@@ -1857,10 +1857,8 @@ following two functions.
wbc_init_bio(@wbc, @bio)
Should be called for each bio carrying writeback data and
- associates the bio with the inode's owner cgroup and the
- corresponding request queue. This must be called after
- a queue (device) has been associated with the bio and
- before submission.
+ associates the bio with the inode's owner cgroup. Can be
+ called anytime between bio allocation and submission.
wbc_account_io(@wbc, @page, @bytes)
Should be called for each data segment being written out.
@@ -1879,7 +1877,7 @@ the configuration, the bio may be executed at a lower priority and if
the writeback session is holding shared resources, e.g. a journal
entry, may lead to priority inversion. There is no one easy solution
for the problem. Filesystems can try to work around specific problem
-cases by skipping wbc_init_bio() or using bio_associate_create_blkg()
+cases by skipping wbc_init_bio() or using bio_associate_blkcg()
directly.
@@ -642,7 +642,7 @@ void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
uint64_t serial_nr;
rcu_read_lock();
- serial_nr = __bio_blkcg(bio)->css.serial_nr;
+ serial_nr = bio_blkcg(bio)->css.serial_nr;
/*
* Check whether blkcg has changed. The condition may trigger
@@ -651,7 +651,7 @@ void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
goto out;
- bfqg = __bfq_bic_change_cgroup(bfqd, bic, __bio_blkcg(bio));
+ bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
/*
* Update blkg_path for bfq_log_* functions. We cache this
* path, and update it here, for the following
@@ -4384,7 +4384,7 @@ static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
rcu_read_lock();
- bfqg = bfq_find_set_group(bfqd, __bio_blkcg(bio));
+ bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio));
if (!bfqg) {
bfqq = &bfqd->oom_bfqq;
goto out;
@@ -609,9 +609,7 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
bio->bi_iter = bio_src->bi_iter;
bio->bi_io_vec = bio_src->bi_io_vec;
- bio_clone_blkg_association(bio, bio_src);
-
- blkcg_bio_issue_init(bio);
+ bio_clone_blkcg_association(bio, bio_src);
}
EXPORT_SYMBOL(__bio_clone_fast);
@@ -1956,151 +1954,69 @@ EXPORT_SYMBOL(bioset_init_from_src);
#ifdef CONFIG_BLK_CGROUP
-/**
- * bio_associate_blkg - associate a bio with the a blkg
- * @bio: target bio
- * @blkg: the blkg to associate
- *
- * This tries to associate @bio with the specified blkg. Association failure
- * is handled by walking up the blkg tree. Therefore, the blkg associated can
- * be anything between @blkg and the root_blkg. This situation only happens
- * when a cgroup is dying and then the remaining bios will spill to the closest
- * alive blkg.
- *
- * A reference will be taken on the @blkg and will be released when @bio is
- * freed.
- */
-int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
-{
- if (unlikely(bio->bi_blkg))
- return -EBUSY;
- bio->bi_blkg = blkg_tryget_closest(blkg);
- return 0;
-}
-
-/**
- * __bio_associate_blkg_from_css - internal blkg association function
- *
- * This in the core association function that all association paths rely on.
- * A blkg reference is taken which is released upon freeing of the bio.
- */
-static int __bio_associate_blkg_from_css(struct bio *bio,
- struct cgroup_subsys_state *css)
-{
- struct request_queue *q = bio->bi_disk->queue;
- struct blkcg_gq *blkg;
- int ret;
-
- rcu_read_lock();
-
- if (!css || !css->parent)
- blkg = q->root_blkg;
- else
- blkg = blkg_lookup_create(css_to_blkcg(css), q);
-
- ret = bio_associate_blkg(bio, blkg);
-
- rcu_read_unlock();
- return ret;
-}
-
-/**
- * bio_associate_blkg_from_css - associate a bio with a specified css
- * @bio: target bio
- * @css: target css
- *
- * Associate @bio with the blkg found by combining the css's blkg and the
- * request_queue of the @bio. This falls back to the queue's root_blkg if
- * the association fails with the css.
- */
-int bio_associate_blkg_from_css(struct bio *bio,
- struct cgroup_subsys_state *css)
-{
- if (unlikely(bio->bi_blkg))
- return -EBUSY;
- return __bio_associate_blkg_from_css(bio, css);
-}
-EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css);
-
#ifdef CONFIG_MEMCG
/**
- * bio_associate_blkg_from_page - associate a bio with the page's blkg
+ * bio_associate_blkcg_from_page - associate a bio with the page's blkcg
* @bio: target bio
* @page: the page to lookup the blkcg from
*
- * Associate @bio with the blkg from @page's owning memcg and the respective
- * request_queue. If cgroup_e_css returns NULL, fall back to the queue's
- * root_blkg.
- *
- * Note: this must be called after bio has an associated device.
+ * Associate @bio with the blkcg from @page's owning memcg. This works like
+ * every other associate function wrt references.
