fs/erofs/super.c

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