[PATCH 23/25] aio: Percpu ioctx refcount

[Kent Overstreet]

This just converts the ioctx refcount to the new generic dynamic percpu
refcount code.

Signed-off-by: Kent Overstreet <koverstr...@google.com>
---
 fs/aio.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 94218b7..0975675 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -36,6 +36,7 @@
 #include <linux/eventfd.h>
 #include <linux/blkdev.h>
 #include <linux/compat.h>
+#include <linux/percpu-refcount.h>
 
 #include <asm/kmap_types.h>
 #include <asm/uaccess.h>
@@ -65,7 +66,7 @@ struct kioctx_cpu {
 };
 
 struct kioctx {
-       atomic_t                users;
+       struct percpu_ref       users;
        atomic_t                dead;
 
        /* This needs improving */
@@ -297,6 +298,8 @@ static void free_ioctx(struct kioctx *ctx)
        struct io_event res;
        unsigned cpu, head, avail;
 
+       pr_debug("freeing %p\n", ctx);
+
        spin_lock_irq(&ctx->ctx_lock);
 
        while (!list_empty(&ctx->active_reqs)) {
@@ -341,14 +344,14 @@ static void free_ioctx(struct kioctx *ctx)
 
        synchronize_rcu();
 
-       pr_debug("freeing %p\n", ctx);
+       pr_debug("freed %p\n", ctx);
        free_percpu(ctx->cpu);
        kmem_cache_free(kioctx_cachep, ctx);
 }
 
 static void put_ioctx(struct kioctx *ctx)
 {
-       if (unlikely(atomic_dec_and_test(&ctx->users)))
+       if (percpu_ref_put(&ctx->users))
                free_ioctx(ctx);
 }
 
@@ -377,7 +380,10 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
 
        ctx->max_reqs = nr_events;
 
-       atomic_set(&ctx->users, 2);
+       percpu_ref_init(&ctx->users);
+       rcu_read_lock();
+       percpu_ref_get(&ctx->users);
+       rcu_read_unlock();
        spin_lock_init(&ctx->ctx_lock);
        spin_lock_init(&ctx->completion_lock);
        mutex_init(&ctx->ring_lock);
@@ -433,12 +439,9 @@ out_freectx:
  */
 static void kill_ioctx(struct kioctx *ctx)
 {
-       if (!atomic_xchg(&ctx->dead, 1)) {
+       if (percpu_ref_kill(&ctx->users)) {
                hlist_del_rcu(&ctx->list);
                synchronize_rcu();
-
-               wake_up_all(&ctx->wait);
-
                put_ioctx(ctx);
        }
 }
@@ -473,12 +476,6 @@ void exit_aio(struct mm_struct *mm)
        struct hlist_node *p, *n;
 
        hlist_for_each_entry_safe(ctx, p, n, &mm->ioctx_list, list) {
-               if (1 != atomic_read(&ctx->users))
-                       printk(KERN_DEBUG
-                               "exit_aio:ioctx still alive: %d %d %d\n",
-                               atomic_read(&ctx->users),
-                               atomic_read(&ctx->dead),
-                               atomic_read(&ctx->reqs_available));
                /*
                 * We don't need to bother with munmap() here -
                 * exit_mmap(mm) is coming and it'll unmap everything.
@@ -597,8 +594,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
 
        hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list)
                if (ctx->user_id == ctx_id){
-                       BUG_ON(atomic_read(&ctx->dead));
-                       atomic_inc(&ctx->users);
+                       percpu_ref_get(&ctx->users);
                        ret = ctx;
                        break;
                }
@@ -838,7 +834,7 @@ static int read_events(struct kioctx *ctx,
                i += ret;
                if (i >= min_nr)
                        break;
-               if (unlikely(atomic_read(&ctx->dead))) {
+               if (unlikely(percpu_ref_dead(&ctx->users))) {
                        ret = -EINVAL;
                        break;
                }
-- 
1.7.12

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