nilfs2: add nilfs_sufile_set_suinfo to update segment usage

Introduce nilfs_sufile_set_suinfo(), which expects an array of
nilfs_suinfo_update structures and updates the segment usage information
accordingly.

This is basically a helper function for the newly introduced
NILFS_IOCTL_SET_SUINFO ioctl.

[konishi.ryusuke@lab.ntt.co.jp: use put_bh() instead of brelse() because we know bh != NULL]
Signed-off-by: Andreas Rohner <andreas.rohner@gmx.net>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nilfs2/sufile.h b/fs/nilfs2/sufile.h
index e84bc5b..366003c 100644
--- a/fs/nilfs2/sufile.h
+++ b/fs/nilfs2/sufile.h
@@ -44,6 +44,7 @@
 int nilfs_sufile_get_stat(struct inode *, struct nilfs_sustat *);
 ssize_t nilfs_sufile_get_suinfo(struct inode *, __u64, void *, unsigned,
 				size_t);
+ssize_t nilfs_sufile_set_suinfo(struct inode *, void *, unsigned , size_t);
 
 int nilfs_sufile_updatev(struct inode *, __u64 *, size_t, int, size_t *,
 			 void (*dofunc)(struct inode *, __u64,