*/
-int bio_associate_blkg_from_page(struct bio *bio, struct page *page)
+int bio_associate_blkcg_from_page(struct bio *bio, struct page *page)
{
- struct cgroup_subsys_state *css;
- int ret;
+ struct cgroup_subsys_state *blkcg_css;
- if (unlikely(bio->bi_blkg))
+ if (unlikely(bio->bi_css))
return -EBUSY;
if (!page->mem_cgroup)
return 0;
-
- rcu_read_lock();
-
- css = cgroup_e_css(page->mem_cgroup->css.cgroup, &io_cgrp_subsys);
-
- ret = __bio_associate_blkg_from_css(bio, css);
-
- rcu_read_unlock();
- return ret;
+ blkcg_css = cgroup_get_e_css(page->mem_cgroup->css.cgroup,
+ &io_cgrp_subsys);
+ bio->bi_css = blkcg_css;
+ return 0;
}
#endif /* CONFIG_MEMCG */
/**
- * bio_associate_create_blkg - associate a bio with a blkg from q
- * @q: request_queue where bio is going
+ * bio_associate_blkcg - associate a bio with the specified blkcg
* @bio: target bio
+ * @blkcg_css: css of the blkcg to associate
+ *
+ * Associate @bio with the blkcg specified by @blkcg_css. Block layer will
+ * treat @bio as if it were issued by a task which belongs to the blkcg.
*
- * Associate @bio with the blkg found from the bio's css and the request_queue.
- * If one is not found, bio_lookup_blkg creates the blkg. This falls back to
- * the queue's root_blkg if association fails.
+ * This function takes an extra reference of @blkcg_css which will be put
+ * when @bio is released. The caller must own @bio and is responsible for
+ * synchronizing calls to this function.
*/
-int bio_associate_create_blkg(struct request_queue *q, struct bio *bio)
+int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css)
{
- struct cgroup_subsys_state *css;
- int ret = 0;
-
- /* someone has already associated this bio with a blkg */
- if (bio->bi_blkg)
- return ret;
-
- rcu_read_lock();
-
- css = blkcg_css();
-
- ret = __bio_associate_blkg_from_css(bio, css);
-
- rcu_read_unlock();
- return ret;
+ if (unlikely(bio->bi_css))
+ return -EBUSY;
+ css_get(blkcg_css);
+ bio->bi_css = blkcg_css;
+ return 0;
}
+EXPORT_SYMBOL_GPL(bio_associate_blkcg);
/**
- * bio_reassociate_blkg - reassociate a bio with a blkg from q
- * @q: request_queue where bio is going
+ * bio_associate_blkg - associate a bio with the specified blkg
* @bio: target bio
+ * @blkg: the blkg to associate
*
- * When submitting a bio, multiple recursive calls to make_request() may occur.
- * This causes the initial associate done in blkcg_bio_issue_check() to be
- * incorrect and reference the prior request_queue. This performs reassociation
- * when this situation happens.
+ * Associate @bio with the blkg specified by @blkg. This is the queue specific
+ * blkcg information associated with the @bio, a reference will be taken on the
+ * @blkg and will be freed when the bio is freed.
*/
-int bio_reassociate_blkg(struct request_queue *q, struct bio *bio)
+int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
{
- if (bio->bi_blkg) {
- blkg_put(bio->bi_blkg);
- bio->bi_blkg = NULL;
- }
-
- return bio_associate_create_blkg(q, bio);
+ if (unlikely(bio->bi_blkg))
+ return -EBUSY;
+ if (!blkg_try_get(blkg))
+ return -ENODEV;
+ bio->bi_blkg = blkg;
+ return 0;
}
/**
@@ -2113,6 +2029,10 @@ void bio_disassociate_task(struct bio *bio)
put_io_context(bio->bi_ioc);
bio->bi_ioc = NULL;
}
+ if (bio->bi_css) {
+ css_put(bio->bi_css);
+ bio->bi_css = NULL;
+ }
if (bio->bi_blkg) {
blkg_put(bio->bi_blkg);
bio->bi_blkg = NULL;
@@ -2120,16 +2040,16 @@ void bio_disassociate_task(struct bio *bio)
}
/**
- * bio_clone_blkg_association - clone blkg association from src to dst bio
+ * bio_clone_blkcg_association - clone blkcg association from src to dst bio
* @dst: destination bio
* @src: source bio
*/
-void bio_clone_blkg_association(struct bio *dst, struct bio *src)
+void bio_clone_blkcg_association(struct bio *dst, struct bio *src)
{
- if (src->bi_blkg)
- bio_associate_blkg(dst, src->bi_blkg);
+ if (src->bi_css)
+ WARN_ON(bio_associate_blkcg(dst, src->bi_css));
}
-EXPORT_SYMBOL_GPL(bio_clone_blkg_association);
+EXPORT_SYMBOL_GPL(bio_clone_blkcg_association);
#endif /* CONFIG_BLK_CGROUP */
static void __init biovec_init_slabs(void)
@@ -84,37 +84,6 @@ static void blkg_free(struct blkcg_gq *blkg)
kfree(blkg);
}
-static void __blkg_release(struct rcu_head *rcu)
-{
- struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head);
-
- percpu_ref_exit(&blkg->refcnt);
-
- /* release the blkcg and parent blkg refs this blkg has been holding */
- css_put(&blkg->blkcg->css);
- if (blkg->parent)
- blkg_put(blkg->parent);
-
- wb_congested_put(blkg->wb_congested);
-
- blkg_free(blkg);
-}
-
-/*
- * A group is RCU protected, but having an rcu lock does not mean that one
- * can access all the fields of blkg and assume these are valid. For
- * example, don't try to follow throtl_data and request queue links.
