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aio: aio_nr decrements don't need to be delayed

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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>
This commit is contained in:
Al Viro
2012-03-10 23:10:35 -05:00
parent e23754f880
commit 2dd542b7ae
1 changed files with 14 additions and 28 deletions
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38
fs/aio.c
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@@ -199,16 +199,7 @@ static int aio_setup_ring(struct kioctx *ctx)
static void ctx_rcu_free(struct rcu_head *head) static void ctx_rcu_free(struct rcu_head *head)
{ {
struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
unsigned nr_events = ctx->max_reqs;
kmem_cache_free(kioctx_cachep, ctx); 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 /* __put_ioctx
@@ -217,6 +208,7 @@ static void ctx_rcu_free(struct rcu_head *head)
*/ */
static void __put_ioctx(struct kioctx *ctx) static void __put_ioctx(struct kioctx *ctx)
{ {
unsigned nr_events = ctx->max_reqs;
BUG_ON(ctx->reqs_active); BUG_ON(ctx->reqs_active);
cancel_delayed_work(&ctx->wq); cancel_delayed_work(&ctx->wq);
@@ -224,6 +216,12 @@ static void __put_ioctx(struct kioctx *ctx)
aio_free_ring(ctx); aio_free_ring(ctx);
mmdrop(ctx->mm); mmdrop(ctx->mm);
ctx->mm = NULL; 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); pr_debug("__put_ioctx: freeing %p\n", ctx);
call_rcu(&ctx->rcu_head, ctx_rcu_free); 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 mm_struct *mm;
struct kioctx *ctx; struct kioctx *ctx;
int did_sync = 0;
int err = -ENOMEM; int err = -ENOMEM;
/* Prevent overflows */ /* Prevent overflows */
@@ -257,7 +254,7 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
return ERR_PTR(-EINVAL); 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); return ERR_PTR(-EAGAIN);
ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
@@ -281,25 +278,14 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
goto out_freectx; goto out_freectx;
/* limit the number of system wide aios */ /* limit the number of system wide aios */
do {
spin_lock_bh(&aio_nr_lock); spin_lock_bh(&aio_nr_lock);
if (aio_nr + nr_events > aio_max_nr || if (aio_nr + nr_events > aio_max_nr ||
aio_nr + nr_events < aio_nr) aio_nr + nr_events < aio_nr) {
ctx->max_reqs = 0; spin_unlock_bh(&aio_nr_lock);
else goto out_cleanup;
}
aio_nr += ctx->max_reqs; aio_nr += ctx->max_reqs;
spin_unlock_bh(&aio_nr_lock); 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;
/* now link into global list. */ /* now link into global list. */
spin_lock(&mm->ioctx_lock); spin_lock(&mm->ioctx_lock);