Commit 356ba2a8 authored by Bodo Stroesser's avatar Bodo Stroesser Committed by Martin K. Petersen
Browse files

scsi: target: tcmu: Make pgr_support and alua_support attributes writable 

Currently in tcmu reservation commands are handled by core's pr
implementation (default) or completely rejected (emulate_pr set to 0). We
additionally want to be able to do full reservation handling in
userspace. Therefore we need a way to set TRANSPORT_FLAG_PASSTHROUGH_PGR.

The inverted flag is displayed by attribute pgr_support.  Since we moved
the flag from transport/backend to se_device in the previous commit, we now
can make it changeable per device by allowing to write the attribute.  The
new field transport_flags_changeable in transport/backend is used to reject
writing if not allowed for a backend.

Regarding ALUA we also want to be able to passthrough commands to userspace
in tcmu. Therefore we need TRANSPORT_FLAG_PASSTHROUGH_ALUA to be
changeable, because by setting it we can switch off all ALUA checks in
core. So we also set TRANSPORT_FLAG_PASSTHROUGH_ALUA in tcmu's
transport_flags_changeable.

Of course, ALUA and reservation handling in userspace will work only, if
session/nexus information is sent to userspace along with every
command. This will be object of a patch series announced by Mike Christie.

Link: https://lore.kernel.org/r/20200427150823.15350-5-bstroesser@ts.fujitsu.com


Reviewed-by: default avatarMike Christie <mchristi@redhat.com>
Signed-off-by: default avatarBodo Stroesser <bstroesser@ts.fujitsu.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 69088a04

drivers/target/target_core_configfs.c

+54 −2
Original line number Diff line number Diff line
@@ -1105,6 +1105,32 @@ static ssize_t alua_support_show(struct config_item *item, char *page) 
			flags & TRANSPORT_FLAG_PASSTHROUGH_ALUA ? 0 : 1);

}



static ssize_t alua_support_store(struct config_item *item,

		const char *page, size_t count)

{

	struct se_dev_attrib *da = to_attrib(item);

	struct se_device *dev = da->da_dev;

	bool flag;

	int ret;



	if (!(dev->transport->transport_flags_changeable &

	      TRANSPORT_FLAG_PASSTHROUGH_ALUA)) {

		pr_err("dev[%p]: Unable to change SE Device alua_support:"

			" alua_support has fixed value\n", dev);

		return -EINVAL;

	}



	ret = strtobool(page, &flag);

	if (ret < 0)

		return ret;



	if (flag)

		dev->transport_flags &= ~TRANSPORT_FLAG_PASSTHROUGH_ALUA;

	else

		dev->transport_flags |= TRANSPORT_FLAG_PASSTHROUGH_ALUA;

	return count;

}



static ssize_t pgr_support_show(struct config_item *item, char *page)

{

	struct se_dev_attrib *da = to_attrib(item);
@@ -1114,6 +1140,32 @@ static ssize_t pgr_support_show(struct config_item *item, char *page) 
			flags & TRANSPORT_FLAG_PASSTHROUGH_PGR ? 0 : 1);

}



static ssize_t pgr_support_store(struct config_item *item,

		const char *page, size_t count)

{

	struct se_dev_attrib *da = to_attrib(item);

	struct se_device *dev = da->da_dev;

	bool flag;

	int ret;



	if (!(dev->transport->transport_flags_changeable &

	      TRANSPORT_FLAG_PASSTHROUGH_PGR)) {

		pr_err("dev[%p]: Unable to change SE Device pgr_support:"

			" pgr_support has fixed value\n", dev);

		return -EINVAL;

	}



	ret = strtobool(page, &flag);

	if (ret < 0)

		return ret;



	if (flag)

		dev->transport_flags &= ~TRANSPORT_FLAG_PASSTHROUGH_PGR;

	else

		dev->transport_flags |= TRANSPORT_FLAG_PASSTHROUGH_PGR;

	return count;

}



CONFIGFS_ATTR(, emulate_model_alias);

CONFIGFS_ATTR(, emulate_dpo);

CONFIGFS_ATTR(, emulate_fua_write);
@@ -1146,8 +1198,8 @@ CONFIGFS_ATTR(, unmap_granularity); 
CONFIGFS_ATTR(, unmap_granularity_alignment);

CONFIGFS_ATTR(, unmap_zeroes_data);

CONFIGFS_ATTR(, max_write_same_len);

CONFIGFS_ATTR_RO(, alua_support);

CONFIGFS_ATTR_RO(, pgr_support);

CONFIGFS_ATTR(, alua_support);

CONFIGFS_ATTR(, pgr_support);



/*

 * dev_attrib attributes for devices using the target core SBC/SPC

drivers/target/target_core_user.c

+2 −0
Original line number Diff line number Diff line
@@ -2617,6 +2617,8 @@ static struct target_backend_ops tcmu_ops = { 
	.name			= "user",

	.owner			= THIS_MODULE,

	.transport_flags_default = TRANSPORT_FLAG_PASSTHROUGH,

	.transport_flags_changeable = TRANSPORT_FLAG_PASSTHROUGH_PGR |

				      TRANSPORT_FLAG_PASSTHROUGH_ALUA,

	.attach_hba		= tcmu_attach_hba,

	.detach_hba		= tcmu_detach_hba,

	.alloc_device		= tcmu_alloc_device,

include/target/target_core_backend.h

+1 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ struct target_backend_ops { 
	struct module *owner;



	u8 transport_flags_default;

	u8 transport_flags_changeable;



	int (*attach_hba)(struct se_hba *, u32);

	void (*detach_hba)(struct se_hba *);