1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Created by Li Guifu <blucerlee@gmail.com>
4 */
5 #include <string.h>
6 #include <stdlib.h>
7 #include "erofs/io.h"
8 #include "erofs/print.h"
9
check_layout_compatibility(struct erofs_sb_info * sbi,struct erofs_super_block * dsb)10 static bool check_layout_compatibility(struct erofs_sb_info *sbi,
11 struct erofs_super_block *dsb)
12 {
13 const unsigned int feature = le32_to_cpu(dsb->feature_incompat);
14
15 sbi->feature_incompat = feature;
16
17 /* check if current kernel meets all mandatory requirements */
18 if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
19 erofs_err("unidentified incompatible feature %x, please upgrade kernel version",
20 feature & ~EROFS_ALL_FEATURE_INCOMPAT);
21 return false;
22 }
23 return true;
24 }
25
erofs_init_devices(struct erofs_sb_info * sbi,struct erofs_super_block * dsb)26 static int erofs_init_devices(struct erofs_sb_info *sbi,
27 struct erofs_super_block *dsb)
28 {
29 unsigned int ondisk_extradevs, i;
30 erofs_off_t pos;
31
32 sbi->total_blocks = sbi->primarydevice_blocks;
33
34 if (!erofs_sb_has_device_table())
35 ondisk_extradevs = 0;
36 else
37 ondisk_extradevs = le16_to_cpu(dsb->extra_devices);
38
39 if (ondisk_extradevs != sbi->extra_devices) {
40 erofs_err("extra devices don't match (ondisk %u, given %u)",
41 ondisk_extradevs, sbi->extra_devices);
42 return -EINVAL;
43 }
44 if (!ondisk_extradevs)
45 return 0;
46
47 sbi->device_id_mask = roundup_pow_of_two(ondisk_extradevs + 1) - 1;
48 sbi->devs = calloc(ondisk_extradevs, sizeof(*sbi->devs));
49 pos = le16_to_cpu(dsb->devt_slotoff) * EROFS_DEVT_SLOT_SIZE;
50 for (i = 0; i < ondisk_extradevs; ++i) {
51 struct erofs_deviceslot dis;
52 int ret;
53
54 ret = dev_read(0, &dis, pos, sizeof(dis));
55 if (ret < 0)
56 return ret;
57
58 sbi->devs[i].mapped_blkaddr = dis.mapped_blkaddr;
59 sbi->total_blocks += dis.blocks;
60 pos += EROFS_DEVT_SLOT_SIZE;
61 }
62 return 0;
63 }
64
erofs_read_superblock(void)65 int erofs_read_superblock(void)
66 {
67 char data[EROFS_BLKSIZ];
68 struct erofs_super_block *dsb;
69 unsigned int blkszbits;
70 int ret;
71
72 ret = blk_read(0, data, 0, 1);
73 if (ret < 0) {
74 erofs_err("cannot read erofs superblock: %d", ret);
75 return -EIO;
76 }
77 dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);
78
79 ret = -EINVAL;
80 if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
81 erofs_err("cannot find valid erofs superblock");
82 return ret;
83 }
84
85 sbi.feature_compat = le32_to_cpu(dsb->feature_compat);
86
87 blkszbits = dsb->blkszbits;
88 /* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
89 if (blkszbits != LOG_BLOCK_SIZE) {
90 erofs_err("blksize %u isn't supported on this platform",
91 1 << blkszbits);
92 return ret;
93 }
94
95 if (!check_layout_compatibility(&sbi, dsb))
96 return ret;
97
98 sbi.primarydevice_blocks = le32_to_cpu(dsb->blocks);
99 sbi.meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
100 sbi.xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
101 sbi.islotbits = EROFS_ISLOTBITS;
102 sbi.root_nid = le16_to_cpu(dsb->root_nid);
103 sbi.inos = le64_to_cpu(dsb->inos);
104 sbi.checksum = le32_to_cpu(dsb->checksum);
105
106 sbi.build_time = le64_to_cpu(dsb->build_time);
107 sbi.build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
108
109 memcpy(&sbi.uuid, dsb->uuid, sizeof(dsb->uuid));
110 return erofs_init_devices(&sbi, dsb);
111 }
112