lib/super.c

// SPDX-License-Identifier: GPL-2.0+ OR Apache-2.0
/*
 * Created by Li Guifu <blucerlee@gmail.com>
 */
#include <string.h>
#include <stdlib.h>
#include "erofs/io.h"
#include "erofs/print.h"
#include "erofs/xattr.h"

static bool check_layout_compatibility(struct erofs_sb_info *sbi,
				       struct erofs_super_block *dsb)
{
	const unsigned int feature = le32_to_cpu(dsb->feature_incompat);

	sbi->feature_incompat = feature;

	/* check if current kernel meets all mandatory requirements */
	if (feature & ~EROFS_ALL_FEATURE_INCOMPAT) {
		erofs_err("unidentified incompatible feature %x, please upgrade kernel version",
			  feature & ~EROFS_ALL_FEATURE_INCOMPAT);
		return false;
	}
	return true;
}

static int erofs_init_devices(struct erofs_sb_info *sbi,
			      struct erofs_super_block *dsb)
{
	unsigned int ondisk_extradevs, i;
	erofs_off_t pos;

	sbi->total_blocks = sbi->primarydevice_blocks;

	if (!erofs_sb_has_device_table(sbi))
		ondisk_extradevs = 0;
	else
		ondisk_extradevs = le16_to_cpu(dsb->extra_devices);

	if (sbi->extra_devices &&
	    ondisk_extradevs != sbi->extra_devices) {
		erofs_err("extra devices don't match (ondisk %u, given %u)",
			  ondisk_extradevs, sbi->extra_devices);
		return -EINVAL;
	}
	if (!ondisk_extradevs)
		return 0;

	sbi->extra_devices = ondisk_extradevs;
	sbi->device_id_mask = roundup_pow_of_two(ondisk_extradevs + 1) - 1;
	sbi->devs = calloc(ondisk_extradevs, sizeof(*sbi->devs));
	if (!sbi->devs)
		return -ENOMEM;
	pos = le16_to_cpu(dsb->devt_slotoff) * EROFS_DEVT_SLOT_SIZE;
	for (i = 0; i < ondisk_extradevs; ++i) {
		struct erofs_deviceslot dis;
		int ret;

		ret = dev_read(sbi, 0, &dis, pos, sizeof(dis));
		if (ret < 0) {
			free(sbi->devs);
			sbi->devs = NULL;
			return ret;
		}

		sbi->devs[i].mapped_blkaddr = le32_to_cpu(dis.mapped_blkaddr);
		sbi->devs[i].blocks = le32_to_cpu(dis.blocks);
		memcpy(sbi->devs[i].tag, dis.tag, sizeof(dis.tag));
		sbi->total_blocks += sbi->devs[i].blocks;
		pos += EROFS_DEVT_SLOT_SIZE;
	}
	return 0;
}

int erofs_read_superblock(struct erofs_sb_info *sbi)
{
	u8 data[EROFS_MAX_BLOCK_SIZE];
	struct erofs_super_block *dsb;
	int ret;

	sbi->blkszbits = ilog2(EROFS_MAX_BLOCK_SIZE);
	ret = blk_read(sbi, 0, data, 0, erofs_blknr(sbi, sizeof(data)));
	if (ret < 0) {
		erofs_err("cannot read erofs superblock: %d", ret);
		return -EIO;
	}
	dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);

	ret = -EINVAL;
	if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
		erofs_err("cannot find valid erofs superblock");
		return ret;
	}

	sbi->feature_compat = le32_to_cpu(dsb->feature_compat);

	sbi->blkszbits = dsb->blkszbits;
	if (sbi->blkszbits < 9 ||
	    sbi->blkszbits > ilog2(EROFS_MAX_BLOCK_SIZE)) {
		erofs_err("blksize %llu isn't supported on this platform",
			  erofs_blksiz(sbi) | 0ULL);
		return ret;
	} else if (!check_layout_compatibility(sbi, dsb)) {
		return ret;
	}

	sbi->primarydevice_blocks = le32_to_cpu(dsb->blocks);
	sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
	sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
	sbi->xattr_prefix_start = le32_to_cpu(dsb->xattr_prefix_start);
	sbi->xattr_prefix_count = dsb->xattr_prefix_count;
	sbi->islotbits = EROFS_ISLOTBITS;
	sbi->root_nid = le16_to_cpu(dsb->root_nid);
	sbi->packed_nid = le64_to_cpu(dsb->packed_nid);
	sbi->inos = le64_to_cpu(dsb->inos);
	sbi->checksum = le32_to_cpu(dsb->checksum);
	sbi->extslots = dsb->sb_extslots;

	sbi->build_time = le64_to_cpu(dsb->build_time);
	sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);

	memcpy(&sbi->uuid, dsb->uuid, sizeof(dsb->uuid));

	if (erofs_sb_has_compr_cfgs(sbi))
		sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);
	else
		sbi->lz4_max_distance = le16_to_cpu(dsb->u1.lz4_max_distance);

	ret = erofs_init_devices(sbi, dsb);
	if (ret)
		return ret;

	ret = erofs_xattr_prefixes_init(sbi);
	if (ret && sbi->devs) {
		free(sbi->devs);
		sbi->devs = NULL;
	}
	return ret;
}

void erofs_put_super(struct erofs_sb_info *sbi)
{
	if (sbi->devs) {
		free(sbi->devs);
		sbi->devs = NULL;
	}
	erofs_xattr_prefixes_cleanup(sbi);
}