diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp index 1dcc9e4a5..1c5bb6c7f 100644 --- a/fs_mgr/fs_mgr.cpp +++ b/fs_mgr/fs_mgr.cpp @@ -301,10 +301,13 @@ static bool is_ext4_superblock_valid(const struct ext4_super_block* es) { return true; } +static bool needs_block_encryption(const FstabEntry& entry); +static bool should_use_metadata_encryption(const FstabEntry& entry); + // Read the primary superblock from an ext4 filesystem. On failure return // false. If it's not an ext4 filesystem, also set FS_STAT_INVALID_MAGIC. -static bool read_ext4_superblock(const std::string& blk_device, struct ext4_super_block* sb, - int* fs_stat) { +static bool read_ext4_superblock(const std::string& blk_device, const FstabEntry& entry, + struct ext4_super_block* sb, int* fs_stat) { android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(blk_device.c_str(), O_RDONLY | O_CLOEXEC))); if (fd < 0) { @@ -321,7 +324,29 @@ static bool read_ext4_superblock(const std::string& blk_device, struct ext4_supe LINFO << "Invalid ext4 superblock on '" << blk_device << "'"; // not a valid fs, tune2fs, fsck, and mount will all fail. *fs_stat |= FS_STAT_INVALID_MAGIC; - return false; + + bool encrypted = should_use_metadata_encryption(entry) || needs_block_encryption(entry); + if (entry.mount_point == "/data" && + (!encrypted || android::base::StartsWith(blk_device, "/dev/block/dm-"))) { + // try backup superblock, if main superblock is corrupted + for (unsigned int blocksize = EXT4_MIN_BLOCK_SIZE; blocksize <= EXT4_MAX_BLOCK_SIZE; + blocksize *= 2) { + unsigned int superblock = blocksize * 8; + if (blocksize == EXT4_MIN_BLOCK_SIZE) superblock++; + + if (TEMP_FAILURE_RETRY(pread(fd, sb, sizeof(*sb), superblock * blocksize)) != + sizeof(*sb)) { + PERROR << "Can't read '" << blk_device << "' superblock"; + return false; + } + if (is_ext4_superblock_valid(sb) && + (1 << (10 + sb->s_log_block_size) == blocksize)) { + *fs_stat &= ~FS_STAT_INVALID_MAGIC; + break; + } + } + } + if (*fs_stat & FS_STAT_INVALID_MAGIC) return false; } *fs_stat |= FS_STAT_IS_EXT4; LINFO << "superblock s_max_mnt_count:" << sb->s_max_mnt_count << "," << blk_device; @@ -663,7 +688,7 @@ static int prepare_fs_for_mount(const std::string& blk_device, const FstabEntry& if (is_extfs(entry.fs_type)) { struct ext4_super_block sb; - if (read_ext4_superblock(blk_device, &sb, &fs_stat)) { + if (read_ext4_superblock(blk_device, entry, &sb, &fs_stat)) { if ((sb.s_feature_incompat & EXT4_FEATURE_INCOMPAT_RECOVER) != 0 || (sb.s_state & EXT4_VALID_FS) == 0) { LINFO << "Filesystem on " << blk_device << " was not cleanly shutdown; " @@ -693,7 +718,7 @@ static int prepare_fs_for_mount(const std::string& blk_device, const FstabEntry& entry.fs_mgr_flags.fs_verity || entry.fs_mgr_flags.ext_meta_csum)) { struct ext4_super_block sb; - if (read_ext4_superblock(blk_device, &sb, &fs_stat)) { + if (read_ext4_superblock(blk_device, entry, &sb, &fs_stat)) { tune_reserved_size(blk_device, entry, &sb, &fs_stat); tune_encrypt(blk_device, entry, &sb, &fs_stat); tune_verity(blk_device, entry, &sb, &fs_stat);