Btrfs: log changed inodes based on the extent map tree

We don't really need to copy extents from the source tree since we have all
of the information already available to us in the extent_map tree.  So
instead just write the extents straight to the log tree and don't bother to
copy the extent items from the source tree.

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

7 files changed, 372 insertions, 210 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 0c5c28ff794f..e8b32641ea90 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -5490,6 +5490,139 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
 	return btrfs_next_old_leaf(root, path, 0);
 }
 
+/* Release the path up to but not including the given level */
+static void btrfs_release_level(struct btrfs_path *path, int level)
+{
+	int i;
+
+	for (i = 0; i < level; i++) {
+		path->slots[i] = 0;
+		if (!path->nodes[i])
+			continue;
+		if (path->locks[i]) {
+			btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
+			path->locks[i] = 0;
+		}
+		free_extent_buffer(path->nodes[i]);
+		path->nodes[i] = NULL;
+	}
+}
+
+/*
+ * This function assumes 2 things
+ *
+ * 1) You are using path->keep_locks
+ * 2) You are not inserting items.
+ *
+ * If either of these are not true do not use this function. If you need a next
+ * leaf with either of these not being true then this function can be easily
+ * adapted to do that, but at the moment these are the limitations.
+ */
+int btrfs_next_leaf_write(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root, struct btrfs_path *path,
+			  int del)
+{
+	struct extent_buffer *b;
+	struct btrfs_key key;
+	u32 nritems;
+	int level = 1;
+	int slot;
+	int ret = 1;
+	int write_lock_level = BTRFS_MAX_LEVEL;
+	int ins_len = del ? -1 : 0;
+
+	WARN_ON(!(path->keep_locks || path->really_keep_locks));
+
+	nritems = btrfs_header_nritems(path->nodes[0]);
+	btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
+
+	while (path->nodes[level]) {
+		nritems = btrfs_header_nritems(path->nodes[level]);
+		if (!(path->locks[level] & BTRFS_WRITE_LOCK)) {
+search:
+			btrfs_release_path(path);
+			ret = btrfs_search_slot(trans, root, &key, path,
+						ins_len, 1);
+			if (ret < 0)
+				goto out;
+			level = 1;
+			continue;
+		}
+
+		if (path->slots[level] >= nritems - 1) {
+			level++;
+			continue;
+		}
+
+		btrfs_release_level(path, level);
+		break;
+	}
+
+	if (!path->nodes[level]) {
+		ret = 1;
+		goto out;
+	}
+
+	path->slots[level]++;
+	b = path->nodes[level];
+
+	while (b) {
+		level = btrfs_header_level(b);
+
+		if (!should_cow_block(trans, root, b))
+			goto cow_done;
+
+		btrfs_set_path_blocking(path);
+		ret = btrfs_cow_block(trans, root, b,
+				      path->nodes[level + 1],
+				      path->slots[level + 1], &b);
+		if (ret)
+			goto out;
+cow_done:
+		path->nodes[level] = b;
+		btrfs_clear_path_blocking(path, NULL, 0);
+		if (level != 0) {
+			ret = setup_nodes_for_search(trans, root, path, b,
+						     level, ins_len,
+						     &write_lock_level);
+			if (ret == -EAGAIN)
+				goto search;
+			if (ret)
+				goto out;
+
+			b = path->nodes[level];
+			slot = path->slots[level];
+
+			ret = read_block_for_search(trans, root, path,
+						    &b, level, slot, &key, 0);
+			if (ret == -EAGAIN)
+				goto search;
+			if (ret)
+				goto out;
+			level = btrfs_header_level(b);
+			if (!btrfs_try_tree_write_lock(b)) {
+				btrfs_set_path_blocking(path);
+				btrfs_tree_lock(b);
+				btrfs_clear_path_blocking(path, b,
+							  BTRFS_WRITE_LOCK);
+			}
+			path->locks[level] = BTRFS_WRITE_LOCK;
+			path->nodes[level] = b;
+			path->slots[level] = 0;
+		} else {
+			path->slots[level] = 0;
+			ret = 0;
+			break;
+		}
+	}
+
+out:
+	if (ret)
+		btrfs_release_path(path);
+
+	return ret;
+}
+
 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
 			u64 time_seq)
 {
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 9ed452f5d062..55aff6764bb9 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3187,6 +3187,9 @@ static inline int btrfs_insert_empty_item(struct btrfs_trans_handle *trans,
 }
 