- *
- * Having a reference to blkg under an rcu allows accesses to only values
- * local to groups like group stats and group rate limits.
- */
-static void blkg_release(struct percpu_ref *ref)
-{
- struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt);
-
- call_rcu(&blkg->rcu_head, __blkg_release);
-}
-
/**
* blkg_alloc - allocate a blkg
* @blkcg: block cgroup the new blkg is associated with
@@ -141,6 +110,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
blkg->q = q;
INIT_LIST_HEAD(&blkg->q_node);
blkg->blkcg = blkcg;
+ atomic_set(&blkg->refcnt, 1);
/* root blkg uses @q->root_rl, init rl only for !root blkgs */
if (blkcg != &blkcg_root) {
@@ -247,11 +217,6 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
blkg_get(blkg->parent);
}
- ret = percpu_ref_init(&blkg->refcnt, blkg_release, 0,
- GFP_NOWAIT | __GFP_NOWARN);
- if (ret)
- goto err_cancel_ref;
-
/* invoke per-policy init */
for (i = 0; i < BLKCG_MAX_POLS; i++) {
struct blkcg_policy *pol = blkcg_policy[i];
@@ -284,8 +249,6 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
blkg_put(blkg);
return ERR_PTR(ret);
-err_cancel_ref:
- percpu_ref_exit(&blkg->refcnt);
err_put_congested:
wb_congested_put(wb_congested);
err_put_css:
@@ -296,7 +259,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
}
/**
- * __blkg_lookup_create - lookup blkg, try to create one if not there
+ * blkg_lookup_create - lookup blkg, try to create one if not there
* @blkcg: blkcg of interest
* @q: request_queue of interest
*
@@ -305,11 +268,12 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
* that all non-root blkg's have access to the parent blkg. This function
* should be called under RCU read lock and @q->queue_lock.
*
- * Returns the blkg or the closest blkg if blkg_create fails as it walks
- * down from root.
+ * Returns pointer to the looked up or created blkg on success, ERR_PTR()
+ * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not
+ * dead and bypassing, returns ERR_PTR(-EBUSY).
*/
-struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q)
+struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
+ struct request_queue *q)
{
struct blkcg_gq *blkg;
@@ -321,7 +285,7 @@ struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
* we shouldn't allow anything to go through for a bypassing queue.
*/
if (unlikely(blk_queue_bypass(q)))
- return q->root_blkg;
+ return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY);
blkg = __blkg_lookup(blkcg, q, true);
if (blkg)
@@ -329,58 +293,23 @@ struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
/*
* Create blkgs walking down from blkcg_root to @blkcg, so that all
- * non-root blkgs have access to their parents. Returns the closest
- * blkg to the intended blkg should blkg_create() fail.
+ * non-root blkgs have access to their parents.
*/
while (true) {
struct blkcg *pos = blkcg;
struct blkcg *parent = blkcg_parent(blkcg);
- struct blkcg_gq *ret_blkg = q->root_blkg;
-
- while (parent) {
- blkg = __blkg_lookup(parent, q, false);
- if (blkg) {
- /* remember closest blkg */
- ret_blkg = blkg;
- break;
- }
+
+ while (parent && !__blkg_lookup(parent, q, false)) {
pos = parent;
parent = blkcg_parent(parent);
}
blkg = blkg_create(pos, q, NULL);
- if (IS_ERR(blkg))
- return ret_blkg;
- if (pos == blkcg)
+ if (pos == blkcg || IS_ERR(blkg))
return blkg;
}
}
-/**
- * blkg_lookup_create - find or create a blkg
- * @blkcg: target block cgroup
- * @q: target request_queue
- *
- * This looks up or creates the blkg representing the unique pair
- * of the blkcg and the request_queue.
