'blk_update_request: critical target error, dev dm-X, sector xyz' messages at the time of booting with WRITE SAME failures

Environment

• Red Hat Enterprise Linux 8
• Red Hat Enterprise Linux 7

Issue

• blk_update_request: critical target error messages seen at the time of booting.

  Mar 27 13:34:28 hostname kernel: blk_update_request: critical target error, dev dm-0, sector 6769416
  Mar 27 13:34:28 hostname kernel: dm-3: WRITE SAME failed. Manually zeroing.
  

Resolution

• Configure udev rule to avoid the mentioned messages.

  # cat /etc/udev/rules.d/99-write_same.rules
  ACTION=="add|change", SUBSYSTEM=="scsi_disk", ATTR{max_write_same_blocks}="0"
  

  If the issue is at the time of booting, no further action is required. Else reload the udev rules with

  #/sbin/udevadm control --reload-rules
  #/sbin/udevadm trigger --type=devices --action=change
  

  For more details on configuring udev rules, see What is udev and how do you write custom udev rules in RHEL7 ?

Root Cause

It is seen that when a storage device rejects a WRITE SAME command we will disable write same functionality for the device and return -EREMOTEIO to the block layer.

"block/blk-core.c"
-------------------

bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
{
        int total_bytes;

        trace_block_rq_complete(req->q, req, nr_bytes);

        if (!req->bio)
                return false;

[.... ]
        if (req->cmd_type == REQ_TYPE_FS)
                req->errors = 0;

        if (error && req->cmd_type == REQ_TYPE_FS &&
            !(req->cmd_flags & REQ_QUIET)) {
                char *error_type;

                switch (error) {
                case -ENOLINK:
                        error_type = "recoverable transport";
                        break;
                case -EREMOTEIO:
                        error_type = "critical target";
                        break;
                case -EBADE:
                        error_type = "critical nexus";
                        break;
                case -ENOSPC:
                        error_type = "critical space allocation";
                        break;
                case -ENODATA:
                        error_type = "critical medium";
                        break;
                case -EIO:
                default:
                        error_type = "I/O";
                        break;
                }
                printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
                                   __func__, error_type, req->rq_disk ?
                                   req->rq_disk->disk_name : "?",
                                   (unsigned long long)blk_rq_pos(req));

        }

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