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authorNicholas Bellinger <nab@linux-iscsi.org>2015-07-30 18:28:13 -0700
committerNicholas Bellinger <nab@linux-iscsi.org>2015-09-11 00:31:39 -0700
commit8f9b565482c537821588444e09ff732c7d65ed6e (patch)
treeb411dd3479eb5f3f86e2eb390c1c973e4b31ee12
parent13a3cf08fa1e4b3a252f24202d47a556242aea03 (diff)
downloadlinux-8f9b565482c537821588444e09ff732c7d65ed6e.tar.bz2
target/qla2xxx: Honor max_data_sg_nents I/O transfer limit
This patch adds an optional fabric driver provided SGL limit that target-core will honor as it's own internal I/O maximum transfer length limit, as exposed by EVPD=0xb0 block limits parameters. This is required for handling cases when host I/O transfer length exceeds the requested EVPD block limits maximum transfer length. The initial user of this logic is qla2xxx, so that we can avoid having to reject I/Os from some legacy FC hosts where EVPD=0xb0 parameters are not honored. When se_cmd payload length exceeds the provided limit in target_check_max_data_sg_nents() code, se_cmd->data_length + se_cmd->prot_length are reset with se_cmd->residual_count plus underflow bit for outgoing TFO response callbacks. It also checks for existing CDB level underflow + overflow and recalculates final residual_count as necessary. Note this patch currently assumes 1:1 mapping of PAGE_SIZE per struct scatterlist entry. Reported-by: Craig Watson <craig.watson@vanguard-rugged.com> Cc: Craig Watson <craig.watson@vanguard-rugged.com> Tested-by: Himanshu Madhani <himanshu.madhani@qlogic.com> Cc: Roland Dreier <roland@purestorage.com> Cc: Arun Easi <arun.easi@qlogic.com> Cc: Giridhar Malavali <giridhar.malavali@qlogic.com> Cc: Andrew Vasquez <andrew.vasquez@qlogic.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
-rw-r--r--drivers/scsi/qla2xxx/tcm_qla2xxx.c5
-rw-r--r--drivers/target/target_core_spc.c13
-rw-r--r--drivers/target/target_core_transport.c51
-rw-r--r--include/target/target_core_fabric.h13
4 files changed, 78 insertions, 4 deletions
diff --git a/drivers/scsi/qla2xxx/tcm_qla2xxx.c b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
index c621623abeed..edeb3aefa6fe 100644
--- a/drivers/scsi/qla2xxx/tcm_qla2xxx.c
+++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
@@ -1808,6 +1808,11 @@ static const struct target_core_fabric_ops tcm_qla2xxx_ops = {
.module = THIS_MODULE,
.name = "qla2xxx",
.node_acl_size = sizeof(struct tcm_qla2xxx_nacl),
+ /*
+ * XXX: Limit assumes single page per scatter-gather-list entry.
