ext4: improve error msg for ext4_mb_seq_groups_show

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. Improve it with ext4_decode_error.

Signed-off-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240118042557.380058-2-yangerkun@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index abe86791590b73d73458c8b09e3bf8e5b5daa6f1..1a3c738ff21ae6b1923700d13e5f139b702ab63b 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3016,6 +3016,7 @@ 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,
@@ -3042,7 +3043,7 @@ 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);