Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4e864e12 authored by Randall Huang's avatar Randall Huang
Browse files

Try to recover corrupted ext4 /data with backup superblock 



If the superblock of /data is corrupted, fs_mgr would skip check_fs.
But, e2fsck actually may reference backup superblock to recover
the filesystem. This fix gives fs_mgr second chance to fix corrupted
ext4 /data.

Bug: 156200421
Test: boot with corrupted ext4 superblock

Signed-off-by: default avatarRandall Huang <huangrandall@google.com>
Change-Id: Ieb89e7274d772962fe37927dcd62567dd5aa4657
(cherry picked from commit 72abd7b2)
parent 2d51d382

fs_mgr/fs_mgr.cpp

+30 −5
Original line number Diff line number Diff line
@@ -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) {
@@ -321,8 +324,30 @@ 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;



        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;

    if (sb->s_max_mnt_count == 0xffff) {  // -1 (int16) in ext2, but uint16 in ext4
@@ -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);