On 5/31/18 7:05 PM, David Disseldorp wrote:
> The new emulate_pr backstore attribute allows for Persistent Reservation
> and SCSI2 RESERVE/RELEASE support to be completely disabled. This can be
> useful for scenarios such as:
> - Enforcing ATS (Compare & Write) usage on recent VMware ESXi initiators
> - Allowing clustered (e.g. tcm-user) backends to block such requests,
> avoiding the multi-node reservation state propagation.
>
> When explicitly disabled, PR and RESERVE/RELEASE requests receive
> Invalid Command Operation Code response sense data.
>
> Signed-off-by: David Disseldorp <ddiss@xxxxxxx>
> ---
> drivers/target/target_core_configfs.c | 21 ++++++++++++++++-----
> drivers/target/target_core_device.c | 1 +
> drivers/target/target_core_pr.c | 22 ++++++++++++++++++++++
> include/target/target_core_base.h | 3 +++
> 4 files changed, 42 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
> index 3f4bf126eed0..17b830e35a08 100644
> --- a/drivers/target/target_core_configfs.c
> +++ b/drivers/target/target_core_configfs.c
> @@ -530,6 +530,7 @@ DEF_CONFIGFS_ATTRIB_SHOW(emulate_tpu);
> DEF_CONFIGFS_ATTRIB_SHOW(emulate_tpws);
> DEF_CONFIGFS_ATTRIB_SHOW(emulate_caw);
> DEF_CONFIGFS_ATTRIB_SHOW(emulate_3pc);
> +DEF_CONFIGFS_ATTRIB_SHOW(emulate_pr);
> DEF_CONFIGFS_ATTRIB_SHOW(pi_prot_type);
> DEF_CONFIGFS_ATTRIB_SHOW(hw_pi_prot_type);
> DEF_CONFIGFS_ATTRIB_SHOW(pi_prot_format);
> @@ -590,6 +591,7 @@ static ssize_t _name##_store(struct config_item *item, const char *page, \
> DEF_CONFIGFS_ATTRIB_STORE_BOOL(emulate_fua_write);
> DEF_CONFIGFS_ATTRIB_STORE_BOOL(emulate_caw);
> DEF_CONFIGFS_ATTRIB_STORE_BOOL(emulate_3pc);
> +DEF_CONFIGFS_ATTRIB_STORE_BOOL(emulate_pr);
> DEF_CONFIGFS_ATTRIB_STORE_BOOL(enforce_pr_isids);
> DEF_CONFIGFS_ATTRIB_STORE_BOOL(is_nonrot);
>
> @@ -1114,6 +1116,7 @@ CONFIGFS_ATTR(, emulate_tpu);
> CONFIGFS_ATTR(, emulate_tpws);
> CONFIGFS_ATTR(, emulate_caw);
> CONFIGFS_ATTR(, emulate_3pc);
> +CONFIGFS_ATTR(, emulate_pr);
> CONFIGFS_ATTR(, pi_prot_type);
> CONFIGFS_ATTR_RO(, hw_pi_prot_type);
> CONFIGFS_ATTR(, pi_prot_format);
> @@ -1154,6 +1157,7 @@ struct configfs_attribute *sbc_attrib_attrs[] = {
> &attr_emulate_tpws,
> &attr_emulate_caw,
> &attr_emulate_3pc,
> + &attr_emulate_pr,
> &attr_pi_prot_type,
> &attr_hw_pi_prot_type,
> &attr_pi_prot_format,
> @@ -1428,6 +1432,9 @@ static ssize_t target_pr_res_holder_show(struct config_item *item, char *page)
> if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_PGR)
> return sprintf(page, "Passthrough\n");
>
> + if (!dev->dev_attrib.emulate_pr)
> + return sprintf(page, "Reservations Disabled\n");
> +
> spin_lock(&dev->dev_reservation_lock);
> if (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS)
> ret = target_core_dev_pr_show_spc2_res(dev, page);
> @@ -1567,10 +1574,12 @@ static ssize_t target_pr_res_type_show(struct config_item *item, char *page)
>
> if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_PGR)
> return sprintf(page, "SPC_PASSTHROUGH\n");
> - else if (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS)
> + if (!dev->dev_attrib.emulate_pr)
> + return sprintf(page, "Reservations Disabled\n");
> + if (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS)
> return sprintf(page, "SPC2_RESERVATIONS\n");
> - else
> - return sprintf(page, "SPC3_PERSISTENT_RESERVATIONS\n");
> +
> + return sprintf(page, "SPC3_PERSISTENT_RESERVATIONS\n");
> }
>
> static ssize_t target_pr_res_aptpl_active_show(struct config_item *item,
> @@ -1578,7 +1587,8 @@ static ssize_t target_pr_res_aptpl_active_show(struct config_item *item,
> {
> struct se_device *dev = pr_to_dev(item);
>
> - if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_PGR)
> + if ((dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH)
> + || !dev->dev_attrib.emulate_pr)
> return 0;
>
> return sprintf(page, "APTPL Bit Status: %s\n",
> @@ -1590,7 +1600,8 @@ static ssize_t target_pr_res_aptpl_metadata_show(struct config_item *item,
> {
> struct se_device *dev = pr_to_dev(item);
