debugfs: better support of superblocks with bad checksums

Allow debugfs to open file systems with a bad checksum, and teach the
show_super_stats command to print the expected checksum value.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index 165f924..1a84cfc 100644 (file)
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -170,8 +170,14 @@ static void open_filesystem(char *device, int open_flags, blk64_t superblock,
                        exit(1);
        }
 
+try_open_again:
        retval = ext2fs_open(device, open_flags, superblock, blocksize,
                             io_ptr, &current_fs);
+       if (retval && !(open_flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
+               open_flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;
+               printf("Checksum errors in superblock!  Retrying...\n");
+               goto try_open_again;
+       }
        if (retval) {
                com_err(device, retval, "while opening filesystem");
                if (retval == EXT2_ET_BAD_MAGIC)
@@ -444,6 +450,17 @@ void do_show_super_stats(int argc, char *argv[])
                units = "cluster";
 
        list_super2(current_fs->super, out);
+       if (ext2fs_has_feature_metadata_csum(current_fs->super) &&
+           !ext2fs_superblock_csum_verify(current_fs,
+                                          current_fs->super)) {
+               __u32 orig_csum = current_fs->super->s_checksum;
+
+               ext2fs_superblock_csum_set(current_fs,
+                                          current_fs->super);
+               fprintf(out, "Expected Checksum:        0x%08x\n",
+                       current_fs->super->s_checksum);
+               current_fs->super->s_checksum = orig_csum;
+       }
        for (i=0; i < current_fs->group_desc_count; i++)
                numdirs += ext2fs_bg_used_dirs_count(current_fs, i);
        fprintf(out, "Directories:              %d\n", numdirs);