Commit ad1dabc8 authored by Yu Kuai's avatar Yu Kuai Committed by Li Lingfeng
Browse files

md/raid1-10: limit the number of plugged bio 

mainline inclusion
from mainline-v6.5-rc1
commit 460af1f9
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I8UKFJ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=460af1f9d9e62acce4a21f9bd00b5bcd5963bcd4



----------------------------------------

bio can be added to plug infinitely, and following writeback test can
trigger huge amount of plugged bio:

Test script:
modprobe brd rd_nr=4 rd_size=10485760
mdadm -CR /dev/md0 -l10 -n4 /dev/ram[0123] --assume-clean --bitmap=internal
echo 0 > /proc/sys/vm/dirty_background_ratio
fio -filename=/dev/md0 -ioengine=libaio -rw=write -bs=4k -numjobs=1 -iodepth=128 -name=test

Test result:
Monitor /sys/block/md0/inflight will found that inflight keep increasing
until fio finish writing, after running for about 2 minutes:

[root@fedora ~]# cat /sys/block/md0/inflight
       0  4474191

Fix the problem by limiting the number of plugged bio based on the number
of copies for original bio.

Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230529131106.2123367-8-yukuai1@huaweicloud.com



Conflicts:
  Commit 309dca30 ("block: store a block_device pointer in struct bio")
  changed "mbio->bi_disk" to "mbio->bi_bdev";
  Commit 2e94275e ("md/raid1: use rdev in raid1_write_request directly")
  changed "conf->mirrors[i].rdev" to "rdev";
Signed-off-by: default avatarLi Lingfeng <lilingfeng3@huawei.com>
parent e675eb72

drivers/md/raid1-10.c

+8 −1
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#define IO_MADE_GOOD ((struct bio *)2)



#define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)

#define MAX_PLUG_BIO 32



/* for managing resync I/O pages */

struct resync_pages {
@@ -31,6 +32,7 @@ struct resync_pages { 
struct raid1_plug_cb {

	struct blk_plug_cb	cb;

	struct bio_list		pending;

	unsigned int		count;

};



static void rbio_pool_free(void *rbio, void *data)
@@ -128,7 +130,7 @@ static inline void raid1_submit_write(struct bio *bio) 
}



static inline bool raid1_add_bio_to_plug(struct mddev *mddev, struct bio *bio,

				      blk_plug_cb_fn unplug)

				      blk_plug_cb_fn unplug, int copies)

{

	struct raid1_plug_cb *plug = NULL;

	struct blk_plug_cb *cb;
@@ -148,6 +150,11 @@ static inline bool raid1_add_bio_to_plug(struct mddev *mddev, struct bio *bio, 


	plug = container_of(cb, struct raid1_plug_cb, cb);

	bio_list_add(&plug->pending, bio);

	if (++plug->count / MAX_PLUG_BIO >= copies) {

		list_del(&cb->list);

		cb->callback(cb, false);

	}





	return true;

}

drivers/md/raid1.c

+1 −1
Original line number Diff line number Diff line
@@ -1528,7 +1528,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, 
		/* flush_pending_writes() needs access to the rdev so...*/

		mbio->bi_disk = (void *)conf->mirrors[i].rdev;



		if (!raid1_add_bio_to_plug(mddev, mbio, raid1_unplug)) {

		if (!raid1_add_bio_to_plug(mddev, mbio, raid1_unplug, disks)) {

			spin_lock_irqsave(&conf->device_lock, flags);

			bio_list_add(&conf->pending_bio_list, mbio);

			spin_unlock_irqrestore(&conf->device_lock, flags);

drivers/md/raid10.c

+1 −1
Original line number Diff line number Diff line
@@ -1252,7 +1252,7 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio, 


	atomic_inc(&r10_bio->remaining);



	if (!raid1_add_bio_to_plug(mddev, mbio, raid10_unplug)) {

	if (!raid1_add_bio_to_plug(mddev, mbio, raid10_unplug, conf->copies)) {

		spin_lock_irqsave(&conf->device_lock, flags);

		bio_list_add(&conf->pending_bio_list, mbio);

		spin_unlock_irqrestore(&conf->device_lock, flags);