- */
-struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q)
-{
- struct blkcg_gq *blkg = blkg_lookup(blkcg, q);
- unsigned long flags;
-
- if (unlikely(!blkg)) {
- spin_lock_irqsave(q->queue_lock, flags);
-
- blkg = __blkg_lookup_create(blkcg, q);
-
- spin_unlock_irqrestore(q->queue_lock, flags);
- }
-
- return blkg;
-}
-
static void blkg_destroy(struct blkcg_gq *blkg)
{
struct blkcg *blkcg = blkg->blkcg;
@@ -424,7 +353,7 @@ static void blkg_destroy(struct blkcg_gq *blkg)
* Put the reference taken at the time of creation so that when all
* queues are gone, group can be destroyed.
*/
- percpu_ref_kill(&blkg->refcnt);
+ blkg_put(blkg);
}
/**
@@ -451,6 +380,29 @@ static void blkg_destroy_all(struct request_queue *q)
q->root_rl.blkg = NULL;
}
+/*
+ * A group is RCU protected, but having an rcu lock does not mean that one
+ * can access all the fields of blkg and assume these are valid. For
+ * example, don't try to follow throtl_data and request queue links.
+ *
+ * Having a reference to blkg under an rcu allows accesses to only values
+ * local to groups like group stats and group rate limits.
+ */
+void __blkg_release_rcu(struct rcu_head *rcu_head)
+{
+ struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head);
+
+ /* release the blkcg and parent blkg refs this blkg has been holding */
+ css_put(&blkg->blkcg->css);
+ if (blkg->parent)
+ blkg_put(blkg->parent);
+
+ wb_congested_put(blkg->wb_congested);
+
+ blkg_free(blkg);
+}
+EXPORT_SYMBOL_GPL(__blkg_release_rcu);
+
/*
* The next function used by blk_queue_for_each_rl(). It's a bit tricky
* because the root blkg uses @q->root_rl instead of its own rl.
@@ -1796,7 +1748,8 @@ void blkcg_maybe_throttle_current(void)
blkg = blkg_lookup(blkcg, q);
if (!blkg)
goto out;
- if (!blkg_tryget(blkg))
+ blkg = blkg_try_get(blkg);
+ if (!blkg)
goto out;
rcu_read_unlock();
@@ -2433,7 +2433,6 @@ blk_qc_t generic_make_request(struct bio *bio)
if (q)
blk_queue_exit(q);
q = bio->bi_disk->queue;
- bio_reassociate_blkg(q, bio);
flags = 0;
if (bio->bi_opf & REQ_NOWAIT)
flags = BLK_MQ_REQ_NOWAIT;
@@ -480,12 +480,34 @@ static void blkcg_iolatency_throttle(struct rq_qos *rqos, struct bio *bio,
spinlock_t *lock)
{
struct blk_iolatency *blkiolat = BLKIOLATENCY(rqos);
- struct blkcg_gq *blkg = bio->bi_blkg;
+ struct blkcg *blkcg;
+ struct blkcg_gq *blkg;
+ struct request_queue *q = rqos->q;
bool issue_as_root = bio_issue_as_root_blkg(bio);
if (!blk_iolatency_enabled(blkiolat))
return;
+ rcu_read_lock();
+ blkcg = bio_blkcg(bio);
+ bio_associate_blkcg(bio, &blkcg->css);
+ blkg = blkg_lookup(blkcg, q);
+ if (unlikely(!blkg)) {
+ if (!lock)
+ spin_lock_irq(q->queue_lock);
+ blkg = blkg_lookup_create(blkcg, q);
+ if (IS_ERR(blkg))
+ blkg = NULL;
+ if (!lock)
+ spin_unlock_irq(q->queue_lock);
+ }
+ if (!blkg)
+ goto out;
+
+ bio_issue_init(&bio->bi_issue, bio_sectors(bio));
+ bio_associate_blkg(bio, blkg);
+out:
+ rcu_read_unlock();
while (blkg && blkg->parent) {
struct iolatency_grp *iolat = blkg_to_lat(blkg);
if (!iolat) {
@@ -706,7 +728,7 @@ static void blkiolatency_timer_fn(struct timer_list *t)
* We could be exiting, don't access the pd unless we have a
* ref on the blkg.
