1 files changed, 50 insertions, 36 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5547607681f4..e40fb318ad99 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;
 }