[PATCH v3] nvmet: add cgroup_path to charge namespace I/O to a cgroup

[PATCH v3] nvmet: add cgroup_path to charge namespace I/O to a cgroup

[Peng Yu]

Scenario:
* Create multiple nvmet subsystems/namespaces.
* The namespaces are backed by different LVM logical volumes.
* Some of the logical volumes share the same physical volumes.
* The subsystems are exported to different users.
* We should provide each user a specific iops/bps quota, thus a noisy
  neighbor won't impact the performance of other logical volumes.

Implementation:
* Add a `cgroup_path` attribute under the nvmet namespace folder, e.g.:
  /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/namespaces/1/cgroup_path
* We can write a cgroup path to it, then that cgroup will control
  the IOs used by the namespace.
* Write an empty string to clear it.
* The cgroup_path could be modified when the namespace is disabled.
* Support both block device backed namespaces and file backed namespaces.
* Only the direct io scenario is supported, enabling a namespace that
  has both cgroup_path and buffered_io set fails with -EINVAL.

Change since v2:
* Fix the in ns->cgroup_path error free issue nvmet_ns_cgroup_path_show.
* Use nvmet_blkcg_begin/end in nvmet_bdev_zmgmt_send_work

Test:
1 Load kernel modules.
sudo modprobe brd rd_nr=2 rd_size=1048576
sudo modprobe nvmet
sudo modprobe nvmet_tcp
sudo modprobe nvme_tcp

2 The two brd devices are used for a bdev backed namespace and a file
backed namespace, remember their major/minor.
lsblk --noheadings --nodeps --output NAME,MAJ:MIN,SIZE /dev/ram0 /dev/ram1
ram0   1:0      1G
ram1   1:1      1G

3 Enable the io controller and create two cgroups, one for the bdev
backed namespace, another for the file backed namespace.
echo "+io" | sudo tee /sys/fs/cgroup/cgroup.subtree_control
sudo mkdir -p /sys/fs/cgroup/nvmet-bdev
sudo mkdir -p /sys/fs/cgroup/nvmet-file

4 Create a file system and a file on ram0.
sudo mkfs.ext4 /dev/ram0
sudo mkdir -p /mnt/nvmet-file
sudo mount -o noatime /dev/ram0 /mnt/nvmet-file
sudo dd if=/dev/zero of=/mnt/nvmet-file/ns.img bs=1M count=512 oflag=direct

5 Create the bdev backed subsystem and namespace.
sudo mkdir -p /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/namespaces/1
echo 1 | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/attr_allow_any_host
echo /dev/ram1 | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/namespaces/1/device_path
echo /nvmet-bdev | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/namespaces/1/cgroup_path
echo 1 | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/namespaces/1/enable

6 Create the file backed subsystem and namespace.
sudo mkdir -p /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file/namespaces/1
echo 1 | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file/attr_allow_any_host
echo /mnt/nvmet-file/ns.img | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file/namespaces/1/device_path
echo /nvmet-file | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file/namespaces/1/cgroup_path
echo 1 | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file/namespaces/1/enable

7 Export the two subsystems to 127.0.0.1.
sudo mkdir -p /sys/kernel/config/nvmet/ports/1
echo ipv4 | sudo tee /sys/kernel/config/nvmet/ports/1/addr_adrfam
echo tcp | sudo tee /sys/kernel/config/nvmet/ports/1/addr_trtype
echo 127.0.0.1 | sudo tee /sys/kernel/config/nvmet/ports/1/addr_traddr
echo 4420 | sudo tee /sys/kernel/config/nvmet/ports/1/addr_trsvcid
sudo ln -s /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev /sys/kernel/config/nvmet/ports/1/subsystems/nqn.2026-09.io.test01:bdev
sudo ln -s /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file /sys/kernel/config/nvmet/ports/1/subsystems/nqn.2026-09.io.test01:file

