On 8/18/25 3:45 PM, Darrick J. Wong wrote:
> On Mon, Aug 18, 2025 at 03:22:02PM -0500, Eric Sandeen wrote:
>> We had a report that a failing scsi disk was oopsing XFS when an xattr
>> read encountered a media error. This is because the media error returned
>> -ENODATA, which we map in xattr code to -ENOATTR and treat specially.
>>
>> In this particular case, it looked like:
>>
>> xfs_attr_leaf_get()
>> error = xfs_attr_leaf_hasname(args, &bp);
>> // here bp is NULL, error == -ENODATA from disk failure
>> // but we define ENOATTR as ENODATA, so ...
>> if (error == -ENOATTR) {
>> // whoops, surprise! bp is NULL, OOPS here
>> xfs_trans_brelse(args->trans, bp);
>> return error;
>> } ...
>>
>> To avoid whack-a-mole "test for null bp" or "which -ENODATA do we really
>> mean in this function?" throughout the xattr code, my first thought is
>> that we should simply map -ENODATA in lower level read functions back to
>> -EIO, which is unambiguous, even if we lose the nuance of the underlying
>> error code. (The block device probably already squawked.) Thoughts?
>
> Uhhhh where does this ENODATA come from? Is it the block layer?
>
> $ git grep -w ENODATA block/
> block/blk-core.c:146: [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" },
That, probably, though I don't speak block layer very well. As mentioned, it was a
SCSI disk error, and it appeared in XFS as -ENODATA:
sd 0:0:23:0: [sdad] tag#937 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=2s
sd 0:0:23:0: [sdad] tag#937 Sense Key : Medium Error [current]
sd 0:0:23:0: [sdad] tag#937 Add. Sense: Read retries exhausted
sd 0:0:23:0: [sdad] tag#937 CDB: Read(16) 88 00 00 00 00 00 9b df 5e 78 00 00 00 08 00 00
critical medium error, dev sdad, sector 2615107192 op 0x0:(READ) flags 0x1000 phys_seg 1 prio class 2
XFS (sdad1): metadata I/O error in "xfs_da_read_buf+0xe1/0x140 [xfs]" at daddr 0x9bdf5678 len 8 error 61
(see error 61, ENODATA)
> --D
>
>> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
>> ---
>>
>> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
>> index f9ef3b2a332a..6ba57ccaa25f 100644
>> --- a/fs/xfs/xfs_buf.c
>> +++ b/fs/xfs/xfs_buf.c
>> @@ -747,6 +747,9 @@ xfs_buf_read_map(
>> /* bad CRC means corrupted metadata */
>> if (error == -EFSBADCRC)
>> error = -EFSCORRUPTED;
>> + /* ENODATA == ENOATTR which confuses xattr layers */
>> + if (error == -ENODATA)
>> + error = -EIO;
>> return error;
>> }
>>
>>
>>
>
