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    Subject[PATCH 24/26] 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 bde360d..931606b 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;
    @@ -343,7 +343,7 @@ 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);
    }

    @@ -372,8 +372,11 @@ 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);
    @@ -445,7 +448,7 @@ 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();
    @@ -491,12 +494,6 @@ 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.
    @@ -507,7 +504,7 @@ 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);
    }
    @@ -619,7 +616,7 @@ 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;
    }
    @@ -839,7 +836,7 @@ retry:
    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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