6.18-stable review patch. If anyone has any objections, please let me know.
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From: Nilay Shroff nilay@linux.ibm.com
[ Upstream commit 0315476e78c050048e80f66334a310e5581b46bb ]
The previous patch introduced ->alloc_sched_data and ->free_sched_data methods. This patch builds upon that by now using these methods during elevator switch and nr_hw_queue update.
It's also ensured that scheduler-specific data is allocated and freed through the new callbacks outside of the ->freeze_lock and ->elevator_lock locking contexts, thereby preventing any dependency on pcpu_alloc_mutex.
Reviewed-by: Ming Lei ming.lei@redhat.com Reviewed-by: Yu Kuai yukuai@fnnas.com Signed-off-by: Nilay Shroff nilay@linux.ibm.com Signed-off-by: Jens Axboe axboe@kernel.dk Stable-dep-of: 9869d3a6fed3 ("block: fix race between wbt_enable_default and IO submission") Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-mq-sched.c | 27 +++++++++++++++++++++------ block/blk-mq-sched.h | 5 ++++- block/elevator.c | 34 ++++++++++++++++++++++------------ block/elevator.h | 4 +++- 4 files changed, 50 insertions(+), 20 deletions(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 03ff16c49976..128f2be9d420 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -428,12 +428,17 @@ void blk_mq_free_sched_tags(struct elevator_tags *et, }
void blk_mq_free_sched_res(struct elevator_resources *res, + struct elevator_type *type, struct blk_mq_tag_set *set) { if (res->et) { blk_mq_free_sched_tags(res->et, set); res->et = NULL; } + if (res->data) { + blk_mq_free_sched_data(type, res->data); + res->data = NULL; + } }
void blk_mq_free_sched_res_batch(struct xarray *elv_tbl, @@ -458,7 +463,7 @@ void blk_mq_free_sched_res_batch(struct xarray *elv_tbl, WARN_ON_ONCE(1); continue; } - blk_mq_free_sched_res(&ctx->res, set); + blk_mq_free_sched_res(&ctx->res, ctx->type, set); } } } @@ -541,7 +546,9 @@ struct elevator_tags *blk_mq_alloc_sched_tags(struct blk_mq_tag_set *set, }
int blk_mq_alloc_sched_res(struct request_queue *q, - struct elevator_resources *res, unsigned int nr_hw_queues) + struct elevator_type *type, + struct elevator_resources *res, + unsigned int nr_hw_queues) { struct blk_mq_tag_set *set = q->tag_set;
@@ -550,6 +557,12 @@ int blk_mq_alloc_sched_res(struct request_queue *q, if (!res->et) return -ENOMEM;
+ res->data = blk_mq_alloc_sched_data(q, type); + if (IS_ERR(res->data)) { + blk_mq_free_sched_tags(res->et, set); + return -ENOMEM; + } + return 0; }
@@ -577,19 +590,21 @@ int blk_mq_alloc_sched_res_batch(struct xarray *elv_tbl, goto out_unwind; }
- ret = blk_mq_alloc_sched_res(q, &ctx->res, - nr_hw_queues); + ret = blk_mq_alloc_sched_res(q, q->elevator->type, + &ctx->res, nr_hw_queues); if (ret) goto out_unwind; } } return 0; + out_unwind: list_for_each_entry_continue_reverse(q, &set->tag_list, tag_set_list) { if (q->elevator) { ctx = xa_load(elv_tbl, q->id); if (ctx) - blk_mq_free_sched_res(&ctx->res, set); + blk_mq_free_sched_res(&ctx->res, + ctx->type, set); } } return ret; @@ -606,7 +621,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e, unsigned long i; int ret;
- eq = elevator_alloc(q, e, et); + eq = elevator_alloc(q, e, res); if (!eq) return -ENOMEM;
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h index 4e1b86e85a8a..02c40a72e959 100644 --- a/block/blk-mq-sched.h +++ b/block/blk-mq-sched.h @@ -26,7 +26,9 @@ void blk_mq_sched_free_rqs(struct request_queue *q); struct elevator_tags *blk_mq_alloc_sched_tags(struct blk_mq_tag_set *set, unsigned int nr_hw_queues, unsigned int nr_requests); int blk_mq_alloc_sched_res(struct request_queue *q, - struct elevator_resources *res, unsigned int nr_hw_queues); + struct elevator_type *type, + struct elevator_resources *res, + unsigned int nr_hw_queues); int blk_mq_alloc_sched_res_batch(struct xarray *elv_tbl, struct blk_mq_tag_set *set, unsigned int nr_hw_queues); int blk_mq_alloc_sched_ctx_batch(struct xarray *elv_tbl, @@ -35,6 +37,7 @@ void blk_mq_free_sched_ctx_batch(struct xarray *elv_tbl); void blk_mq_free_sched_tags(struct elevator_tags *et, struct blk_mq_tag_set *set); void blk_mq_free_sched_res(struct elevator_resources *res, + struct elevator_type *type, struct blk_mq_tag_set *set); void blk_mq_free_sched_res_batch(struct xarray *et_table, struct blk_mq_tag_set *set); diff --git a/block/elevator.c b/block/elevator.c index cbec292a4af5..5b37ef44f52d 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -121,7 +121,7 @@ static struct elevator_type *elevator_find_get(const char *name) static const struct kobj_type elv_ktype;
