The Block I/O (blkio) subsystem controls and monitors access to I/O on
block devices by tasks in cgroups. With the introduced changes, a
backstore will be like a task in a specified group.
One of interesting feature is an ability to set limits on a number of
I/O operations and bytes per seconds.
A new attribute is added for backstores, it is called blkio_cgroup.
If we write 1 to the attribute file, a blkio cgroup from the current
process is attached to the backstore.
If we write 0 to the attribute file, a current group will be detached
from the backstore.
When we know a blkio cgroup the only thing, what we need to do to make it
work, is to set this group for bio-s.
How to use:
# Create a test backstore
$ targetcli
targetcli shell version 2.1.fb46
Copyright 2011-2013 by Datera, Inc and others.
/backstores/block> create dev=/dev/loop0 loop0
Created block storage object loop0 using /dev/loop0.
/backstores/block> cd /loopback
/loopback> create
Created target naa.50014056fd3f341c.
/loopback> cd naa.50014056fd3f341c/luns
/loopback/naa...fd3f341c/luns> create /backstores/block/loop0
Created LUN 0.
/loopback/naa...fd3f341c/luns> exit
# Create a test cgroup and set it to a test backstore
$ CG_PATH=/sys/fs/cgroup/blkio/test
$ BS_PATH=/sys/kernel/config/target/core/iblock_0/loop0/attrib/blkio_cgroup
$ mkdir -p $CG_PATH
$ bash -c "echo 0 > $CG_PATH/tasks && echo 1 > $BS_PATH"
$ cat $BS_PATH
/test
# Set 6 MB/sec for the backstore
$ echo "7:0 6291456" > $CG_PATH/blkio.throttle.read_bps_device
# Check that everything work as expected
$ dd if=/dev/sda of=/dev/null iflag=direct bs=1M count=100
100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 16.6958 s, 6.3 MB/s
Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx>
---
drivers/target/target_core_configfs.c | 55 +++++++++++++++++++++++++++++++++++
drivers/target/target_core_device.c | 6 ++++
drivers/target/target_core_iblock.c | 18 +++++++++++-
include/target/target_core_base.h | 2 ++
4 files changed, 80 insertions(+), 1 deletion(-)
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 3f4bf126eed0..62155cbd07cc 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -1021,6 +1021,59 @@ static ssize_t queue_depth_store(struct config_item *item,
return count;
}
+static ssize_t blkio_cgroup_show(struct config_item *item, char *page)
+{
+ struct se_dev_attrib *da = to_attrib(item);
+ struct se_device *dev = da->da_dev;
+ int rb;
+
+ read_lock(&dev->dev_attrib_lock);
+ if (dev->dev_attrib.blk_css) {
+ rb = cgroup_path(dev->dev_attrib.blk_css->cgroup,
+ page, PAGE_SIZE - 1);
+ if (rb == 0)
+ rb = strlen(page);
+ page[rb] = '\n';
+ page[rb + 1] = 0;
+ rb++;
+ } else
+ rb = 0;
+ read_unlock(&dev->dev_attrib_lock);
+
+ return rb;
+}
+
+static ssize_t blkio_cgroup_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;
+ struct cgroup_subsys_state *css, *pcss;
+ int ret;
+ u32 val;
+
+ ret = kstrtou32(page, 0, &val);
+ if (ret < 0)
+ return ret;
+
+ if (val > 1)
+ return -EINVAL;
+ if (val == 1)
+ css = task_get_css(current, io_cgrp_id);
+ else
+ css = NULL;
+
+ write_lock(&dev->dev_attrib_lock);
+ pcss = dev->dev_attrib.blk_css;
+ dev->dev_attrib.blk_css = css;
+ write_unlock(&dev->dev_attrib_lock);
+
+ if (pcss)
+ css_put(pcss);
+
+ return count;
+}
+
static ssize_t optimal_sectors_store(struct config_item *item,
const char *page, size_t count)
{
@@ -1128,6 +1181,7 @@ CONFIGFS_ATTR_RO(, hw_max_sectors);
CONFIGFS_ATTR(, optimal_sectors);
CONFIGFS_ATTR_RO(, hw_queue_depth);
CONFIGFS_ATTR(, queue_depth);
+CONFIGFS_ATTR(, blkio_cgroup);
