f2fs: expose main_blkaddr in sysfs
Expose in /sys/fs/f2fs/<blockdev>/main_blkaddr the block address where the
main area starts. This allows user mode programs to determine:
- That pinned files that are made exclusively of fully allocated 2MB
segments will never be unpinned by the file system.
- Where the main area starts. This is required by programs that want to
verify if a file is made exclusively of 2MB f2fs segments, the alignment
boundary for segments starts at this address. Testing for 2MB alignment
relative to the start of the device is incorrect, because for some
filesystems main_blkaddr is not at a 2MB boundary relative to the start
of the device.
The entry will be used when validating reliable pinning file feature proposed
by "f2fs: support aligned pinned file".
Signed-off-by: Ramon Pantin <pantin@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
3 files changed