 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path);
+int btrfs_next_leaf_write(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root, struct btrfs_path *path,
+			  int del);
 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
 			u64 time_seq);
 static inline int btrfs_next_old_item(struct btrfs_root *root,
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 85ae2b6fe03b..fff2c28497b6 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -49,7 +49,7 @@ void extent_map_tree_init(struct extent_map_tree *tree)
 struct extent_map *alloc_extent_map(void)
 {
 	struct extent_map *em;
-	em = kmem_cache_alloc(extent_map_cache, GFP_NOFS);
+	em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
 	if (!em)
 		return NULL;
 	em->in_tree = 0;
@@ -198,16 +198,15 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
 			merge = rb_entry(rb, struct extent_map, rb_node);
 		if (rb && mergable_maps(merge, em)) {
 			em->start = merge->start;
+			em->orig_start = merge->orig_start;
 			em->len += merge->len;
 			em->block_len += merge->block_len;
 			em->block_start = merge->block_start;
 			merge->in_tree = 0;
-			if (merge->generation > em->generation) {
-				em->mod_start = em->start;
-				em->mod_len = em->len;
-				em->generation = merge->generation;
-				list_move(&em->list, &tree->modified_extents);
-			}
+			em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
+			em->mod_start = merge->mod_start;
+			em->generation = max(em->generation, merge->generation);
+			list_move(&em->list, &tree->modified_extents);
 
 			list_del_init(&merge->list);
 			rb_erase(&merge->rb_node, &tree->map);
@@ -223,11 +222,8 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
 		em->block_len += merge->len;
 		rb_erase(&merge->rb_node, &tree->map);
 		merge->in_tree = 0;
-		if (merge->generation > em->generation) {
-			em->mod_len = em->len;
-			em->generation = merge->generation;
-			list_move(&em->list, &tree->modified_extents);
-		}
+		em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
+		em->generation = max(em->generation, merge->generation);
 		list_del_init(&merge->list);
 		free_extent_map(merge);
 	}
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 6810145f4e97..c56088ece500 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -621,7 +621,7 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 			} else {
 				split->block_len = split->len;
 				split->block_start = em->block_start + diff;
-				split->orig_start = split->start;
+				split->orig_start = em->orig_start;
 			}
 
 			ret = add_extent_mapping(em_tree, split);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 73e6833dcc21..355a297e7988 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -95,6 +95,10 @@ static noinline int cow_file_range(struct inode *inode,
 				   struct page *locked_page,
 				   u64 start, u64 end, int *page_started,
 				   unsigned long *nr_written, int unlock);
+static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
+					   u64 len, u64 orig_start,
+					   u64 block_start, u64 block_len,
+					   u64 orig_block_len, int type);
 
 static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
 				     struct inode *inode,  struct inode *dir,
@@ -704,10 +708,14 @@ retry:
 		em->compress_type = async_extent->compress_type;
 		set_bit(EXTENT_FLAG_PINNED, &em->flags);
 		set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+		em->generation = -1;
 
 		while (1) {
 			write_lock(&em_tree->lock);
 			ret = add_extent_mapping(em_tree, em);
+			if (!ret)
+				list_move(&em->list,
+					  &em_tree->modified_extents);
 			write_unlock(&em_tree->lock);
 			if (ret != -EEXIST) {
 				free_extent_map(em);
@@ -890,10 +898,14 @@ static noinline int __cow_file_range(struct btrfs_trans_handle *trans,
 		em->orig_block_len = ins.offset;
 		em->bdev = root->fs_info->fs_devices->latest_bdev;
 		set_bit(EXTENT_FLAG_PINNED, &em->flags);
+		em->generation = -1;
 
