diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 4febe2e..ad72741 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -69,11 +69,27 @@
 
 	/* IO errors */
 	int errors;
+	int mirror_num;
 
 	/* for reads, this is the bio we are copying the data into */
 	struct bio *orig_bio;
+
+	/*
+	 * the start of a variable length array of checksums only
+	 * used by reads
+	 */
+	u32 sums;
 };
 
+static inline int compressed_bio_size(struct btrfs_root *root,
+				      unsigned long disk_size)
+{
+	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
+	return sizeof(struct compressed_bio) +
+		((disk_size + root->sectorsize - 1) / root->sectorsize) *
+		csum_size;
+}
+
 static struct bio *compressed_bio_alloc(struct block_device *bdev,
 					u64 first_byte, gfp_t gfp_flags)
 {
@@ -96,6 +112,47 @@
 	return bio;
 }
 
+static int check_compressed_csum(struct inode *inode,
+				 struct compressed_bio *cb,
+				 u64 disk_start)
+{
+	int ret;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct page *page;
+	unsigned long i;
+	char *kaddr;
+	u32 csum;
+	u32 *cb_sum = &cb->sums;
+
+	if (btrfs_test_opt(root, NODATASUM) ||
+	    btrfs_test_flag(inode, NODATASUM))
+		return 0;
+
+	for (i = 0; i < cb->nr_pages; i++) {
+		page = cb->compressed_pages[i];
+		csum = ~(u32)0;
+
+		kaddr = kmap_atomic(page, KM_USER0);
+		csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE);
+		btrfs_csum_final(csum, (char *)&csum);
+		kunmap_atomic(kaddr, KM_USER0);
+
+		if (csum != *cb_sum) {
+			printk("btrfs csum failed ino %lu extent %llu csum %u "
+			       "wanted %u mirror %d\n", inode->i_ino,
+			       (unsigned long long)disk_start,
+			       csum, *cb_sum, cb->mirror_num);
+			ret = -EIO;
+			goto fail;
+		}
+		cb_sum++;
+
+	}
+	ret = 0;
+fail:
+	return ret;
+}
+
 /* when we finish reading compressed pages from the disk, we
  * decompress them and then run the bio end_io routines on the
  * decompressed pages (in the inode address space).
@@ -124,16 +181,21 @@
 	if (!atomic_dec_and_test(&cb->pending_bios))
 		goto out;
 
+	inode = cb->inode;
+	ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9);
+	if (ret)
+		goto csum_failed;
+
 	/* ok, we're the last bio for this extent, lets start
 	 * the decompression.
 	 */
-	inode = cb->inode;
 	tree = &BTRFS_I(inode)->io_tree;
 	ret = btrfs_zlib_decompress_biovec(cb->compressed_pages,
 					cb->start,
 					cb->orig_bio->bi_io_vec,
 					cb->orig_bio->bi_vcnt,
 					cb->compressed_len);
+csum_failed:
 	if (ret)
 		cb->errors = 1;
 
@@ -148,8 +210,21 @@
 	/* do io completion on the original bio */
 	if (cb->errors) {
 		bio_io_error(cb->orig_bio);
-	} else
+	} else {
+		int bio_index = 0;
+		struct bio_vec *bvec = cb->orig_bio->bi_io_vec;
+
+		/*
+		 * we have verified the checksum already, set page
+		 * checked so the end_io handlers know about it
+		 */
+		while(bio_index < cb->orig_bio->bi_vcnt) {
+			SetPageChecked(bvec->bv_page);
+			bvec++;
+			bio_index++;
+		}
 		bio_endio(cb->orig_bio, 0);
+	}
 
 	/* finally free the cb struct */
 	kfree(cb->compressed_pages);
@@ -277,12 +352,13 @@
 	int ret;
 
 	WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
-	cb = kmalloc(sizeof(*cb), GFP_NOFS);
+	cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
 	atomic_set(&cb->pending_bios, 0);
 	cb->errors = 0;
 	cb->inode = inode;
 	cb->start = start;
 	cb->len = len;
+	cb->mirror_num = 0;
 	cb->compressed_pages = compressed_pages;
 	cb->compressed_len = compressed_len;
 	cb->orig_bio = NULL;
@@ -290,9 +366,6 @@
 
 	bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
 
-	ret = btrfs_csum_file_bytes(root, inode, start, len);
-	BUG_ON(ret);
-
 	bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
 	bio->bi_private = cb;
 	bio->bi_end_io = end_compressed_bio_write;
@@ -325,6 +398,9 @@
 			ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
 			BUG_ON(ret);
 
+			ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
+			BUG_ON(ret);
+
 			ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
 			BUG_ON(ret);
 
@@ -348,6 +424,9 @@
 	ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
 	BUG_ON(ret);
 
+	ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
+	BUG_ON(ret);
+
 	ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
 	BUG_ON(ret);
 
@@ -510,6 +589,7 @@
 	u64 em_start;
 	struct extent_map *em;
 	int ret;
+	u32 *sums;
 
 	tree = &BTRFS_I(inode)->io_tree;
 	em_tree = &BTRFS_I(inode)->extent_tree;
@@ -521,15 +601,18 @@
 				   PAGE_CACHE_SIZE);
 	spin_unlock(&em_tree->lock);
 
-	cb = kmalloc(sizeof(*cb), GFP_NOFS);
+	compressed_len = em->block_len;
+	cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
 	atomic_set(&cb->pending_bios, 0);
 	cb->errors = 0;
 	cb->inode = inode;
+	cb->mirror_num = mirror_num;
+	sums = &cb->sums;
 
 	cb->start = em->orig_start;
-	compressed_len = em->block_len;
 	em_len = em->len;
 	em_start = em->start;
+
 	free_extent_map(em);
 	em = NULL;
 
@@ -551,11 +634,6 @@
 
 	add_ra_bio_pages(inode, em_start + em_len, cb);
 
