diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index bf0d61567f3d..fd7fa2a74f06 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -98,6 +98,12 @@ struct inode *lookup_free_space_inode(struct btrfs_root *root,
 		return inode;
 
 	spin_lock(&block_group->lock);
+	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) {
+		printk(KERN_INFO "Old style space inode found, converting.\n");
+		BTRFS_I(inode)->flags &= ~BTRFS_INODE_NODATASUM;
+		block_group->disk_cache_state = BTRFS_DC_CLEAR;
+	}
+
 	if (!btrfs_fs_closing(root->fs_info)) {
 		block_group->inode = igrab(inode);
 		block_group->iref = 1;
@@ -135,7 +141,7 @@ int __create_free_space_inode(struct btrfs_root *root,
 	btrfs_set_inode_gid(leaf, inode_item, 0);
 	btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 	btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
-			      BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
+			      BTRFS_INODE_PREALLOC);
 	btrfs_set_inode_nlink(leaf, inode_item, 1);
 	btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 	btrfs_set_inode_block_group(leaf, inode_item, offset);
@@ -239,17 +245,12 @@ int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 	struct btrfs_free_space_header *header;
 	struct extent_buffer *leaf;
 	struct page *page;
-	u32 *checksums = NULL, *crc;
-	char *disk_crcs = NULL;
 	struct btrfs_key key;
 	struct list_head bitmaps;
 	u64 num_entries;
 	u64 num_bitmaps;
 	u64 generation;
-	u32 cur_crc = ~(u32)0;
 	pgoff_t index = 0;
-	unsigned long first_page_offset;
-	int num_checksums;
 	int ret = 0;
 
 	INIT_LIST_HEAD(&bitmaps);
@@ -292,16 +293,6 @@ int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 	if (!num_entries)
 		goto out;
 
-	/* Setup everything for doing checksumming */
-	num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
-	checksums = crc = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
-	if (!checksums)
-		goto out;
-	first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
-	disk_crcs = kzalloc(first_page_offset, GFP_NOFS);
-	if (!disk_crcs)
-		goto out;
-
 	ret = readahead_cache(inode);
 	if (ret)
 		goto out;
@@ -311,17 +302,11 @@ int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 		struct btrfs_free_space *e;
 		void *addr;
 		unsigned long offset = 0;
-		unsigned long start_offset = 0;
 		int need_loop = 0;
 
 		if (!num_entries && !num_bitmaps)
 			break;
 
-		if (index == 0) {
-			start_offset = first_page_offset;
-			offset = start_offset;
-		}
-
 		page = grab_cache_page(inode->i_mapping, index);
 		if (!page)
 			goto free_cache;
@@ -342,8 +327,15 @@ int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 		if (index == 0) {
 			u64 *gen;
 
-			memcpy(disk_crcs, addr, first_page_offset);
-			gen = addr + (sizeof(u32) * num_checksums);
+			/*
+			 * We put a bogus crc in the front of the first page in
+			 * case old kernels try to mount a fs with the new
+			 * format to make sure they discard the cache.
+			 */
+			addr += sizeof(u64);
+			offset += sizeof(u64);
+
+			gen = addr;
 			if (*gen != BTRFS_I(inode)->generation) {
 				printk(KERN_ERR "btrfs: space cache generation"
 				       " (%llu) does not match inode (%llu)\n",
@@ -355,24 +347,10 @@ int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 				page_cache_release(page);
 				goto free_cache;
 			}
-			crc = (u32 *)disk_crcs;
+			addr += sizeof(u64);
+			offset += sizeof(u64);
 		}
-		entry = addr + start_offset;
-
-		/* First lets check our crc before we do anything fun */
-		cur_crc = ~(u32)0;
-		cur_crc = btrfs_csum_data(root, addr + start_offset, cur_crc,
-					  PAGE_CACHE_SIZE - start_offset);
-		btrfs_csum_final(cur_crc, (char *)&cur_crc);
-		if (cur_crc != *crc) {
-			printk(KERN_ERR "btrfs: crc mismatch for page %lu\n",
-			       index);
-			kunmap(page);
-			unlock_page(page);
-			page_cache_release(page);
-			goto free_cache;
-		}
-		crc++;
+		entry = addr;
 
 		while (1) {
 			if (!num_entries)
@@ -470,8 +448,6 @@ next:
 
 	ret = 1;
 out:
-	kfree(checksums);
-	kfree(disk_crcs);
 	return ret;
 free_cache:
 	__btrfs_remove_free_space_cache(ctl);
@@ -569,8 +545,7 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 	struct btrfs_key key;
 	u64 start, end, len;
 	u64 bytes = 0;
-	u32 *crc, *checksums;
-	unsigned long first_page_offset;
+	u32 crc = ~(u32)0;
 	int index = 0, num_pages = 0;
 	int entries = 0;
 	int bitmaps = 0;
@@ -590,34 +565,13 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 	num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 		PAGE_CACHE_SHIFT;
 
-	/* Since the first page has all of our checksums and our generation we
-	 * need to calculate the offset into the page that we can start writing
-	 * our entries.
-	 */
-	first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);
-
 	filemap_write_and_wait(inode->i_mapping);
 	btrfs_wait_ordered_range(inode, inode->i_size &
 				 ~(root->sectorsize - 1), (u64)-1);
 
