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blk-mq: fix schedule from atomic context 

blk_mq_put_ctx() has to be called before io_schedule() in
bt_get().

This patch fixes the problem by taking similar approach from
percpu_ida allocation for the situation.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei 2014-06-01 00:43:37 +08:00 committed by Jens Axboe
parent 1aecfe4887
commit cb96a42cc1
4 changed files with 78 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
block/blk-mq-tag.c
View File

@ -221,8 +221,10 @@ static struct bt_wait_state *bt_wait_ptr(struct blk_mq_bitmap_tags *bt,
return bs;
}
static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx,
unsigned int *last_tag, gfp_t gfp)
static int bt_get(struct blk_mq_alloc_data *data,
struct blk_mq_bitmap_tags *bt,
struct blk_mq_hw_ctx *hctx,
unsigned int *last_tag)
{
struct bt_wait_state *bs;
DEFINE_WAIT(wait);
@ -232,7 +234,7 @@ static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx,
if (tag != -1)
return tag;
if (!(gfp & __GFP_WAIT))
if (!(data->gfp & __GFP_WAIT))
return -1;
bs = bt_wait_ptr(bt, hctx);
@ -249,50 +251,62 @@ static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx,
if (was_empty)
atomic_set(&bs->wait_cnt, bt->wake_cnt);
blk_mq_put_ctx(data->ctx);
io_schedule();
data->ctx = blk_mq_get_ctx(data->q);
data->hctx = data->q->mq_ops->map_queue(data->q,
data->ctx->cpu);
if (data->reserved) {
bt = &data->hctx->tags->breserved_tags;
} else {
last_tag = &data->ctx->last_tag;
hctx = data->hctx;
bt = &hctx->tags->bitmap_tags;
}
finish_wait(&bs->wait, &wait);
bs = bt_wait_ptr(bt, hctx);
} while (1);
finish_wait(&bs->wait, &wait);
return tag;
}
static unsigned int __blk_mq_get_tag(struct blk_mq_tags *tags,
struct blk_mq_hw_ctx *hctx,
unsigned int *last_tag, gfp_t gfp)
static unsigned int __blk_mq_get_tag(struct blk_mq_alloc_data *data)
{
int tag;
tag = bt_get(&tags->bitmap_tags, hctx, last_tag, gfp);
tag = bt_get(data, &data->hctx->tags->bitmap_tags, data->hctx,
&data->ctx->last_tag);
if (tag >= 0)
return tag + tags->nr_reserved_tags;
return tag + data->hctx->tags->nr_reserved_tags;
return BLK_MQ_TAG_FAIL;
}
static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_tags *tags,
gfp_t gfp)
static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_alloc_data *data)
{
int tag, zero = 0;
if (unlikely(!tags->nr_reserved_tags)) {
if (unlikely(!data->hctx->tags->nr_reserved_tags)) {
WARN_ON_ONCE(1);
return BLK_MQ_TAG_FAIL;
}
tag = bt_get(&tags->breserved_tags, NULL, &zero, gfp);
tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL, &zero);
if (tag < 0)
return BLK_MQ_TAG_FAIL;
return tag;
}
unsigned int blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, unsigned int *last_tag,
gfp_t gfp, bool reserved)
unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
{
if (!reserved)
return __blk_mq_get_tag(hctx->tags, hctx, last_tag, gfp);
if (!data->reserved)
return __blk_mq_get_tag(data);
return __blk_mq_get_reserved_tag(hctx->tags, gfp);
return __blk_mq_get_reserved_tag(data);
}
static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt)

2
block/blk-mq-tag.h
View File

@ -48,7 +48,7 @@ struct blk_mq_tags {
extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int reserved_tags, int node);
extern void blk_mq_free_tags(struct blk_mq_tags *tags);
extern unsigned int blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, unsigned int *last_tag, gfp_t gfp, bool reserved);
extern unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data);
extern void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag, unsigned int *last_tag);
extern bool blk_mq_has_free_tags(struct blk_mq_tags *tags);
extern ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page);

