2 files changed, 143 insertions, 59 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index ec96f3a6d536..9d4ba3470c17 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -37,6 +37,11 @@ static int balance_node_right(struct btrfs_trans_handle *trans,
                               struct extent_buffer *src_buf);
 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                    struct btrfs_path *path, int level, int slot);
+static int setup_items_for_insert(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root, struct btrfs_path *path,
+                        struct btrfs_key *cpu_key, u32 *data_size,
+                        u32 total_data, u32 total_size, int nr);
+
 
 struct btrfs_path *btrfs_alloc_path(void)
 {
@@ -2997,75 +3002,85 @@ again:
         return ret;
 }
 
-/*
- * This function splits a single item into two items,
- * giving 'new_key' to the new item and splitting the
- * old one at split_offset (from the start of the item).
- *
- * The path may be released by this operation.  After
- * the split, the path is pointing to the old item.  The
- * new item is going to be in the same node as the old one.
- *
- * Note, the item being split must be smaller enough to live alone on
- * a tree block with room for one extra struct btrfs_item
- *
- * This allows us to split the item in place, keeping a lock on the
- * leaf the entire time.
- */
-int btrfs_split_item(struct btrfs_trans_handle *trans,
-                     struct btrfs_root *root,
-                     struct btrfs_path *path,
-                     struct btrfs_key *new_key,
-                     unsigned long split_offset)
+static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
+                                         struct btrfs_root *root,
+                                         struct btrfs_path *path, int ins_len)
 {
-        u32 item_size;
+        struct btrfs_key key;
         struct extent_buffer *leaf;
-        struct btrfs_key orig_key;
-        struct btrfs_item *item;
-        struct btrfs_item *new_item;
-        int ret = 0;
-        int slot;
-        u32 nritems;
-        u32 orig_offset;
-        struct btrfs_disk_key disk_key;
-        char *buf;
+        struct btrfs_file_extent_item *fi;
+        u64 extent_len = 0;
+        u32 item_size;
+        int ret;
 
         leaf = path->nodes[0];
-        btrfs_item_key_to_cpu(leaf, &orig_key, path->slots[0]);
-        if (btrfs_leaf_free_space(root, leaf) >= sizeof(struct btrfs_item))
-                goto split;
+        btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+        BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
+               key.type != BTRFS_EXTENT_CSUM_KEY);
+
+        if (btrfs_leaf_free_space(root, leaf) >= ins_len)
+                return 0;
 
         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+        if (key.type == BTRFS_EXTENT_DATA_KEY) {
+                fi = btrfs_item_ptr(leaf, path->slots[0],
+                                    struct btrfs_file_extent_item);
+                extent_len = btrfs_file_extent_num_bytes(leaf, fi);
+        }
         btrfs_release_path(root, path);
 
-        path->search_for_split = 1;
         path->keep_locks = 1;
-
-        ret = btrfs_search_slot(trans, root, &orig_key, path, 0, 1);
+        path->search_for_split = 1;
+        ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
         path->search_for_split = 0;
+        if (ret < 0)
+                goto err;
 
+        ret = -EAGAIN;
+        leaf = path->nodes[0];
         /* if our item isn't there or got smaller, return now */
-        if (ret != 0 || item_size != btrfs_item_size_nr(path->nodes[0],
-                                                        path->slots[0])) {
-                path->keep_locks = 0;
-                return -EAGAIN;
+        if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
+                goto err;
+
+        if (key.type == BTRFS_EXTENT_DATA_KEY) {
+                fi = btrfs_item_ptr(leaf, path->slots[0],
+                                    struct btrfs_file_extent_item);
+                if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
+                        goto err;
         }
 
         btrfs_set_path_blocking(path);
-        ret = split_leaf(trans, root, &orig_key, path,
-                         sizeof(struct btrfs_item), 1);
-        path->keep_locks = 0;
+        ret = split_leaf(trans, root, &key, path, ins_len, 1);
         BUG_ON(ret);
 
+        path->keep_locks = 0;
         btrfs_unlock_up_safe(path, 1);
+        return 0;
+err:
+        path->keep_locks = 0;
+        return ret;
+}
+
+static noinline int split_item(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *root,
+                               struct btrfs_path *path,
+                               struct btrfs_key *new_key,
+                               unsigned long split_offset)
+{
+        struct extent_buffer *leaf;
+        struct btrfs_item *item;
+        struct btrfs_item *new_item;
+        int slot;
+        char *buf;
+        u32 nritems;
+        u32 item_size;
+        u32 orig_offset;
+        struct btrfs_disk_key disk_key;
+
         leaf = path->nodes[0];
         BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
 
