[PATCH] Add support for SoftwareWriteProtect and fix bugs in modeselect

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Fix a bug in sbc_mode_page_update. We only have a subpagecode in byte 1
IFF the SPF bit in byte 0 is set.

Add support for using modeselect for the CONTROLS page and set the
mask to allow SWP to be changed.

Add a SWP flag to the device attributes and update this as the CONTROLS/SWP
flag is set by the initiator.

Update SBC so that we treat writeprotect as either the current ->readonly flag
that is used to se the hard property for the lun,   or the ->swp flag
that is set in software by the initiators.
Thus like on a real disk, SWP can be used to turn a read-write LUN to become
temporarily readonly, but SWP can NOT be used to turn a physically readonly
medium to become read-write.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
---
 usr/sbc.c    |   37 +++++++++++++++++++++++++++++++------
 usr/spc.c    |    1 +
 usr/target.c |    2 ++
 usr/tgtd.h   |    1 +
 4 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/usr/sbc.c b/usr/sbc.c
index 1f50191..c4f012c 100644
--- a/usr/sbc.c
+++ b/usr/sbc.c
@@ -69,17 +69,21 @@ static off_t find_next_hole(struct scsi_lu *dev, off_t offset)
 static int sbc_mode_page_update(struct scsi_cmd *cmd, uint8_t *data, int *changed)
 {
 	uint8_t pcode = data[0] & 0x3f;
-	uint8_t subpcode = data[1];
+	uint8_t subpcode = 0;
 	struct mode_pg *pg;
 	uint8_t old;
 
+	if (data[0] & 0x40)
+		subpcode = data[1];
+
 	pg = find_mode_page(cmd->dev, pcode, subpcode);
 	if (pg == NULL)
 		return 1;
 
 	eprintf("%x %x\n", pg->mode_data[0], data[2]);
 
-	if (pcode == 0x08) {
+	switch (pcode) {
+	case 0x08: /* Cachning mode page */
 		old = pg->mode_data[0];
 		if (0x4 & data[2])
 			pg->mode_data[0] |= 0x4;
@@ -90,6 +94,19 @@ static int sbc_mode_page_update(struct scsi_cmd *cmd, uint8_t *data, int *change
 			*changed = 1;
 
 		return 0;
+	case 0x0a: /* Control mode page */
+		old = pg->mode_data[2];
+		if (0x8 & data[4])
+			pg->mode_data[2] |= 0x8;
+		else
+			pg->mode_data[2] &= ~0x8;
+
+		if (old != pg->mode_data[2])
+			*changed = 1;
+
+		cmd->dev->attrs.swp = (0x8 & data[4]) ? 1 : 0;
+
+		return 0;
 	}
 
 	return 1;
@@ -110,7 +127,8 @@ static int sbc_mode_sense(int host_no, struct scsi_cmd *cmd)
 	 * If this is a read-only lun, we must modify the data and set the
 	 * write protect bit
 	 */
-	if (cmd->dev->attrs.readonly && ret == SAM_STAT_GOOD) {
+	if ((cmd->dev->attrs.readonly || cmd->dev->attrs.swp)
+	&& ret == SAM_STAT_GOOD) {
 		uint8_t *data, mode6;
 
 		mode6 = (cmd->scb[0] == 0x1a);
@@ -141,7 +159,7 @@ static int sbc_format_unit(int host_no, struct scsi_cmd *cmd)
 		goto sense;
 	}
 
-	if (cmd->dev->attrs.readonly) {
+	if (cmd->dev->attrs.readonly || cmd->dev->attrs.swp) {
 		key = DATA_PROTECT;
 		asc = ASC_WRITE_PROTECT;
 		goto sense;
@@ -199,7 +217,7 @@ static int sbc_unmap(int host_no, struct scsi_cmd *cmd)
 		goto sense;
 	}
 
-	if (lu->attrs.readonly) {
+	if (lu->attrs.readonly || cmd->dev->attrs.swp) {
 		key = DATA_PROTECT;
 		asc = ASC_WRITE_PROTECT;
 		goto sense;
@@ -290,7 +308,7 @@ static int sbc_rw(int host_no, struct scsi_cmd *cmd)
 		break;
 	}
 
-	if (lu->attrs.readonly) {
+	if (lu->attrs.readonly || cmd->dev->attrs.swp) {
 		switch (cmd->scb[0]) {
 		case WRITE_6:
 		case WRITE_10:
@@ -736,6 +754,13 @@ static tgtadm_err sbc_lu_init(struct scsi_lu *lu)
 
 	/* Control page */
 	add_mode_page(lu, "0x0a:0:10:2:0x10:0:0:0:0:0:0:2:0");
+	{
+		uint8_t mask[10];
+		memset(mask, 0, sizeof(mask));
+		mask[2] = 0x08; /* allow changing SWP */
+
+		set_mode_page_changeable_mask(lu, 0x0a, 0, mask);
+	}
 
 	/* Control Extensions mode page:  TCMOS:1 */
 	add_mode_page(lu, "0x0a:1:0x1c:0x04:0x00:0x00");
diff --git a/usr/spc.c b/usr/spc.c
index 0cbba95..15077ca 100644
--- a/usr/spc.c
+++ b/usr/spc.c
@@ -2028,6 +2028,7 @@ int spc_lu_init(struct scsi_lu *lu)
 	lu->attrs.thinprovisioning = 0;
 	lu->attrs.removable = 0;
 	lu->attrs.readonly = 0;
+	lu->attrs.swp = 0;
 	lu->attrs.sense_format = 0;
 
 	snprintf(lu->attrs.vendor_id, sizeof(lu->attrs.vendor_id),
diff --git a/usr/target.c b/usr/target.c
index 9a8f2fd..fd087ad 100644
--- a/usr/target.c
+++ b/usr/target.c
@@ -2023,6 +2023,7 @@ tgtadm_err tgt_target_show_all(struct concat_buf *b)
 				_TAB3 "Removable media: %s\n"
 				_TAB3 "Prevent removal: %s\n"
 				_TAB3 "Readonly: %s\n"
+				_TAB3 "SWP: %s\n"
 				_TAB3 "Thin-provisioning: %s\n"
 				_TAB3 "Backing store type: %s\n"
 				_TAB3 "Backing store path: %s\n"
@@ -2037,6 +2038,7 @@ tgtadm_err tgt_target_show_all(struct concat_buf *b)
 				lu->attrs.removable ? "Yes" : "No",
 				lu_prevent_removal(lu) ? "Yes" : "No",
 				lu->attrs.readonly ? "Yes" : "No",
+				lu->attrs.swp ? "Yes" : "No",
 				lu->attrs.thinprovisioning ? "Yes" : "No",
 				lu->bst ?
 					(lu->bst->bs_name ? : "Unknown") :
diff --git a/usr/tgtd.h b/usr/tgtd.h
index f3d9674..484e6e9 100644
--- a/usr/tgtd.h
+++ b/usr/tgtd.h
@@ -74,6 +74,7 @@ struct lu_phy_attr {
 	char qualifier;		/* Peripheral Qualifier */
 	char removable;		/* Removable media */
 	char readonly;          /* Read-Only media */
+	char swp;               /* Software Write Protect */
 	char thinprovisioning;  /* Use thin-provisioning for this LUN */
 	char online;		/* Logical Unit online */
 	char sense_format;	/* Descrptor format sense data supported */
-- 
1.7.3.1

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