*/
- if (!blkg_tryget(blkg))
+ if (!blkg_try_get(blkg))
continue;
iolat = blkg_to_lat(blkg);
@@ -2115,11 +2115,21 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td)
}
#endif
+static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio)
+{
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+ /* 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
+}
+
bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
struct bio *bio)
{
struct throtl_qnode *qn = NULL;
- struct throtl_grp *tg = blkg_to_tg(blkg);
+ struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg);
struct throtl_service_queue *sq;
bool rw = bio_data_dir(bio);
bool throttled = false;
@@ -2138,6 +2148,7 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
if (unlikely(blk_queue_bypass(q)))
goto out_unlock;
+ blk_throtl_assoc_bio(tg, bio);
blk_throtl_update_idletime(tg);
sq = &tg->service_queue;
@@ -276,9 +276,7 @@ static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
}
}
- bio_clone_blkg_association(bio, bio_src);
-
- blkcg_bio_issue_init(bio);
+ bio_clone_blkcg_association(bio, bio_src);
return bio;
}
@@ -3759,7 +3759,7 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
uint64_t serial_nr;
rcu_read_lock();
- serial_nr = __bio_blkcg(bio)->css.serial_nr;
+ serial_nr = bio_blkcg(bio)->css.serial_nr;
rcu_read_unlock();
/*
@@ -3824,7 +3824,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
struct cfq_group *cfqg;
rcu_read_lock();
- cfqg = cfq_lookup_cfqg(cfqd, __bio_blkcg(bio));
+ cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
if (!cfqg) {
cfqq = &cfqd->oom_cfqq;
goto out;
@@ -77,7 +77,6 @@
#include <linux/falloc.h>
#include <linux/uio.h>
#include <linux/ioprio.h>
-#include <linux/blk-cgroup.h>
#include "loop.h"
@@ -1761,8 +1760,8 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
/* always use the first bio's css */
#ifdef CONFIG_BLK_CGROUP
- if (cmd->use_aio && rq->bio && rq->bio->bi_blkg) {
- cmd->css = &bio_blkcg(rq->bio)->css;
+ if (cmd->use_aio && rq->bio && rq->bio->bi_css) {
+ cmd->css = rq->bio->bi_css;
css_get(cmd->css);
} else
#endif
@@ -542,7 +542,7 @@ static void raid0_handle_discard(struct mddev *mddev, struct bio *bio)
!discard_bio)
continue;
bio_chain(discard_bio, bio);
- bio_clone_blkg_association(discard_bio, bio);
+ bio_clone_blkcg_association(discard_bio, bio);
if (mddev->gendisk)
trace_block_bio_remap(bdev_get_queue(rdev->bdev),
discard_bio, disk_devt(mddev->gendisk),
@@ -3060,6 +3060,11 @@ static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
*/
bio = bio_alloc(GFP_NOIO, 1);
+ if (wbc) {
+ wbc_init_bio(wbc, bio);
+ wbc_account_io(wbc, bh->b_page, bh->b_size);
+ }
+
bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
bio_set_dev(bio, bh->b_bdev);
bio->bi_write_hint = write_hint;
@@ -3079,11 +3084,6 @@ static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
op_flags |= REQ_PRIO;
bio_set_op_attrs(bio, op, op_flags);
- if (wbc) {
- wbc_init_bio(wbc, bio);
- wbc_account_io(wbc, bh->b_page, bh->b_size);
- }
-
submit_bio(bio);
return 0;
}
@@ -374,13 +374,13 @@ static int io_submit_init_bio(struct ext4_io_submit *io,
bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
if (!bio)
return -ENOMEM;
+ wbc_init_bio(io->io_wbc, bio);
bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
bio_set_dev(bio, bh->b_bdev);
bio->bi_end_io = ext4_end_bio;
bio->bi_private = ext4_get_io_end(io->io_end);
io->io_bio = bio;
io->io_next_block = bh->b_blocknr;
- wbc_init_bio(io->io_wbc, bio);
return 0;
}
@@ -503,31 +503,23 @@ do { \
disk_devt((bio)->bi_disk)
#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
-int bio_associate_blkg_from_page(struct bio *bio, struct page *page);
+int bio_associate_blkcg_from_page(struct bio *bio, struct page *page);
#else
-static inline int bio_associate_blkg_from_page(struct bio *bio,
- struct page *page) { return 0; }
+static inline int bio_associate_blkcg_from_page(struct bio *bio,
+ struct page *page) { return 0; }
#endif
#ifdef CONFIG_BLK_CGROUP
+int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg);
-int bio_associate_blkg_from_css(struct bio *bio,
- struct cgroup_subsys_state *css);
-int bio_associate_create_blkg(struct request_queue *q, struct bio *bio);
-int bio_reassociate_blkg(struct request_queue *q, struct bio *bio);
void bio_disassociate_task(struct bio *bio);
-void bio_clone_blkg_association(struct bio *dst, struct bio *src);
+void bio_clone_blkcg_association(struct bio *dst, struct bio *src);
#else /* CONFIG_BLK_CGROUP */
-static inline int bio_associate_blkg_from_css(struct bio *bio,
- struct cgroup_subsys_state *css)
-{ return 0; }
-static inline int bio_associate_create_blkg(struct request_queue *q,
- struct bio *bio) { return 0; }
-static inline int bio_reassociate_blkg(struct request_queue *q, struct bio *bio)
-{ return 0; }
+static inline int bio_associate_blkcg(struct bio *bio,
+ struct cgroup_subsys_state *blkcg_css) { return 0; }
static inline void bio_disassociate_task(struct bio *bio) { }
-static inline void bio_clone_blkg_association(struct bio *dst,
- struct bio *src) { }
+static inline void bio_clone_blkcg_association(struct bio *dst,
+ struct bio *src) { }
#endif /* CONFIG_BLK_CGROUP */
#ifdef CONFIG_HIGHMEM
@@ -126,7 +126,7 @@ struct blkcg_gq {
struct request_list rl;
/* reference count */
- struct percpu_ref refcnt;
+ atomic_t refcnt;
/* is this blkg online? protected by both blkcg and q locks */
bool online;
@@ -184,8 +184,6 @@ extern struct cgroup_subsys_state * const blkcg_root_css;
struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
struct request_queue *q, bool update_hint);
-struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q);
struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
struct request_queue *q);
int blkcg_init_queue(struct request_queue *q);
@@ -232,59 +230,22 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
char *input, struct blkg_conf_ctx *ctx);
void blkg_conf_finish(struct blkg_conf_ctx *ctx);
-/**
- * blkcg_css - find the current css
- *
- * Find the css associated with either the kthread or the current task.
