compression enabled files using F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE
ioctls like the below.
-To decompress a file,
+To decompress a file::
-fd = open(filename, O_WRONLY, 0);
-ret = ioctl(fd, F2FS_IOC_DECOMPRESS_FILE);
+ fd = open(filename, O_WRONLY, 0);
+ ret = ioctl(fd, F2FS_IOC_DECOMPRESS_FILE);
-To compress a file,
+To compress a file::
-fd = open(filename, O_WRONLY, 0);
-ret = ioctl(fd, F2FS_IOC_COMPRESS_FILE);
+ fd = open(filename, O_WRONLY, 0);
+ ret = ioctl(fd, F2FS_IOC_COMPRESS_FILE);
NVMe Zoned Namespace devices
----------------------------
external usage is complete, the device aliasing file can be deleted, releasing
the reserved space back to F2FS for its own use.
-<use-case>
-
-# ls /dev/vd*
-/dev/vdb (32GB) /dev/vdc (32GB)
-# mkfs.ext4 /dev/vdc
-# mkfs.f2fs -c /dev/vdc@vdc.file /dev/vdb
-# mount /dev/vdb /mnt/f2fs
-# ls -l /mnt/f2fs
-vdc.file
-# df -h
-/dev/vdb 64G 33G 32G 52% /mnt/f2fs
-
-# mount -o loop /dev/vdc /mnt/ext4
-# df -h
-/dev/vdb 64G 33G 32G 52% /mnt/f2fs
-/dev/loop7 32G 24K 30G 1% /mnt/ext4
-# umount /mnt/ext4
-
-# f2fs_io getflags /mnt/f2fs/vdc.file
-get a flag on /mnt/f2fs/vdc.file ret=0, flags=nocow(pinned),immutable
-# f2fs_io setflags noimmutable /mnt/f2fs/vdc.file
-get a flag on noimmutable ret=0, flags=800010
-set a flag on /mnt/f2fs/vdc.file ret=0, flags=noimmutable
-# rm /mnt/f2fs/vdc.file
-# df -h
-/dev/vdb 64G 753M 64G 2% /mnt/f2fs
+.. code-block::
+
+ # ls /dev/vd*
+ /dev/vdb (32GB) /dev/vdc (32GB)
+ # mkfs.ext4 /dev/vdc
+ # mkfs.f2fs -c /dev/vdc@vdc.file /dev/vdb
+ # mount /dev/vdb /mnt/f2fs
+ # ls -l /mnt/f2fs
+ vdc.file
+ # df -h
+ /dev/vdb 64G 33G 32G 52% /mnt/f2fs
+
+ # mount -o loop /dev/vdc /mnt/ext4
+ # df -h
+ /dev/vdb 64G 33G 32G 52% /mnt/f2fs
+ /dev/loop7 32G 24K 30G 1% /mnt/ext4
+ # umount /mnt/ext4
+
+ # f2fs_io getflags /mnt/f2fs/vdc.file
+ get a flag on /mnt/f2fs/vdc.file ret=0, flags=nocow(pinned),immutable
+ # f2fs_io setflags noimmutable /mnt/f2fs/vdc.file
+ get a flag on noimmutable ret=0, flags=800010
+ set a flag on /mnt/f2fs/vdc.file ret=0, flags=noimmutable
+ # rm /mnt/f2fs/vdc.file
+ # df -h
+ /dev/vdb 64G 753M 64G 2% /mnt/f2fs
So, the key idea is, user can do any file operations on /dev/vdc, and
reclaim the space after the use, while the space is counted as /data.