Btrfs Gets Some Useful Fixes/Improvements With The Linux 5.2 Kernel

[phoronix]

Phoronix: Btrfs Gets Some Useful Fixes/Improvements With The Linux 5.2 Kernel

David Sterba sent in the Btrfs file-system updates already for the now-open Linux 5.2 merge window...

http://www.phoronix.com/scan.php?page=news_item&px=Btrfs-Linux-5.2-Fixes

[coder]

TRIM/Discard now skips unallocated chunks not touched since the last mount

This is great, but what about when the filesystem is newly-created? Will fstrim still reclaim the empty space, or will I have to fill the filesystem with a giant file and delete it, just to trim the blocks from whatever was on the previous filesystem?

[waxhead]

This is great, but what about when the filesystem is newly-created? Will fstrim still reclaim the empty space, or will I have to fill the filesystem with a giant file and delete it, just to trim the blocks from whatever was on the previous filesystem?

https://btrfs.wiki.kernel.org/index.php/Manpage/mkfs.btrfs

the -K | --nodiscard option prevents trim from being executed at mkfs time... there you go

[intelfx]

This is great, but what about when the filesystem is newly-created? Will fstrim still reclaim the empty space, or will I have to fill the filesystem with a giant file and delete it, just to trim the blocks from whatever was on the previous filesystem?

mkfs.btrfs will discard the whole block device for you prior to actually creating the filesystem.