 		while (1) {
 			write_lock(&em_tree->lock);
 			ret = add_extent_mapping(em_tree, em);
+			if (!ret)
+				list_move(&em->list,
+					  &em_tree->modified_extents);
 			write_unlock(&em_tree->lock);
 			if (ret != -EEXIST) {
 				free_extent_map(em);
@@ -1320,7 +1332,7 @@ out_check:
 			em = alloc_extent_map();
 			BUG_ON(!em); /* -ENOMEM */
 			em->start = cur_offset;
-			em->orig_start = em->start;
+			em->orig_start = found_key.offset - extent_offset;
 			em->len = num_bytes;
 			em->block_len = num_bytes;
 			em->block_start = disk_bytenr;
@@ -1328,9 +1340,13 @@ out_check:
 			em->bdev = root->fs_info->fs_devices->latest_bdev;
 			set_bit(EXTENT_FLAG_PINNED, &em->flags);
 			set_bit(EXTENT_FLAG_FILLING, &em->flags);
+			em->generation = -1;
 			while (1) {
 				write_lock(&em_tree->lock);
 				ret = add_extent_mapping(em_tree, em);
+				if (!ret)
+					list_move(&em->list,
+						  &em_tree->modified_extents);
 				write_unlock(&em_tree->lock);
 				if (ret != -EEXIST) {
 					free_extent_map(em);
@@ -5371,6 +5387,7 @@ again:
 		if (start + len <= found_key.offset)
 			goto not_found;
 		em->start = start;
+		em->orig_start = start;
 		em->len = found_key.offset - start;
 		goto not_found_em;
 	}
@@ -5423,7 +5440,7 @@ again:
 		em->len = (copy_size + root->sectorsize - 1) &
 			~((u64)root->sectorsize - 1);
 		em->orig_block_len = em->len;
-		em->orig_start = EXTENT_MAP_INLINE;
+		em->orig_start = em->start;
 		if (compress_type) {
 			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 			em->compress_type = compress_type;
@@ -5476,6 +5493,7 @@ again:
 	}
 not_found:
 	em->start = start;
+	em->orig_start = start;
 	em->len = len;
 not_found_em:
 	em->block_start = EXTENT_MAP_HOLE;
@@ -5677,30 +5695,14 @@ out:
 }
 
 static struct extent_map *btrfs_new_extent_direct(struct inode *inode,
-						  struct extent_map *em,
 						  u64 start, u64 len)
 {
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_trans_handle *trans;
-	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_map *em;
 	struct btrfs_key ins;
 	u64 alloc_hint;
 	int ret;
-	bool insert = false;
-
-	/*
-	 * Ok if the extent map we looked up is a hole and is for the exact
-	 * range we want, there is no reason to allocate a new one, however if
-	 * it is not right then we need to free this one and drop the cache for
-	 * our range.
-	 */
-	if (em->block_start != EXTENT_MAP_HOLE || em->start != start ||
-	    em->len != len) {
-		free_extent_map(em);
-		em = NULL;
-		insert = true;
-		btrfs_drop_extent_cache(inode, start, start + len - 1, 0);
-	}
 
 	trans = btrfs_join_transaction(root);
 	if (IS_ERR(trans))
@@ -5716,38 +5718,10 @@ static struct extent_map *btrfs_new_extent_direct(struct inode *inode,
 		goto out;
 	}
 
