diff options
| -rw-r--r-- | block/blk-core.c | 25 | ||||
| -rw-r--r-- | block/blk-ioc.c | 62 | ||||
| -rw-r--r-- | block/blk.h | 36 | ||||
| -rw-r--r-- | block/cfq-iosched.c | 2 |
4 files changed, 71 insertions, 54 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index fd47493..6804fdf 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -771,9 +771,12 @@ static struct request *get_request(struct request_queue *q, int rw_flags, { struct request *rq = NULL; struct request_list *rl = &q->rq; - struct io_context *ioc = NULL; + struct io_context *ioc; const bool is_sync = rw_is_sync(rw_flags) != 0; + bool retried = false; int may_queue; +retry: + ioc = current->io_context; if (unlikely(blk_queue_dead(q))) return NULL; @@ -784,7 +787,20 @@ static struct request *get_request(struct request_queue *q, int rw_flags, if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { if (rl->count[is_sync]+1 >= q->nr_requests) { - ioc = current_io_context(GFP_ATOMIC, q->node); + /* + * We want ioc to record batching state. If it's + * not already there, creating a new one requires + * dropping queue_lock, which in turn requires + * retesting conditions to avoid queue hang. + */ + if (!ioc && !retried) { + spin_unlock_irq(q->queue_lock); + create_io_context(current, gfp_mask, q->node); + spin_lock_irq(q->queue_lock); + retried = true; + goto retry; + } + /* * The queue will fill after this allocation, so set * it as full, and mark this process as "batching". @@ -892,7 +908,6 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags, rq = get_request(q, rw_flags, bio, GFP_NOIO); while (!rq) { DEFINE_WAIT(wait); - struct io_context *ioc; struct request_list *rl = &q->rq; if (unlikely(blk_queue_dead(q))) @@ -912,8 +927,8 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags, * up to a big batch of them for a small period time. * See ioc_batching, ioc_set_batching */ - ioc = current_io_context(GFP_NOIO, q->node); - ioc_set_batching(q, ioc); + create_io_context(current, GFP_NOIO, q->node); + ioc_set_batching(q, current->io_context); spin_lock_irq(q->queue_lock); finish_wait(&rl->wait[is_sync], &wait); diff --git a/block/blk-ioc.c b/block/blk-ioc.c index fb23965..e23c797 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -205,16 +205,15 @@ void exit_io_context(struct task_struct *task) put_io_context(ioc, NULL); } -static struct io_context *create_task_io_context(struct task_struct *task, - gfp_t gfp_flags, int node, - bool take_ref) +void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags, + int node) { struct io_context *ioc; ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO, node); if (unlikely(!ioc)) - return NULL; + return; /* initialize */ atomic_long_set(&ioc->refcount, 1); @@ -226,42 +225,13 @@ static struct io_context *create_task_io_context(struct task_struct *task, /* try to install, somebody might already have beaten us to it */ task_lock(task); - - if (!task->io_context && !(task->flags & PF_EXITING)) { + if (!task->io_context && !(task->flags & PF_EXITING)) task->io_context = ioc; - } else { + else kmem_cache_free(iocontext_cachep, ioc); - ioc = task->io_context; - } - - if (ioc && take_ref) - get_io_context(ioc); - task_unlock(task); - return ioc; } - -/** - * current_io_context - get io_context of %current - * @gfp_flags: allocation flags, used if allocation is necessary - * @node: allocation node, used if allocation is necessary - * - * Return io_context of %current. If it doesn't exist, it is created with - * @gfp_flags and @node. The returned io_context does NOT have its - * reference count incremented. Because io_context is exited only on task - * exit, %current can be sure that the returned io_context is valid and - * alive as long as it is executing. - */ -struct io_context *current_io_context(gfp_t gfp_flags, int node) -{ - might_sleep_if(gfp_flags & __GFP_WAIT); - - if (current->io_context) - return current->io_context; - - return create_task_io_context(current, gfp_flags, node, false); -} -EXPORT_SYMBOL(current_io_context); +EXPORT_SYMBOL(create_io_context_slowpath); /** * get_task_io_context - get io_context of a task @@ -274,7 +244,7 @@ EXPORT_SYMBOL(current_io_context); * incremented. * * This function always goes through task_lock() and it's better to use - * current_io_context() + get_io_context() for %current. + * %current->io_context + get_io_context() for %current. */ struct io_context *get_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node) @@ -283,16 +253,18 @@ struct io_context *get_task_io_context(struct task_struct *task, might_sleep_if(gfp_flags & __GFP_WAIT); - task_lock(task); - ioc = task->io_context; - if (likely(ioc)) { - get_io_context(ioc); + do { + task_lock(task); + ioc = task->io_context; + if (likely(ioc)) { + get_io_context(ioc); + task_unlock(task); + return ioc; + } task_unlock(task); - return ioc; - } - task_unlock(task); + } while (create_io_context(task, gfp_flags, node)); - return create_task_io_context(task, gfp_flags, node, true); + return NULL; } EXPORT_SYMBOL(get_task_io_context); diff --git a/block/blk.h b/block/blk.h index 8d42115..5bca266 100644 --- a/block/blk.h +++ b/block/blk.h @@ -127,9 +127,6 @@ static inline int blk_should_fake_timeout(struct request_queue *q) } #endif -void get_io_context(struct io_context *ioc); -struct io_context *current_io_context(gfp_t gfp_flags, int node); - int ll_back_merge_fn(struct request_queue *q, struct request *req, struct bio *bio); int ll_front_merge_fn(struct request_queue *q, struct request *req, @@ -198,6 +195,39 @@ static inline int blk_do_io_stat(struct request *rq) (rq->cmd_flags & REQ_DISCARD)); } +/* + * Internal io_context interface + */ +void get_io_context(struct io_context *ioc); + +void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_mask, + int node); + +/** + * create_io_context - try to create task->io_context + * @task: target task + * @gfp_mask: allocation mask + * @node: allocation node + * + * If @task->io_context is %NULL, allocate a new io_context and install it. + * Returns the current @task->io_context which may be %NULL if allocation + * failed. + * + * Note that this function can't be called with IRQ disabled because + * task_lock which protects @task->io_context is IRQ-unsafe. + */ +static inline struct io_context *create_io_context(struct task_struct *task, + gfp_t gfp_mask, int node) +{ + WARN_ON_ONCE(irqs_disabled()); + if (unlikely(!task->io_context)) + create_io_context_slowpath(task, gfp_mask, node); + return task->io_context; +} + +/* + * Internal throttling interface + */ #ifdef CONFIG_BLK_DEV_THROTTLING extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio); extern void blk_throtl_drain(struct request_queue *q); diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 3b07ce1..5f7e4d1 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3012,7 +3012,7 @@ static int cfq_create_cic(struct cfq_data *cfqd, gfp_t gfp_mask) might_sleep_if(gfp_mask & __GFP_WAIT); /* allocate stuff */ - ioc = current_io_context(gfp_mask, q->node); + ioc = create_io_context(current, gfp_mask, q->node); if (!ioc) goto out; |
