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: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/aio.c b/fs/aio.c
index d09b560..216eb37 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -199,16 +199,7 @@
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 __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 @@
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 @@
{
struct mm_struct *mm;
struct kioctx *ctx;
- int did_sync = 0;
int err = -ENOMEM;
/* Prevent overflows */
@@ -257,7 +254,7 @@
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 @@
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;
+ spin_lock_bh(&aio_nr_lock);
+ if (aio_nr + nr_events > aio_max_nr ||
+ 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);