From d03f6cdc1fc422accb734c7c07a661a0018d8631 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Thu, 2 Feb 2017 15:56:51 +0100
Subject: [PATCH] block: Dynamically allocate and refcount backing_dev_info
Instead of storing backing_dev_info inside struct request_queue,
allocate it dynamically, reference count it, and free it when the last
reference is dropped. Currently only request_queue holds the reference
but in the following patch we add other users referencing
backing_dev_info.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
---
block/blk-core.c | 12 +++++------
block/blk-sysfs.c | 2 +-
include/linux/backing-dev-defs.h | 2 ++
include/linux/backing-dev.h | 10 +++++++++-
include/linux/blkdev.h | 1 -
mm/backing-dev.c | 34 +++++++++++++++++++++++++++++++-
6 files changed, 50 insertions(+), 11 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index dcac0352c14c0..d2bba4700e652 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -713,7 +713,6 @@ static void blk_rq_timed_out_timer(unsigned long data)
struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
{
struct request_queue *q;
- int err;
q = kmem_cache_alloc_node(blk_requestq_cachep,
gfp_mask | __GFP_ZERO, node_id);
@@ -728,17 +727,16 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
if (!q->bio_split)
goto fail_id;
- q->backing_dev_info = &q->_backing_dev_info;
+ q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id);
+ if (!q->backing_dev_info)
+ goto fail_split;
+
q->backing_dev_info->ra_pages =
(VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
q->backing_dev_info->name = "block";
q->node = node_id;
- err = bdi_init(q->backing_dev_info);
- if (err)
- goto fail_split;
-
setup_timer(&q->backing_dev_info->laptop_mode_wb_timer,
laptop_mode_timer_fn, (unsigned long) q);
setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
@@ -789,7 +787,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
fail_ref:
percpu_ref_exit(&q->q_usage_counter);
fail_bdi:
- bdi_destroy(q->backing_dev_info);
+ bdi_put(q->backing_dev_info);
fail_split:
bioset_free(q->bio_split);
fail_id:
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 05841be1f30f3..3e204789b8d3e 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -799,7 +799,7 @@ static void blk_release_queue(struct kobject *kobj)
container_of(kobj, struct request_queue, kobj);
wbt_exit(q);
- bdi_exit(q->backing_dev_info);
+ bdi_put(q->backing_dev_info);
blkcg_exit_queue(q);
if (q->elevator) {
diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index e850e76acaaf1..ad955817916d0 100644
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -10,6 +10,7 @@
#include <linux/flex_proportions.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
+#include <linux/kref.h>
struct page;
struct device;
@@ -144,6 +145,7 @@ struct backing_dev_info {
char *name;
+ struct kref refcnt; /* Reference counter for the structure */
unsigned int capabilities; /* Device capabilities */
unsigned int min_ratio;
unsigned int max_ratio, max_prop_frac;
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 43b93a947e61b..efb6ca992d058 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -18,7 +18,14 @@
#include <linux/slab.h>
int __must_check bdi_init(struct backing_dev_info *bdi);
-void bdi_exit(struct backing_dev_info *bdi);
+
+static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
+{
+ kref_get(&bdi->refcnt);
+ return bdi;
+}
+
+void bdi_put(struct backing_dev_info *bdi);
__printf(3, 4)
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
@@ -29,6 +36,7 @@ void bdi_unregister(struct backing_dev_info *bdi);
int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
void bdi_destroy(struct backing_dev_info *bdi);
+struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
bool range_cyclic, enum wb_reason reason);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a75e42de34ab6..e77c1039fd0e4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -433,7 +433,6 @@ struct request_queue {
struct delayed_work delay_work;
struct backing_dev_info *backing_dev_info;
- struct backing_dev_info _backing_dev_info;
/*
* The queue owner gets to use this for whatever they like.
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 3bfed5ab2475c..28ce6cf7b2ff1 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -237,6 +237,7 @@ static __init int bdi_class_init(void)
bdi_class->dev_groups = bdi_dev_groups;
bdi_debug_init();
+
return 0;
}
postcore_initcall(bdi_class_init);
@@ -776,6 +777,7 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->dev = NULL;
+ kref_init(&bdi->refcnt);
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = FPROP_FRAC_BASE;
@@ -791,6 +793,22 @@ int bdi_init(struct backing_dev_info *bdi)
}
EXPORT_SYMBOL(bdi_init);
+struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id)
+{
+ struct backing_dev_info *bdi;
+
+ bdi = kmalloc_node(sizeof(struct backing_dev_info),
+ gfp_mask | __GFP_ZERO, node_id);
+ if (!bdi)
+ return NULL;
+
+ if (bdi_init(bdi)) {
+ kfree(bdi);
+ return NULL;
+ }
+ return bdi;
+}
+
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
{
@@ -871,12 +889,26 @@ void bdi_unregister(struct backing_dev_info *bdi)
}
}
-void bdi_exit(struct backing_dev_info *bdi)
+static void bdi_exit(struct backing_dev_info *bdi)
{
WARN_ON_ONCE(bdi->dev);
wb_exit(&bdi->wb);
}
+static void release_bdi(struct kref *ref)
+{
+ struct backing_dev_info *bdi =
+ container_of(ref, struct backing_dev_info, refcnt);
+
+ bdi_exit(bdi);
+ kfree(bdi);
+}
+
+void bdi_put(struct backing_dev_info *bdi)
+{
+ kref_put(&bdi->refcnt, release_bdi);
+}
+
void bdi_destroy(struct backing_dev_info *bdi)
{
bdi_unregister(bdi);
--
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