patch: aio + bio for raw io

[Benjamin LaHaise <bcrl@redhat.com>]

Quick message: this patch makes aio use bio directly for brw_kvec_async.  
This is against yesterday's patchset.  Comments?

		-ben

===== fs/Makefile 1.15 vs 1.16 =====
--- 1.15/fs/Makefile	Wed Jan 30 02:21:55 2002
+++ 1.16/fs/Makefile	Fri Feb  8 14:57:54 2002
@@ -22,6 +22,7 @@
 obj-y += noquot.o
 endif
 
+export-objs += aio.o
 obj-y += aio.o
 
 subdir-$(CONFIG_PROC_FS)	+= proc
===== fs/buffer.c 1.60 vs 1.61 =====
--- 1.60/fs/buffer.c	Tue Jan 15 05:53:34 2002
+++ 1.61/fs/buffer.c	Fri Feb  8 17:22:14 2002
@@ -54,6 +54,8 @@
 #include <asm/bitops.h>
 #include <asm/mmu_context.h>
 
+extern struct bio *bio_setup_from_kvec(int gfp_mask, struct kvec *kvec);
+
 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
 #define NR_RESERVED (10*MAX_BUF_PER_PAGE)
 #define MAX_UNUSED_BUFFERS NR_RESERVED+20 /* don't ever have more than this 
@@ -2764,16 +2766,26 @@
  * It is up to the caller to make sure that there are enough blocks
  * passed in to completely map the iobufs to disk.
  */
+static int brw_kvec_end_io(struct bio *bio, int nr_sectors)
+{
+	kvec_cb_t cb = bio->cb;
+	int res = nr_sectors * 512;
+	if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+		res = -EIO;
+	bio_put(bio);
+	cb.fn(cb.data, cb.vec, res);
+	return 0;
+}
 
-int brw_kvec_async(int rw, kvec_cb_t cb, kdev_t dev, unsigned blocks, unsigned long blknr, int sector_shift)
+int brw_kvec_async(int rw, kvec_cb_t cb, kdev_t dev, unsigned blocks, sector_t blknr, int sector_shift)
 {
 	struct kvec	*vec = cb.vec;
 	struct kveclet	*veclet;
-	int		err;
 	int		length;
 	unsigned	sector_size = 1 << sector_shift;
 	int		i;
 
+	struct bio	*bio;
 	struct brw_cb	*brw_cb;
 
 	if (!vec->nr)
@@ -2795,125 +2807,21 @@
 	if (length < (blocks << sector_shift))
 		BUG();
 
-	/* 
-	 * OK to walk down the iovec doing page IO on each page we find. 
-	 */
-	err = 0;
-
 	if (!blocks) {
 		printk("brw_kiovec_async: !i\n");
 		return -EINVAL;
 	}
 
-	/* FIXME: tie into userbeans here */
-	brw_cb = kmalloc(sizeof(*brw_cb) + (blocks * sizeof(struct buffer_head *)), GFP_KERNEL);
-	if (!brw_cb)
+	bio = bio_setup_from_kvec(GFP_KERNEL, vec);
+	if (unlikely(!bio))
 		return -ENOMEM;
-
-	brw_cb->cb = cb;
-	brw_cb->nr = 0;
-
-	/* This is ugly.  FIXME. */
-	for (i=0, veclet=vec->veclet; i<vec->nr; i++,veclet++) {
-		struct page *page = veclet->page;
-		unsigned offset = veclet->offset;
-		unsigned length = veclet->length;
-
-		if (!page)
-			BUG();
-
-		while (length > 0) {
-			struct buffer_head *tmp;
-			tmp = kmem_cache_alloc(bh_cachep, GFP_NOIO);
-			err = -ENOMEM;
-			if (!tmp)
-				goto error;
-
-			tmp->b_dev = B_FREE;
-			tmp->b_size = sector_size;
-			set_bh_page(tmp, page, offset);
-			tmp->b_this_page = tmp;
-
-			init_buffer(tmp, end_buffer_io_kiobuf_async, NULL);
-			tmp->b_dev = dev;
-			tmp->b_blocknr = blknr++;
-			tmp->b_state = (1 << BH_Mapped) | (1 << BH_Lock)
-					| (1 << BH_Req);
-			tmp->b_private = brw_cb;
-
-			if (rw == WRITE) {
-				set_bit(BH_Uptodate, &tmp->b_state);
-				clear_bit(BH_Dirty, &tmp->b_state);
-			}
-
-			brw_cb->bh[brw_cb->nr++] = tmp;
-			length -= sector_size;
-			offset += sector_size;
-
-			if (offset >= PAGE_SIZE) {
-				offset = 0;
-				break;
-			}
-
-			if (brw_cb->nr >= blocks)
-				goto submit;
-		} /* End of block loop */
-	} /* End of page loop */		
-
-submit:
-	atomic_set(&brw_cb->io_count, brw_cb->nr+1);
-	/* okay, we've setup all our io requests, now fire them off! */
-	for (i=0; i<brw_cb->nr; i++) 
-		submit_bh(rw, brw_cb->bh[i]);
-	brw_cb_put(brw_cb);
+	bio->cb = cb;
+	bio->bi_sector = blknr;
+	bio->bi_dev = dev;
+	bio->bi_vcnt = vec->nr;
+	bio->bi_size = length;
+	bio->bi_end_io = brw_kvec_end_io;
+	submit_bio(rw, bio);
 
