[PATCH 24/32] 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 | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index e415b33..b26ad5c 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>
@@ -65,8 +66,7 @@ struct kioctx_cpu {
 };
 
 struct kioctx {
-       atomic_t                users;
-       atomic_t                dead;
+       struct percpu_ref       users;
 
        /* This needs improving */
        unsigned long           user_id;
@@ -340,7 +340,7 @@ static void free_ioctx(struct kioctx *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);
 }
 
@@ -369,8 +369,11 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
 
        ctx->max_reqs = nr_events;
 
-       atomic_set(&ctx->users, 2);
-       atomic_set(&ctx->dead, 0);
+       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);
@@ -442,7 +445,7 @@ static void kill_ioctx_rcu(struct rcu_head *head)
  */
 static void kill_ioctx(struct kioctx *ctx)
 {
-       if (!atomic_xchg(&ctx->dead, 1)) {
+       if (percpu_ref_kill(&ctx->users)) {
                hlist_del_rcu(&ctx->list);
                /* Between hlist_del_rcu() and dropping the initial ref */
                synchronize_rcu();
@@ -488,12 +491,6 @@ 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.
@@ -504,7 +501,7 @@ void exit_aio(struct mm_struct *mm)
                 */
                ctx->mmap_size = 0;
 
-               if (!atomic_xchg(&ctx->dead, 1)) {
+               if (percpu_ref_kill(&ctx->users)) {
                        hlist_del_rcu(&ctx->list);
                        call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
                }
@@ -616,7 +613,7 @@ 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){
-                       atomic_inc(&ctx->users);
+                       percpu_ref_get(&ctx->users);
                        ret = ctx;
                        break;
                }
@@ -830,7 +827,7 @@ static bool aio_read_events(struct kioctx *ctx, long 
min_nr, long nr,
        if (ret > 0)
                *i += ret;
 
-       if (unlikely(atomic_read(&ctx->dead)))
+       if (unlikely(percpu_ref_dead(&ctx->users)))
                ret = -EINVAL;
 
        if (!*i)
-- 
1.7.12

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/