Commit ca16eb34 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'for-linus-20180906' of git://git.kernel.dk/linux-block 

Pull block fixes from Jens Axboe:
 "Small collection of fixes that should go into this release. This
  contains:

   - Small series that fixes a race between blkcg teardown and writeback
     (Dennis Zhou)

   - Fix disallowing invalid block size settings from the nbd ioctl (me)

   - BFQ fix for a use-after-free on last release of a bfqg (Konstantin
     Khlebnikov)

   - Fix for the "don't warn for flush" fix (Mikulas)"

* tag 'for-linus-20180906' of git://git.kernel.dk/linux-block:
  block: bfq: swap puts in bfqg_and_blkg_put
  block: don't warn when doing fsync on read-only devices
  nbd: don't allow invalid blocksize settings
  blkcg: use tryget logic when associating a blkg with a bio
  blkcg: delay blkg destruction until after writeback has finished
  Revert "blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()"
parents db44bf4b d5274b3c

block/bfq-cgroup.c

+2 −2
Original line number Diff line number Diff line
@@ -275,9 +275,9 @@ static void bfqg_and_blkg_get(struct bfq_group *bfqg) 


void bfqg_and_blkg_put(struct bfq_group *bfqg)

{

	bfqg_put(bfqg);



	blkg_put(bfqg_to_blkg(bfqg));



	bfqg_put(bfqg);

}



/* @stats = 0 */

block/bio.c

+2 −1
Original line number Diff line number Diff line
@@ -2015,7 +2015,8 @@ int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg) 
{

	if (unlikely(bio->bi_blkg))

		return -EBUSY;

	blkg_get(blkg);

	if (!blkg_try_get(blkg))

		return -ENODEV;

	bio->bi_blkg = blkg;

	return 0;

}

block/blk-cgroup.c

+48 −57
Original line number Diff line number Diff line
@@ -310,28 +310,11 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, 
	}

}



static void blkg_pd_offline(struct blkcg_gq *blkg)

{

	int i;



	lockdep_assert_held(blkg->q->queue_lock);

	lockdep_assert_held(&blkg->blkcg->lock);



	for (i = 0; i < BLKCG_MAX_POLS; i++) {

		struct blkcg_policy *pol = blkcg_policy[i];



		if (blkg->pd[i] && !blkg->pd[i]->offline &&

		    pol->pd_offline_fn) {

			pol->pd_offline_fn(blkg->pd[i]);

			blkg->pd[i]->offline = true;

		}

	}

}



static void blkg_destroy(struct blkcg_gq *blkg)

{

	struct blkcg *blkcg = blkg->blkcg;

	struct blkcg_gq *parent = blkg->parent;

	int i;



	lockdep_assert_held(blkg->q->queue_lock);

	lockdep_assert_held(&blkcg->lock);
@@ -340,6 +323,13 @@ static void blkg_destroy(struct blkcg_gq *blkg) 
	WARN_ON_ONCE(list_empty(&blkg->q_node));

	WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));



	for (i = 0; i < BLKCG_MAX_POLS; i++) {

		struct blkcg_policy *pol = blkcg_policy[i];



		if (blkg->pd[i] && pol->pd_offline_fn)

			pol->pd_offline_fn(blkg->pd[i]);

	}



	if (parent) {

		blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes);

		blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios);
@@ -382,7 +372,6 @@ static void blkg_destroy_all(struct request_queue *q) 
		struct blkcg *blkcg = blkg->blkcg;



		spin_lock(&blkcg->lock);

		blkg_pd_offline(blkg);

		blkg_destroy(blkg);

		spin_unlock(&blkcg->lock);

	}
@@ -1053,59 +1042,64 @@ static struct cftype blkcg_legacy_files[] = { 
	{ }	/* terminate */

};



/*

 * blkcg destruction is a three-stage process.

 *

 * 1. Destruction starts.  The blkcg_css_offline() callback is invoked

 *    which offlines writeback.  Here we tie the next stage of blkg destruction

 *    to the completion of writeback associated with the blkcg.  This lets us

 *    avoid punting potentially large amounts of outstanding writeback to root

 *    while maintaining any ongoing policies.  The next stage is triggered when

 *    the nr_cgwbs count goes to zero.

 *

 * 2. When the nr_cgwbs count goes to zero, blkcg_destroy_blkgs() is called

 *    and handles the destruction of blkgs.  Here the css reference held by

 *    the blkg is put back eventually allowing blkcg_css_free() to be called.

 *    This work may occur in cgwb_release_workfn() on the cgwb_release

 *    workqueue.  Any submitted ios that fail to get the blkg ref will be

 *    punted to the root_blkg.

 *

 * 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called.

 *    This finally frees the blkcg.

 */



/**

 * blkcg_css_offline - cgroup css_offline callback

 * @css: css of interest

 *

 * This function is called when @css is about to go away and responsible

 * for offlining all blkgs pd and killing all wbs associated with @css.

 * blkgs pd offline should be done while holding both q and blkcg locks.

