[AIO]: Split ki_user_obj into a 2 member union.

This documents how this member is used in two
ways, 1) as a pointer to a user ioctx and 2)
as a pointer to a task struct to wake up.

diff --git a/fs/aio.c b/fs/aio.c
index 597648e214a7282193b280e8601609aae8a50aef..ed984b58fe7d602fa8c9045e64d4ea72cba37f8e 100644 (file)
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -394,7 +394,7 @@ static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx)
        req->ki_ctx = ctx;
        req->ki_cancel = NULL;
        req->ki_retry = NULL;
-       req->ki_user_obj = NULL;
+       req->ki_obj.user = NULL;
 
        /* Check if the completion queue has enough free space to
         * accept an event from this io.
@@ -437,7 +437,7 @@ static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
 {
        req->ki_ctx = NULL;
        req->ki_filp = NULL;
-       req->ki_user_obj = NULL;
+       req->ki_obj.user = NULL;
        kmem_cache_free(kiocb_cachep, req);
        ctx->reqs_active--;
 
@@ -605,7 +605,7 @@ void fastcall kick_iocb(struct kiocb *iocb)
         * single context. */
        if (is_sync_kiocb(iocb)) {
                kiocbSetKicked(iocb);
-               wake_up_process(iocb->ki_user_obj);
+               wake_up_process(iocb->ki_obj.tsk);
                return;
        }
 
@@ -653,7 +653,7 @@ int fastcall aio_complete(struct kiocb *iocb, long res, long res2)
                        spin_unlock_irq(&ctx->ctx_lock);
                }
                /* sync iocbs put the task here for us */
-               wake_up_process(iocb->ki_user_obj);
+               wake_up_process(iocb->ki_obj.tsk);
                return ret;
        }
 
@@ -673,13 +673,13 @@ int fastcall aio_complete(struct kiocb *iocb, long res, long res2)
        event = aio_ring_event(info, tail, KM_IRQ0);
        tail = (tail + 1) % info->nr;
 
-       event->obj = (u64)(unsigned long)iocb->ki_user_obj;
+       event->obj = (u64)(unsigned long)iocb->ki_obj.user;
        event->data = iocb->ki_user_data;
        event->res = res;
        event->res2 = res2;
 
        dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
-               ctx, tail, iocb, iocb->ki_user_obj, iocb->ki_user_data,
+               ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
                res, res2);
 
        /* after flagging the request as done, we
@@ -1022,7 +1022,7 @@ int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                goto out_put_req;
        }
 
-       req->ki_user_obj = user_iocb;
+       req->ki_obj.user = user_iocb;
        req->ki_user_data = iocb->aio_data;
        req->ki_pos = iocb->aio_offset;
 
@@ -1148,7 +1148,7 @@ struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key
        /* TODO: use a hash or array, this sucks. */
        list_for_each(pos, &ctx->active_reqs) {
                struct kiocb *kiocb = list_kiocb(pos);
-               if (kiocb->ki_user_obj == iocb && kiocb->ki_key == key)
+               if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
                        return kiocb;
        }
        return NULL;
@@ -1195,7 +1195,7 @@ asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
                struct io_event tmp;
                pr_debug("calling cancel\n");
                memset(&tmp, 0, sizeof(tmp));
-               tmp.obj = (u64)(unsigned long)kiocb->ki_user_obj;
+               tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
                tmp.data = kiocb->ki_user_data;
                ret = cancel(kiocb, &tmp);
                if (!ret) {

diff --git a/include/linux/aio.h b/include/linux/aio.h
index 6e88c87c901e94f466434e2b239db975df213d4d..93fe7880074034fbce00c574c94d8e6c1e858fc2 100644 (file)
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -59,7 +59,10 @@ struct kiocb {
        struct list_head        ki_list;        /* the aio core uses this
                                                 * for cancellation */
 
-       void __user             *ki_user_obj;   /* pointer to userland's iocb */
+       union {
+               void __user             *user;
+               struct task_struct      *tsk;
+       } ki_obj;
        __u64                   ki_user_data;   /* user's data for completion */
        loff_t                  ki_pos;
 
@@ -76,7 +79,7 @@ struct kiocb {
                (x)->ki_filp = (filp);                  \
                (x)->ki_ctx = &tsk->active_mm->default_kioctx;  \
                (x)->ki_cancel = NULL;                  \
-               (x)->ki_user_obj = tsk;                 \
+               (x)->ki_obj.tsk = tsk;                  \
        } while (0)
 
 #define AIO_RING_MAGIC                 0xa10a10a1