-	if (!btrfs_test_opt(root, NODATASUM) &&
-	    !btrfs_test_flag(inode, NODATASUM)) {
-		btrfs_lookup_bio_sums(root, inode, cb->orig_bio);
-	}
-
 	/* include any pages we added in add_ra-bio_pages */
 	uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
 	cb->len = uncompressed_len;
@@ -568,6 +646,8 @@
 	for (page_index = 0; page_index < nr_pages; page_index++) {
 		page = cb->compressed_pages[page_index];
 		page->mapping = inode->i_mapping;
+		page->index = em_start >> PAGE_CACHE_SHIFT;
+
 		if (comp_bio->bi_size)
 			ret = tree->ops->merge_bio_hook(page, 0,
 							PAGE_CACHE_SIZE,
@@ -591,7 +671,16 @@
 			 */
 			atomic_inc(&cb->pending_bios);
 
-			ret = btrfs_map_bio(root, READ, comp_bio, 0, 0);
+			if (!btrfs_test_opt(root, NODATASUM) &&
+			    !btrfs_test_flag(inode, NODATASUM)) {
+				btrfs_lookup_bio_sums(root, inode, comp_bio,
+						      sums);
+			}
+			sums += (comp_bio->bi_size + root->sectorsize - 1) /
+				root->sectorsize;
+
+			ret = btrfs_map_bio(root, READ, comp_bio,
+					    mirror_num, 0);
 			BUG_ON(ret);
 
 			bio_put(comp_bio);
@@ -610,7 +699,12 @@
 	ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
 	BUG_ON(ret);
 
-	ret = btrfs_map_bio(root, READ, comp_bio, 0, 0);
+	if (!btrfs_test_opt(root, NODATASUM) &&
+	    !btrfs_test_flag(inode, NODATASUM)) {
+		btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
+	}
+
+	ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
 	BUG_ON(ret);
 
 	bio_put(comp_bio);
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 96f2ec7..242b961 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -73,6 +73,9 @@
 /* directory objectid inside the root tree */
 #define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
 
+/* holds checksums of all the data extents */
+#define BTRFS_CSUM_TREE_OBJECTID 7ULL
+
 /* orhpan objectid for tracking unlinked/truncated files */
 #define BTRFS_ORPHAN_OBJECTID -5ULL
 
@@ -84,6 +87,13 @@
 #define BTRFS_TREE_RELOC_OBJECTID -8ULL
 #define BTRFS_DATA_RELOC_TREE_OBJECTID -9ULL
 
+/*
+ * extent checksums all have this objectid
+ * this allows them to share the logging tree
+ * for fsyncs
+ */
+#define BTRFS_EXTENT_CSUM_OBJECTID -10ULL
+
 /* dummy objectid represents multiple objectids */
 #define BTRFS_MULTIPLE_OBJECTIDS -255ULL
 
@@ -634,6 +644,7 @@
 	struct btrfs_root *chunk_root;
 	struct btrfs_root *dev_root;
 	struct btrfs_root *fs_root;
+	struct btrfs_root *csum_root;
 
 	/* the log root tree is a directory of all the other log roots */
 	struct btrfs_root *log_root_tree;
@@ -716,6 +727,7 @@
 	struct btrfs_workers workers;
 	struct btrfs_workers delalloc_workers;
 	struct btrfs_workers endio_workers;
+	struct btrfs_workers endio_meta_workers;
 	struct btrfs_workers endio_write_workers;
 	struct btrfs_workers submit_workers;
 	/*
@@ -858,13 +870,12 @@
  * extent data is for file data
  */
 #define BTRFS_EXTENT_DATA_KEY	108
+
 /*
- * csum items have the checksums for data in the extents
+ * extent csums are stored in a separate tree and hold csums for
+ * an entire extent on disk.
  */
-#define BTRFS_CSUM_ITEM_KEY	120
-
-
-/* reserve 21-31 for other file/dir stuff */
+#define BTRFS_EXTENT_CSUM_KEY	128
 
 /*
  * root items point to tree roots.  There are typically in the root
@@ -1917,7 +1928,7 @@
 
 /* file-item.c */
 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
-			  struct bio *bio);
+			  struct bio *bio, u32 *dst);
 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
 			     struct btrfs_root *root,
 			     u64 objectid, u64 pos,
@@ -1929,17 +1940,16 @@
 			     struct btrfs_path *path, u64 objectid,
 			     u64 bytenr, int mod);
 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
-			   struct btrfs_root *root, struct inode *inode,
+			   struct btrfs_root *root,
 			   struct btrfs_ordered_sum *sums);
 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
-		       struct bio *bio);
+		       struct bio *bio, u64 file_start, int contig);
 int btrfs_csum_file_bytes(struct btrfs_root *root, struct inode *inode,
 			  u64 start, unsigned long len);
 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
 					  struct btrfs_root *root,
 					  struct btrfs_path *path,
-					  u64 objectid, u64 offset,
-					  int cow);
+					  u64 bytenr, int cow);
 int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root, struct btrfs_path *path,
 			u64 isize);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3eb7c25..61dc3b2 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -445,11 +445,18 @@
 	end_io_wq->error = err;
 	end_io_wq->work.func = end_workqueue_fn;
 	end_io_wq->work.flags = 0;
-	if (bio->bi_rw & (1 << BIO_RW))
+
+	if (bio->bi_rw & (1 << BIO_RW)) {
 		btrfs_queue_worker(&fs_info->endio_write_workers,
 				   &end_io_wq->work);
-	else
-		btrfs_queue_worker(&fs_info->endio_workers, &end_io_wq->work);
+	} else {
+		if (end_io_wq->metadata)
+			btrfs_queue_worker(&fs_info->endio_meta_workers,
+					   &end_io_wq->work);
+		else
+			btrfs_queue_worker(&fs_info->endio_workers,
+					   &end_io_wq->work);
+	}
 }
 
