[stgt] [PATCH] Add an optional supported-opcode-array to the backingstore template

[Ronnie Sahlberg]

Add an array that deswcribes which opcodes are supported by the RDWR backend.
Opcodes that are supported are flagged with 1, and opcodes that are not
supported are flagged with 0.

This allows backends to specify which opcodes it is prepared to process
and which commands should fail with invalid op code

This is most useful for block devices where we have several different backends
and where some backends only support a subset of the commands.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg at gmail.com>
---
 usr/bs_rdwr.c |   20 ++++++++++++++++++++
 usr/scsi.c    |    6 ++++++
 usr/tgtd.h    |    1 +
 3 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/usr/bs_rdwr.c b/usr/bs_rdwr.c
index 47d2d99..b65fa6a 100644
--- a/usr/bs_rdwr.c
+++ b/usr/bs_rdwr.c
@@ -412,6 +412,25 @@ static void bs_rdwr_exit(struct scsi_lu *lu)
 	bs_thread_close(info);
 }
 
+static const char bs_ops_supported[256] = {
+/* 0x00-0x0F */  1, 0, 0, 1,  1, 0, 0, 0,  1, 0, 1, 0,  0, 0, 0, 0,
+/* 0x10-0x1F */  0, 0, 1, 0,  0, 1, 1, 1,  0, 0, 1, 1,  0, 1, 1, 0,
+/* 0x20-0x2F */  0, 0, 0, 0,  0, 1, 0, 0,  1, 0, 1, 0,  0, 0, 1, 1,
+/* 0x30-0x3F */  0, 0, 0, 0,  1, 1, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+/* 0x40-0x4F */  0, 1, 1, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+/* 0x50-0x5F */  0, 0, 0, 0,  0, 1, 0, 0,  0, 0, 1, 0,  0, 0, 1, 1,
+/* 0x60-0x6F */  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+/* 0x70-0x7F */  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+/* 0x80-0x8F */  0, 0, 0, 0,  0, 0, 0, 0,  1, 0, 1, 1,  0, 0, 1, 1,
+/* 0x90-0x9F */  1, 1, 0, 1,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 1, 0,
+/* 0xA0-0xAF */  1, 0, 0, 1,  0, 0, 0, 0,  1, 0, 1, 0,  0, 0, 1, 1,
+/* 0xB0-0xBF */  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+/* 0xC0-0xCF */  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+/* 0xD0-0xDF */  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+/* 0xE0-0xEF */  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+/* 0xF0-0xFF */  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,
+};
+
 static struct backingstore_template rdwr_bst = {
 	.bs_name		= "rdwr",
 	.bs_datasize		= sizeof(struct bs_thread_info),
@@ -421,6 +440,7 @@ static struct backingstore_template rdwr_bst = {
 	.bs_exit		= bs_rdwr_exit,
 	.bs_cmd_submit		= bs_thread_cmd_submit,
 	.bs_oflags_supported    = O_SYNC | O_DIRECT,
+	.bs_ops_supported	= bs_ops_supported,
 };
 
 __attribute__((constructor)) static void bs_rdwr_constructor(void)
diff --git a/usr/scsi.c b/usr/scsi.c
index 2636a5c..991974d 100644
--- a/usr/scsi.c
+++ b/usr/scsi.c
@@ -492,6 +492,12 @@ int scsi_cmd_perform(int host_no, struct scsi_cmd *cmd)
 	if (spc_access_check(cmd))
 		return SAM_STAT_RESERVATION_CONFLICT;
 
+	if (cmd->dev->bst->bs_ops_supported
+	&& !cmd->dev->bst->bs_ops_supported[op]) {
+		sense_data_build(cmd, ILLEGAL_REQUEST, ASC_INVALID_OP_CODE);
+		return SAM_STAT_CHECK_CONDITION;
+	}
+ 
 	return cmd->dev->dev_type_template.ops[op].cmd_perform(host_no, cmd);
 }
 
diff --git a/usr/tgtd.h b/usr/tgtd.h
index 484e6e9..70f6306 100644
--- a/usr/tgtd.h
+++ b/usr/tgtd.h
@@ -165,6 +165,7 @@ struct backingstore_template {
 	void (*bs_exit)(struct scsi_lu *dev);
 	int (*bs_cmd_submit)(struct scsi_cmd *cmd);
 	int bs_oflags_supported;
+	const char *bs_ops_supported;
 
 	struct list_head backingstore_siblings;
 };
-- 
1.7.3.1

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