- * This may return a dying css, so it is up to the caller to use tryget logic
- * to confirm it is alive and well.
- */
-static inline struct cgroup_subsys_state *blkcg_css(void)
-{
- struct cgroup_subsys_state *css;
-
- css = kthread_blkcg();
- if (css)
- return css;
- return task_css(current, io_cgrp_id);
-}
static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
{
return css ? container_of(css, struct blkcg, css) : NULL;
}
-/**
- * __bio_blkcg - internal version of bio_blkcg for bfq and cfq
- *
- * DO NOT USE.
- * There is a flaw using this version of the function. In particular, this was
- * used in a broken paradigm where association was called on the given css. It
- * is possible though that the returned css from task_css() is in the process
- * of dying due to migration of the current task. So it is improper to assume
- * *_get() is going to succeed. Both BFQ and CFQ rely on this logic and will
- * take additional work to handle more gracefully.
- */
-static inline struct blkcg *__bio_blkcg(struct bio *bio)
-{
- if (bio && bio->bi_blkg)
- return bio->bi_blkg->blkcg;
- return css_to_blkcg(blkcg_css());
-}
-
-/**
- * bio_blkcg - grab the blkcg associated with a bio
- * @bio: target bio
- *
- * This returns the blkcg associated with a bio, NULL if not associated.
- * Callers are expected to either handle NULL or know association has been
- * done prior to calling this.
- */
static inline struct blkcg *bio_blkcg(struct bio *bio)
{
- if (bio && bio->bi_blkg)
- return bio->bi_blkg->blkcg;
- return NULL;
+ struct cgroup_subsys_state *css;
+
+ if (bio && bio->bi_css)
+ return css_to_blkcg(bio->bi_css);
+ css = kthread_blkcg();
+ if (css)
+ return css_to_blkcg(css);
+ return css_to_blkcg(task_css(current, io_cgrp_id));
}
static inline bool blk_cgroup_congested(void)
@@ -490,35 +451,26 @@ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
*/
static inline void blkg_get(struct blkcg_gq *blkg)
{
- percpu_ref_get(&blkg->refcnt);
+ WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
+ atomic_inc(&blkg->refcnt);
}
/**
- * blkg_tryget - try and get a blkg reference
+ * blkg_try_get - try and get a blkg reference
* @blkg: blkg to get
*
* This is for use when doing an RCU lookup of the blkg. We may be in the midst
* of freeing this blkg, so we can only use it if the refcnt is not zero.
*/
-static inline bool blkg_tryget(struct blkcg_gq *blkg)
+static inline struct blkcg_gq *blkg_try_get(struct blkcg_gq *blkg)
{
- return percpu_ref_tryget(&blkg->refcnt);
+ if (atomic_inc_not_zero(&blkg->refcnt))
+ return blkg;
+ return NULL;
}
-/**
- * blkg_tryget_closest - try and get a blkg ref on the closet blkg
- * @blkg: blkg to get
- *
- * This walks up the blkg tree to find the closest non-dying blkg and returns
- * the blkg that it did association with as it may not be the passed in blkg.
- */
-static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg)
-{
- while (!percpu_ref_tryget(&blkg->refcnt))
- blkg = blkg->parent;
- return blkg;
-}
+void __blkg_release_rcu(struct rcu_head *rcu);
/**
* blkg_put - put a blkg reference
@@ -526,7 +478,9 @@ static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg)
*/
static inline void blkg_put(struct blkcg_gq *blkg)
{
- percpu_ref_put(&blkg->refcnt);
+ WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
+ if (atomic_dec_and_test(&blkg->refcnt))
+ call_rcu(&blkg->rcu_head, __blkg_release_rcu);
}
/**
@@ -579,36 +533,25 @@ static inline struct request_list *blk_get_rl(struct request_queue *q,
rcu_read_lock();
- if (bio && bio->bi_blkg) {
- blkcg = bio->bi_blkg->blkcg;
- if (blkcg == &blkcg_root)
- goto rl_use_root;
-
- blkg_get(bio->bi_blkg);
- rcu_read_unlock();
- return &bio->bi_blkg->rl;
- }
+ blkcg = bio_blkcg(bio);
- blkcg = css_to_blkcg(blkcg_css());
+ /* bypass blkg lookup and use @q->root_rl directly for root */
if (blkcg == &blkcg_root)
- goto rl_use_root;
+ goto root_rl;
+ /*
+ * Try to use blkg->rl. blkg lookup may fail under memory pressure
+ * or if either the blkcg or queue is going away. Fall back to
+ * root_rl in such cases.
