libata: make ata_eh_qc_retry() bump scmd->allowed on bogus failures

commit f13e2201 upstream.

libata EH decrements scmd->retries when the command failed for reasons
unrelated to the command itself so that, for example, commands aborted
due to suspend / resume cycle don't get penalized; however,
decrementing scmd->retries isn't enough for ATA passthrough commands.

Without this fix, ATA passthrough commands are not resend to the
drive, and no error is signalled to the caller because:

- allowed retry count is 1
- ata_eh_qc_complete fill the sense data, so result is valid
- sense data is filled with untouched ATA registers.
Signed-off-by: Gwendal Grignou <gwendal@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/ata/libata-eh.c

@@ -1287,14 +1287,14 @@ void ata_eh_qc_complete(struct ata_queued_cmd *qc)
  *	should be retried.  To be used from EH.
  *
  *	SCSI midlayer limits the number of retries to scmd->allowed.
- *	scmd->retries is decremented for commands which get retried
+ *	scmd->allowed is incremented for commands which get retried
  *	due to unrelated failures (qc->err_mask is zero).
  */
 void ata_eh_qc_retry(struct ata_queued_cmd *qc)
 {
 	struct scsi_cmnd *scmd = qc->scsicmd;
-	if (!qc->err_mask && scmd->retries)
-		scmd->retries--;
+	if (!qc->err_mask)
+		scmd->allowed++;
 	__ata_eh_qc_complete(qc);
 }