Package: e2fsprogs Version: 1.42.13-1 Severity: wishlist Tags: upstream
Hey Ted. It would be nice if filefrag supports btrfs compression. Right now, it seems to assume that each 128KiB compression "block" is one extent, though, AFAIU discussion on linux-btrfs, it's in realliy one extent. Example: /var/log/daemon.1.log is on a btrfs with *no* compression: # filefrag -v /var/log/daemon.log.1 Filesystem type is: 9123683e File size of /var/log/daemon.log.1 is 1436385 (351 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 220: 62079406.. 62079626: 221: 1: 221.. 255: 13664057.. 13664091: 35: 62079627: 2: 256.. 319: 15844162.. 15844225: 64: 13664092: 3: 320.. 350: 13515969.. 13515999: 31: 15844226: last,eof /var/log/daemon.log.1: 4 extents found => it actually *is* fragmented. Copying it somewhere else, with no --reflink set: # cp /var/log/daemon.log.1 ~/ # filefrag -v ~/daemon.log.1 Filesystem type is: 9123683e File size of /root/daemon.log.1 is 1436385 (351 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 350: 42929147.. 42929497: 351: last,eof /root/daemon.log.1: 1 extent found Now copying it to another btrfs, mounted with compress-force=zlib: # cp /var/log/daemon.log.1 /mnt/ # filefrag -v /mnt/daemon.log.1 Filesystem type is: 9123683e File size of /mnt/daemon.log.1 is 1436385 (351 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 31: 3072.. 3103: 32: encoded 1: 32.. 63: 3078.. 3109: 32: 3104: encoded 2: 64.. 95: 3084.. 3115: 32: 3110: encoded 3: 96.. 127: 3090.. 3121: 32: 3116: encoded 4: 128.. 159: 3096.. 3127: 32: 3122: encoded 5: 160.. 191: 3102.. 3133: 32: 3128: encoded 6: 192.. 223: 3108.. 3139: 32: 3134: encoded 7: 224.. 255: 3114.. 3145: 32: 3140: encoded 8: 256.. 287: 3120.. 3151: 32: 3146: encoded 9: 288.. 319: 3125.. 3156: 32: 3152: encoded 10: 320.. 350: 3132.. 3162: 31: 3157: last,encoded,eof /mnt/daemon.log.1: 11 extents found Shows exactly those 128KiB blocks distribution. Cheers, Chris.