8 Connect the two subsystems from 127.0.0.1.
sudo nvme connect -t tcp -a 127.0.0.1 -s 4420 -n nqn.2026-09.io.test01:bdev
sudo nvme connect -t tcp -a 127.0.0.1 -s 4420 -n nqn.2026-09.io.test01:file
sudo udevadm settle

9 Set riops to 20k and run fio.
echo "1:1 riops=20000 wiops=max rbps=max wbps=max" | sudo tee /sys/fs/cgroup/nvmet-bdev/io.max
echo "1:0 riops=20000 wiops=max rbps=max wbps=max" | sudo tee /sys/fs/cgroup/nvmet-file/io.max

sudo fio --name=t --filename=/dev/nvme0n1 --rw=randread --bs=4k --iodepth=32 --numjobs=1 \
--direct=1 --ioengine=libaio --time_based --runtime=10 --ramp_time=3 \
--group_reporting 2>/dev/null | grep -E '^ +(read|write): IOPS'
  read: IOPS=20.0k, BW=78.1MiB/s (81.9MB/s)(781MiB/10001msec)

sudo fio --name=t --filename=/dev/nvme1n1 --rw=randread --bs=4k --iodepth=32 --numjobs=1 \
--direct=1 --ioengine=libaio --time_based --runtime=10 --ramp_time=3 \
--group_reporting 2>/dev/null | grep -E '^ +(read|write): IOPS'
  read: IOPS=20.0k, BW=78.1MiB/s (81.9MB/s)(781MiB/10001msec)

10 Set rbps to 100M and run fio.
echo "1:1 riops=max wiops=max rbps=104857600 wbps=max" | sudo tee /sys/fs/cgroup/nvmet-bdev/io.max
echo "1:0 riops=max wiops=max rbps=104857600 wbps=max" | sudo tee /sys/fs/cgroup/nvmet-file/io.max

sudo fio --name=t --filename=/dev/nvme0n1 --rw=read --bs=1M --iodepth=32 --numjobs=1 \
--direct=1 --ioengine=libaio --time_based --runtime=10 --ramp_time=3 \
--group_reporting 2>/dev/null | grep -E '^ +(read|write): IOPS'
  read: IOPS=97, BW=100MiB/s (105MB/s)(1033MiB/10304msec)

sudo fio --name=t --filename=/dev/nvme1n1 --rw=read --bs=1M --iodepth=32 --numjobs=1 \
--direct=1 --ioengine=libaio --time_based --runtime=10 --ramp_time=3 \
--group_reporting 2>/dev/null | grep -E '^ +(read|write): IOPS'
  read: IOPS=97, BW=100MiB/s (105MB/s)(1031MiB/10297msec)

11 Set wiops to 20k and run fio.
echo "1:1 riops=max wiops=20000 rbps=max wbps=max" | sudo tee /sys/fs/cgroup/nvmet-bdev/io.max
echo "1:0 riops=max wiops=20000 rbps=max wbps=max" | sudo tee /sys/fs/cgroup/nvmet-file/io.max

sudo fio --name=t --filename=/dev/nvme0n1 --rw=randwrite --bs=4k --iodepth=32 --numjobs=1 \
--direct=1 --ioengine=libaio --time_based --runtime=10 --ramp_time=3 \
--group_reporting 2>/dev/null | grep -E '^ +(read|write): IOPS'
  write: IOPS=20.0k, BW=78.1MiB/s (81.9MB/s)(781MiB/10001msec); 0 zone resets

sudo fio --name=t --filename=/dev/nvme1n1 --rw=randwrite --bs=4k --iodepth=32 --numjobs=1 \
--direct=1 --ioengine=libaio --time_based --runtime=10 --ramp_time=3 \
--group_reporting 2>/dev/null | grep -E '^ +(read|write): IOPS'
  write: IOPS=20.0k, BW=78.1MiB/s (81.9MB/s)(781MiB/10001msec); 0 zone resets