 int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
@@ -1208,6 +1215,9 @@
 	info = (struct btrfs_fs_info *)bdi->unplug_io_data;
 	list_for_each(cur, &info->fs_devices->devices) {
 		device = list_entry(cur, struct btrfs_device, dev_list);
+		if (!device->bdev)
+			continue;
+
 		bdi = blk_get_backing_dev_info(device->bdev);
 		if (bdi->unplug_io_fn) {
 			bdi->unplug_io_fn(bdi, page);
@@ -1344,7 +1354,7 @@
 	 * blocksize <= pagesize, it is basically a noop
 	 */
 	if (end_io_wq->metadata && !bio_ready_for_csum(bio)) {
-		btrfs_queue_worker(&fs_info->endio_workers,
+		btrfs_queue_worker(&fs_info->endio_meta_workers,
 				   &end_io_wq->work);
 		return;
 	}
@@ -1454,6 +1464,8 @@
 	struct buffer_head *bh;
 	struct btrfs_root *extent_root = kzalloc(sizeof(struct btrfs_root),
 						 GFP_NOFS);
+	struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root),
+						 GFP_NOFS);
 	struct btrfs_root *tree_root = kzalloc(sizeof(struct btrfs_root),
 					       GFP_NOFS);
 	struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
@@ -1470,7 +1482,7 @@
 	struct btrfs_super_block *disk_super;
 
 	if (!extent_root || !tree_root || !fs_info ||
-	    !chunk_root || !dev_root) {
+	    !chunk_root || !dev_root || !csum_root) {
 		err = -ENOMEM;
 		goto fail;
 	}
@@ -1487,6 +1499,7 @@
 	init_completion(&fs_info->kobj_unregister);
 	fs_info->tree_root = tree_root;
 	fs_info->extent_root = extent_root;
+	fs_info->csum_root = csum_root;
 	fs_info->chunk_root = chunk_root;
 	fs_info->dev_root = dev_root;
 	fs_info->fs_devices = fs_devices;
@@ -1652,6 +1665,8 @@
 	btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1);
 	btrfs_init_workers(&fs_info->endio_workers, "endio",
 			   fs_info->thread_pool_size);
+	btrfs_init_workers(&fs_info->endio_meta_workers, "endio-meta",
+			   fs_info->thread_pool_size);
 	btrfs_init_workers(&fs_info->endio_write_workers, "endio-write",
 			   fs_info->thread_pool_size);
 
@@ -1667,6 +1682,8 @@
 	btrfs_start_workers(&fs_info->delalloc_workers, 1);
 	btrfs_start_workers(&fs_info->fixup_workers, 1);
 	btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
+	btrfs_start_workers(&fs_info->endio_meta_workers,
+			    fs_info->thread_pool_size);
 	btrfs_start_workers(&fs_info->endio_write_workers,
 			    fs_info->thread_pool_size);
 
@@ -1751,6 +1768,13 @@
 	if (ret)
 		goto fail_extent_root;
 
+	ret = find_and_setup_root(tree_root, fs_info,
+				  BTRFS_CSUM_TREE_OBJECTID, csum_root);
+	if (ret)
+		goto fail_extent_root;
+
+	csum_root->track_dirty = 1;
+
 	btrfs_read_block_groups(extent_root);
 
 	fs_info->generation = generation + 1;
@@ -1761,7 +1785,7 @@
 	fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
 					       "btrfs-cleaner");
 	if (!fs_info->cleaner_kthread)
-		goto fail_extent_root;
+		goto fail_csum_root;
 
 	fs_info->transaction_kthread = kthread_run(transaction_kthread,
 						   tree_root,
@@ -1825,6 +1849,8 @@
 	filemap_write_and_wait(fs_info->btree_inode->i_mapping);
 	invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
 
+fail_csum_root:
+	free_extent_buffer(csum_root->node);
 fail_extent_root:
 	free_extent_buffer(extent_root->node);
 fail_tree_root:
@@ -1838,6 +1864,7 @@
 	btrfs_stop_workers(&fs_info->delalloc_workers);
 	btrfs_stop_workers(&fs_info->workers);
 	btrfs_stop_workers(&fs_info->endio_workers);
+	btrfs_stop_workers(&fs_info->endio_meta_workers);
 	btrfs_stop_workers(&fs_info->endio_write_workers);
 	btrfs_stop_workers(&fs_info->submit_workers);
 fail_iput:
@@ -1853,6 +1880,7 @@
 	kfree(fs_info);
 	kfree(chunk_root);
 	kfree(dev_root);
+	kfree(csum_root);
 	return ERR_PTR(err);
 }
 
@@ -2131,6 +2159,9 @@
 	if (root->fs_info->dev_root->node);
 		free_extent_buffer(root->fs_info->dev_root->node);
 
+	if (root->fs_info->csum_root->node);
+		free_extent_buffer(root->fs_info->csum_root->node);
+
 	btrfs_free_block_groups(root->fs_info);
 
 	del_fs_roots(fs_info);
@@ -2141,6 +2172,7 @@
 	btrfs_stop_workers(&fs_info->delalloc_workers);
 	btrfs_stop_workers(&fs_info->workers);
 	btrfs_stop_workers(&fs_info->endio_workers);
+	btrfs_stop_workers(&fs_info->endio_meta_workers);
 	btrfs_stop_workers(&fs_info->endio_write_workers);
 	btrfs_stop_workers(&fs_info->submit_workers);
 
@@ -2163,6 +2195,7 @@
 	kfree(fs_info->tree_root);
 	kfree(fs_info->chunk_root);
 	kfree(fs_info->dev_root);
+	kfree(fs_info->csum_root);
 	return 0;
 }
 
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index c3dfe2a..7449ecf 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1732,6 +1732,9 @@
 	int whole_page;
 	int ret;
 
+	if (err)
+		uptodate = 0;
+
 	do {
 		struct page *page = bvec->bv_page;
 		tree = &BTRFS_I(page->mapping->host)->io_tree;
@@ -1761,6 +1764,8 @@
 			if (ret == 0) {
 				uptodate =
 					test_bit(BIO_UPTODATE, &bio->bi_flags);
+				if (err)
+					uptodate = 0;
 				continue;
 			}
 		}
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 234ed44..a3ad2ce 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -74,8 +74,7 @@
 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
 					  struct btrfs_root *root,
 					  struct btrfs_path *path,
-					  u64 objectid, u64 offset,
-					  int cow)
+					  u64 bytenr, int cow)
 {
 	int ret;
 	struct btrfs_key file_key;
@@ -87,9 +86,9 @@
 		btrfs_super_csum_size(&root->fs_info->super_copy);
 	int csums_in_item;
 
