target: Fix reporting of supported VPD pages

The current handling of VPD page 00h (Supported VPD Pages) for INQUIRY
commands has a couple of problems:

 - The page length field is incorrectly set to 3, so the entry for 86h
   (Extended INQUIRY Data) is ignored since it is in the fourth slot.
 - Even though the code handles pages B0h and B2h, those pages aren't
   mentioned in the Supported VPD Pages list, so eg the Linux SCSI stack
   won't actually try to use them.

Fix these problems and make things more robust to avoid future problems
by moving to a table of supported VPD pages, which means that any added
VPD page support will automatically get reported on page 0.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_cdb.c

@@ -114,31 +114,6 @@ target_emulate_inquiry_std(struct se_cmd *cmd)
 	return 0;
 }
 
-/* supported vital product data pages */
-static int
-target_emulate_evpd_00(struct se_cmd *cmd, unsigned char *buf)
-{
-	buf[1] = 0x00;
-	if (cmd->data_length < 8)
-		return 0;
-
-	buf[4] = 0x0;
-	/*
-	 * Only report the INQUIRY EVPD=1 pages after a valid NAA
-	 * Registered Extended LUN WWN has been set via ConfigFS
-	 * during device creation/restart.
-	 */
-	if (cmd->se_dev->se_sub_dev->su_dev_flags &
-			SDF_EMULATED_VPD_UNIT_SERIAL) {
-		buf[3] = 3;
-		buf[5] = 0x80;
-		buf[6] = 0x83;
-		buf[7] = 0x86;
-	}
-
-	return 0;
-}
-
 /* unit serial number */
 static int
 target_emulate_evpd_80(struct se_cmd *cmd, unsigned char *buf)
@@ -146,7 +121,6 @@ target_emulate_evpd_80(struct se_cmd *cmd, unsigned char *buf)
 	struct se_device *dev = cmd->se_dev;
 	u16 len = 0;
 
-	buf[1] = 0x80;
 	if (dev->se_sub_dev->su_dev_flags &
 			SDF_EMULATED_VPD_UNIT_SERIAL) {
 		u32 unit_serial_len;
@@ -190,7 +164,6 @@ target_emulate_evpd_83(struct se_cmd *cmd, unsigned char *buf)
 	int i;
 	u16 len = 0, id_len;
 
-	buf[1] = 0x83;
 	off = 4;
 
 	/*
@@ -471,7 +444,6 @@ target_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf)
 	if (cmd->data_length < 60)
 		return 0;
 
-	buf[1] = 0x86;
 	buf[2] = 0x3c;
 	/* Set HEADSUP, ORDSUP, SIMPSUP */
 	buf[5] = 0x07;
@@ -512,7 +484,6 @@ target_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
 	}
 
 	buf[0] = dev->transport->get_device_type(dev);
-	buf[1] = 0xb0;
 	buf[3] = have_tp ? 0x3c : 0x10;
 
 	/*
@@ -579,7 +550,6 @@ target_emulate_evpd_b2(struct se_cmd *cmd, unsigned char *buf)
 	 * defined in table 162.
 	 */
 	buf[0] = dev->transport->get_device_type(dev);
-	buf[1] = 0xb2;
 
 	/*
 	 * Set Hardcoded length mentioned above for DP=0
@@ -617,12 +587,52 @@ target_emulate_evpd_b2(struct se_cmd *cmd, unsigned char *buf)
 	return 0;
 }
 
+static int
+target_emulate_evpd_00(struct se_cmd *cmd, unsigned char *buf);
+
+static struct {
+	uint8_t		page;
+	int		(*emulate)(struct se_cmd *, unsigned char *);
+} evpd_handlers[] = {
+	{ .page = 0x00, .emulate = target_emulate_evpd_00 },
+	{ .page = 0x80, .emulate = target_emulate_evpd_80 },
+	{ .page = 0x83, .emulate = target_emulate_evpd_83 },
+	{ .page = 0x86, .emulate = target_emulate_evpd_86 },
+	{ .page = 0xb0, .emulate = target_emulate_evpd_b0 },
+	{ .page = 0xb2, .emulate = target_emulate_evpd_b2 },
+};
+
+/* supported vital product data pages */
+static int
+target_emulate_evpd_00(struct se_cmd *cmd, unsigned char *buf)
+{
+	int p;
+
+	if (cmd->data_length < 8)
+		return 0;
+	/*
+	 * Only report the INQUIRY EVPD=1 pages after a valid NAA
+	 * Registered Extended LUN WWN has been set via ConfigFS
+	 * during device creation/restart.
+	 */
+	if (cmd->se_dev->se_sub_dev->su_dev_flags &
+			SDF_EMULATED_VPD_UNIT_SERIAL) {
+		buf[3] = ARRAY_SIZE(evpd_handlers);
+		for (p = 0; p < min_t(int, ARRAY_SIZE(evpd_handlers),
+				      cmd->data_length - 4); ++p)
+			buf[p + 4] = evpd_handlers[p].page;
+	}
+
+	return 0;
+}
+
 static int
 target_emulate_inquiry(struct se_cmd *cmd)
 {
 	struct se_device *dev = cmd->se_dev;
 	unsigned char *buf = cmd->t_task_buf;
 	unsigned char *cdb = cmd->t_task_cdb;
+	int p;
 
 	if (!(cdb[1] & 0x1))
 		return target_emulate_inquiry_std(cmd);
@@ -641,25 +651,14 @@ target_emulate_inquiry(struct se_cmd *cmd)
 	}
 	buf[0] = dev->transport->get_device_type(dev);
 
-	switch (cdb[2]) {
-	case 0x00:
-		return target_emulate_evpd_00(cmd, buf);
-	case 0x80:
-		return target_emulate_evpd_80(cmd, buf);
-	case 0x83:
-		return target_emulate_evpd_83(cmd, buf);
-	case 0x86:
-		return target_emulate_evpd_86(cmd, buf);
-	case 0xb0:
-		return target_emulate_evpd_b0(cmd, buf);
-	case 0xb2:
-		return target_emulate_evpd_b2(cmd, buf);
-	default:
-		printk(KERN_ERR "Unknown VPD Code: 0x%02x\n", cdb[2]);
-		return -EINVAL;
-	}
+	for (p = 0; p < ARRAY_SIZE(evpd_handlers); ++p)
+		if (cdb[2] == evpd_handlers[p].page) {
+			buf[1] = cdb[2];
+			return evpd_handlers[p].emulate(cmd, buf);
+		}
 
-	return 0;
+	printk(KERN_ERR "Unknown VPD Code: 0x%02x\n", cdb[2]);
+	return -EINVAL;
 }
 
 static int