12 Set wbps to 100M and run fio.
echo "1:1 riops=max wiops=max rbps=max wbps=104857600" | sudo tee /sys/fs/cgroup/nvmet-bdev/io.max
echo "1:0 riops=max wiops=max rbps=max wbps=104857600" | sudo tee /sys/fs/cgroup/nvmet-file/io.max

sudo fio --name=t --filename=/dev/nvme0n1 --rw=write --bs=1M --iodepth=32 --numjobs=1 \
--direct=1 --ioengine=libaio --time_based --runtime=10 --ramp_time=3 \
--group_reporting 2>/dev/null | grep -E '^ +(read|write): IOPS'
  write: IOPS=97, BW=100MiB/s (105MB/s)(1031MiB/10305msec); 0 zone resets

sudo fio --name=t --filename=/dev/nvme1n1 --rw=write --bs=1M --iodepth=32 --numjobs=1 \
--direct=1 --ioengine=libaio --time_based --runtime=10 --ramp_time=3 \
--group_reporting 2>/dev/null | grep -E '^ +(read|write): IOPS'
  write: IOPS=97, BW=100MiB/s (105MB/s)(1032MiB/10297msec); 0 zone resets

13 Cleanup the environment.
sudo nvme disconnect -n nqn.2026-09.io.test01:bdev
sudo nvme disconnect -n nqn.2026-09.io.test01:file
sudo udevadm settle

sudo rm -f /sys/kernel/config/nvmet/ports/1/subsystems/nqn.2026-09.io.test01:bdev
sudo rm -f /sys/kernel/config/nvmet/ports/1/subsystems/nqn.2026-09.io.test01:file
sudo rmdir /sys/kernel/config/nvmet/ports/1

echo 0 | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/namespaces/1/enable
sudo rmdir /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/namespaces/1
sudo rmdir /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev

echo 0 | sudo tee /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file/namespaces/1/enable
sudo rmdir /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file/namespaces/1
sudo rmdir /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:file

sudo umount /mnt/nvmet-file
sudo rmdir /mnt/nvmet-file
sudo modprobe -r brd

sudo rmdir /sys/fs/cgroup/nvmet-bdev
sudo rmdir /sys/fs/cgroup/nvmet-file

sudo rmmod nvme_tcp
sudo rmmod nvmet_tcp
sudo rmmod nvmet

Signed-off-by: Peng Yu <yupeng0921@gmail.com>
Assisted-by: Claude:claude-fable-5 [Claude Code]
Assisted-by: Claude:claude-opus-5 [Claude Code]
---
 drivers/nvme/target/configfs.c    | 61 +++++++++++++++++++++++++
 drivers/nvme/target/core.c        | 75 +++++++++++++++++++++++++++++++
 drivers/nvme/target/io-cmd-bdev.c | 18 +++++++-
 drivers/nvme/target/io-cmd-file.c | 21 ++++++++-
 drivers/nvme/target/nvmet.h       | 47 +++++++++++++++++++
 drivers/nvme/target/zns.c         |  5 +++
 6 files changed, 224 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 6286e38436dd..f46227585e4b 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -561,6 +561,64 @@ static ssize_t nvmet_ns_device_path_store(struct config_item *item,
 
 CONFIGFS_ATTR(nvmet_ns_, device_path);
 