struct elevator_queue *elevator_alloc(struct request_queue *q, - struct elevator_type *e, struct elevator_tags *et) + struct elevator_type *e, struct elevator_resources *res) { struct elevator_queue *eq;
@@ -134,7 +134,8 @@ struct elevator_queue *elevator_alloc(struct request_queue *q, kobject_init(&eq->kobj, &elv_ktype); mutex_init(&eq->sysfs_lock); hash_init(eq->hash); - eq->et = et; + eq->et = res->et; + eq->elevator_data = res->data;
return eq; } @@ -617,7 +618,7 @@ static void elv_exit_and_release(struct elv_change_ctx *ctx, mutex_unlock(&q->elevator_lock); blk_mq_unfreeze_queue(q, memflags); if (e) { - blk_mq_free_sched_res(&ctx->res, q->tag_set); + blk_mq_free_sched_res(&ctx->res, ctx->type, q->tag_set); kobject_put(&e->kobj); } } @@ -628,12 +629,15 @@ static int elevator_change_done(struct request_queue *q, int ret = 0;
if (ctx->old) { - struct elevator_resources res = {.et = ctx->old->et}; + struct elevator_resources res = { + .et = ctx->old->et, + .data = ctx->old->elevator_data + }; bool enable_wbt = test_bit(ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT, &ctx->old->flags);
elv_unregister_queue(q, ctx->old); - blk_mq_free_sched_res(&res, q->tag_set); + blk_mq_free_sched_res(&res, ctx->old->type, q->tag_set); kobject_put(&ctx->old->kobj); if (enable_wbt) wbt_enable_default(q->disk); @@ -658,7 +662,8 @@ static int elevator_change(struct request_queue *q, struct elv_change_ctx *ctx) lockdep_assert_held(&set->update_nr_hwq_lock);
if (strncmp(ctx->name, "none", 4)) { - ret = blk_mq_alloc_sched_res(q, &ctx->res, set->nr_hw_queues); + ret = blk_mq_alloc_sched_res(q, ctx->type, &ctx->res, + set->nr_hw_queues); if (ret) return ret; } @@ -681,11 +686,12 @@ static int elevator_change(struct request_queue *q, struct elv_change_ctx *ctx) blk_mq_unfreeze_queue(q, memflags); if (!ret) ret = elevator_change_done(q, ctx); + /* * Free sched resource if it's allocated but we couldn't switch elevator. */ if (!ctx->new) - blk_mq_free_sched_res(&ctx->res, set); + blk_mq_free_sched_res(&ctx->res, ctx->type, set);
return ret; } @@ -711,11 +717,12 @@ void elv_update_nr_hw_queues(struct request_queue *q, blk_mq_unfreeze_queue_nomemrestore(q); if (!ret) WARN_ON_ONCE(elevator_change_done(q, ctx)); + /* * Free sched resource if it's allocated but we couldn't switch elevator. */ if (!ctx->new) - blk_mq_free_sched_res(&ctx->res, set); + blk_mq_free_sched_res(&ctx->res, ctx->type, set); }
/* @@ -729,7 +736,6 @@ void elevator_set_default(struct request_queue *q) .no_uevent = true, }; int err; - struct elevator_type *e;
/* now we allow to switch elevator */ blk_queue_flag_clear(QUEUE_FLAG_NO_ELV_SWITCH, q); @@ -742,8 +748,8 @@ void elevator_set_default(struct request_queue *q) * have multiple queues or mq-deadline is not available, default * to "none". */ - e = elevator_find_get(ctx.name); - if (!e) + ctx.type = elevator_find_get(ctx.name); + if (!ctx.type) return;
if ((q->nr_hw_queues == 1 || @@ -753,7 +759,7 @@ void elevator_set_default(struct request_queue *q) pr_warn(""%s" elevator initialization, failed %d, falling back to "none"\n", ctx.name, err); } - elevator_put(e); + elevator_put(ctx.type); }
void elevator_set_none(struct request_queue *q) @@ -802,6 +808,7 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, ctx.name = strstrip(elevator_name);
elv_iosched_load_module(ctx.name); + ctx.type = elevator_find_get(ctx.name);
down_read(&set->update_nr_hwq_lock); if (!blk_queue_no_elv_switch(q)) { @@ -812,6 +819,9 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, ret = -ENOENT; } up_read(&set->update_nr_hwq_lock); + + if (ctx.type) + elevator_put(ctx.type); return ret; }
diff --git a/block/elevator.h b/block/elevator.h index e34043f6da26..3ee1d494f48a 100644 --- a/block/elevator.h +++ b/block/elevator.h @@ -33,6 +33,8 @@ struct elevator_tags { };
struct elevator_resources { + /* holds elevator data */ + void *data; /* holds elevator tags */ struct elevator_tags *et; }; @@ -185,7 +187,7 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *page, size_t count);
extern bool elv_bio_merge_ok(struct request *, struct bio *); struct elevator_queue *elevator_alloc(struct request_queue *, - struct elevator_type *, struct elevator_tags *); + struct elevator_type *, struct elevator_resources *);
/* * Helper functions.