On Nov 27, 2020, at 4:33 AM, Jan Kara <jack@suse.cz> wrote:
> 
> We convert errno's to ext4 on-disk format error codes in
> save_error_info(). Add a function and a bit of macro magic to make this
> simpler.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>

In hindsight, it would have been better (IMHO) if the EXT4_ERR_* values mapped
to the standard x86_64 errors in errno.h, since that is what most admins/users
are familiar with (e.g. 5 = EIO, 12 = ENOMEM, 28 = ENOSPC, 30 = EROFS).  That
would avoid the need to look up the EXT4_ERR_* values, since it doesn't look
like dumpe2fs even handles these fields yet.

I guess I never noticed the original patch when it was submitted, so water under
the bridge, I guess...

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> ---
> fs/ext4/super.c | 95 ++++++++++++++++++++++++---------------------------------
> 1 file changed, 40 insertions(+), 55 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 7948c07d0a90..8add06d08495 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -551,76 +551,61 @@ static bool system_going_down(void)
> 		|| system_state == SYSTEM_RESTART;
> }
> 
> +struct ext4_err_translation {
> +	int code;
> +	int errno;
> +};
> +
> +#define EXT4_ERR_TRANSLATE(err) { .code = EXT4_ERR_##err, .errno = err }
> +
> +static struct ext4_err_translation err_translation[] = {
> +	EXT4_ERR_TRANSLATE(EIO),
> +	EXT4_ERR_TRANSLATE(ENOMEM),
> +	EXT4_ERR_TRANSLATE(EFSBADCRC),
> +	EXT4_ERR_TRANSLATE(EFSCORRUPTED),
> +	EXT4_ERR_TRANSLATE(ENOSPC),
> +	EXT4_ERR_TRANSLATE(ENOKEY),
> +	EXT4_ERR_TRANSLATE(EROFS),
> +	EXT4_ERR_TRANSLATE(EFBIG),
> +	EXT4_ERR_TRANSLATE(EEXIST),
> +	EXT4_ERR_TRANSLATE(ERANGE),
> +	EXT4_ERR_TRANSLATE(EOVERFLOW),
> +	EXT4_ERR_TRANSLATE(EBUSY),
> +	EXT4_ERR_TRANSLATE(ENOTDIR),
> +	EXT4_ERR_TRANSLATE(ENOTEMPTY),
> +	EXT4_ERR_TRANSLATE(ESHUTDOWN),
> +	EXT4_ERR_TRANSLATE(EFAULT),
> +};
> +
> +static int ext4_errno_to_code(int errno)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(err_translation); i++)
> +		if (err_translation[i].errno == errno)
> +			return err_translation[i].code;
> +	return EXT4_ERR_UNKNOWN;
> +}
> +
> static void __save_error_info(struct super_block *sb, int error,
> 			      __u32 ino, __u64 block,
> 			      const char *func, unsigned int line)
> {
> 	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
> -	int err;
> 
> 	EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
> 	if (bdev_read_only(sb->s_bdev))
> 		return;
> +	/* We default to EFSCORRUPTED error... */
> +	if (error == 0)
> +		error = EFSCORRUPTED;
> 	es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
> 	ext4_update_tstamp(es, s_last_error_time);
> 	strncpy(es->s_last_error_func, func, sizeof(es->s_last_error_func));
> 	es->s_last_error_line = cpu_to_le32(line);
> 	es->s_last_error_ino = cpu_to_le32(ino);
> 	es->s_last_error_block = cpu_to_le64(block);
> -	switch (error) {
> -	case EIO:
> -		err = EXT4_ERR_EIO;
> -		break;
> -	case ENOMEM:
> -		err = EXT4_ERR_ENOMEM;
> -		break;
> -	case EFSBADCRC:
> -		err = EXT4_ERR_EFSBADCRC;
> -		break;
> -	case 0:
> -	case EFSCORRUPTED:
> -		err = EXT4_ERR_EFSCORRUPTED;
> -		break;
> -	case ENOSPC:
> -		err = EXT4_ERR_ENOSPC;
> -		break;
> -	case ENOKEY:
> -		err = EXT4_ERR_ENOKEY;
> -		break;
> -	case EROFS:
> -		err = EXT4_ERR_EROFS;
> -		break;
> -	case EFBIG:
> -		err = EXT4_ERR_EFBIG;
> -		break;
> -	case EEXIST:
> -		err = EXT4_ERR_EEXIST;
> -		break;
> -	case ERANGE:
> -		err = EXT4_ERR_ERANGE;
> -		break;
> -	case EOVERFLOW:
> -		err = EXT4_ERR_EOVERFLOW;
> -		break;
> -	case EBUSY:
> -		err = EXT4_ERR_EBUSY;
> -		break;
> -	case ENOTDIR:
> -		err = EXT4_ERR_ENOTDIR;
> -		break;
> -	case ENOTEMPTY:
> -		err = EXT4_ERR_ENOTEMPTY;
> -		break;
> -	case ESHUTDOWN:
> -		err = EXT4_ERR_ESHUTDOWN;
> -		break;
> -	case EFAULT:
> -		err = EXT4_ERR_EFAULT;
> -		break;
> -	default:
> -		err = EXT4_ERR_UNKNOWN;
> -	}
> -	es->s_last_error_errcode = err;
> +	es->s_last_error_errcode = ext4_errno_to_code(error);
> 	if (!es->s_first_error_time) {
> 		es->s_first_error_time = es->s_last_error_time;
> 		es->s_first_error_time_hi = es->s_last_error_time_hi;
> --
> 2.16.4
> 


Cheers, Andreas