+#ifdef CONFIG_BLK_CGROUP
+static ssize_t nvmet_ns_cgroup_path_show(struct config_item *item, char *page)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+	struct nvmet_subsys *subsys = ns->subsys;
+	ssize_t ret;
+
+	mutex_lock(&subsys->lock);
+	ret = snprintf(page, PAGE_SIZE, "%s\n", ns->cgroup_path ?: "");
+	mutex_unlock(&subsys->lock);
+	return ret;
+}
+
+static ssize_t nvmet_ns_cgroup_path_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+	struct nvmet_subsys *subsys = ns->subsys;
+	size_t len;
+	const char *path;
+	int ret = count;
+
+	mutex_lock(&subsys->lock);
+
+	if (ns->enabled) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
+	len = strcspn(page, "\n");
+	if (!len) {
+		/* An empty write clears the association. */
+		kfree(ns->cgroup_path);
+		ns->cgroup_path = NULL;
+		goto out_unlock;
+	}
+
+	if (page[0] != '/' || len >= PATH_MAX) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	path = kmemdup_nul(page, len, GFP_KERNEL);
+	if (!path) {
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
+	kfree(ns->cgroup_path);
+	ns->cgroup_path = path;
+
+out_unlock:
+	mutex_unlock(&subsys->lock);
+	return ret;
+}
+
+CONFIGFS_ATTR(nvmet_ns_, cgroup_path);
+#endif /* CONFIG_BLK_CGROUP */
+
 #ifdef CONFIG_PCI_P2PDMA
 static ssize_t nvmet_ns_p2pmem_show(struct config_item *item, char *page)
 {
@@ -833,6 +891,9 @@ static struct configfs_attribute *nvmet_ns_attrs[] = {
 	&nvmet_ns_attr_buffered_io,
 	&nvmet_ns_attr_revalidate_size,
 	&nvmet_ns_attr_resv_enable,
+#ifdef CONFIG_BLK_CGROUP
+	&nvmet_ns_attr_cgroup_path,
+#endif
 #ifdef CONFIG_PCI_P2PDMA
 	&nvmet_ns_attr_p2pmem,
 #endif
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 43871a8f56ca..3e4972513c3e 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -4,6 +4,7 @@
  * Copyright (c) 2015-2016 HGST, a Western Digital Company.
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/cgroup.h>
 #include <linux/hex.h>
 #include <linux/module.h>
 #include <linux/random.h>
@@ -474,8 +475,77 @@ void nvmet_put_namespace(struct nvmet_ns *ns)
 	percpu_ref_put(&ns->ref);
 }
 
+#ifdef CONFIG_BLK_CGROUP
+static int nvmet_blkcg_ns_enable(struct nvmet_ns *ns)
+{
+	struct cgroup_subsys_state *css;
+	struct cgroup *cgrp;
+
+	if (!ns->cgroup_path)
+		return 0;
+
+	/*
+	 * Buffered writes will be handled by a separate thread,
+	 * these IOs have no namespace/cgroup information at that time,
+	 * so we don't support buffered io.
+	 */
+	if (ns->buffered_io) {
+		pr_err("cgroup_path is not supported with buffered_io: %s\n",
+		       ns->device_path);
+		return -EINVAL;
+	}
+
+	cgrp = cgroup_get_from_path(ns->cgroup_path);
+	if (IS_ERR(cgrp)) {
+		pr_err("failed to resolve cgroup path %s: %ld\n",
+		       ns->cgroup_path, PTR_ERR(cgrp));
+		return PTR_ERR(cgrp);
+	}
+
+	css = cgroup_get_e_css(cgrp, &io_cgrp_subsys);
+	if (!css || css->cgroup != cgrp) {
+		pr_err("the io controller is not enabled in cgroup %s\n",
+		       ns->cgroup_path);
+		if (css)
+			css_put(css);
+		cgroup_put(cgrp);
+		return -EINVAL;
+	}
+	ns->blkcg_css = css;
+	cgroup_put(cgrp);
+	return 0;
+}
+
+static void nvmet_blkcg_ns_disable(struct nvmet_ns *ns)
+{
+	if (ns->blkcg_css) {
+		css_put(ns->blkcg_css);
+		ns->blkcg_css = NULL;
+	}
+}
+
+static void nvmet_blkcg_ns_free(struct nvmet_ns *ns)
+{
+	kfree(ns->cgroup_path);
+}
+#else
+static inline int nvmet_blkcg_ns_enable(struct nvmet_ns *ns)
+{
+	return 0;
+}
+
+static inline void nvmet_blkcg_ns_disable(struct nvmet_ns *ns)
+{
+}
+
+static inline void nvmet_blkcg_ns_free(struct nvmet_ns *ns)
+{
+}
+#endif /* CONFIG_BLK_CGROUP */
+
 static void nvmet_ns_dev_disable(struct nvmet_ns *ns)
 {
+	nvmet_blkcg_ns_disable(ns);
 	nvmet_bdev_ns_disable(ns);
 	nvmet_file_ns_disable(ns);
 }
@@ -602,6 +672,10 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
 	if (ret)
 		goto out_unlock;
 