+ */
blkg = blkg_lookup(blkcg, q);
if (unlikely(!blkg))
- blkg = __blkg_lookup_create(blkcg, q);
-
- if (blkg->blkcg == &blkcg_root || !blkg_tryget(blkg))
- goto rl_use_root;
+ goto root_rl;
+ blkg_get(blkg);
rcu_read_unlock();
return &blkg->rl;
-
- /*
- * Each blkg has its own request_list, however, the root blkcg
- * uses the request_queue's root_rl. This is to avoid most
- * overhead for the root blkcg.
- */
-rl_use_root:
+root_rl:
rcu_read_unlock();
return &q->root_rl;
}
@@ -854,26 +797,32 @@ static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg
struct bio *bio) { return false; }
#endif
-
-static inline void blkcg_bio_issue_init(struct bio *bio)
-{
- bio_issue_init(&bio->bi_issue, bio_sectors(bio));
-}
-
static inline bool blkcg_bio_issue_check(struct request_queue *q,
struct bio *bio)
{
+ struct blkcg *blkcg;
struct blkcg_gq *blkg;
bool throtl = false;
rcu_read_lock();
+ blkcg = bio_blkcg(bio);
+
+ /* associate blkcg if bio hasn't attached one */
+ bio_associate_blkcg(bio, &blkcg->css);
- bio_associate_create_blkg(q, bio);
- blkg = bio->bi_blkg;
+ blkg = blkg_lookup(blkcg, q);
+ if (unlikely(!blkg)) {
+ spin_lock_irq(q->queue_lock);
+ blkg = blkg_lookup_create(blkcg, q);
+ if (IS_ERR(blkg))
+ blkg = NULL;
+ spin_unlock_irq(q->queue_lock);
+ }
throtl = blk_throtl_bio(q, blkg, bio);
if (!throtl) {
+ blkg = blkg ?: q->root_blkg;
/*
* If the bio is flagged with BIO_QUEUE_ENTERED it means this
* is a split bio and we would have already accounted for the
@@ -885,8 +834,6 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q,
blkg_rwstat_add(&blkg->stat_ios, bio->bi_opf, 1);
}
- blkcg_bio_issue_init(bio);
-
rcu_read_unlock();
return !throtl;
}
@@ -983,7 +930,6 @@ static inline int blkcg_activate_policy(struct request_queue *q,
static inline void blkcg_deactivate_policy(struct request_queue *q,
const struct blkcg_policy *pol) { }
-static inline struct blkcg *__bio_blkcg(struct bio *bio) { return NULL; }
static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
@@ -999,7 +945,6 @@ static inline void blk_put_rl(struct request_list *rl) { }
static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
-static inline void blkcg_bio_issue_init(struct bio *bio) { }
static inline bool blkcg_bio_issue_check(struct request_queue *q,
struct bio *bio) { return true; }
@@ -178,6 +178,7 @@ struct bio {
* release. Read comment on top of bio_associate_current().
*/
struct io_context *bi_ioc;
+ struct cgroup_subsys_state *bi_css;
struct blkcg_gq *bi_blkg;
struct bio_issue bi_issue;
#endif
@@ -93,8 +93,6 @@ extern struct css_set init_css_set;
bool css_has_online_children(struct cgroup_subsys_state *css);
struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
-struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgroup,
- struct cgroup_subsys *ss);
struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup,
struct cgroup_subsys *ss);
struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
@@ -246,8 +246,7 @@ static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
*
* @bio is a part of the writeback in progress controlled by @wbc. Perform
* writeback specific initialization. This is used to apply the cgroup
- * writeback context. Must be called after the bio has been associated with
- * a device.
+ * writeback context.
*/
static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio)
{
@@ -258,7 +257,7 @@ static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio)
* regular writeback instead of writing things out itself.
*/
if (wbc->wb)
- bio_associate_blkg_from_css(bio, wbc->wb->blkcg_css);
+ bio_associate_blkcg(bio, wbc->wb->blkcg_css);
}
#else /* CONFIG_CGROUP_WRITEBACK */
@@ -492,7 +492,7 @@ static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
}
/**
- * cgroup_e_css_by_mask - obtain a cgroup's effective css for the specified ss
+ * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
* @cgrp: the cgroup of interest
* @ss: the subsystem of interest (%NULL returns @cgrp->self)
*
@@ -501,8 +501,8 @@ static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
* enabled. If @ss is associated with the hierarchy @cgrp is on, this
* function is guaranteed to return non-NULL css.
