1 files changed, 50 insertions, 36 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5547607681f..e40fb318ad9 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -46,27 +46,6 @@ static int check_tree_block(struct btrfs_root *root, struct extent_buffer *buf)
 
 static struct extent_io_ops btree_extent_io_ops;
 
-struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
-					    u64 bytenr, u32 blocksize)
-{
-	struct inode *btree_inode = root->fs_info->btree_inode;
-	struct extent_buffer *eb;
-	eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
-				bytenr, blocksize, GFP_NOFS);
-	return eb;
-}
-
-struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
-						 u64 bytenr, u32 blocksize)
-{
-	struct inode *btree_inode = root->fs_info->btree_inode;
-	struct extent_buffer *eb;
-
-	eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
-				 bytenr, blocksize, NULL, GFP_NOFS);
-	return eb;
-}
-
 struct extent_map *btree_get_extent(struct inode *inode, struct page *page,
 				    size_t page_offset, u64 start, u64 len,
 				    int create)
@@ -380,36 +359,29 @@ static int close_all_devices(struct btrfs_fs_info *fs_info)
 	return 0;
 }
 
-struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
-				      u32 blocksize)
+int btrfs_verify_block_csum(struct btrfs_root *root,
+			    struct extent_buffer *buf)
 {
-	struct extent_buffer *buf = NULL;
-	struct inode *btree_inode = root->fs_info->btree_inode;
 	struct extent_io_tree *io_tree;
 	u64 end;
 	int ret;
 
-	io_tree = &BTRFS_I(btree_inode)->io_tree;
-
-	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
-	if (!buf)
-		return NULL;
-	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree, buf, 0, 1,
-				 btree_get_extent);
-
+	io_tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
 	if (buf->flags & EXTENT_CSUM)
-		return buf;
+		return 0;
 
-	end = buf->start + PAGE_CACHE_SIZE - 1;
+	end = min_t(u64, buf->len, PAGE_CACHE_SIZE);
+	end = buf->start + end - 1;
 	if (test_range_bit(io_tree, buf->start, end, EXTENT_CSUM, 1)) {
 		buf->flags |= EXTENT_CSUM;
-		return buf;
+		return 0;
 	}
 
 	lock_extent(io_tree, buf->start, end, GFP_NOFS);
 
 	if (test_range_bit(io_tree, buf->start, end, EXTENT_CSUM, 1)) {
 		buf->flags |= EXTENT_CSUM;
+		ret = 0;
 		goto out_unlock;
 	}
 
@@ -419,6 +391,48 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 
 out_unlock:
 	unlock_extent(io_tree, buf->start, end, GFP_NOFS);
+	return ret;
+}
+
+struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
+					    u64 bytenr, u32 blocksize)
+{
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	struct extent_buffer *eb;
+	eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
+				bytenr, blocksize, GFP_NOFS);
+	return eb;
+}
+
+struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
+						 u64 bytenr, u32 blocksize)
+{
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	struct extent_buffer *eb;
+
+	eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
+				 bytenr, blocksize, NULL, GFP_NOFS);
+	return eb;
+}
+
+
+struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
+				      u32 blocksize)
+{
+	struct extent_buffer *buf = NULL;
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	struct extent_io_tree *io_tree;
+	int ret;
+
+	io_tree = &BTRFS_I(btree_inode)->io_tree;
+
+	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
+	if (!buf)
+		return NULL;
+	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree, buf, 0, 1,
+				 btree_get_extent);
+
+	ret = btrfs_verify_block_csum(root, buf);
 	return buf;
 }