+	ret = nvmet_blkcg_ns_enable(ns);
+	if (ret)
+		goto out_dev_disable;
+
 	ret = nvmet_p2pmem_ns_enable(ns);
 	if (ret)
 		goto out_dev_disable;
@@ -699,6 +773,7 @@ void nvmet_ns_free(struct nvmet_ns *ns)
 	up_write(&nvmet_ana_sem);
 
 	kfree(ns->device_path);
+	nvmet_blkcg_ns_free(ns);
 	kfree(ns);
 }
 
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index f2d9e8901df4..0014e5ef2853 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -297,6 +297,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
 		bio = bio_alloc(req->ns->bdev, bio_max_segs(sg_cnt), opf,
 				GFP_KERNEL);
 	}
+	nvmet_blkcg_set_bio(req->ns, bio);
 	bio->bi_iter.bi_sector = sector;
 	bio->bi_private = req;
 	bio->bi_end_io = nvmet_bio_done;
@@ -322,6 +323,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
 
 			bio = bio_alloc(req->ns->bdev, bio_max_segs(sg_cnt),
 					opf, GFP_KERNEL);
+			nvmet_blkcg_set_bio(req->ns, bio);
 			bio->bi_iter.bi_sector = sector;
 
 			bio_chain(bio, prev);
@@ -358,6 +360,7 @@ static void nvmet_bdev_execute_flush(struct nvmet_req *req)
 
 	bio_init(bio, req->ns->bdev, req->inline_bvec,
 		 ARRAY_SIZE(req->inline_bvec), REQ_OP_WRITE | REQ_PREFLUSH);
+	nvmet_blkcg_set_bio(req->ns, bio);
 	bio->bi_private = req;
 	bio->bi_end_io = nvmet_bio_done;
 
@@ -366,10 +369,16 @@ static void nvmet_bdev_execute_flush(struct nvmet_req *req)
 
 u16 nvmet_bdev_flush(struct nvmet_req *req)
 {
+	bool associated;
+	int ret;
+
 	if (!bdev_write_cache(req->ns->bdev))
 		return 0;
 
-	if (blkdev_issue_flush(req->ns->bdev))
+	associated = nvmet_blkcg_begin(req->ns);
+	ret = blkdev_issue_flush(req->ns->bdev);
+	nvmet_blkcg_end(associated);
+	if (ret)
 		return NVME_SC_INTERNAL | NVME_STATUS_DNR;
 	return 0;
 }
@@ -380,9 +389,11 @@ static void nvmet_bdev_execute_discard(struct nvmet_req *req)
 	struct nvme_dsm_range range;
 	struct bio *bio = NULL;
 	sector_t nr_sects;
+	bool associated;
 	int i;
 	u16 status = NVME_SC_SUCCESS;
 
+	associated = nvmet_blkcg_begin(ns);
 	for (i = 0; i <= le32_to_cpu(req->cmd->dsm.nr); i++) {
 		status = nvmet_copy_from_sgl(req, i * sizeof(range), &range,
 				sizeof(range));
@@ -394,6 +405,7 @@ static void nvmet_bdev_execute_discard(struct nvmet_req *req)
 				nvmet_lba_to_sect(ns, range.slba), nr_sects,
 				GFP_KERNEL, &bio);
 	}
+	nvmet_blkcg_end(associated);
 
 	if (bio) {
 		bio->bi_private = req;
@@ -431,6 +443,7 @@ static void nvmet_bdev_execute_write_zeroes(struct nvmet_req *req)
 	struct bio *bio = NULL;
 	sector_t sector;
 	sector_t nr_sector;
+	bool associated;
 	int ret;
 
 	if (!nvmet_check_transfer_len(req, 0))
@@ -440,8 +453,11 @@ static void nvmet_bdev_execute_write_zeroes(struct nvmet_req *req)
 	nr_sector = (((sector_t)le16_to_cpu(write_zeroes->length) + 1) <<
 		(req->ns->blksize_shift - 9));
 