-	file_key.objectid = objectid;
-	file_key.offset = offset;
-	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+	file_key.offset = bytenr;
+	btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 	ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 	if (ret < 0)
 		goto fail;
@@ -100,11 +99,10 @@
 			goto fail;
 		path->slots[0]--;
 		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-		if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
-		    found_key.objectid != objectid) {
+		if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
 			goto fail;
-		}
-		csum_offset = (offset - found_key.offset) >>
+
+		csum_offset = (bytenr - found_key.offset) >>
 				root->fs_info->sb->s_blocksize_bits;
 		csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 		csums_in_item /= csum_size;
@@ -143,7 +141,7 @@
 }
 
 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
-			  struct bio *bio)
+			  struct bio *bio, u32 *dst)
 {
 	u32 sum;
 	struct bio_vec *bvec = bio->bi_io_vec;
@@ -151,6 +149,7 @@
 	u64 offset;
 	u64 item_start_offset = 0;
 	u64 item_last_offset = 0;
+	u64 disk_bytenr;
 	u32 diff;
 	u16 csum_size =
 		btrfs_super_csum_size(&root->fs_info->super_copy);
@@ -165,21 +164,22 @@
 
 	WARN_ON(bio->bi_vcnt <= 0);
 
+	disk_bytenr = (u64)bio->bi_sector << 9;
 	while(bio_index < bio->bi_vcnt) {
 		offset = page_offset(bvec->bv_page) + bvec->bv_offset;
-		ret = btrfs_find_ordered_sum(inode, offset, &sum);
+		ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
 		if (ret == 0)
 			goto found;
 
-		if (!item || offset < item_start_offset ||
-		    offset >= item_last_offset) {
+		if (!item || disk_bytenr < item_start_offset ||
+		    disk_bytenr >= item_last_offset) {
 			struct btrfs_key found_key;
 			u32 item_size;
 
 			if (item)
 				btrfs_release_path(root, path);
-			item = btrfs_lookup_csum(NULL, root, path,
-						 inode->i_ino, offset, 0);
+			item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
+						 path, disk_bytenr, 0);
 			if (IS_ERR(item)) {
 				ret = PTR_ERR(item);
 				if (ret == -ENOENT || ret == -EFBIG)
@@ -208,7 +208,7 @@
 		 * this byte range must be able to fit inside
 		 * a single leaf so it will also fit inside a u32
 		 */
-		diff = offset - item_start_offset;
+		diff = disk_bytenr - item_start_offset;
 		diff = diff / root->sectorsize;
 		diff = diff * csum_size;
 
@@ -216,7 +216,11 @@
 				   ((unsigned long)item) + diff,
 				   csum_size);
 found:
-		set_state_private(io_tree, offset, sum);
+		if (dst)
+			*dst++ = sum;
+		else
+			set_state_private(io_tree, offset, sum);
+		disk_bytenr += bvec->bv_len;
 		bio_index++;
 		bvec++;
 	}
@@ -224,75 +228,8 @@
 	return 0;
 }
 
-int btrfs_csum_file_bytes(struct btrfs_root *root, struct inode *inode,
-			  u64 start, unsigned long len)
-{
-	struct btrfs_ordered_sum *sums;
-	struct btrfs_sector_sum *sector_sum;
-	struct btrfs_ordered_extent *ordered;
-	char *data;
-	struct page *page;
-	unsigned long total_bytes = 0;
-	unsigned long this_sum_bytes = 0;
-
-	sums = kzalloc(btrfs_ordered_sum_size(root, len), GFP_NOFS);
-	if (!sums)
-		return -ENOMEM;
-
-	sector_sum = sums->sums;
-	sums->file_offset = start;
-	sums->len = len;
-	INIT_LIST_HEAD(&sums->list);
-	ordered = btrfs_lookup_ordered_extent(inode, sums->file_offset);
-	BUG_ON(!ordered);
-
-	while(len > 0) {
-		if (start >= ordered->file_offset + ordered->len ||
-		    start < ordered->file_offset) {
-			sums->len = this_sum_bytes;
-			this_sum_bytes = 0;
-			btrfs_add_ordered_sum(inode, ordered, sums);
-			btrfs_put_ordered_extent(ordered);
-
-			sums = kzalloc(btrfs_ordered_sum_size(root, len),
-				       GFP_NOFS);
-			BUG_ON(!sums);
-			sector_sum = sums->sums;
-			sums->len = len;
-			sums->file_offset = start;
-			ordered = btrfs_lookup_ordered_extent(inode,
-						      sums->file_offset);
-			BUG_ON(!ordered);
-		}
-
-		page = find_get_page(inode->i_mapping,
-				     start >> PAGE_CACHE_SHIFT);
-
-		data = kmap_atomic(page, KM_USER0);
-		sector_sum->sum = ~(u32)0;
-		sector_sum->sum = btrfs_csum_data(root, data, sector_sum->sum,
-						  PAGE_CACHE_SIZE);
-		kunmap_atomic(data, KM_USER0);
-		btrfs_csum_final(sector_sum->sum,
-				 (char *)&sector_sum->sum);
-		sector_sum->offset = page_offset(page);
-		page_cache_release(page);
-
-		sector_sum++;
-		total_bytes += PAGE_CACHE_SIZE;
-		this_sum_bytes += PAGE_CACHE_SIZE;
-		start += PAGE_CACHE_SIZE;
-
-		WARN_ON(len < PAGE_CACHE_SIZE);
-		len -= PAGE_CACHE_SIZE;
-	}
-	btrfs_add_ordered_sum(inode, ordered, sums);
-	btrfs_put_ordered_extent(ordered);
-	return 0;
-}
-
 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
-		       struct bio *bio)
+		       struct bio *bio, u64 file_start, int contig)
 {
 	struct btrfs_ordered_sum *sums;
 	struct btrfs_sector_sum *sector_sum;
@@ -303,6 +240,7 @@
 	unsigned long total_bytes = 0;
 	unsigned long this_sum_bytes = 0;
 	u64 offset;
+	u64 disk_bytenr;
 
