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 the 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 patch, 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.
Signed-off-by: Bodo Stroesser <bstroesser@xxxxxxxxxxxxxx>
---
drivers/target/target_core_configfs.c | 56 +++++++++++++++++++++++++++++++++--
drivers/target/target_core_user.c | 2 ++
include/target/target_core_backend.h | 1 +
3 files changed, 57 insertions(+), 2 deletions(-)
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 279989e32e64..f04352285155 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -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
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 264f19ba8453..b02760b2e9c0 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -2618,6 +2618,8 @@ 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,
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 959163504f82..f51452e3b984 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -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 *);
--
2.12.3