-	if (!em) {
-		em = alloc_extent_map();
-		if (!em) {
-			em = ERR_PTR(-ENOMEM);
-			goto out;
-		}
-	}
-
-	em->start = start;
-	em->orig_start = em->start;
-	em->len = ins.offset;
-
-	em->block_start = ins.objectid;
-	em->block_len = ins.offset;
-	em->orig_block_len = ins.offset;
-	em->bdev = root->fs_info->fs_devices->latest_bdev;
-
-	/*
-	 * We need to do this because if we're using the original em we searched
-	 * for, we could have EXTENT_FLAG_VACANCY set, and we don't want that.
-	 */
-	em->flags = 0;
-	set_bit(EXTENT_FLAG_PINNED, &em->flags);
-
-	while (insert) {
-		write_lock(&em_tree->lock);
-		ret = add_extent_mapping(em_tree, em);
-		write_unlock(&em_tree->lock);
-		if (ret != -EEXIST)
-			break;
-		btrfs_drop_extent_cache(inode, start, start + em->len - 1, 0);
-	}
+	em = create_pinned_em(inode, start, ins.offset, start, ins.objectid,
+			      ins.offset, ins.offset, 0);
+	if (IS_ERR(em))
+		goto out;
 
 	ret = btrfs_add_ordered_extent_dio(inode, start, ins.objectid,
 					   ins.offset, ins.offset, 0);
@@ -5943,6 +5917,7 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
 	em->block_start = block_start;
 	em->bdev = root->fs_info->fs_devices->latest_bdev;
 	em->orig_block_len = orig_block_len;
+	em->generation = -1;
 	set_bit(EXTENT_FLAG_PINNED, &em->flags);
 	if (type == BTRFS_ORDERED_PREALLOC)
 		set_bit(EXTENT_FLAG_FILLING, &em->flags);
@@ -5952,6 +5927,9 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
 				em->start + em->len - 1, 0);
 		write_lock(&em_tree->lock);
 		ret = add_extent_mapping(em_tree, em);
+		if (!ret)
+			list_move(&em->list,
+				  &em_tree->modified_extents);
 		write_unlock(&em_tree->lock);
 	} while (ret == -EEXIST);
 
@@ -6078,7 +6056,7 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
 			goto must_cow;
 
 		if (can_nocow_odirect(trans, inode, start, len) == 1) {
-			u64 orig_start = em->start;
+			u64 orig_start = em->orig_start;
 			u64 orig_block_len = em->orig_block_len;
 
 			if (type == BTRFS_ORDERED_PREALLOC) {
@@ -6110,7 +6088,8 @@ must_cow:
 	 * it above
 	 */
 	len = bh_result->b_size;
-	em = btrfs_new_extent_direct(inode, em, start, len);
+	free_extent_map(em);
+	em = btrfs_new_extent_direct(inode, start, len);
 	if (IS_ERR(em)) {
 		ret = PTR_ERR(em);
 		goto unlock_err;
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index ab7168ee618f..72444811d275 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3150,145 +3150,220 @@ static int extent_cmp(void *priv, struct list_head *a, struct list_head *b)
 	return 0;
 }
 