 	WARN_ON(bio->bi_vcnt <= 0);
 	sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
@@ -310,16 +248,25 @@
 		return -ENOMEM;
 
 	sector_sum = sums->sums;
-	sums->file_offset = page_offset(bvec->bv_page) + bvec->bv_offset;
+	disk_bytenr = (u64)bio->bi_sector << 9;
 	sums->len = bio->bi_size;
 	INIT_LIST_HEAD(&sums->list);
-	ordered = btrfs_lookup_ordered_extent(inode, sums->file_offset);
+
+	if (contig)
+		offset = file_start;
+	else
+		offset = page_offset(bvec->bv_page) + bvec->bv_offset;
+
+	ordered = btrfs_lookup_ordered_extent(inode, offset);
 	BUG_ON(!ordered);
+	sums->bytenr = ordered->start;
 
 	while(bio_index < bio->bi_vcnt) {
-		offset = page_offset(bvec->bv_page) + bvec->bv_offset;
-		if (offset >= ordered->file_offset + ordered->len ||
-		    offset < ordered->file_offset) {
+		if (!contig)
+			offset = page_offset(bvec->bv_page) + bvec->bv_offset;
+
+		if (!contig && (offset >= ordered->file_offset + ordered->len ||
+		    offset < ordered->file_offset)) {
 			unsigned long bytes_left;
 			sums->len = this_sum_bytes;
 			this_sum_bytes = 0;
@@ -333,10 +280,9 @@
 			BUG_ON(!sums);
 			sector_sum = sums->sums;
 			sums->len = bytes_left;
-			sums->file_offset = offset;
-			ordered = btrfs_lookup_ordered_extent(inode,
-						      sums->file_offset);
+			ordered = btrfs_lookup_ordered_extent(inode, offset);
 			BUG_ON(!ordered);
+			sums->bytenr = ordered->start;
 		}
 
 		data = kmap_atomic(bvec->bv_page, KM_USER0);
@@ -348,13 +294,14 @@
 		kunmap_atomic(data, KM_USER0);
 		btrfs_csum_final(sector_sum->sum,
 				 (char *)&sector_sum->sum);
-		sector_sum->offset = page_offset(bvec->bv_page) +
-			bvec->bv_offset;
+		sector_sum->bytenr = disk_bytenr;
 
 		sector_sum++;
 		bio_index++;
 		total_bytes += bvec->bv_len;
 		this_sum_bytes += bvec->bv_len;
+		disk_bytenr += bvec->bv_len;
+		offset += bvec->bv_len;
 		bvec++;
 	}
 	this_sum_bytes = 0;
@@ -364,11 +311,10 @@
 }
 
 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
-			   struct btrfs_root *root, struct inode *inode,
+			   struct btrfs_root *root,
 			   struct btrfs_ordered_sum *sums)
 {
-	u64 objectid = inode->i_ino;
-	u64 offset;
+	u64 bytenr;
 	int ret;
 	struct btrfs_key file_key;
 	struct btrfs_key found_key;
@@ -396,13 +342,12 @@
 again:
 	next_offset = (u64)-1;
 	found_next = 0;
-	offset = sector_sum->offset;
-	file_key.objectid = objectid;
-	file_key.offset = offset;
-	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+	file_key.offset = sector_sum->bytenr;
+	bytenr = sector_sum->bytenr;
+	btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 
-	mutex_lock(&BTRFS_I(inode)->csum_mutex);
-	item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
+	item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 	if (!IS_ERR(item)) {
 		leaf = path->nodes[0];
 		ret = 0;
@@ -432,8 +377,8 @@
 			slot = 0;
 		}
 		btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
-		if (found_key.objectid != objectid ||
-		    found_key.type != BTRFS_CSUM_ITEM_KEY) {
+		if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+		    found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 			found_next = 1;
 			goto insert;
 		}
@@ -460,10 +405,10 @@
 	path->slots[0]--;
 	leaf = path->nodes[0];
 	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-	csum_offset = (offset - found_key.offset) >>
+	csum_offset = (bytenr - found_key.offset) >>
 			root->fs_info->sb->s_blocksize_bits;
-	if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
-	    found_key.objectid != objectid ||
+	if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
+	    found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 	    csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 		goto insert;
 	}
@@ -482,8 +427,18 @@
 	btrfs_release_path(root, path);
 	csum_offset = 0;
 	if (found_next) {
-		u64 tmp = min((u64)i_size_read(inode), next_offset);
-		tmp -= offset & ~((u64)root->sectorsize -1);
+		u64 tmp = total_bytes + root->sectorsize;
+		u64 next_sector = sector_sum->bytenr;
+		struct btrfs_sector_sum *next = sector_sum + 1;
+
+		while(tmp < sums->len) {
+			if (next_sector + root->sectorsize != next->bytenr)
+				break;
+			tmp += root->sectorsize;
+			next_sector = next->bytenr;
+			next++;
+		}
+		tmp = min(tmp, next_offset - file_key.offset);
 		tmp >>= root->fs_info->sb->s_blocksize_bits;
 		tmp = max((u64)1, tmp);
 		tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
@@ -510,7 +465,6 @@
 	item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 				      btrfs_item_size_nr(leaf, path->slots[0]));
 	eb_token = NULL;
-	mutex_unlock(&BTRFS_I(inode)->csum_mutex);
 	cond_resched();
 next_sector:
 
@@ -541,9 +495,9 @@
 	if (total_bytes < sums->len) {
 		item = (struct btrfs_csum_item *)((char *)item +
 						  csum_size);
-		if (item < item_end && offset + PAGE_CACHE_SIZE ==
-		    sector_sum->offset) {
-			    offset = sector_sum->offset;
+		if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
+		    sector_sum->bytenr) {
+			bytenr = sector_sum->bytenr;
 			goto next_sector;
 		}
 	}
@@ -562,7 +516,6 @@
 	return ret;
 
 fail_unlock:
-	mutex_unlock(&BTRFS_I(inode)->csum_mutex);
 	goto out;
 }
 
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 09efc94..c03d847 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1221,7 +1221,7 @@
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	int ret = 0;
 