CONFIGFS_ATTR(, max_unmap_lba_count);
CONFIGFS_ATTR(, max_unmap_block_desc_count);
CONFIGFS_ATTR(, unmap_granularity);
@@ -1168,6 +1222,7 @@ struct configfs_attribute *sbc_attrib_attrs[] = {
&attr_optimal_sectors,
&attr_hw_queue_depth,
&attr_queue_depth,
+ &attr_blkio_cgroup,
&attr_max_unmap_lba_count,
&attr_max_unmap_block_desc_count,
&attr_unmap_granularity,
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index e27db4d45a9d..64274a5a1b32 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -773,6 +773,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
INIT_LIST_HEAD(&dev->delayed_cmd_list);
INIT_LIST_HEAD(&dev->state_list);
INIT_LIST_HEAD(&dev->qf_cmd_list);
+ rwlock_init(&dev->dev_attrib_lock);
spin_lock_init(&dev->execute_task_lock);
spin_lock_init(&dev->delayed_cmd_lock);
spin_lock_init(&dev->dev_reservation_lock);
@@ -820,6 +821,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
dev->dev_attrib.unmap_zeroes_data =
DA_UNMAP_ZEROES_DATA_DEFAULT;
dev->dev_attrib.max_write_same_len = DA_MAX_WRITE_SAME_LEN;
+ dev->dev_attrib.blk_css = NULL;
xcopy_lun = &dev->xcopy_lun;
rcu_assign_pointer(xcopy_lun->lun_se_dev, dev);
@@ -1080,6 +1082,10 @@ void target_free_device(struct se_device *dev)
if (dev->transport->free_prot)
dev->transport->free_prot(dev);
+ if (dev->dev_attrib.blk_css)
+ css_put(dev->dev_attrib.blk_css);
+ dev->dev_attrib.blk_css = NULL;
+
dev->transport->free_device(dev);
}
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 07c814c42648..b952eacb84ed 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -35,6 +35,7 @@
#include <linux/genhd.h>
#include <linux/file.h>
#include <linux/module.h>
+#include <linux/cgroup.h>
#include <scsi/scsi_proto.h>
#include <asm/unaligned.h>
@@ -694,6 +695,7 @@ iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
u32 sg_num = sgl_nents;
unsigned bio_cnt;
int i, op, op_flags = 0;
+ struct cgroup_subsys_state *blk_css = NULL;
if (data_direction == DMA_TO_DEVICE) {
struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
@@ -724,9 +726,17 @@ iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
return 0;
}
+ read_lock(&dev->dev_attrib_lock);
+ blk_css = dev->dev_attrib.blk_css;
+ if (blk_css)
+ css_get(blk_css);
+ read_unlock(&dev->dev_attrib_lock);
+
bio = iblock_get_bio(cmd, block_lba, sgl_nents, op, op_flags);
if (!bio)
goto fail_free_ibr;
+ if (blk_css)
+ bio_associate_blkcg(bio, blk_css);
bio_start = bio;
bio_list_init(&list);
@@ -752,6 +762,8 @@ iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
op_flags);
if (!bio)
goto fail_put_bios;
+ if (blk_css)
+ bio_associate_blkcg(bio, blk_css);
refcount_inc(&ibr->pending);
bio_list_add(&list, bio);
@@ -774,9 +786,13 @@ iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
return 0;
fail_put_bios:
- while ((bio = bio_list_pop(&list)))
+ while ((bio = bio_list_pop(&list))) {
+ bio_disassociate_task(bio);
bio_put(bio);
+ }
fail_free_ibr:
+ if (blk_css)
+ css_put(blk_css);
kfree(ibr);
fail:
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 9f9f5902af38..014bee5657b4 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -688,6 +688,7 @@ struct se_dev_attrib {
u32 max_bytes_per_io;
struct se_device *da_dev;
struct config_group da_group;
+ struct cgroup_subsys_state *blk_css;
};
struct se_port_stat_grps {
@@ -777,6 +778,7 @@ struct se_device {
atomic_t dev_ordered_sync;
atomic_t dev_qf_count;
u32 export_count;
+ rwlock_t dev_attrib_lock;
spinlock_t delayed_cmd_lock;
spinlock_t execute_task_lock;
spinlock_t dev_reservation_lock;
--
2.14.3
--
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