[PATCH] libata: improve failed qc reporting

Improve failed qc reporting.  The original message didn't include the
actual command nor full error status and it was necessary to
temporarily patch the code to find out exactly which command is
causing problem.  This patch makes EH report full command and result
TFs along with data direction and length.  This change will make bug
reports more useful.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/libata-eh.c

@@ -1433,16 +1433,38 @@ static void ata_eh_report(struct ata_port *ap)
 	}
 
 	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		static const char *dma_str[] = {
+			[DMA_BIDIRECTIONAL]	= "bidi",
+			[DMA_TO_DEVICE]		= "out",
+			[DMA_FROM_DEVICE]	= "in",
+			[DMA_NONE]		= "",
+		};
 		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+		struct ata_taskfile *cmd = &qc->tf, *res = &qc->result_tf;
+		unsigned int nbytes;
 
 		if (!(qc->flags & ATA_QCFLAG_FAILED) || !qc->err_mask)
 			continue;
 
-		ata_dev_printk(qc->dev, KERN_ERR, "tag %d cmd 0x%x "
-			       "Emask 0x%x stat 0x%x err 0x%x (%s)\n",
-			       qc->tag, qc->tf.command, qc->err_mask,
-			       qc->result_tf.command, qc->result_tf.feature,
-			       ata_err_string(qc->err_mask));
+		nbytes = qc->nbytes;
+		if (!nbytes)
+			nbytes = qc->nsect << 9;
+
+		ata_dev_printk(qc->dev, KERN_ERR,
+			"cmd %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
+			"tag %d data %u %s\n         "
+			"res %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
+			"Emask 0x%x (%s)\n",
+			cmd->command, cmd->feature, cmd->nsect,
+			cmd->lbal, cmd->lbam, cmd->lbah,
+			cmd->hob_feature, cmd->hob_nsect,
+			cmd->hob_lbal, cmd->hob_lbam, cmd->hob_lbah,
+			cmd->device, qc->tag, nbytes, dma_str[qc->dma_dir],
+			res->command, res->feature, res->nsect,
+			res->lbal, res->lbam, res->lbah,
+			res->hob_feature, res->hob_nsect,
+			res->hob_lbal, res->hob_lbam, res->hob_lbah,
+			res->device, qc->err_mask, ata_err_string(qc->err_mask));
 	}
 }