概述
上節說的“PARTNAME=super”和"PARTNAME=vbmeta"在哪裏賦值。
2. 調用流程
register_disk(struct device *parent, struct gendisk *disk)
------->int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
2. 代碼
2.1 efi_partition
692 int efi_partition(struct parsed_partitions *state)
693 {
694 gpt_header *gpt = NULL;
695 gpt_entry *ptes = NULL;
696 u32 i;
697 unsigned ssz = bdev_logical_block_size(state->bdev) / 512;
698
699 if (!find_valid_gpt(state, &gpt, &ptes) || !gpt || !ptes) {
700 kfree(gpt);
701 kfree(ptes);
702 return 0;
703 }
704
705 pr_debug("GUID Partition Table is valid! Yea!\n");
706
707 for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
708 struct partition_meta_info *info;
709 unsigned label_count = 0;
710 unsigned label_max;
711 u64 start = le64_to_cpu(ptes[i].starting_lba);
712 u64 size = le64_to_cpu(ptes[i].ending_lba) -
713 le64_to_cpu(ptes[i].starting_lba) + 1ULL;
714
715 if (!is_pte_valid(&ptes[i], last_lba(state->bdev)))
716 continue;
717
718 put_partition(state, i+1, start * ssz, size * ssz);
719
720 /* If this is a RAID volume, tell md */
721 if (!efi_guidcmp(ptes[i].partition_type_guid, PARTITION_LINUX_RAID_GUID))
722 state->parts[i + 1].flags = ADDPART_FLAG_RAID;
723
724 info = &state->parts[i + 1].info;
725 efi_guid_to_str(&ptes[i].unique_partition_guid, info->uuid);
726
727 /* Naively convert UTF16-LE to 7 bits. */
728 label_max = min(ARRAY_SIZE(info->volname) - 1,
729 ARRAY_SIZE(ptes[i].partition_name));
730 info->volname[label_max] = 0;
731 while (label_count < label_max) {
732 u8 c = ptes[i].partition_name[label_count] & 0xff;
733 if (c && !isprint(c))
734 c = '!';
735 info->volname[label_count] = c;
736 label_count++;
737 }
738 state->parts[i + 1].has_info = true;
739
740 printk(KERN_ERR "tom F=%s L=%d volname=%s",__FUNCTION__,__LINE__,info->volname);
741 }
742 printk(KERN_ERR "tom F=%s L=%d ",__FUNCTION__,__LINE__);
743 kfree(ptes);
744 kfree(gpt);
745 strlcat(state->pp_buf, "\n", PAGE_SIZE);
746 return 1;
747 }
說明：在735行，可以看出info->volnam的賦值。
調試信息:
[ 1.204013] tom F=efi_partition L=740 volname=vbmeta
[ 1.204424] tom F=efi_partition L=740 volname=super
分區信息：
在block/partition-generic.c中，read_dev_sector函數:
658 unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
659 {
660 struct address_space *mapping = bdev->bd_inode->i_mapping;
661 struct page *page;
662
663 page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_SHIFT-9)), NULL);
664 if (!IS_ERR(page)) {
665 if (PageError(page))
666 goto fail;
667 p->v = page;
668 return (unsigned char *)page_address(page) + ((n & ((1 << (PAGE_SHIFT - 9)) - 1)) << 9);
669 fail:
670 put_page(page);
671 }
672 p->v = NULL;
673 return NULL;
674 }
GPT信息是從bdev->bd_inode->i_mapping中撈數據的。
2.3 問題：
下一步繼續探討賦值問題。