zonefs is a very simple file system exposing each zone of a zoned block device as a file. Unlike a regular file system with zoned block device support (e.g. f2fs or the on-going btrfs effort), zonefs does not hide the sequential write constraint of zoned block devices to the user. Files representing sequential write zones of the device must be written sequentially starting from the end of the file (append only writes). zonefs is not a POSIX compliant file system. It's goal is to simplify the implementation of zoned block devices support in applications by replacing raw block device file accesses with a richer file based API, avoiding relying on direct block device file ioctls which may be more obscure to developers. One example of this approach is the implementation of LSM (log-structured merge) tree structures (such as used in RocksDB and LevelDB) on zoned block devices by allowing SSTables to be stored in a zone file similarly to a regular file system rather than as a range of sectors of a zoned device. The introduction of the higher level construct "one file is one zone" can help reducing the amount of changes needed in the application while at the same time allowing the use of zoned block devices with various programming languages other than C. zonefs IO management implementation uses the new iomap generic code. Damien Le Moal (2): fs: New zonefs file system zonefs: Add documentation Documentation/filesystems/zonefs.txt | 150 ++++ MAINTAINERS | 10 + fs/Kconfig | 1 + fs/Makefile | 1 + fs/zonefs/Kconfig | 9 + fs/zonefs/Makefile | 4 + fs/zonefs/super.c | 1158 ++++++++++++++++++++++++++ fs/zonefs/zonefs.h | 169 ++++ include/uapi/linux/magic.h | 1 + 9 files changed, 1503 insertions(+) create mode 100644 Documentation/filesystems/zonefs.txt create mode 100644 fs/zonefs/Kconfig create mode 100644 fs/zonefs/Makefile create mode 100644 fs/zonefs/super.c create mode 100644 fs/zonefs/zonefs.h -- 2.23.0