 * As blkcg lock is nested inside q lock, this function performs reverse

 * double lock dancing.

 *

 * This is the blkcg counterpart of ioc_release_fn().

 * This function is called when @css is about to go away.  Here the cgwbs are

 * offlined first and only once writeback associated with the blkcg has

 * finished do we start step 2 (see above).

 */

static void blkcg_css_offline(struct cgroup_subsys_state *css)

{

	struct blkcg *blkcg = css_to_blkcg(css);

	struct blkcg_gq *blkg;



	spin_lock_irq(&blkcg->lock);



	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {

		struct request_queue *q = blkg->q;



		if (spin_trylock(q->queue_lock)) {

			blkg_pd_offline(blkg);

			spin_unlock(q->queue_lock);

		} else {

			spin_unlock_irq(&blkcg->lock);

			cpu_relax();

			spin_lock_irq(&blkcg->lock);

		}

	}



	spin_unlock_irq(&blkcg->lock);



	/* this prevents anyone from attaching or migrating to this blkcg */

	wb_blkcg_offline(blkcg);



	/* put the base cgwb reference allowing step 2 to be triggered */

	blkcg_cgwb_put(blkcg);

}



/**

 * blkcg_destroy_all_blkgs - destroy all blkgs associated with a blkcg

 * blkcg_destroy_blkgs - responsible for shooting down blkgs

 * @blkcg: blkcg of interest

 *

 * This function is called when blkcg css is about to free and responsible for

 * destroying all blkgs associated with @blkcg.

 * blkgs should be removed while holding both q and blkcg locks.  As blkcg lock

 * is nested inside q lock, this function performs reverse double lock dancing.

 * Destroying the blkgs releases the reference held on the blkcg's css allowing

 * blkcg_css_free to eventually be called.

 *

 * This is the blkcg counterpart of ioc_release_fn().

 */

static void blkcg_destroy_all_blkgs(struct blkcg *blkcg)

void blkcg_destroy_blkgs(struct blkcg *blkcg)

{

	spin_lock_irq(&blkcg->lock);



	while (!hlist_empty(&blkcg->blkg_list)) {

		struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,

						    struct blkcg_gq,

						    blkcg_node);

						struct blkcg_gq, blkcg_node);

		struct request_queue *q = blkg->q;



		if (spin_trylock(q->queue_lock)) {
@@ -1117,6 +1111,7 @@ static void blkcg_destroy_all_blkgs(struct blkcg *blkcg) 
			spin_lock_irq(&blkcg->lock);

		}

	}



	spin_unlock_irq(&blkcg->lock);

}
@@ -1125,8 +1120,6 @@ static void blkcg_css_free(struct cgroup_subsys_state *css) 
	struct blkcg *blkcg = css_to_blkcg(css);

	int i;



	blkcg_destroy_all_blkgs(blkcg);



	mutex_lock(&blkcg_pol_mutex);



	list_del(&blkcg->all_blkcgs_node);
@@ -1189,6 +1182,7 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) 
	INIT_HLIST_HEAD(&blkcg->blkg_list);

#ifdef CONFIG_CGROUP_WRITEBACK

	INIT_LIST_HEAD(&blkcg->cgwb_list);

	refcount_set(&blkcg->cgwb_refcnt, 1);

#endif

	list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs);
@@ -1480,11 +1474,8 @@ void blkcg_deactivate_policy(struct request_queue *q, 


	list_for_each_entry(blkg, &q->blkg_list, q_node) {

		if (blkg->pd[pol->plid]) {

			if (!blkg->pd[pol->plid]->offline &&

			    pol->pd_offline_fn) {

			if (pol->pd_offline_fn)

				pol->pd_offline_fn(blkg->pd[pol->plid]);

				blkg->pd[pol->plid]->offline = true;

			}

			pol->pd_free_fn(blkg->pd[pol->plid]);

			blkg->pd[pol->plid] = NULL;

		}

block/blk-core.c

+4 −1
Original line number Diff line number Diff line
@@ -2163,9 +2163,12 @@ static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part) 
{

	const int op = bio_op(bio);



	if (part->policy && (op_is_write(op) && !op_is_flush(op))) {

	if (part->policy && op_is_write(op)) {

		char b[BDEVNAME_SIZE];



		if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))

			return false;



		WARN_ONCE(1,

		       "generic_make_request: Trying to write "

			"to read-only block-device %s (partno %d)\n",

block/blk-throttle.c

+3 −2
Original line number Diff line number Diff line
@@ -2129,8 +2129,9 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td) 
static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio)

{

#ifdef CONFIG_BLK_DEV_THROTTLING_LOW

	if (bio->bi_css)

		bio_associate_blkg(bio, tg_to_blkg(tg));

	/* fallback to root_blkg if we fail to get a blkg ref */

	if (bio->bi_css && (bio_associate_blkg(bio, tg_to_blkg(tg)) == -ENODEV))

		bio_associate_blkg(bio, bio->bi_disk->queue->root_blkg);

	bio_issue_init(&bio->bi_issue, bio_sectors(bio));

#endif

}

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