-split:
-        /*
-         * make sure any changes to the path from split_leaf leave it
-         * in a blocking state
-         */
         btrfs_set_path_blocking(path);
 
         item = btrfs_item_nr(leaf, path->slots[0]);
@@ -3073,19 +3088,19 @@ split:
         item_size = btrfs_item_size(leaf, item);
 
         buf = kmalloc(item_size, GFP_NOFS);
+        if (!buf)
+                return -ENOMEM;
+
         read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
                             path->slots[0]), item_size);
-        slot = path->slots[0] + 1;
-        leaf = path->nodes[0];
 
+        slot = path->slots[0] + 1;
         nritems = btrfs_header_nritems(leaf);
-
         if (slot != nritems) {
                 /* shift the items */
                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
-                              btrfs_item_nr_offset(slot),
-                              (nritems - slot) * sizeof(struct btrfs_item));
-
+                                btrfs_item_nr_offset(slot),
+                                (nritems - slot) * sizeof(struct btrfs_item));
         }
 
         btrfs_cpu_key_to_disk(&disk_key, new_key);
@@ -3113,16 +3128,81 @@ split:
                             item_size - split_offset);
         btrfs_mark_buffer_dirty(leaf);
 
-        ret = 0;
-        if (btrfs_leaf_free_space(root, leaf) < 0) {
-                btrfs_print_leaf(root, leaf);
-                BUG();
-        }
+        BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
         kfree(buf);
+        return 0;
+}
+
+/*
+ * This function splits a single item into two items,
+ * giving 'new_key' to the new item and splitting the
+ * old one at split_offset (from the start of the item).
+ *
+ * The path may be released by this operation.  After
+ * the split, the path is pointing to the old item.  The
+ * new item is going to be in the same node as the old one.
+ *
+ * Note, the item being split must be smaller enough to live alone on
+ * a tree block with room for one extra struct btrfs_item
+ *
+ * This allows us to split the item in place, keeping a lock on the
+ * leaf the entire time.
+ */
+int btrfs_split_item(struct btrfs_trans_handle *trans,
+                     struct btrfs_root *root,
+                     struct btrfs_path *path,
+                     struct btrfs_key *new_key,
+                     unsigned long split_offset)
+{
+        int ret;
+        ret = setup_leaf_for_split(trans, root, path,
+                                   sizeof(struct btrfs_item));
+        if (ret)
+                return ret;
+
+        ret = split_item(trans, root, path, new_key, split_offset);
         return ret;
 }
 
 /*
+ * This function duplicate a item, giving 'new_key' to the new item.
+ * It guarantees both items live in the same tree leaf and the new item
+ * is contiguous with the original item.
+ *
+ * This allows us to split file extent in place, keeping a lock on the
+ * leaf the entire time.
+ */
+int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
+                         struct btrfs_root *root,
+                         struct btrfs_path *path,
+                         struct btrfs_key *new_key)
+{
+        struct extent_buffer *leaf;
+        int ret;
+        u32 item_size;
+
+        leaf = path->nodes[0];
+        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+        ret = setup_leaf_for_split(trans, root, path,
+                                   item_size + sizeof(struct btrfs_item));
+        if (ret)
+                return ret;
+
+        path->slots[0]++;
+        ret = setup_items_for_insert(trans, root, path, new_key, &item_size,
+                                     item_size, item_size +
+                                     sizeof(struct btrfs_item), 1);
+        BUG_ON(ret);
+
+        leaf = path->nodes[0];
+        memcpy_extent_buffer(leaf,
+                             btrfs_item_ptr_offset(leaf, path->slots[0]),
+                             btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
+                             item_size);
+        return 0;
+}
+
+/*
  * make the item pointed to by the path smaller.  new_size indicates
  * how small to make it, and from_end tells us if we just chop bytes
  * off the end of the item or if we shift the item to chop bytes off
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 444b3e9b92a4..e3b58001162d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2089,6 +2089,10 @@ int btrfs_split_item(struct btrfs_trans_handle *trans,
                      struct btrfs_path *path,
                      struct btrfs_key *new_key,
                      unsigned long split_offset);
+int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
+                         struct btrfs_root *root,
+                         struct btrfs_path *path,
+                         struct btrfs_key *new_key);
 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
                       *root, struct btrfs_key *key, struct btrfs_path *p, int
                       ins_len, int cow);