>
> - if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_PGR)
> + if ((dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH)
> + || !dev->dev_attrib.emulate_pr)
> return 0;
>
> return sprintf(page, "Ready to process PR APTPL metadata..\n");
> diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
> index e27db4d45a9d..96a60072e446 100644
> --- a/drivers/target/target_core_device.c
> +++ b/drivers/target/target_core_device.c
> @@ -806,6 +806,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
> dev->dev_attrib.emulate_tpws = DA_EMULATE_TPWS;
> dev->dev_attrib.emulate_caw = DA_EMULATE_CAW;
> dev->dev_attrib.emulate_3pc = DA_EMULATE_3PC;
> + dev->dev_attrib.emulate_pr = DA_EMULATE_PR;
> dev->dev_attrib.pi_prot_type = TARGET_DIF_TYPE0_PROT;
> dev->dev_attrib.enforce_pr_isids = DA_ENFORCE_PR_ISIDS;
> dev->dev_attrib.force_pr_aptpl = DA_FORCE_PR_APTPL;
> diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
> index 2e865fdaa362..9960a44c3a59 100644
> --- a/drivers/target/target_core_pr.c
> +++ b/drivers/target/target_core_pr.c
> @@ -208,6 +208,11 @@ target_scsi2_reservation_release(struct se_cmd *cmd)
> struct se_portal_group *tpg;
> int rc;
>
> + if (!dev->dev_attrib.emulate_pr) {
> + pr_err("failing SCSI2 RELEASE with emulate_pr disabled\n");
> + return TCM_UNSUPPORTED_SCSI_OPCODE;
> + }
> +
> if (!sess || !sess->se_tpg)
> goto out;
> rc = target_check_scsi2_reservation_conflict(cmd);
> @@ -255,6 +260,11 @@ target_scsi2_reservation_reserve(struct se_cmd *cmd)
> sense_reason_t ret = 0;
> int rc;
>
> + if (!dev->dev_attrib.emulate_pr) {
> + pr_err("failing SCSI2 RESERVE with emulate_pr disabled\n");
> + return TCM_UNSUPPORTED_SCSI_OPCODE;
> + }
> +
> if ((cmd->t_task_cdb[1] & 0x01) &&
> (cmd->t_task_cdb[1] & 0x02)) {
> pr_err("LongIO and Obsolete Bits set, returning ILLEGAL_REQUEST\n");
> @@ -3560,6 +3570,11 @@ target_scsi3_emulate_pr_out(struct se_cmd *cmd)
> int spec_i_pt = 0, all_tg_pt = 0, unreg = 0;
> sense_reason_t ret;
>
> + if (!dev->dev_attrib.emulate_pr) {
> + pr_err("failing PROUT with emulate_pr disabled\n");
> + return TCM_UNSUPPORTED_SCSI_OPCODE;
> + }
> +
> /*
> * Following spc2r20 5.5.1 Reservations overview:
> *
> @@ -4045,6 +4060,11 @@ target_scsi3_emulate_pr_in(struct se_cmd *cmd)
> {
> sense_reason_t ret;
>
> + if (!cmd->se_dev->dev_attrib.emulate_pr) {
> + pr_err("failing PRIN with emulate_pr disabled\n");
> + return TCM_UNSUPPORTED_SCSI_OPCODE;
> + }
> +
> /*
> * Following spc2r20 5.5.1 Reservations overview:
> *
> @@ -4097,6 +4117,8 @@ target_check_reservation(struct se_cmd *cmd)
> return 0;
> if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_PGR)
> return 0;
> + if (!dev->dev_attrib.emulate_pr)
> + return 0;
>
> spin_lock(&dev->dev_reservation_lock);
> if (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS)
> diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
> index 9f9f5902af38..06d88645938b 100644
> --- a/include/target/target_core_base.h
> +++ b/include/target/target_core_base.h
> @@ -87,6 +87,8 @@
> #define DA_EMULATE_3PC 1
> /* No Emulation for PSCSI by default */
> #define DA_EMULATE_ALUA 0
> +/* Emulate SCSI2 RESERVE/RELEASE and Persistent Reservations by default */
> +#define DA_EMULATE_PR 1
> /* Enforce SCSI Initiator Port TransportID with 'ISID' for PR */
> #define DA_ENFORCE_PR_ISIDS 1
> /* Force SPC-3 PR Activate Persistence across Target Power Loss */
> @@ -665,6 +667,7 @@ struct se_dev_attrib {
> int emulate_tpws;
> int emulate_caw;
> int emulate_3pc;
> + int emulate_pr;
> int pi_prot_format;
> enum target_prot_type pi_prot_type;
> enum target_prot_type hw_pi_prot_type;
You need to handle the passthrough case also, so you'll need to look at:
https://elixir.bootlin.com/linux/v4.17-rc7/source/drivers/target/target_core_device.c#L1179
In those cases you'll notice it calls some of the functions you changed
to address new attribute, but the return code is overwritten.
-Bryant
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