+	associated = nvmet_blkcg_begin(req->ns);
 	ret = __blkdev_issue_zeroout(req->ns->bdev, sector, nr_sector,
 			GFP_KERNEL, &bio, 0);
+	nvmet_blkcg_end(associated);
+
 	if (bio) {
 		bio->bi_private = req;
 		bio->bi_end_io = nvmet_bio_done;
diff --git a/drivers/nvme/target/io-cmd-file.c b/drivers/nvme/target/io-cmd-file.c
index 0b22d183f927..570e65259ad8 100644
--- a/drivers/nvme/target/io-cmd-file.c
+++ b/drivers/nvme/target/io-cmd-file.c
@@ -79,6 +79,8 @@ static ssize_t nvmet_file_submit_bvec(struct nvmet_req *req, loff_t pos,
 	struct kiocb *iocb = &req->f.iocb;
 	ssize_t (*call_iter)(struct kiocb *iocb, struct iov_iter *iter);
 	struct iov_iter iter;
+	bool associated;
+	ssize_t ret;
 	int rw;
 
 	if (req->cmd->rw.opcode == nvme_cmd_write) {
@@ -97,7 +99,10 @@ static ssize_t nvmet_file_submit_bvec(struct nvmet_req *req, loff_t pos,
 	iocb->ki_filp = req->ns->file;
 	iocb->ki_flags = ki_flags | iocb->ki_filp->f_iocb_flags;
 
-	return call_iter(iocb, &iter);
+	associated = nvmet_blkcg_begin(req->ns);
+	ret = call_iter(iocb, &iter);
+	nvmet_blkcg_end(associated);
+	return ret;
 }
 
 static void nvmet_file_io_done(struct kiocb *iocb, long ret)
@@ -251,7 +256,13 @@ static void nvmet_file_execute_rw(struct nvmet_req *req)
 
 u16 nvmet_file_flush(struct nvmet_req *req)
 {
-	return errno_to_nvme_status(req, vfs_fsync(req->ns->file, 1));
+	bool associated;
+	int ret;
+
+	associated = nvmet_blkcg_begin(req->ns);
+	ret = vfs_fsync(req->ns->file, 1);
+	nvmet_blkcg_end(associated);
+	return errno_to_nvme_status(req, ret);
 }
 
 static void nvmet_file_flush_work(struct work_struct *w)
@@ -274,10 +285,12 @@ static void nvmet_file_execute_discard(struct nvmet_req *req)
 	int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
 	struct nvme_dsm_range range;
 	loff_t offset, len;
+	bool associated;
 	u16 status = 0;
 	int ret;
 	int i;
 
+	associated = nvmet_blkcg_begin(req->ns);
 	for (i = 0; i <= le32_to_cpu(req->cmd->dsm.nr); i++) {
 		status = nvmet_copy_from_sgl(req, i * sizeof(range), &range,
 					sizeof(range));
@@ -300,6 +313,7 @@ static void nvmet_file_execute_discard(struct nvmet_req *req)
 			break;
 		}
 	}
+	nvmet_blkcg_end(associated);
 
 	nvmet_req_complete(req, status);
 }
@@ -336,6 +350,7 @@ static void nvmet_file_write_zeroes_work(struct work_struct *w)
 	int mode = FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE;
 	loff_t offset;
 	loff_t len;
+	bool associated;
 	int ret;
 
 	offset = le64_to_cpu(write_zeroes->slba) << req->ns->blksize_shift;
@@ -347,7 +362,9 @@ static void nvmet_file_write_zeroes_work(struct work_struct *w)
 		return;
 	}
 