-	ret = btrfs_csum_one_bio(root, inode, bio);
+	ret = btrfs_csum_one_bio(root, inode, bio, 0, 0);
 	BUG_ON(ret);
 	return 0;
 }
@@ -1259,12 +1259,11 @@
 		btrfs_test_flag(inode, NODATASUM);
 
 	if (!(rw & (1 << BIO_RW))) {
-
-		if (bio_flags & EXTENT_BIO_COMPRESSED)
+		if (bio_flags & EXTENT_BIO_COMPRESSED) {
 			return btrfs_submit_compressed_read(inode, bio,
 						    mirror_num, bio_flags);
-		else if (!skip_sum)
-			btrfs_lookup_bio_sums(root, inode, bio);
+		} else if (!skip_sum)
+			btrfs_lookup_bio_sums(root, inode, bio, NULL);
 		goto mapit;
 	} else if (!skip_sum) {
 		/* we're doing a write, do the async checksumming */
@@ -1292,8 +1291,8 @@
 	btrfs_set_trans_block_group(trans, inode);
 	list_for_each(cur, list) {
 		sum = list_entry(cur, struct btrfs_ordered_sum, list);
-		btrfs_csum_file_blocks(trans, BTRFS_I(inode)->root,
-				       inode, sum);
+		btrfs_csum_file_blocks(trans,
+		       BTRFS_I(inode)->root->fs_info->csum_root, sum);
 	}
 	return 0;
 }
@@ -1545,6 +1544,7 @@
 	u64 start;
 	u64 len;
 	u64 logical;
+	unsigned long bio_flags;
 	int last_mirror;
 };
 
@@ -1563,7 +1563,6 @@
 	int ret;
 	int rw;
 	u64 logical;
-	unsigned long bio_flags = 0;
 
 	ret = get_state_private(failure_tree, start, &private);
 	if (ret) {
@@ -1573,6 +1572,7 @@
 		failrec->start = start;
 		failrec->len = end - start + 1;
 		failrec->last_mirror = 0;
+		failrec->bio_flags = 0;
 
 		spin_lock(&em_tree->lock);
 		em = lookup_extent_mapping(em_tree, start, failrec->len);
@@ -1588,8 +1588,10 @@
 		}
 		logical = start - em->start;
 		logical = em->block_start + logical;
-		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
-			bio_flags = EXTENT_BIO_COMPRESSED;
+		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
+			logical = em->block_start;
+			failrec->bio_flags = EXTENT_BIO_COMPRESSED;
+		}
 		failrec->logical = logical;
 		free_extent_map(em);
 		set_extent_bits(failure_tree, start, end, EXTENT_LOCKED |
@@ -1626,6 +1628,7 @@
 	bio->bi_sector = failrec->logical >> 9;
 	bio->bi_bdev = failed_bio->bi_bdev;
 	bio->bi_size = 0;
+
 	bio_add_page(bio, page, failrec->len, start - page_offset(page));
 	if (failed_bio->bi_rw & (1 << BIO_RW))
 		rw = WRITE;
@@ -1634,7 +1637,7 @@
 
 	BTRFS_I(inode)->io_tree.ops->submit_bio_hook(inode, rw, bio,
 						      failrec->last_mirror,
-						      bio_flags);
+						      failrec->bio_flags);
 	return 0;
 }
 
@@ -1688,9 +1691,14 @@
 	u32 csum = ~(u32)0;
 	unsigned long flags;
 
+	if (PageChecked(page)) {
+		ClearPageChecked(page);
+		goto good;
+	}
 	if (btrfs_test_opt(root, NODATASUM) ||
 	    btrfs_test_flag(inode, NODATASUM))
 		return 0;
+
 	if (state && state->start == start) {
 		private = state->private;
 		ret = 0;
@@ -1709,7 +1717,7 @@
 	}
 	kunmap_atomic(kaddr, KM_IRQ0);
 	local_irq_restore(flags);
-
+good:
 	/* if the io failure tree for this inode is non-empty,
 	 * check to see if we've recovered from a failed IO
 	 */
@@ -2243,6 +2251,7 @@
 	return err;
 }
 
+#if 0
 /*
  * when truncating bytes in a file, it is possible to avoid reading
  * the leaves that contain only checksum items.  This can be the
@@ -2410,6 +2419,8 @@
 	return ret;
 }
 
+#endif
+
 /*
  * this can truncate away extent items, csum items and directory items.
  * It starts at a high offset and removes keys until it can't find
@@ -2459,9 +2470,6 @@
 
 	btrfs_init_path(path);
 
-	ret = drop_csum_leaves(trans, root, path, inode, new_size);
-	BUG_ON(ret);
-
 search_again:
 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 	if (ret < 0) {
@@ -2509,16 +2517,11 @@
 			}
 			item_end--;
 		}
-		if (found_type == BTRFS_CSUM_ITEM_KEY) {
-			ret = btrfs_csum_truncate(trans, root, path,
-						  new_size);
-			BUG_ON(ret);
-		}
 		if (item_end < new_size) {
 			if (found_type == BTRFS_DIR_ITEM_KEY) {
 				found_type = BTRFS_INODE_ITEM_KEY;
 			} else if (found_type == BTRFS_EXTENT_ITEM_KEY) {
-				found_type = BTRFS_CSUM_ITEM_KEY;
+				found_type = BTRFS_EXTENT_DATA_KEY;
 			} else if (found_type == BTRFS_EXTENT_DATA_KEY) {
 				found_type = BTRFS_XATTR_ITEM_KEY;
 			} else if (found_type == BTRFS_XATTR_ITEM_KEY) {
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b4da53d5..6228b69 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -714,8 +714,7 @@
 	u64 len = olen;
 	u64 bs = root->fs_info->sb->s_blocksize;
 	u64 hint_byte;
-	u16 csum_size =
-		btrfs_super_csum_size(&root->fs_info->super_copy);
+
 	/*
 	 * TODO:
 	 * - split compressed inline extents.  annoying: we need to
@@ -833,7 +832,7 @@
 		slot = path->slots[0];
 
 		btrfs_item_key_to_cpu(leaf, &key, slot);
-		if (btrfs_key_type(&key) > BTRFS_CSUM_ITEM_KEY ||
+		if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
 		    key.objectid != src->i_ino)
 			break;
 
