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Subject[PATCH 24/32] aio: Percpu ioctx refcount
Date
This just converts the ioctx refcount to the new generic dynamic percpu
refcount code.

Signed-off-by: Kent Overstreet <koverstreet@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


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