+	associated = nvmet_blkcg_begin(req->ns);
 	ret = vfs_fallocate(req->ns->file, mode, offset, len);
+	nvmet_blkcg_end(associated);
 	nvmet_req_complete(req, ret < 0 ? errno_to_nvme_status(req, ret) : 0);
 }
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index dbda55895f4f..1ef7be97a244 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -21,6 +21,7 @@
 #include <linux/radix-tree.h>
 #include <linux/t10-pi.h>
 #include <linux/kfifo.h>
+#include <linux/kthread.h>
 
 #define NVMET_DEFAULT_VS		NVME_VS(2, 1, 0)
 
@@ -115,6 +116,16 @@ struct nvmet_ns {
 	struct nvmet_subsys	*subsys;
 	const char		*device_path;
 
+#ifdef CONFIG_BLK_CGROUP
+	const char	*cgroup_path;
+	/*
+	 * Resolved from ->cgroup_path when the namespace is enabled and
+	 * released when it is disabled, so it has the same lifetime and
+	 * visibility rules as ->bdev and ->file.
+	 */
+	struct cgroup_subsys_state *blkcg_css;
+#endif
+
 	struct config_group	device_group;
 	struct config_group	group;
 
@@ -732,6 +743,42 @@ void nvmet_bdev_execute_zone_mgmt_recv(struct nvmet_req *req);
 void nvmet_bdev_execute_zone_mgmt_send(struct nvmet_req *req);
 void nvmet_bdev_execute_zone_append(struct nvmet_req *req);
 
+#ifdef CONFIG_BLK_CGROUP
+static inline void nvmet_blkcg_set_bio(struct nvmet_ns *ns, struct bio *bio)
+{
+	if (ns->blkcg_css)
+		bio_associate_blkg_from_css(bio, ns->blkcg_css);
+}
+
+static inline bool nvmet_blkcg_begin(struct nvmet_ns *ns)
+{
+	if (!ns->blkcg_css || !in_task() || !(current->flags & PF_KTHREAD))
+		return false;
+
+	kthread_associate_blkcg(ns->blkcg_css);
+	return true;
+}
+
+static inline void nvmet_blkcg_end(bool associated)
+{
+	if (associated)
+		kthread_associate_blkcg(NULL);
+}
+#else
+static inline void nvmet_blkcg_set_bio(struct nvmet_ns *ns, struct bio *bio)
+{
+}
+
+static inline bool nvmet_blkcg_begin(struct nvmet_ns *ns)
+{
+	return false;
+}
+
+static inline void nvmet_blkcg_end(bool associated)
+{
+}
+#endif /* CONFIG_BLK_CGROUP */
+
 static inline u32 nvmet_rw_data_len(struct nvmet_req *req)
 {
 	return ((u32)le16_to_cpu(req->cmd->rw.length) + 1) <<
diff --git a/drivers/nvme/target/zns.c b/drivers/nvme/target/zns.c
index 23a17c02abee..a9836d44f5e6 100644
--- a/drivers/nvme/target/zns.c
+++ b/drivers/nvme/target/zns.c
@@ -480,8 +480,11 @@ static void nvmet_bdev_zmgmt_send_work(struct work_struct *w)
 	struct block_device *bdev = req->ns->bdev;
 	sector_t zone_sectors = bdev_zone_sectors(bdev);
 	u16 status = NVME_SC_SUCCESS;
+	bool associated;
 	int ret;
 
+	associated = nvmet_blkcg_begin(req->ns);
+
 	if (op == REQ_OP_LAST) {
 		req->error_loc = offsetof(struct nvme_zone_mgmt_send_cmd, zsa);
 		status = NVME_SC_ZONE_INVALID_TRANSITION | NVME_STATUS_DNR;
@@ -511,6 +514,7 @@ static void nvmet_bdev_zmgmt_send_work(struct work_struct *w)
 		status = blkdev_zone_mgmt_errno_to_nvme_status(ret);
 
 out:
+	nvmet_blkcg_end(associated);
 	nvmet_req_complete(req, status);
 }
 
@@ -580,6 +584,7 @@ void nvmet_bdev_execute_zone_append(struct nvmet_req *req)
 		bio = bio_alloc(req->ns->bdev, req->sg_cnt, opf, GFP_KERNEL);
 	}
 
