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// SPDX-License-Identifier: GPL-2.0+
#include "internal.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())
ondisk_extradevs = 0;
else
ondisk_extradevs = le16_to_cpu(dsb->extra_devices);
if (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->device_id_mask = roundup_pow_of_two(ondisk_extradevs + 1) - 1;
sbi->devs = calloc(ondisk_extradevs, sizeof(*sbi->devs));
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 = erofs_dev_read(0, &dis, pos, sizeof(dis));
if (ret < 0)
return ret;
sbi->devs[i].mapped_blkaddr = dis.mapped_blkaddr;
sbi->total_blocks += dis.blocks;
pos += EROFS_DEVT_SLOT_SIZE;
}
return 0;
}
int erofs_read_superblock(void)
{
char data[EROFS_BLKSIZ];
struct erofs_super_block *dsb;
unsigned int blkszbits;
int ret;
ret = erofs_blk_read(data, 0, 1);
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);
blkszbits = dsb->blkszbits;
/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
if (blkszbits != LOG_BLOCK_SIZE) {
erofs_err("blksize %u isn't supported on this platform",
1 << blkszbits);
return ret;
}
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.islotbits = EROFS_ISLOTBITS;
sbi.root_nid = le16_to_cpu(dsb->root_nid);
sbi.inos = le64_to_cpu(dsb->inos);
sbi.checksum = le32_to_cpu(dsb->checksum);
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));
return erofs_init_devices(&sbi, dsb);
}
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