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

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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: Mike Christie <mchristi@redhat.com>
Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bodo Stroesser 2020-04-27 17:08:23 +02:00 committed by Martin K. Petersen
parent 69088a0494
commit 356ba2a8bc
3 changed files with 57 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
drivers/target/target_core_configfs.c
View File

@ -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

2
drivers/target/target_core_user.c
View File

@ -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,

1
include/target/target_core_backend.h
View File

@ -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 *);