+	nvmet_blkcg_set_bio(req->ns, bio);
 	bio->bi_end_io = nvmet_bdev_zone_append_bio_done;
 	bio->bi_iter.bi_sector = sect;
 	bio->bi_private = req;

base-commit: d9cc476535d29a44df3f2aa3b14af9a833fddf90
-- 
2.53.0

Re: [PATCH v3] nvmet: add cgroup_path to charge namespace I/O to a cgroup

[Michal Koutný]

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On Wed, Sep 23, 2026 at 08:26:53AM -0700, Peng Yu <yupeng0921@gmail.com> wrote:
> Scenario:
> * Create multiple nvmet subsystems/namespaces.
> * The namespaces are backed by different LVM logical volumes.
> * Some of the logical volumes share the same physical volumes.

Why are LVMs mentioned? (The test scenario doesn't seem to use those.
And the example is backed by RAM, so where would be any IO to control at
all? Note: I'm only giving this part of my attention span.)

> * The subsystems are exported to different users.
> * We should provide each user a specific iops/bps quota, thus a noisy
>   neighbor won't impact the performance of other logical volumes.

Why cannot you place users into respective cgroups and configure
appropriate per-device limits?

Thanks for providing more context about the scenario so that I can
understand what's the goal and obstacle.

Michal

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Re: [PATCH v3] nvmet: add cgroup_path to charge namespace I/O to a cgroup

[Tejun Heo]

Hello, Peng.

On Wed, 23 Sep 2026 08:26:53 -0700, Peng Yu wrote:
> Implementation:
> * Add a `cgroup_path` attribute under the nvmet namespace folder, e.g.:
>   /sys/kernel/config/nvmet/subsystems/nqn.2026-09.io.test01:bdev/namespaces/1/cgroup_path

Maybe take a cgroup ID instead of a path? Userspace can read it as the
inode number of the cgroup directory, and cgroup_get_from_id() resolves it
at enable time the same way cgroup_get_from_path() does now. The attribute
then becomes a u64, which drops the string allocation and freeing along
with the path validation. IDs are also never reused, while a path can
later name a different cgroup created at the same location.

Thanks.

--
tejun

Re: [PATCH v3] nvmet: add cgroup_path to charge namespace I/O to a cgroup

[peng yu]

On Wed, Sep 23, 2026 at 8:53 AM Michal Koutný <mkoutny@suse.com> wrote:
>
> On Wed, Sep 23, 2026 at 08:26:53AM -0700, Peng Yu <yupeng0921@gmail.com> wrote:
> > Scenario:
> > * Create multiple nvmet subsystems/namespaces.
> > * The namespaces are backed by different LVM logical volumes.
> > * Some of the logical volumes share the same physical volumes.
>
> Why are LVMs mentioned? (The test scenario doesn't seem to use those.
> And the example is backed by RAM, so where would be any IO to control at
> all? Note: I'm only giving this part of my attention span.)

The LVMs are close to my real use case, so I mentioned them to explain why
I need this feature.
When I write the testing code, I try to demonstrate the usage in a
simpler way, so
I use RAM devices.
Sorry for the inconsistency.


> > * The subsystems are exported to different users.
> > * We should provide each user a specific iops/bps quota, thus a noisy
> >   neighbor won't impact the performance of other logical volumes.
>
> Why cannot you place users into respective cgroups and configure
> appropriate per-device limits?

I export the devices to nvme target. Per my understanding, the IOs are
controlled by kernel threads. The users are remote users, so I can't find
a way to put them in a local cgroup.

> Thanks for providing more context about the scenario so that I can
> understand what's the goal and obstacle.
>
> Michal