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Commit 2dd542b7 authored by Al Viro's avatar Al Viro
Browse files

aio: aio_nr decrements don't need to be delayed 



we can do that right in __put_ioctx(); as the result, the loop
in ioctx_alloc() can be killed.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e23754f8

fs/aio.c

+14 −28
Original line number Diff line number Diff line
@@ -199,16 +199,7 @@ static int aio_setup_ring(struct kioctx *ctx) 
static void ctx_rcu_free(struct rcu_head *head)

{

	struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);

	unsigned nr_events = ctx->max_reqs;



	kmem_cache_free(kioctx_cachep, ctx);



	if (nr_events) {

		spin_lock(&aio_nr_lock);

		BUG_ON(aio_nr - nr_events > aio_nr);

		aio_nr -= nr_events;

		spin_unlock(&aio_nr_lock);

	}

}



/* __put_ioctx
@@ -217,6 +208,7 @@ static void ctx_rcu_free(struct rcu_head *head) 
 */

static void __put_ioctx(struct kioctx *ctx)

{

	unsigned nr_events = ctx->max_reqs;

	BUG_ON(ctx->reqs_active);



	cancel_delayed_work(&ctx->wq);
@@ -224,6 +216,12 @@ static void __put_ioctx(struct kioctx *ctx) 
	aio_free_ring(ctx);

	mmdrop(ctx->mm);

	ctx->mm = NULL;

	if (nr_events) {

		spin_lock(&aio_nr_lock);

		BUG_ON(aio_nr - nr_events > aio_nr);

		aio_nr -= nr_events;

		spin_unlock(&aio_nr_lock);

	}

	pr_debug("__put_ioctx: freeing %p\n", ctx);

	call_rcu(&ctx->rcu_head, ctx_rcu_free);

}
@@ -247,7 +245,6 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 
{

	struct mm_struct *mm;

	struct kioctx *ctx;

	int did_sync = 0;

	int err = -ENOMEM;



	/* Prevent overflows */
@@ -257,7 +254,7 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 
		return ERR_PTR(-EINVAL);

	}



	if ((unsigned long)nr_events > aio_max_nr)

	if (!nr_events || (unsigned long)nr_events > aio_max_nr)

		return ERR_PTR(-EAGAIN);



	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
@@ -281,25 +278,14 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 
		goto out_freectx;



	/* limit the number of system wide aios */

	do {

	spin_lock_bh(&aio_nr_lock);

	if (aio_nr + nr_events > aio_max_nr ||

		    aio_nr + nr_events < aio_nr)

			ctx->max_reqs = 0;

		else

			aio_nr += ctx->max_reqs;

	    aio_nr + nr_events < aio_nr) {

		spin_unlock_bh(&aio_nr_lock);

		if (ctx->max_reqs || did_sync)

			break;



		/* wait for rcu callbacks to have completed before giving up */

		synchronize_rcu();

		did_sync = 1;

		ctx->max_reqs = nr_events;

	} while (1);



	if (ctx->max_reqs == 0)

		goto out_cleanup;

	}

	aio_nr += ctx->max_reqs;

	spin_unlock_bh(&aio_nr_lock);



	/* now link into global list. */

	spin_lock(&mm->ioctx_lock);