36
block/blk-mq.c
View File

@ -210,24 +210,23 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
}
static struct request *
__blk_mq_alloc_request(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx, int rw, gfp_t gfp, bool reserved)
__blk_mq_alloc_request(struct blk_mq_alloc_data *data, int rw)
{
struct request *rq;
unsigned int tag;
tag = blk_mq_get_tag(hctx, &ctx->last_tag, gfp, reserved);
tag = blk_mq_get_tag(data);
if (tag != BLK_MQ_TAG_FAIL) {
rq = hctx->tags->rqs[tag];
rq = data->hctx->tags->rqs[tag];
rq->cmd_flags = 0;
if (blk_mq_tag_busy(hctx)) {
if (blk_mq_tag_busy(data->hctx)) {
rq->cmd_flags = REQ_MQ_INFLIGHT;
atomic_inc(&hctx->nr_active);
atomic_inc(&data->hctx->nr_active);
}
rq->tag = tag;
blk_mq_rq_ctx_init(q, ctx, rq, rw);
blk_mq_rq_ctx_init(data->q, data->ctx, rq, rw);
return rq;
}
@ -240,22 +239,27 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp,
struct blk_mq_ctx *ctx;
struct blk_mq_hw_ctx *hctx;
struct request *rq;
struct blk_mq_alloc_data alloc_data;
if (blk_mq_queue_enter(q))
return NULL;
ctx = blk_mq_get_ctx(q);
hctx = q->mq_ops->map_queue(q, ctx->cpu);
blk_mq_set_alloc_data(&alloc_data, q, gfp & ~__GFP_WAIT,
reserved, ctx, hctx);
rq = __blk_mq_alloc_request(q, hctx, ctx, rw, gfp & ~__GFP_WAIT,
reserved);
rq = __blk_mq_alloc_request(&alloc_data, rw);
if (!rq && (gfp & __GFP_WAIT)) {
__blk_mq_run_hw_queue(hctx);
blk_mq_put_ctx(ctx);
ctx = blk_mq_get_ctx(q);
hctx = q->mq_ops->map_queue(q, ctx->cpu);
rq = __blk_mq_alloc_request(q, hctx, ctx, rw, gfp, reserved);
blk_mq_set_alloc_data(&alloc_data, q, gfp, reserved, ctx,
hctx);
rq = __blk_mq_alloc_request(&alloc_data, rw);
ctx = alloc_data.ctx;
}
blk_mq_put_ctx(ctx);
return rq;
@ -1136,6 +1140,7 @@ static struct request *blk_mq_map_request(struct request_queue *q,
struct blk_mq_ctx *ctx;
struct request *rq;
int rw = bio_data_dir(bio);
struct blk_mq_alloc_data alloc_data;
if (unlikely(blk_mq_queue_enter(q))) {
bio_endio(bio, -EIO);
@ -1149,7 +1154,9 @@ static struct request *blk_mq_map_request(struct request_queue *q,
rw |= REQ_SYNC;
trace_block_getrq(q, bio, rw);
rq = __blk_mq_alloc_request(q, hctx, ctx, rw, GFP_ATOMIC, false);
blk_mq_set_alloc_data(&alloc_data, q, GFP_ATOMIC, false, ctx,
hctx);
rq = __blk_mq_alloc_request(&alloc_data, rw);
if (unlikely(!rq)) {
__blk_mq_run_hw_queue(hctx);
blk_mq_put_ctx(ctx);
@ -1157,8 +1164,11 @@ static struct request *blk_mq_map_request(struct request_queue *q,
ctx = blk_mq_get_ctx(q);
hctx = q->mq_ops->map_queue(q, ctx->cpu);
rq = __blk_mq_alloc_request(q, hctx, ctx, rw,
__GFP_WAIT|GFP_ATOMIC, false);
blk_mq_set_alloc_data(&alloc_data, q,
__GFP_WAIT|GFP_ATOMIC, false, ctx, hctx);
rq = __blk_mq_alloc_request(&alloc_data, rw);
ctx = alloc_data.ctx;
hctx = alloc_data.hctx;
}
hctx->queued++;

23
block/blk-mq.h
View File

@ -91,4 +91,27 @@ static inline void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
put_cpu();
}
struct blk_mq_alloc_data {
/* input parameter */
struct request_queue *q;
gfp_t gfp;
bool reserved;
/* input & output parameter */
struct blk_mq_ctx *ctx;
struct blk_mq_hw_ctx *hctx;
};
static inline void blk_mq_set_alloc_data(struct blk_mq_alloc_data *data,
struct request_queue *q, gfp_t gfp, bool reserved,
struct blk_mq_ctx *ctx,
struct blk_mq_hw_ctx *hctx)
{
data->q = q;
data->gfp = gfp;
data->reserved = reserved;
data->ctx = ctx;
data->hctx = hctx;
}
#endif