Hi, Hannes:

On 06/05/2013 03:11 PM, Hannes Reinecke wrote:
When a medium error is detected the SCSI stack should return
ENODATA to the upper layers.

Signed-off-by: Hannes Reinecke<[email protected]>
---
  drivers/scsi/scsi_error.c | 7 ++++++-
  drivers/scsi/scsi_lib.c   | 5 +++++
  include/scsi/scsi.h       | 2 ++
  3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index bf5e61a..2ded10a 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -235,6 +235,7 @@ static inline void scsi_eh_prt_fail_stats(struct Scsi_Host 
*shost,
   *    NEEDS_RETRY
   *    TARGET_ERROR
   *    ALLOC_ERROR
+ *     MEDIA_FAILURE
   *
   * Notes:
   *    When a deferred error is detected the current command has
@@ -375,7 +376,7 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
                if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
                    sshdr.asc == 0x13 || /* AMNF DATA FIELD */
                    sshdr.asc == 0x14) { /* RECORD NOT FOUND */
-                       return TARGET_ERROR;
+                       return MEDIA_FAILURE;
                }
                return NEEDS_RETRY;

@@ -1598,6 +1599,10 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
                        /* target hit out-of-space condition */
                        set_host_byte(scmd, DID_ALLOC_FAILURE);
                        rtn = SUCCESS;
+               } else if (rtn == MEDIA_FAILURE) {
+                       /* medium error */
+                       set_host_byte(scmd, DID_MEDIUM_ERROR);
+                       rtn = SUCCESS;
                }
                /* if rtn == FAILED, we have no sense information;
                 * returning FAILED will wake the error handler thread
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 209a4d5..39d626e 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -711,6 +711,7 @@ EXPORT_SYMBOL(scsi_release_buffers);
   * -EREMOTEIO permanent target failure, do not retry
   * -EBADE     permanent nexus failure, retry on other path
   * -ENOSPC    No write space available
+ * -ENODATA    Medium error
   */
  static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
  {
@@ -732,6 +733,10 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd 
*cmd, int result)
                set_host_byte(cmd, DID_OK);
                error = -ENOSPC;
                break;
+       case DID_MEDIUM_ERROR:
+               set_host_byte(cmd, DID_OK);
+               error = -ENODATA;
+               break;

It seems that there is a debugging requirement to announce the
meaning of these new added error codes in the function
blk_update_request()like this:

diff --git a/block/blk-core.c b/block/blk-core.c
index 33c33bc..a396eb6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2315,6 +2315,12 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
                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";

# To tell the truth, I'm not understand why this patchset is needed
# in practice for I've only just got limited info about LSF. I guess
# this is one of the improvements for SCSI EH. Could you give an
# example/condition the upper layers interest in?

Thanks,
Ren

        default:
                error = -EIO;
                break;
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 5ead86b..c397684 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -453,6 +453,7 @@ static inline int scsi_is_wlun(unsigned int lun)
  #define DID_NEXUS_FAILURE 0x11  /* Permanent nexus failure, retry on other
                                 * paths might yield different results */
  #define DID_ALLOC_FAILURE 0x12  /* Space allocation on the device failed */
+#define DID_MEDIUM_ERROR  0x13  /* Medium error */
  #define DRIVER_OK       0x00  /* Driver status                           */

  /*
@@ -484,6 +485,7 @@ static inline int scsi_is_wlun(unsigned int lun)
  #define FAST_IO_FAIL  0x2009
  #define TARGET_ERROR    0x200A
  #define ALLOC_ERROR     0x200B
+#define MEDIA_FAILURE   0x200C

  /*
   * Midlevel queue return values.

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