-	/* make sure we don't overflow that first page */
-	if (first_page_offset + sizeof(struct btrfs_free_space_entry) >= PAGE_CACHE_SIZE) {
-		/* this is really the same as running out of space, where we also return 0 */
-		printk(KERN_CRIT "Btrfs: free space cache was too big for the crc page\n");
-		ret = 0;
-		goto out_update;
-	}
-
-	/* We need a checksum per page. */
-	crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);
-	if (!crc)
-		return -1;
-
 	pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
-	if (!pages) {
-		kfree(crc);
+	if (!pages)
 		return -1;
-	}
 
 	/* Get the cluster for this block_group if it exists */
 	if (block_group && !list_empty(&block_group->cluster_list))
@@ -648,7 +602,7 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 				unlock_page(pages[i]);
 				page_cache_release(pages[i]);
 			}
-			goto out_free;
+			goto out;
 		}
 		pages[index] = page;
 		index++;
@@ -668,17 +622,11 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 	/* Write out the extent entries */
 	do {
 		struct btrfs_free_space_entry *entry;
-		void *addr;
+		void *addr, *orig;
 		unsigned long offset = 0;
-		unsigned long start_offset = 0;
 
 		next_page = false;
 
-		if (index == 0) {
-			start_offset = first_page_offset;
-			offset = start_offset;
-		}
-
 		if (index >= num_pages) {
 			out_of_space = true;
 			break;
@@ -686,10 +634,26 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 
 		page = pages[index];
 
-		addr = kmap(page);
-		entry = addr + start_offset;
+		orig = addr = kmap(page);
+		if (index == 0) {
+			u64 *gen;
 
-		memset(addr, 0, PAGE_CACHE_SIZE);
+			/*
+			 * We're going to put in a bogus crc for this page to
+			 * make sure that old kernels who aren't aware of this
+			 * format will be sure to discard the cache.
+			 */
+			addr += sizeof(u64);
+			offset += sizeof(u64);
+
+			gen = addr;
+			*gen = trans->transid;
+			addr += sizeof(u64);
+			offset += sizeof(u64);
+		}
+		entry = addr;
+
+		memset(addr, 0, PAGE_CACHE_SIZE - offset);
 		while (node && !next_page) {
 			struct btrfs_free_space *e;
 
@@ -752,13 +716,19 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 				next_page = true;
 			entry++;
 		}
-		*crc = ~(u32)0;
-		*crc = btrfs_csum_data(root, addr + start_offset, *crc,
-				       PAGE_CACHE_SIZE - start_offset);
-		kunmap(page);
 
-		btrfs_csum_final(*crc, (char *)crc);
-		crc++;
+		/* Generate bogus crc value */
+		if (index == 0) {
+			u32 *tmp;
+			crc = btrfs_csum_data(root, orig + sizeof(u64), crc,
+					      PAGE_CACHE_SIZE - sizeof(u64));
+			btrfs_csum_final(crc, (char *)&crc);
+			crc++;
+			tmp = orig;
+			*tmp = crc;
+		}
+
+		kunmap(page);
 
 		bytes += PAGE_CACHE_SIZE;
 
@@ -779,11 +749,7 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 
 		addr = kmap(page);
 		memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
-		*crc = ~(u32)0;
-		*crc = btrfs_csum_data(root, addr, *crc, PAGE_CACHE_SIZE);
 		kunmap(page);
-		btrfs_csum_final(*crc, (char *)crc);
-		crc++;
 		bytes += PAGE_CACHE_SIZE;
 
 		list_del_init(&entry->list);
@@ -796,7 +762,7 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 				     i_size_read(inode) - 1, &cached_state,
 				     GFP_NOFS);
 		ret = 0;
-		goto out_free;
+		goto out;
 	}
 
 	/* Zero out the rest of the pages just to make sure */
@@ -811,20 +777,6 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 		index++;
 	}
 
-	/* Write the checksums and trans id to the first page */
-	{
-		void *addr;
-		u64 *gen;
-
-		page = pages[0];
-
-		addr = kmap(page);
-		memcpy(addr, checksums, sizeof(u32) * num_pages);
-		gen = addr + (sizeof(u32) * num_pages);
-		*gen = trans->transid;
-		kunmap(page);
-	}
-
 	ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
 					    bytes, &cached_state);
 	btrfs_drop_pages(pages, num_pages);
@@ -833,7 +785,7 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 
 	if (ret) {
 		ret = 0;
-		goto out_free;
+		goto out;
 	}
 
 	BTRFS_I(inode)->generation = trans->transid;
@@ -850,7 +802,7 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 		clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 				 EXTENT_DIRTY | EXTENT_DELALLOC |
 				 EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
-		goto out_free;
+		goto out;
 	}
 	leaf = path->nodes[0];
 	if (ret > 0) {
@@ -866,7 +818,7 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 					 EXTENT_DO_ACCOUNTING, 0, 0, NULL,
 					 GFP_NOFS);
 			btrfs_release_path(path);
-			goto out_free;
+			goto out;
 		}
 	}
 	header = btrfs_item_ptr(leaf, path->slots[0],
@@ -879,11 +831,8 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 
 	ret = 1;
 
-out_free:
-	kfree(checksums);
+out:
 	kfree(pages);
-
-out_update:
 	if (ret != 1) {
 		invalidate_inode_pages2_range(inode->i_mapping, 0, index);
 		BTRFS_I(inode)->generation = 0;