1 files changed, 15 insertions, 101 deletions

diff --git a/fs/aio.c b/fs/aio.c
index d3bff60..263ebce 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -510,108 +510,27 @@ void exit_aio(struct mm_struct *mm)
  * This prevents races between the aio code path referencing the
  * req (after submitting it) and aio_complete() freeing the req.
  */
-static struct kiocb *__aio_get_req(struct kioctx *ctx)
+static inline struct kiocb *aio_get_req(struct kioctx *ctx)
 {
-	struct kiocb *req = NULL;
+	struct kiocb *req;
+
+	if (atomic_read(&ctx->reqs_active) >= ctx->ring_info.nr)
+		return NULL;
+
+	if (atomic_inc_return(&ctx->reqs_active) > ctx->ring_info.nr - 1)
+		goto out_put;
 
 	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
 	if (unlikely(!req))
-		return NULL;
+		goto out_put;
 
 	atomic_set(&req->ki_users, 2);
 	req->ki_ctx = ctx;
 
 	return req;
-}
-
-/*
- * struct kiocb's are allocated in batches to reduce the number of
- * times the ctx lock is acquired and released.
- */
-#define KIOCB_BATCH_SIZE	32L
-struct kiocb_batch {
-	struct list_head head;
-	long count; /* number of requests left to allocate */
-};
-
-static void kiocb_batch_init(struct kiocb_batch *batch, long total)
-{
-	INIT_LIST_HEAD(&batch->head);
-	batch->count = total;
-}
-
-static void kiocb_batch_free(struct kioctx *ctx, struct kiocb_batch *batch)
-{
-	struct kiocb *req, *n;
-
-	if (list_empty(&batch->head))
-		return;
-
-	spin_lock_irq(&ctx->ctx_lock);
-	list_for_each_entry_safe(req, n, &batch->head, ki_batch) {
-		list_del(&req->ki_batch);
-		kmem_cache_free(kiocb_cachep, req);
-		atomic_dec(&ctx->reqs_active);
-	}
-	spin_unlock_irq(&ctx->ctx_lock);
-}
-
-/*
- * Allocate a batch of kiocbs.  This avoids taking and dropping the
- * context lock a lot during setup.
- */
-static int kiocb_batch_refill(struct kioctx *ctx, struct kiocb_batch *batch)
-{
-	unsigned short allocated, to_alloc;
-	long avail;
-	struct kiocb *req, *n;
-
-	to_alloc = min(batch->count, KIOCB_BATCH_SIZE);
-	for (allocated = 0; allocated < to_alloc; allocated++) {
-		req = __aio_get_req(ctx);
-		if (!req)
-			/* allocation failed, go with what we've got */
-			break;
-		list_add(&req->ki_batch, &batch->head);
-	}
-
-	if (allocated == 0)
-		goto out;
-
-	spin_lock_irq(&ctx->ctx_lock);
-
-	avail = ctx->ring_info.nr - atomic_read(&ctx->reqs_active) - 1;
-	BUG_ON(avail < 0);
-	if (avail < allocated) {
-		/* Trim back the number of requests. */
-		list_for_each_entry_safe(req, n, &batch->head, ki_batch) {
-			list_del(&req->ki_batch);
-			kmem_cache_free(kiocb_cachep, req);
-			if (--allocated <= avail)
-				break;
-		}
-	}
-
-	batch->count -= allocated;
-	atomic_add(allocated, &ctx->reqs_active);
-
-	spin_unlock_irq(&ctx->ctx_lock);
-
-out:
-	return allocated;
-}
-
-static inline struct kiocb *aio_get_req(struct kioctx *ctx,
-					struct kiocb_batch *batch)
-{
-	struct kiocb *req;
-
-	if (list_empty(&batch->head))
-		if (kiocb_batch_refill(ctx, batch) == 0)
-			return NULL;
-	req = list_first_entry(&batch->head, struct kiocb, ki_batch);
-	list_del(&req->ki_batch);
-	return req;
+out_put:
+	atomic_dec(&ctx->reqs_active);
+	return NULL;
 }
 
 static void kiocb_free(struct kiocb *req)
@@ -1198,8 +1117,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
 }
 
 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
-			 struct iocb *iocb, struct kiocb_batch *batch,
-			 bool compat)
+			 struct iocb *iocb, bool compat)
 {
 	struct kiocb *req;
 	ssize_t ret;
@@ -1220,7 +1138,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 		return -EINVAL;
 	}
 
-	req = aio_get_req(ctx, batch);  /* returns with 2 references to req */
+	req = aio_get_req(ctx);  /* returns with 2 references to req */
 	if (unlikely(!req))
 		return -EAGAIN;
 
@@ -1293,7 +1211,6 @@ long do_io_submit(aio_context_t ctx_id, long nr,
 	long ret = 0;
 	int i = 0;
 	struct blk_plug plug;
-	struct kiocb_batch batch;
 
 	if (unlikely(nr < 0))
 		return -EINVAL;
@@ -1310,8 +1227,6 @@ long do_io_submit(aio_context_t ctx_id, long nr,
 		return -EINVAL;
 	}
 
-	kiocb_batch_init(&batch, nr);
-
 	blk_start_plug(&plug);
 
 	/*
@@ -1332,13 +1247,12 @@ long do_io_submit(aio_context_t ctx_id, long nr,
 			break;
 		}
 
-		ret = io_submit_one(ctx, user_iocb, &tmp, &batch, compat);
+		ret = io_submit_one(ctx, user_iocb, &tmp, compat);
 		if (ret)
 			break;
 	}
 	blk_finish_plug(&plug);
 
-	kiocb_batch_free(ctx, &batch);
 	put_ioctx(ctx);
 	return i ? i : ret;
 }