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Subject[PATCH-v2 1/3] target/sbc: Seperate WRITE_SAME based on UNMAP flag in sbc_ops
Date
From: Nicholas Bellinger <nab@linux-iscsi.org>

This patch adds a new sbc_ops->execute_write_same_unmap() caller for use
with WRITE_SAME w/ UNMAP=1, and performs the ->execute_cmd() setup based
this bit within sbc_setup_write_same() code.

Also, makes the changes in sbc_parse_cdb() to handle a sense_reason_t
return from sbc_setup_write_same() on error.

Reported-by: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
drivers/target/target_core_sbc.c | 51 +++++++++++++++------------------
include/target/target_core_backend.h | 1 +
2 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index b802421..a5a8f46 100644
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -235,26 +235,30 @@ static inline unsigned long long transport_lba_64_ext(unsigned char *cdb)
return ((unsigned long long)__v2) | (unsigned long long)__v1 << 32;
}

-static int sbc_write_same_supported(struct se_device *dev,
- unsigned char *flags)
+static sense_reason_t
+sbc_setup_write_same(struct se_cmd *cmd, unsigned char *flags, struct sbc_ops *ops)
{
if ((flags[0] & 0x04) || (flags[0] & 0x02)) {
pr_err("WRITE_SAME PBDATA and LBDATA"
" bits not supported for Block Discard"
" Emulation\n");
- return -ENOSYS;
+ return TCM_UNSUPPORTED_SCSI_OPCODE;
}
-
/*
- * Currently for the emulated case we only accept
- * tpws with the UNMAP=1 bit set.
+ * Special case for WRITE_SAME w/ UNMAP=1 that ends up getting
+ * translated into block discard requests within backend code.
*/
- if (!(flags[0] & 0x08)) {
- pr_err("WRITE_SAME w/o UNMAP bit not"
- " supported for Block Discard Emulation\n");
- return -ENOSYS;
+ if (flags[0] & 0x08) {
+ if (!ops->execute_write_same_unmap)
+ return TCM_UNSUPPORTED_SCSI_OPCODE;
+
+ cmd->execute_cmd = ops->execute_write_same_unmap;
+ return 0;
}
+ if (!ops->execute_write_same)
+ return TCM_UNSUPPORTED_SCSI_OPCODE;

+ cmd->execute_cmd = ops->execute_write_same;
return 0;
}

@@ -418,9 +422,6 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
cmd->se_cmd_flags |= SCF_FUA;
break;
case WRITE_SAME_32:
- if (!ops->execute_write_same)
- return TCM_UNSUPPORTED_SCSI_OPCODE;
-
sectors = transport_get_sectors_32(cdb);
if (!sectors) {
pr_err("WSNZ=1, WRITE_SAME w/sectors=0 not"
@@ -431,9 +432,9 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
size = sbc_get_size(cmd, 1);
cmd->t_task_lba = get_unaligned_be64(&cdb[12]);

- if (sbc_write_same_supported(dev, &cdb[10]) < 0)
- return TCM_UNSUPPORTED_SCSI_OPCODE;
- cmd->execute_cmd = ops->execute_write_same;
+ ret = sbc_setup_write_same(cmd, &cdb[10], ops);
+ if (ret < 0)
+ return ret;
break;
default:
pr_err("VARIABLE_LENGTH_CMD service action"
@@ -495,9 +496,6 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
cmd->execute_cmd = ops->execute_unmap;
break;
case WRITE_SAME_16:
- if (!ops->execute_write_same)
- return TCM_UNSUPPORTED_SCSI_OPCODE;
-
sectors = transport_get_sectors_16(cdb);
if (!sectors) {
pr_err("WSNZ=1, WRITE_SAME w/sectors=0 not supported\n");
@@ -507,14 +505,11 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
size = sbc_get_size(cmd, 1);
cmd->t_task_lba = get_unaligned_be64(&cdb[2]);

- if (sbc_write_same_supported(dev, &cdb[1]) < 0)
- return TCM_UNSUPPORTED_SCSI_OPCODE;
- cmd->execute_cmd = ops->execute_write_same;
+ ret = sbc_setup_write_same(cmd, &cdb[1], ops);
+ if (ret < 0)
+ return ret;
break;
case WRITE_SAME:
- if (!ops->execute_write_same)
- return TCM_UNSUPPORTED_SCSI_OPCODE;
-
sectors = transport_get_sectors_10(cdb);
if (!sectors) {
pr_err("WSNZ=1, WRITE_SAME w/sectors=0 not supported\n");
@@ -528,9 +523,9 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
* Follow sbcr26 with WRITE_SAME (10) and check for the existence
* of byte 1 bit 3 UNMAP instead of original reserved field
*/
- if (sbc_write_same_supported(dev, &cdb[1]) < 0)
- return TCM_UNSUPPORTED_SCSI_OPCODE;
- cmd->execute_cmd = ops->execute_write_same;
+ ret = sbc_setup_write_same(cmd, &cdb[1], ops);
+ if (ret < 0)
+ return ret;
break;
case VERIFY:
size = 0;
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index aa86809..3393ab1 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -41,6 +41,7 @@ struct sbc_ops {
sense_reason_t (*execute_rw)(struct se_cmd *cmd);
sense_reason_t (*execute_sync_cache)(struct se_cmd *cmd);
sense_reason_t (*execute_write_same)(struct se_cmd *cmd);
+ sense_reason_t (*execute_write_same_unmap)(struct se_cmd *cmd);
sense_reason_t (*execute_unmap)(struct se_cmd *cmd);
};

--
1.7.2.5


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