HI,
/dev/nvme0n1p8 on / type btrfs (rw,relatime,seclabel,ssd,space_cache,subvolid=258,subvol=/root) I've got a test folder with +C set and then copied a test file into it. $ lsattr ----------------C-- ./system@2547b430ecdc441c9cf82569eeb22065-0000000000000001-00054c3c31bec567.journal So now it's inherited +C. Next check fragments and compression. $ sudo ~/Applications/btrfs-debugfs -f system@2547b430ecdc441c9cf82569eeb22065-0000000000000001-00054c3c31bec567.journal (290662 0): ram 100663296 disk 17200840704 disk_size 100663296 file: system@2547b430ecdc441c9cf82569eeb22065-0000000000000001-00054c3c31bec567.journal extents 1 disk size 100663296 logical size 100663296 ratio 1.00 Try to compress it. $ sudo btrfs fi defrag -c system@2547b430ecdc441c9cf82569eeb22065-0000000000000001-00054c3c31bec567.journal Check again. [snip faux fragments] file: system@2547b430ecdc441c9cf82569eeb22065-0000000000000001-00054c3c31bec567.journal extents 768 disk size 21504000 logical size 100663296 ratio 4.68 It's compressed! OK?? OK delete that file, and add +c to the temp folder. $ lsattr --------c-------C-- ./temp Copy another test file into temp. $ lsattr --------c-------C-- ./system@2547b430ecdc441c9cf82569eeb22065-000000000002eb9f-00054d4ebb44b135.journal $ sudo ~/Applications/btrfs-debugfs -f system@2547b430ecdc441c9cf82569eeb22065-000000000002eb9f-00054d4ebb44b135.journal (290739 0): ram 83886080 disk 21764243456 disk_size 83886080 file: system@2547b430ecdc441c9cf82569eeb22065-000000000002eb9f-00054d4ebb44b135.journal extents 1 disk size 83886080 logical size 83886080 ratio 1.00 Not compressed. Hmmm. So somehow btrfs fi defrag -c will force compression even on nocow files? I've also done this without -c option, with a Btrfs mounted using compress option; and the file does compress also. I thought nocow files were always no compress, but it seems there's exceptions. Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