+ * Current maximum is ~4.9 MB per se_cmd->t_data_sg with PAGE_SIZE=4096
+ */
+ .max_data_sg_nents = 1200,
.get_fabric_name = tcm_qla2xxx_get_fabric_name,
.tpg_get_wwn = tcm_qla2xxx_get_fabric_wwn,
.tpg_get_tag = tcm_qla2xxx_get_tag,
diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index a07d455e0dd5..0e0456f6a282 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -477,8 +477,8 @@ static sense_reason_t
spc_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
{
struct se_device *dev = cmd->se_dev;
- int have_tp = 0;
- int opt, min;
+ u32 mtl = 0;
+ int have_tp = 0, opt, min;
/*
* Following spc3r22 section 6.5.3 Block Limits VPD page, when
@@ -509,8 +509,15 @@ spc_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
/*
* Set MAXIMUM TRANSFER LENGTH
+ *
+ * XXX: Currently assumes single PAGE_SIZE per scatterlist for fabrics
+ * enforcing maximum HW scatter-gather-list entry limit
*/
- put_unaligned_be32(dev->dev_attrib.hw_max_sectors, &buf[8]);
+ if (cmd->se_tfo->max_data_sg_nents) {
+ mtl = (cmd->se_tfo->max_data_sg_nents * PAGE_SIZE) /
+ dev->dev_attrib.block_size;
+ }
+ put_unaligned_be32(min_not_zero(mtl, dev->dev_attrib.hw_max_sectors), &buf[8]);
/*
* Set OPTIMAL TRANSFER LENGTH
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 3f0b50082de4..62bafaa670f4 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1075,6 +1075,55 @@ transport_set_vpd_ident(struct t10_vpd *vpd, unsigned char *page_83)
}
EXPORT_SYMBOL(transport_set_vpd_ident);
+static sense_reason_t
+target_check_max_data_sg_nents(struct se_cmd *cmd, struct se_device *dev,
+ unsigned int size)
+{
+ u32 mtl;
+
+ if (!cmd->se_tfo->max_data_sg_nents)
+ return TCM_NO_SENSE;
+ /*
+ * Check if fabric enforced maximum SGL entries per I/O descriptor
+ * exceeds se_cmd->data_length. If true, set SCF_UNDERFLOW_BIT +
+ * residual_count and reduce original cmd->data_length to maximum
+ * length based on single PAGE_SIZE entry scatter-lists.
+ */
+ mtl = (cmd->se_tfo->max_data_sg_nents * PAGE_SIZE);
+ if (cmd->data_length > mtl) {
+ /*
+ * If an existing CDB overflow is present, calculate new residual
+ * based on CDB size minus fabric maximum transfer length.
+ *
+ * If an existing CDB underflow is present, calculate new residual
+ * based on original cmd->data_length minus fabric maximum transfer
+ * length.
+ *
+ * Otherwise, set the underflow residual based on cmd->data_length
+ * minus fabric maximum transfer length.
+ */
+ if (cmd->se_cmd_flags & SCF_OVERFLOW_BIT) {
+ cmd->residual_count = (size - mtl);
+ } else if (cmd->se_cmd_flags & SCF_UNDERFLOW_BIT) {
+ u32 orig_dl = size + cmd->residual_count;
+ cmd->residual_count = (orig_dl - mtl);
+ } else {
+ cmd->se_cmd_flags |= SCF_UNDERFLOW_BIT;
+ cmd->residual_count = (cmd->data_length - mtl);
+ }
+ cmd->data_length = mtl;
+ /*
+ * Reset sbc_check_prot() calculated protection payload
+ * length based upon the new smaller MTL.
+ */
+ if (cmd->prot_length) {
+ u32 sectors = (mtl / dev->dev_attrib.block_size);
+ cmd->prot_length = dev->prot_length * sectors;
+ }
+ }
+ return TCM_NO_SENSE;
+}
+
sense_reason_t
target_cmd_size_check(struct se_cmd *cmd, unsigned int size)
{
@@ -1120,7 +1169,7 @@ target_cmd_size_check(struct se_cmd *cmd, unsigned int size)
}
}
- return 0;
+ return target_check_max_data_sg_nents(cmd, dev, size);
}
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index 69355feabd1d..7fb2557a760e 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -5,6 +5,19 @@ struct target_core_fabric_ops {
struct module *module;
const char *name;
size_t node_acl_size;
+ /*
+ * Limits number of scatterlist entries per SCF_SCSI_DATA_CDB payload.
+ * Setting this value tells target-core to enforce this limit, and
+ * report as INQUIRY EVPD=b0 MAXIMUM TRANSFER LENGTH.
+ *
+ * target-core will currently reset se_cmd->data_length to this
+ * maximum size, and set UNDERFLOW residual count if length exceeds
+ * this limit.
+ *
+ * XXX: Not all initiator hosts honor this block-limit EVPD
+ * XXX: Currently assumes single PAGE_SIZE per scatterlist entry
+ */
+ u32 max_data_sg_nents;
char *(*get_fabric_name)(void);
char *(*tpg_get_wwn)(struct se_portal_group *);
u16 (*tpg_get_tag)(struct se_portal_group *);