@@ -958,56 +957,6 @@
 			btrfs_mark_buffer_dirty(leaf);
 		}
 
-		if (btrfs_key_type(&key) == BTRFS_CSUM_ITEM_KEY) {
-			u32 size;
-			struct btrfs_key new_key;
-			u64 coverslen;
-			int coff, clen;
-
-			size = btrfs_item_size_nr(leaf, slot);
-			coverslen = (size / csum_size) <<
-				root->fs_info->sb->s_blocksize_bits;
-			printk("csums for %llu~%llu\n",
-			       key.offset, coverslen);
-			if (key.offset + coverslen < off ||
-			    key.offset >= off+len)
-				goto next;
-
-			read_extent_buffer(leaf, buf,
-					   btrfs_item_ptr_offset(leaf, slot),
-					   size);
-			btrfs_release_path(root, path);
-
-			coff = 0;
-			if (off > key.offset)
-				coff = ((off - key.offset) >>
-					root->fs_info->sb->s_blocksize_bits) *
-					csum_size;
-			clen = size - coff;
-			if (key.offset + coverslen > off+len)
-				clen -= ((key.offset+coverslen-off-len) >>
-					 root->fs_info->sb->s_blocksize_bits) *
-					csum_size;
-			printk(" will dup %d~%d of %d\n",
-			       coff, clen, size);
-
-			memcpy(&new_key, &key, sizeof(new_key));
-			new_key.objectid = inode->i_ino;
-			new_key.offset = key.offset + destoff - off;
-
-			ret = btrfs_insert_empty_item(trans, root, path,
-						      &new_key, clen);
-			if (ret)
-				goto out;
-
-			leaf = path->nodes[0];
-			slot = path->slots[0];
-			write_extent_buffer(leaf, buf + coff,
-					    btrfs_item_ptr_offset(leaf, slot),
-					    clen);
-			btrfs_mark_buffer_dirty(leaf);
-		}
-
 	next:
 		btrfs_release_path(root, path);
 		key.offset++;
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 027ad6b..d9e2322 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -610,7 +610,8 @@
  * try to find a checksum.  This is used because we allow pages to
  * be reclaimed before their checksum is actually put into the btree
  */
-int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u32 *sum)
+int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr,
+			   u32 *sum)
 {
 	struct btrfs_ordered_sum *ordered_sum;
 	struct btrfs_sector_sum *sector_sums;
@@ -629,11 +630,11 @@
 	mutex_lock(&tree->mutex);
 	list_for_each_prev(cur, &ordered->list) {
 		ordered_sum = list_entry(cur, struct btrfs_ordered_sum, list);
-		if (offset >= ordered_sum->file_offset) {
+		if (disk_bytenr >= ordered_sum->bytenr) {
 			num_sectors = ordered_sum->len / sectorsize;
 			sector_sums = ordered_sum->sums;
 			for (i = 0; i < num_sectors; i++) {
-				if (sector_sums[i].offset == offset) {
+				if (sector_sums[i].bytenr == disk_bytenr) {
 					*sum = sector_sums[i].sum;
 					ret = 0;
 					goto out;
diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
index 260bf95..ab66d5e 100644
--- a/fs/btrfs/ordered-data.h
+++ b/fs/btrfs/ordered-data.h
@@ -33,15 +33,17 @@
  * the ordered extent are on disk
  */
 struct btrfs_sector_sum {
-	u64 offset;
+	/* bytenr on disk */
+	u64 bytenr;
 	u32 sum;
 };
 
 struct btrfs_ordered_sum {
-	u64 file_offset;
+	/* bytenr is the start of this extent on disk */
+	u64 bytenr;
+
 	/*
 	 * this is the length in bytes covered by the sums array below.
-	 * But, the sums array may not be contiguous in the file.
 	 */
 	unsigned long len;
 	struct list_head list;
@@ -147,7 +149,7 @@
 btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset);
 int btrfs_ordered_update_i_size(struct inode *inode,
 				struct btrfs_ordered_extent *ordered);
-int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u32 *sum);
+int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr, u32 *sum);
 int btrfs_wait_on_page_writeback_range(struct address_space *mapping,
 				       pgoff_t start, pgoff_t end);
 int btrfs_fdatawrite_range(struct address_space *mapping, loff_t start,
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index c766649..08469ec0 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -934,24 +934,17 @@
 	unsigned long file_bytes;
 	struct btrfs_ordered_sum *sums;
 	struct btrfs_sector_sum *sector_sum;
-	struct inode *inode;
 	unsigned long ptr;
 
 	file_bytes = (item_size / csum_size) * root->sectorsize;
-	inode = read_one_inode(root, key->objectid);
-	if (!inode) {
-		return -EIO;
-	}
-
 	sums = kzalloc(btrfs_ordered_sum_size(root, file_bytes), GFP_NOFS);
 	if (!sums) {
-		iput(inode);
 		return -ENOMEM;
 	}
 
 	INIT_LIST_HEAD(&sums->list);
 	sums->len = file_bytes;
-	sums->file_offset = key->offset;
+	sums->bytenr = key->offset;
 
 	/*
 	 * copy all the sums into the ordered sum struct
@@ -960,7 +953,7 @@
 	cur_offset = key->offset;
 	ptr = btrfs_item_ptr_offset(eb, slot);
 	while(item_size > 0) {
-		sector_sum->offset = cur_offset;
+		sector_sum->bytenr = cur_offset;
 		read_extent_buffer(eb, &sector_sum->sum, ptr, csum_size);
 		sector_sum++;
 		item_size -= csum_size;
@@ -969,11 +962,9 @@
 	}
 
