Finally Supporting Btrfs Copy-On-Write

KDE developers remain as busy as ever, especially when it comes to fixing bugs...

http://www.phoronix.com/scan.php?page=news_item&px=KDE-Finally-Does-Btrfs-CoW

[VoodaGod]

Why is btrfs copy on write something a desktop environment has to support? what happens if it isn't supported?

[smitty3268]

Why is btrfs copy on write something a desktop environment has to support? what happens if it isn't supported?

// Share data blocks ("reflink") on supporting filesystems, like brfs and XFS
int ret = ::ioctl (dest_file.handle(), FICLONE, src_file.handle());
if (ret != -1) {
processedSize(src_file.size());
}
else {
// if fs does not support reflinking, files are on different devices...
...
//old code here
}

[ALRBP]

I wonder if it is possible to have that working with SSHFS (FUSE) when the remote FS supports reflinks.

[andyprough]

For anyone wanting to put the latest KDE 19.2 on a Debian system (testing or unstable), Norbert Preining has repos you can use. Norbert has been the main developer of TeX Live and most TeX related packages in Debian since 2005. Just duckduckgo or searx Norbert Preining Debian KDE 19.2 and you'll find his blog with all the instructions and repo links.

Also works on MX and on Devuan in my personal experience, as long as you also enable the relevant testing or unstable repo.

[bug77]

Why is btrfs copy on write something a desktop environment has to support? what happens if it isn't supported?

Yeah, kinda baffling. You'd think this is something the file system driver would take care of behind the scenes.
Otherwise, btrfs should be advertised as "offering support for CoW".

[andreduartesp]

I wonder if it is possible to have that working with SSHFS (FUSE) when the remote FS supports reflinks.

This feature must be implementedtede on the server side. The part who interact with the filesystem directly. The server can enable it in 2 ways, it would be transparent for the client ou it would require a flag from the client to enable the feature.

[shmerl]

When will Debian testing update Plasma already? It's been stuck forever.

[fredvej]

As far as I can tell, btrfs' Copy on Write makes a hard link instead of copying the data. How is that useful? If I want a hard link I make a hard link, if I want a copy of the data (e.g. for editing without changing the original) I copy the file. How does btrfs handle making an actual copy of a file, not a hard link?

[evilhamsterman]

The difference fredvej, is that in the case of a hard link if you modify the contents of the file using one link the same modification will be visible in the other link. But with a CoW reflink copy the changes made to one copy will not be visible in the other copy and you only save the difference between the two essentially deduping the data and saving on disk space.