aio: separate out ring reservation from req allocation

This is in preparation for certain types of IO not needing a ring
reserveration.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 17 insertions, 13 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 6f32d30d7f45..7556709b9b8d 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -902,7 +902,7 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
         local_irq_restore(flags);
 }
 
-static bool get_reqs_available(struct kioctx *ctx)
+static bool __get_reqs_available(struct kioctx *ctx)
 {
         struct kioctx_cpu *kcpu;
         bool ret = false;
@@ -994,6 +994,14 @@ static void user_refill_reqs_available(struct kioctx *ctx)
         spin_unlock_irq(&ctx->completion_lock);
 }
 
+static bool get_reqs_available(struct kioctx *ctx)
+{
+        if (__get_reqs_available(ctx))
+                return true;
+        user_refill_reqs_available(ctx);
+        return __get_reqs_available(ctx);
+}
+
 /* aio_get_req
  *      Allocate a slot for an aio request.
  * Returns NULL if no requests are free.
@@ -1002,24 +1010,15 @@ static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
 {
         struct aio_kiocb *req;
 
-        if (!get_reqs_available(ctx)) {
-                user_refill_reqs_available(ctx);
-                if (!get_reqs_available(ctx))
-                        return NULL;
-        }
-
         req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
         if (unlikely(!req))
-                goto out_put;
+                return NULL;
 
         percpu_ref_get(&ctx->reqs);
         INIT_LIST_HEAD(&req->ki_list);
         refcount_set(&req->ki_refcnt, 0);
         req->ki_ctx = ctx;
         return req;
-out_put:
-        put_reqs_available(ctx, 1);
-        return NULL;
 }
 
 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
@@ -1807,9 +1806,13 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                 return -EINVAL;
         }
 
+        if (!get_reqs_available(ctx))
+                return -EAGAIN;
+
+        ret = -EAGAIN;
         req = aio_get_req(ctx);
         if (unlikely(!req))
-                return -EAGAIN;
+                goto out_put_reqs_available;
 
         if (iocb.aio_flags & IOCB_FLAG_RESFD) {
                 /*
@@ -1872,11 +1875,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                 goto out_put_req;
         return 0;
 out_put_req:
-        put_reqs_available(ctx, 1);
         percpu_ref_put(&ctx->reqs);
         if (req->ki_eventfd)
                 eventfd_ctx_put(req->ki_eventfd);
         kmem_cache_free(kiocb_cachep, req);
+out_put_reqs_available:
+        put_reqs_available(ctx, 1);
         return ret;
 }