 	return 0;
-
-error:
-	/* Walk brw_cb_table freeing all the goop associated with each kiobuf */
-	if (brw_cb) {
-		/* We got an error allocating the bh'es.  Just free the current
-		   buffer_heads and exit. */
-		for (i=0; i<brw_cb->nr; i++)
-			kmem_cache_free(bh_cachep, brw_cb->bh[i]);
-		kfree(brw_cb);
-	}
-
-	return err;
-}
-#if 0
-int brw_kiovec(int rw, int nr, struct kiobuf *iovec[],
-		kdev_t dev, int nr_blocks, unsigned long b[], int sector_size)
-{
-	int i;
-	int transferred = 0;
-	int err = 0;
-
-	if (!nr)
-		return 0;
-
-	/* queue up and trigger the io */
-	err = brw_kiovec_async(rw, nr, iovec, dev, nr_blocks, b, sector_size);
-	if (err)
-		goto out;
-
-	/* wait on the last iovec first -- it's more likely to finish last */
-	for (i=nr; --i >= 0; )
-		kiobuf_wait_for_io(iovec[i]);
-
-	run_task_queue(&tq_disk);
-
-	/* okay, how much data actually got through? */
-	for (i=0; i<nr; i++) {
-		if (iovec[i]->errno) {
-			if (!err)
-				err = iovec[i]->errno;
-			break;
-		}
-		transferred += iovec[i]->length;
-	}
-
-out:
-	return transferred ? transferred : err;
 }
-#endif
===== fs/bio.c 1.14 vs 1.15 =====
--- 1.14/fs/bio.c	Thu Feb  7 16:13:25 2002
+++ 1.15/fs/bio.c	Fri Feb  8 17:22:14 2002
@@ -151,6 +151,22 @@
 	return NULL;
 }
 
+struct bio *bio_setup_from_kvec(int gfp_mask, struct kvec *kvec)
+{
+	struct bio *bio = mempool_alloc(bio_pool, gfp_mask);
+	struct bio_vec *bvl = NULL;
+
+	if (unlikely(!bio))
+		return NULL;
+
+	bio->bi_max = kvec->max_nr;
+	bio_init(bio);
+	bio->bi_destructor = bio_destructor;
+	bio->bi_io_vec = (struct bio_vec *)kvec->veclet;	/* shoot me */
+	bio->bi_flags |= 1 << BIO_CLONED;	/* don't free the vec */
+	return bio;
+}
+
 /**
  * bio_put - release a reference to a bio
  * @bio:   bio to release reference to
===== include/linux/kiovec.h 1.1 vs 1.2 =====
--- 1.1/include/linux/kiovec.h	Sat Jan 12 02:19:10 2002
+++ 1.2/include/linux/kiovec.h	Fri Feb  8 15:00:54 2002
@@ -6,8 +6,8 @@
 
 struct kveclet {
 	struct page	*page;
-	unsigned	offset;
 	unsigned	length;
+	unsigned	offset;
 };
 
 struct kvec {
===== include/linux/bio.h 1.11 vs 1.12 =====
--- 1.11/include/linux/bio.h	Wed Feb  6 01:23:04 2002
+++ 1.12/include/linux/bio.h	Fri Feb  8 17:22:23 2002
@@ -26,6 +26,8 @@
 #define BIO_VMERGE_BOUNDARY	0
 #endif
 
+#include <linux/kiovec.h>
+
 #define BIO_DEBUG
 
 #ifdef BIO_DEBUG
@@ -91,6 +93,7 @@
 	void			*bi_private;
 
 	bio_destructor_t	*bi_destructor;	/* destructor */
+	kvec_cb_t		cb;
 };
 
 /*
===== fs/aio.c 1.1 vs 1.2 =====
--- 1.1/fs/aio.c	Wed Jan 30 13:12:34 2002
+++ 1.2/fs/aio.c	Fri Feb  8 14:58:10 2002
@@ -37,6 +37,7 @@
 #include <linux/smp_lock.h>
 #include <linux/compiler.h>
 #include <linux/poll.h>
+#include <linux/module.h>
 
 #include <asm/uaccess.h>
 
@@ -964,3 +965,8 @@
 }
 
 __initcall(aio_setup);
+EXPORT_SYMBOL_GPL(generic_file_kvec_read);
+EXPORT_SYMBOL_GPL(generic_file_aio_read);
+EXPORT_SYMBOL_GPL(generic_file_kvec_write);
+EXPORT_SYMBOL_GPL(generic_file_aio_write);
+EXPORT_SYMBOL_GPL(generic_file_new_read);