The current code only associates with the existing blkcg when aio is
used to access the backing file. This patch covers all types of i/o to
the backing file and also associates the memcg so if the backing file is
on tmpfs, memory is charged appropriately.
This patch also exports cgroup_get_e_css so it can be used by the loop
module.
Signed-off-by: Dan Schatzberg <schatzberg.dan@xxxxxxxxx>
---
drivers/block/loop.c | 59 ++++++++++++++++++++++++--------------
drivers/block/loop.h | 3 +-
include/linux/memcontrol.h | 6 ++++
kernel/cgroup/cgroup.c | 1 +
4 files changed, 47 insertions(+), 22 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 78e5005c6742..cc091a66b0d0 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -77,6 +77,7 @@
#include <linux/uio.h>
#include <linux/ioprio.h>
#include <linux/blk-cgroup.h>
+#include <linux/sched/mm.h>
#include "loop.h"
@@ -134,7 +135,7 @@ static struct loop_func_table xor_funcs = {
.number = LO_CRYPT_XOR,
.transfer = transfer_xor,
.init = xor_init
-};
+};
/* xfer_funcs[0] is special - its release function is never called */
static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
@@ -504,8 +505,6 @@ static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2)
{
struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
- if (cmd->css)
- css_put(cmd->css);
cmd->ret = ret;
lo_rw_aio_do_completion(cmd);
}
@@ -566,8 +565,6 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
cmd->iocb.ki_complete = lo_rw_aio_complete;
cmd->iocb.ki_flags = IOCB_DIRECT;
cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
- if (cmd->css)
- kthread_associate_blkcg(cmd->css);
if (rw == WRITE)
ret = call_write_iter(file, &cmd->iocb, &iter);
@@ -575,7 +572,6 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
ret = call_read_iter(file, &cmd->iocb, &iter);
lo_rw_aio_do_completion(cmd);
- kthread_associate_blkcg(NULL);
if (ret != -EIOCBQUEUED)
cmd->iocb.ki_complete(&cmd->iocb, ret, 0);
@@ -913,7 +909,7 @@ struct loop_worker {
struct list_head cmd_list;
struct list_head idle_list;
struct loop_device *lo;
- struct cgroup_subsys_state *css;
+ struct cgroup_subsys_state *blkcg_css;
unsigned long last_ran_at;
};
@@ -930,7 +926,7 @@ static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
spin_lock_irq(&lo->lo_lock);
- if (!cmd->css)
+ if (!cmd->blkcg_css)
goto queue_work;
node = &(lo->worker_tree.rb_node);
@@ -938,10 +934,10 @@ static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
while (*node) {
parent = *node;
cur_worker = container_of(*node, struct loop_worker, rb_node);
- if ((long)cur_worker->css == (long)cmd->css) {
+ if ((long)cur_worker->blkcg_css == (long)cmd->blkcg_css) {
worker = cur_worker;
break;
- } else if ((long)cur_worker->css < (long)cmd->css) {
+ } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
node = &((*node)->rb_left);
} else {
node = &((*node)->rb_right);
@@ -954,13 +950,16 @@ static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
GFP_NOWAIT | __GFP_NOWARN);
/*
* In the event we cannot allocate a worker, just queue on the
- * rootcg worker
+ * rootcg worker and issue the I/O as the rootcg
*/
- if (!worker)
+ if (!worker) {
+ cmd->blkcg_css = NULL;
+ cmd->memcg_css = NULL;
goto queue_work;
+ }
- worker->css = cmd->css;
- css_get(worker->css);
+ worker->blkcg_css = cmd->blkcg_css;
+ css_get(worker->blkcg_css);
INIT_WORK(&worker->work, loop_workfn);
INIT_LIST_HEAD(&worker->cmd_list);
INIT_LIST_HEAD(&worker->idle_list);
@@ -2007,13 +2006,18 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
}
/* always use the first bio's css */
+ cmd->blkcg_css = NULL;
+ cmd->memcg_css = NULL;
#ifdef CONFIG_BLK_CGROUP
- if (cmd->use_aio && rq->bio && rq->bio->bi_blkg) {
- cmd->css = &bio_blkcg(rq->bio)->css;
- css_get(cmd->css);
- } else
+ if (rq->bio && rq->bio->bi_blkg) {
+ cmd->blkcg_css = &bio_blkcg(rq->bio)->css;
+#ifdef CONFIG_MEMCG
+ cmd->memcg_css =
+ cgroup_get_e_css(cmd->blkcg_css->cgroup,
+ &memory_cgrp_subsys);
+#endif
+ }
#endif
- cmd->css = NULL;
loop_queue_work(lo, cmd);
return BLK_STS_OK;
@@ -2031,8 +2035,21 @@ static void loop_handle_cmd(struct loop_cmd *cmd)
goto failed;
}
+ if (cmd->blkcg_css)
+ kthread_associate_blkcg(cmd->blkcg_css);
+ if (cmd->memcg_css)
+ memalloc_use_memcg(mem_cgroup_from_css(cmd->memcg_css));
+
ret = do_req_filebacked(lo, rq);
- failed:
+
+ if (cmd->blkcg_css)
+ kthread_associate_blkcg(NULL);
+
+ if (cmd->memcg_css) {
+ memalloc_unuse_memcg();
+ css_put(cmd->memcg_css);
+ }
+failed:
/* complete non-aio request */
if (!cmd->use_aio || ret) {
cmd->ret = ret ? -EIO : 0;
@@ -2106,7 +2123,7 @@ static void loop_free_idle_workers(struct timer_list *timer)
break;
list_del(&worker->idle_list);
rb_erase(&worker->rb_node, &lo->worker_tree);
- css_put(worker->css);
+ css_put(worker->blkcg_css);
kfree(worker);
}
if (!list_empty(&lo->idle_worker_list))
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index 87fd0e372227..3e65acf7a0e9 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -74,7 +74,8 @@ struct loop_cmd {
long ret;
struct kiocb iocb;
struct bio_vec *bvec;
- struct cgroup_subsys_state *css;
+ struct cgroup_subsys_state *blkcg_css;
+ struct cgroup_subsys_state *memcg_css;
};
/* Support for loadable transfer modules */
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a7a0a1a5c8d5..aeb51f2ded46 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -922,6 +922,12 @@ static inline struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
return NULL;
}
+static inline
+struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css)
+{
+ return NULL;
+}
+
static inline void mem_cgroup_put(struct mem_cgroup *memcg)
{
}
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 75f687301bbf..c3896c2e0942 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -587,6 +587,7 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
rcu_read_unlock();
return css;
}
+EXPORT_SYMBOL_GPL(cgroup_get_e_css);
static void cgroup_get_live(struct cgroup *cgrp)
{
--
2.17.1