 	/* let btrfs_csum_file_blocks add them into the file */
-	ret = btrfs_csum_file_blocks(trans, root, inode, sums);
+	ret = btrfs_csum_file_blocks(trans, root->fs_info->csum_root, sums);
 	BUG_ON(ret);
 	kfree(sums);
-	iput(inode);
-
 	return 0;
 }
 /*
@@ -1670,7 +1661,7 @@
 			ret = replay_one_extent(wc->trans, root, path,
 						eb, i, &key);
 			BUG_ON(ret);
-		} else if (key.type == BTRFS_CSUM_ITEM_KEY) {
+		} else if (key.type == BTRFS_EXTENT_CSUM_KEY) {
 			ret = replay_one_csum(wc->trans, root, path,
 					      eb, i, &key);
 			BUG_ON(ret);
@@ -2466,6 +2457,85 @@
 	return 0;
 }
 
+static noinline int copy_extent_csums(struct btrfs_trans_handle *trans,
+				      struct list_head *list,
+				      struct btrfs_root *root,
+				      u64 disk_bytenr, u64 len)
+{
+	struct btrfs_ordered_sum *sums;
+	struct btrfs_sector_sum *sector_sum;
+	int ret;
+	struct btrfs_path *path;
+	struct btrfs_csum_item *item = NULL;
+	u64 end = disk_bytenr + len;
+	u64 item_start_offset = 0;
+	u64 item_last_offset = 0;
+	u32 diff;
+	u32 sum;
+	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
+
+	sums = kzalloc(btrfs_ordered_sum_size(root, len), GFP_NOFS);
+
+	sector_sum = sums->sums;
+	sums->bytenr = disk_bytenr;
+	sums->len = len;
+	list_add_tail(&sums->list, list);
+
+	path = btrfs_alloc_path();
+	while(disk_bytenr < end) {
+		if (!item || disk_bytenr < item_start_offset ||
+		    disk_bytenr >= item_last_offset) {
+			struct btrfs_key found_key;
+			u32 item_size;
+
+			if (item)
+				btrfs_release_path(root, path);
+			item = btrfs_lookup_csum(NULL, root, path,
+						 disk_bytenr, 0);
+			if (IS_ERR(item)) {
+				ret = PTR_ERR(item);
+				if (ret == -ENOENT || ret == -EFBIG)
+					ret = 0;
+				sum = 0;
+				printk("log no csum found for byte %llu\n",
+				       (unsigned long long)disk_bytenr);
+				item = NULL;
+				btrfs_release_path(root, path);
+				goto found;
+			}
+			btrfs_item_key_to_cpu(path->nodes[0], &found_key,
+					      path->slots[0]);
+
+			item_start_offset = found_key.offset;
+			item_size = btrfs_item_size_nr(path->nodes[0],
+						       path->slots[0]);
+			item_last_offset = item_start_offset +
+				(item_size / csum_size) *
+				root->sectorsize;
+			item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+					      struct btrfs_csum_item);
+		}
+		/*
+		 * this byte range must be able to fit inside
+		 * a single leaf so it will also fit inside a u32
+		 */
+		diff = disk_bytenr - item_start_offset;
+		diff = diff / root->sectorsize;
+		diff = diff * csum_size;
+
+		read_extent_buffer(path->nodes[0], &sum,
+				   ((unsigned long)item) + diff,
+				   csum_size);
+found:
+		sector_sum->bytenr = disk_bytenr;
+		sector_sum->sum = sum;
+		disk_bytenr += root->sectorsize;
+		sector_sum++;
+	}
+	btrfs_free_path(path);
+	return 0;
+}
+
 static noinline int copy_items(struct btrfs_trans_handle *trans,
 			       struct btrfs_root *log,
 			       struct btrfs_path *dst_path,
@@ -2481,6 +2551,9 @@
 	u32 *ins_sizes;
 	char *ins_data;
 	int i;
+	struct list_head ordered_sums;
+
+	INIT_LIST_HEAD(&ordered_sums);
 
 	ins_data = kmalloc(nr * sizeof(struct btrfs_key) +
 			   nr * sizeof(u32), GFP_NOFS);
@@ -2535,6 +2608,9 @@
 								   extent);
 				u64 dl = btrfs_file_extent_disk_num_bytes(src,
 								      extent);
+				u64 cs = btrfs_file_extent_offset(src, extent);
+				u64 cl = btrfs_file_extent_num_bytes(src,
+								     extent);;
 				/* ds == 0 is a hole */
 				if (ds != 0) {
 					ret = btrfs_inc_extent_ref(trans, log,
@@ -2544,6 +2620,11 @@
 						   trans->transid,
 						   ins_keys[i].objectid);
 					BUG_ON(ret);
+					ret = copy_extent_csums(trans,
+						&ordered_sums,
+						log->fs_info->csum_root,
+						ds + cs, cl);
+					BUG_ON(ret);
 				}
 			}
 		}
@@ -2553,6 +2634,20 @@
 	btrfs_mark_buffer_dirty(dst_path->nodes[0]);
 	btrfs_release_path(log, dst_path);
 	kfree(ins_data);
+
+	/*
+	 * we have to do this after the loop above to avoid changing the
+	 * log tree while trying to change the log tree.
+	 */
+	while(!list_empty(&ordered_sums)) {
+		struct btrfs_ordered_sum *sums = list_entry(ordered_sums.next,
+						   struct btrfs_ordered_sum,
+						   list);
+		ret = btrfs_csum_file_blocks(trans, log, sums);
+		BUG_ON(ret);
+		list_del(&sums->list);
+		kfree(sums);
+	}
 	return 0;
 }
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6c523b3..2049d17 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2771,6 +2771,7 @@
 	device->work.func = pending_bios_fn;
 	fs_devices->num_devices++;
 	spin_lock_init(&device->io_lock);
+	INIT_LIST_HEAD(&device->dev_alloc_list);
 	memcpy(device->uuid, dev_uuid, BTRFS_UUID_SIZE);
 	return device;
 }