1 files changed, 104 insertions, 7 deletions

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index d9fd7f4d3794..93d42d650820 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -3,6 +3,9 @@
 #include "disk-io.h"
 #include "transaction.h"
 
+#define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
+                                 sizeof(struct btrfs_item)) / \
+                                sizeof(struct btrfs_csum_item)) - 1))
 int btrfs_alloc_file_extent(struct btrfs_trans_handle *trans,
                                struct btrfs_root *root,
                                u64 objectid, u64 offset,
@@ -43,6 +46,54 @@ int btrfs_alloc_file_extent(struct btrfs_trans_handle *trans,
         return 0;
 }
 
+static struct btrfs_csum_item *__lookup_csum_item(struct btrfs_root *root,
+                                                  struct btrfs_path *path,
+                                                  u64 objectid, u64 offset)
+{
+        int ret;
+        struct btrfs_key file_key;
+        struct btrfs_key found_key;
+        struct btrfs_csum_item *item;
+        struct btrfs_leaf *leaf;
+        u64 csum_offset = 0;
+
+        file_key.objectid = objectid;
+        file_key.offset = offset;
+        file_key.flags = 0;
+        btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+        ret = btrfs_search_slot(NULL, root, &file_key, path, 0, 0);
+        if (ret < 0)
+                goto fail;
+        leaf = btrfs_buffer_leaf(path->nodes[0]);
+        if (ret > 0) {
+                ret = 1;
+                if (path->slots[0] == 0)
+                        goto fail;
+                path->slots[0]--;
+                btrfs_disk_key_to_cpu(&found_key,
+                                      &leaf->items[path->slots[0]].key);
+                if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
+                    found_key.objectid != objectid) {
+                        goto fail;
+                }
+                csum_offset = (offset - found_key.offset) >>
+                                root->fs_info->sb->s_blocksize_bits;
+                if (csum_offset >=
+                    btrfs_item_size(leaf->items + path->slots[0]) /
+                    sizeof(struct btrfs_csum_item)) {
+                        goto fail;
+                }
+        }
+        item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
+        item += csum_offset;
+        return item;
+fail:
+        if (ret > 0)
+                ret = -EIO;
+        return ERR_PTR(ret);
+}
+
+
 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root,
                              struct btrfs_path *path, u64 objectid,
@@ -52,11 +103,16 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
         struct btrfs_key file_key;
         int ins_len = mod < 0 ? -1 : 0;
         int cow = mod != 0;
+        struct btrfs_csum_item *csum_item;
 
+        csum_item = __lookup_csum_item(root, path, objectid, offset);
+        if (IS_ERR(csum_item))
+                return PTR_ERR(csum_item);
         file_key.objectid = objectid;
-        file_key.offset = offset;
+        file_key.offset = btrfs_csum_extent_offset(csum_item);
         file_key.flags = 0;
         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
+        btrfs_release_path(root, path);
         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
         return ret;
 }
@@ -64,12 +120,16 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root,
                           u64 objectid, u64 offset,
+                          u64 extent_offset,
                           char *data, size_t len)
 {
         int ret;
         struct btrfs_key file_key;
+        struct btrfs_key found_key;
         struct btrfs_path *path;
         struct btrfs_csum_item *item;
+        struct btrfs_leaf *leaf;
+        u64 csum_offset;
 
         path = btrfs_alloc_path();
         BUG_ON(!path);
@@ -78,14 +138,50 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
         file_key.offset = offset;
         file_key.flags = 0;
         btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+        ret = btrfs_search_slot(trans, root, &file_key, path,
+                                sizeof(struct btrfs_csum_item), 1);
+        if (ret < 0)
+                goto fail;
+        if (ret == 0) {
+                csum_offset = 0;
+                goto csum;
+        }
+        if (path->slots[0] == 0) {
+                btrfs_release_path(root, path);
+                goto insert;
+        }
+        path->slots[0]--;
+        leaf = btrfs_buffer_leaf(path->nodes[0]);
+        btrfs_disk_key_to_cpu(&found_key, &leaf->items[path->slots[0]].key);
+        csum_offset = (offset - found_key.offset) >>
+                        root->fs_info->sb->s_blocksize_bits;
+        if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
+            found_key.objectid != objectid ||
+            csum_offset >= MAX_CSUM_ITEMS(root)) {
+                btrfs_release_path(root, path);
+                goto insert;
+        }
+        if (csum_offset >= btrfs_item_size(leaf->items + path->slots[0]) /
+            sizeof(struct btrfs_csum_item)) {
+                ret = btrfs_extend_item(trans, root, path,
+                                        sizeof(struct btrfs_csum_item));
+                BUG_ON(ret);
+                goto csum;
+        }
+
+insert:
+        csum_offset = 0;
         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
-                                      BTRFS_CSUM_SIZE);
+                                      sizeof(struct btrfs_csum_item));
         if (ret != 0 && ret != -EEXIST)
                 goto fail;
+csum:
         item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                               struct btrfs_csum_item);
         ret = 0;
+        item += csum_offset;
         ret = btrfs_csum_data(root, data, len, item->csum);
+        btrfs_set_csum_extent_offset(item, extent_offset);
         btrfs_mark_buffer_dirty(path->nodes[0]);
 fail:
         btrfs_release_path(root, path);
@@ -111,12 +207,13 @@ int btrfs_csum_verify_file_block(struct btrfs_root *root,
         file_key.flags = 0;
         btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
         mutex_lock(&root->fs_info->fs_mutex);
-        ret = btrfs_search_slot(NULL, root, &file_key, path, 0, 0);
-        if (ret)
+
+        item = __lookup_csum_item(root, path, objectid, offset);
+        if (IS_ERR(item)) {
+                ret = PTR_ERR(item);
                 goto fail;
-        item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
-                              struct btrfs_csum_item);
-        ret = 0;
+        }
+
         ret = btrfs_csum_data(root, data, len, result);
         WARN_ON(ret);
         if (memcmp(result, item->csum, BTRFS_CSUM_SIZE))