aio: remove request submission batching

This should be useless now that we have on-stack plugging. So lets just
kill it.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

fs/aio.c

@@ -34,8 +34,6 @@
 #include <linux/security.h>
 #include <linux/eventfd.h>
 #include <linux/blkdev.h>
-#include <linux/mempool.h>
-#include <linux/hash.h>
 #include <linux/compat.h>
 
 #include <asm/kmap_types.h>
@@ -65,14 +63,6 @@ static DECLARE_WORK(fput_work, aio_fput_routine);
 static DEFINE_SPINLOCK(fput_lock);
 static LIST_HEAD(fput_head);
 
-#define AIO_BATCH_HASH_BITS	3 /* allocated on-stack, so don't go crazy */
-#define AIO_BATCH_HASH_SIZE	(1 << AIO_BATCH_HASH_BITS)
-struct aio_batch_entry {
-	struct hlist_node list;
-	struct address_space *mapping;
-};
-mempool_t *abe_pool;
-
 static void aio_kick_handler(struct work_struct *);
 static void aio_queue_work(struct kioctx *);
 
@@ -86,8 +76,7 @@ static int __init aio_setup(void)
 	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 
 	aio_wq = create_workqueue("aio");
-	abe_pool = mempool_create_kmalloc_pool(1, sizeof(struct aio_batch_entry));
-	BUG_ON(!aio_wq || !abe_pool);
+	BUG_ON(!aio_wq);
 
 	pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
 
@@ -1512,59 +1501,8 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
 	return 0;
 }
 
-static void aio_batch_add(struct address_space *mapping,
-			  struct hlist_head *batch_hash)
-{
-	struct aio_batch_entry *abe;
-	struct hlist_node *pos;
-	unsigned bucket;
-
-	bucket = hash_ptr(mapping, AIO_BATCH_HASH_BITS);
-	hlist_for_each_entry(abe, pos, &batch_hash[bucket], list) {
-		if (abe->mapping == mapping)
-			return;
-	}
-
-	abe = mempool_alloc(abe_pool, GFP_KERNEL);
-
-	/*
-	 * we should be using igrab here, but
-	 * we don't want to hammer on the global
-	 * inode spinlock just to take an extra
-	 * reference on a file that we must already
-	 * have a reference to.
-	 *
-	 * When we're called, we always have a reference
-	 * on the file, so we must always have a reference
-	 * on the inode, so ihold() is safe here.
-	 */
-	ihold(mapping->host);
-	abe->mapping = mapping;
-	hlist_add_head(&abe->list, &batch_hash[bucket]);
-	return;
-}
-
-static void aio_batch_free(struct hlist_head *batch_hash)
-{
-	struct aio_batch_entry *abe;
-	struct hlist_node *pos, *n;
-	int i;
-
-	/*
-	 * TODO: kill this
-	 */
-	for (i = 0; i < AIO_BATCH_HASH_SIZE; i++) {
-		hlist_for_each_entry_safe(abe, pos, n, &batch_hash[i], list) {
-			iput(abe->mapping->host);
-			hlist_del(&abe->list);
-			mempool_free(abe, abe_pool);
-		}
-	}
-}
-
 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
-			 struct iocb *iocb, struct hlist_head *batch_hash,
-			 bool compat)
+			 struct iocb *iocb, bool compat)
 {
 	struct kiocb *req;
 	struct file *file;
@@ -1638,11 +1576,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 			;
 	}
 	spin_unlock_irq(&ctx->ctx_lock);
-	if (req->ki_opcode == IOCB_CMD_PREAD ||
-	    req->ki_opcode == IOCB_CMD_PREADV ||
-	    req->ki_opcode == IOCB_CMD_PWRITE ||
-	    req->ki_opcode == IOCB_CMD_PWRITEV)
-		aio_batch_add(file->f_mapping, batch_hash);
 
 	aio_put_req(req);	/* drop extra ref to req */
 	return 0;
@@ -1659,7 +1592,6 @@ long do_io_submit(aio_context_t ctx_id, long nr,
 	struct kioctx *ctx;
 	long ret = 0;
 	int i;
-	struct hlist_head batch_hash[AIO_BATCH_HASH_SIZE] = { { 0, }, };
 	struct blk_plug plug;
 
 	if (unlikely(nr < 0))
@@ -1697,12 +1629,11 @@ long do_io_submit(aio_context_t ctx_id, long nr,
 			break;
 		}
 
-		ret = io_submit_one(ctx, user_iocb, &tmp, batch_hash, compat);
+		ret = io_submit_one(ctx, user_iocb, &tmp, compat);
 		if (ret)
 			break;
 	}
 	blk_finish_plug(&plug);
-	aio_batch_free(batch_hash);
 
 	put_ioctx(ctx);
 	return i ? i : ret;