This series allows mkfs.nilfs2 to issue trim/discard command to the device. The trim/discard is used to inform a solid-state drive or a thin-provisioned storage which blocks of data are no longer considered in use and can be wiped internally. This feature is known to be helpful for handling garbage collection overhead in recent SSDs. With this series, mkfs2.nilfs2 attempts to use it by default to wipe out the partition. If the device doesn't support the discard, only the head and tail of the partition will be zero-filled as before. User can see if the discard is succeeded or not with "verbose" mode option (-v): $ sudo mkfs -t nilfs2 -v /dev/sdb1 mkfs.nilfs2 (nilfs-utils 2.0.20) Start writing file system initial data to the device Blocksize:4096 Device:/dev/sdb1 Device Size:80023716864 Discard device from 1024 to 80023716864: succeeded. Discard succeeded and will return 0s - skip wiping File system initialization succeeded !! If "-K" option is specified, mkfs.nilfs2 will turn off the discard. The discard here is only applied at mkfs time. To let the nilfs2 filesystem use it, user needs to specify "discard" mount option, which is (experimentally) available since kernel 2.6.34. Thanks, Ryusuke Konishi -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html