While cat mb_groups for a mounted ext4 image which has some corrupted group, the string return to userspace was just "I/O error" which confuse me a lot. Use ext4_decode_error to help distinguish different error. Signed-off-by: yangerkun <yangerkun@xxxxxxxxxx> --- fs/ext4/mballoc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 139f232bdbb5..77d6113e2822 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2991,6 +2991,7 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v) struct super_block *sb = pde_data(file_inode(seq->file)); ext4_group_t group = (ext4_group_t) ((unsigned long) v); int i, err; + char nbuf[16]; struct ext4_buddy e4b; struct ext4_group_info *grinfo; unsigned char blocksize_bits = min_t(unsigned char, @@ -3017,7 +3018,7 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v) if (unlikely(EXT4_MB_GRP_NEED_INIT(grinfo))) { err = ext4_mb_load_buddy(sb, group, &e4b); if (err) { - seq_printf(seq, "#%-5u: I/O error\n", group); + seq_printf(seq, "#%-5u: %s\n", group, ext4_decode_error(NULL, err, nbuf)); return 0; } ext4_mb_unload_buddy(&e4b); -- 2.39.2