*/
-static struct cgroup_subsys_state *cgroup_e_css_by_mask(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
+static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
{
lockdep_assert_held(&cgroup_mutex);
@@ -522,35 +522,6 @@ static struct cgroup_subsys_state *cgroup_e_css_by_mask(struct cgroup *cgrp,
return cgroup_css(cgrp, ss);
}
-/**
- * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest
- *
- * Find and get the effective css of @cgrp for @ss. The effective css is
- * defined as the matching css of the nearest ancestor including self which
- * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
- * the root css is returned, so this function always returns a valid css.
- *
- * The returned css is not guaranteed to be online, and therefore it is the
- * callers responsiblity to tryget a reference for it.
- */
-struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
-{
- struct cgroup_subsys_state *css;
-
- do {
- css = cgroup_css(cgrp, ss);
-
- if (css)
- return css;
- cgrp = cgroup_parent(cgrp);
- } while (cgrp);
-
- return init_css_set.subsys[ss->id];
-}
-
/**
* cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
* @cgrp: the cgroup of interest
@@ -633,11 +604,10 @@ EXPORT_SYMBOL_GPL(of_css);
*
* Should be called under cgroup_[tree_]mutex.
*/
-#define for_each_e_css(css, ssid, cgrp) \
- for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
- if (!((css) = cgroup_e_css_by_mask(cgrp, \
- cgroup_subsys[(ssid)]))) \
- ; \
+#define for_each_e_css(css, ssid, cgrp) \
+ for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
+ if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \
+ ; \
else
/**
@@ -1036,7 +1006,7 @@ static struct css_set *find_existing_css_set(struct css_set *old_cset,
* @ss is in this hierarchy, so we want the
* effective css from @cgrp.
*/
- template[i] = cgroup_e_css_by_mask(cgrp, ss);
+ template[i] = cgroup_e_css(cgrp, ss);
} else {
/*
* @ss is not in this hierarchy, so we don't want
@@ -3049,7 +3019,7 @@ static int cgroup_apply_control(struct cgroup *cgrp)
return ret;
/*
- * At this point, cgroup_e_css_by_mask() results reflect the new csses
+ * At this point, cgroup_e_css() results reflect the new csses
* making the following cgroup_update_dfl_csses() properly update
* css associations of all tasks in the subtree.
*/
@@ -764,9 +764,9 @@ blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
return NULL;
- if (!bio->bi_blkg)
+ if (!bio->bi_css)
return NULL;
- return cgroup_get_kernfs_id(bio_blkcg(bio)->css.cgroup);
+ return cgroup_get_kernfs_id(bio->bi_css->cgroup);
}
#else
static union kernfs_node_id *
@@ -339,7 +339,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
goto out;
}
bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
- bio_associate_blkg_from_page(bio, page);
+ bio_associate_blkcg_from_page(bio, page);
count_swpout_vm_event(page);
set_page_writeback(page);
unlock_page(page);
This reverts a series committed earlier due to null pointer exception bug report in [1]. It seems there are edge case interactions that I did not consider and will need some time to understand what causes the adverse interactions. The original series can be found in [2] with a follow up series in [3]. [1] https://www.spinics.net/lists/cgroups/msg20719.html [2] https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@gmail.com/ [3] https://lore.kernel.org/lkml/20181020185612.51587-1-dennis@kernel.org/ This reverts the following commits: d459d853c2ed, b2c3fa546705, 101246ec02b5, b3b9f24f5fcc, e2b0989954ae, f0fcb3ec89f3, c839e7a03f92, bdc2491708c4, 74b7c02a9bc1, 5bf9a1f3b4ef, a7b39b4e961c, 07b05bcc3213, 49f4c2dc2b50, 27e6fa996c53 Signed-off-by: Dennis Zhou <dennis@kernel.org> --- Documentation/admin-guide/cgroup-v2.rst | 8 +- block/bfq-cgroup.c | 4 +- block/bfq-iosched.c | 2 +- block/bio.c | 174 +++++++----------------- block/blk-cgroup.c | 123 ++++++----------- block/blk-core.c | 1 - block/blk-iolatency.c | 26 +++- block/blk-throttle.c | 13 +- block/bounce.c | 4 +- block/cfq-iosched.c | 4 +- drivers/block/loop.c | 5 +- drivers/md/raid0.c | 2 +- fs/buffer.c | 10 +- fs/ext4/page-io.c | 2 +- include/linux/bio.h | 26 ++-- include/linux/blk-cgroup.h | 145 ++++++-------------- include/linux/blk_types.h | 1 + include/linux/cgroup.h | 2 - include/linux/writeback.h | 5 +- kernel/cgroup/cgroup.c | 48 ++----- kernel/trace/blktrace.c | 4 +- mm/page_io.c | 2 +- 22 files changed, 208 insertions(+), 403 deletions(-)