f2fs 空闲块的分配

#define NEXT_FREE_BLKADDR(sbi,curseg)                                          (START_BLOCK(sbi,(curseg)->segno) + (curseg)->next_blkoff)

.....

void f2fs_allocate_data_block(struct f2fs_sb_info *sbi,struct page *page,block_t old_blkaddr,block_t *new_blkaddr,struct f2fs_summary *sum,int type,struct f2fs_io_info *fio,bool add_list)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct curseg_info *curseg = CURSEG_I(sbi,type);

        down_read(&SM_I(sbi)->curseg_lock);

        mutex_lock(&curseg->curseg_mutex);
        down_write(&sit_i->sentry_lock);

        *new_blkaddr = NEXT_FREE_BLKADDR(sbi,curseg);

        f2fs_wait_discard_bio(sbi,*new_blkaddr);

                ....