This patch adds a dynamic management feature to the existing device
aliasing functionality. It allows users to dynamically reserve or
release specific devices from the filesystem's free pool at runtime
through new ioctls.

To support this, three new ioctls are introduced:
- F2FS_IOC_RESERVE_DEV_ALIAS: This reclaims the space occupied by a
  device aliasing file. It first performs a capacity check, resets GC
  victim information for the target range, marks the segments as in-use
  to prevent new allocations, and then triggers GC to migrate existing
  valid data out of the range. Finally, it reserves these blocks in the
  SIT to effectively exclude the device from the usable capacity.

- F2FS_IOC_RELEASE_DEV_ALIAS: This releases the reserved space of a
  previously reserved device aliasing file. It truncates the blocks
  associated with the file, which makes them available for general
  filesystem allocation again.

- F2FS_IOC_GET_DEV_ALIAS_STATUS: This retrieves the current aliasing
  status of a device aliasing file, returning whether the file is
  released (inactive alias) or reserved (active alias, with blocks
  fully allocated on the device).

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

This patch adds an ioctl to give a per-file priority hint to attach
REQ_PRIO.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

F2FS should understand how the device aliasing file works and support
deleting the file after use. A device aliasing file can be created by
mkfs.f2fs tool and it can map the whole device with an extent, not
using node blocks. The file space should be pinned and normally used for
read-only usages.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

introduce a new ioctl to replace the whole content of a file atomically,
which means it induces truncate and content update at the same time.
We can start it with F2FS_IOC_START_ATOMIC_REPLACE and complete it with
F2FS_IOC_COMMIT_ATOMIC_WRITE. Or abort it with
F2FS_IOC_ABORT_ATOMIC_WRITE.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

F2FS_IOC_ABORT_VOLATILE_WRITE was used to abort a atomic write before.
However it was removed accidentally. So revive it by changing the name,
since volatile write had gone.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Fiexes: 7bc155fec5b3("f2fs: kill volatile write support")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Added two ioctl to decompress/compress explicitly the compression
enabled file in "compress_mode=user" mount option.

Using these two ioctls, the users can make a control of compression
and decompression of their files.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Added a new F2FS_IOC_SET_COMPRESS_OPTION ioctl to change file
compression option of a file.

struct f2fs_comp_option {
    u8 algorithm;         => compression algorithm
                          => 0:lzo, 1:lz4, 2:zstd, 3:lzorle
    u8 log_cluster_size;  => log scale cluster size
                          => 2 ~ 8
};

struct f2fs_comp_option option;

option.algorithm = 1;
option.log_cluster_size = 7;

ioctl(fd, F2FS_IOC_SET_COMPRESS_OPTION, &option);

Signed-off-by: Daeho Jeong <daehojeong@google.com>
[Chao Yu: remove f2fs_is_compress_algorithm_valid()]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Added a new F2FS_IOC_GET_COMPRESS_OPTION ioctl to get file compression
option of a file.

struct f2fs_comp_option {
    u8 algorithm;         => compression algorithm
                          => 0:lzo, 1:lz4, 2:zstd, 3:lzorle
    u8 log_cluster_size;  => log scale cluster size
                          => 2 ~ 8
};

struct f2fs_comp_option option;

ioctl(fd, F2FS_IOC_GET_COMPRESS_OPTION, &option);

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Like other filesystem does, we introduce a new file f2fs.h in path of
include/uapi/linux/, and move f2fs-specified ioctl interface definitions
to that file, after then, in order to use those definitions, userspace
developer only need to include the new header file rather than
copy & paste definitions from fs/f2fs/f2fs.h.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>