-struct log_args {
-	struct extent_buffer *src;
-	u64 next_offset;
-	int start_slot;
-	int nr;
-};
+static int drop_adjacent_extents(struct btrfs_trans_handle *trans,
+				 struct btrfs_root *root, struct inode *inode,
+				 struct extent_map *em,
+				 struct btrfs_path *path)
+{
+	struct btrfs_file_extent_item *fi;
+	struct extent_buffer *leaf;
+	struct btrfs_key key, new_key;
+	struct btrfs_map_token token;
+	u64 extent_end;
+	u64 extent_offset = 0;
+	int extent_type;
+	int del_slot = 0;
+	int del_nr = 0;
+	int ret = 0;
+
+	while (1) {
+		btrfs_init_map_token(&token);
+		leaf = path->nodes[0];
+		path->slots[0]++;
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			if (del_nr) {
+				ret = btrfs_del_items(trans, root, path,
+						      del_slot, del_nr);
+				if (ret)
+					return ret;
+				del_nr = 0;
+			}
+
+			ret = btrfs_next_leaf_write(trans, root, path, 1);
+			if (ret < 0)
+				return ret;
+			if (ret > 0)
+				return 0;
+			leaf = path->nodes[0];
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		if (key.objectid != btrfs_ino(inode) ||
+		    key.type != BTRFS_EXTENT_DATA_KEY ||
+		    key.offset >= em->start + em->len)
+			break;
+
+		fi = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_file_extent_item);
+		extent_type = btrfs_token_file_extent_type(leaf, fi, &token);
+		if (extent_type == BTRFS_FILE_EXTENT_REG ||
+		    extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+			extent_offset = btrfs_token_file_extent_offset(leaf,
+								fi, &token);
+			extent_end = key.offset +
+				btrfs_token_file_extent_num_bytes(leaf, fi,
+								  &token);
+		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+			extent_end = key.offset +
+				btrfs_file_extent_inline_len(leaf, fi);
+		} else {
+			BUG();
+		}
+
+		if (extent_end <= em->len + em->start) {
+			if (!del_nr) {
+				del_slot = path->slots[0];
+			}
+			del_nr++;
+			continue;
+		}
+
+		/*
+		 * Ok so we'll ignore previous items if we log a new extent,
+		 * which can lead to overlapping extents, so if we have an
+		 * existing extent we want to adjust we _have_ to check the next
+		 * guy to make sure we even need this extent anymore, this keeps
+		 * us from panicing in set_item_key_safe.
+		 */
+		if (path->slots[0] < btrfs_header_nritems(leaf) - 1) {
+			struct btrfs_key tmp_key;
+
+			btrfs_item_key_to_cpu(leaf, &tmp_key,
+					      path->slots[0] + 1);
+			if (tmp_key.objectid == btrfs_ino(inode) &&
+			    tmp_key.type == BTRFS_EXTENT_DATA_KEY &&
+			    tmp_key.offset <= em->start + em->len) {
+				if (!del_nr)
+					del_slot = path->slots[0];
+				del_nr++;
+				continue;
+			}
+		}
+
+		BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
+		memcpy(&new_key, &key, sizeof(new_key));
+		new_key.offset = em->start + em->len;
+		btrfs_set_item_key_safe(trans, root, path, &new_key);
+		extent_offset += em->start + em->len - key.offset;
+		btrfs_set_token_file_extent_offset(leaf, fi, extent_offset,
+						   &token);
+		btrfs_set_token_file_extent_num_bytes(leaf, fi, extent_end -
+						      (em->start + em->len),
+						      &token);
+		btrfs_mark_buffer_dirty(leaf);
+	}
+
+	if (del_nr)
+		ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
+
+	return ret;
+}
 
 static int log_one_extent(struct btrfs_trans_handle *trans,
 			  struct inode *inode, struct btrfs_root *root,
-			  struct extent_map *em, struct btrfs_path *path,
-			  struct btrfs_path *dst_path, struct log_args *args)
+			  struct extent_map *em, struct btrfs_path *path)
 {
 	struct btrfs_root *log = root->log_root;
+	struct btrfs_file_extent_item *fi;
+	struct extent_buffer *leaf;
+	struct list_head ordered_sums;
 	struct btrfs_key key;
-	u64 start = em->mod_start;
-	u64 search_start = start;
-	u64 len = em->mod_len;
-	u64 num_bytes;
-	int nritems;
+	u64 csum_offset = em->mod_start - em->start;
+	u64 csum_len = em->mod_len;
+	u64 extent_offset = em->start - em->orig_start;
+	u64 block_len;
 	int ret;
+	bool skip_csum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
 
-	if (BTRFS_I(inode)->logged_trans == trans->transid) {
-		ret = __btrfs_drop_extents(trans, log, inode, dst_path, start,
-					   start + len, NULL, 0);
-		if (ret)
-			return ret;
+	INIT_LIST_HEAD(&ordered_sums);
+	key.objectid = btrfs_ino(inode);
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = em->start;
+	path->really_keep_locks = 1;
+
+	ret = btrfs_insert_empty_item(trans, log, path, &key, sizeof(*fi));
+	if (ret && ret != -EEXIST) {
+		path->really_keep_locks = 0;
+		return ret;
+	}
+	leaf = path->nodes[0];
+	fi = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+	btrfs_set_file_extent_generation(leaf, fi, em->generation);
+	if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
+		skip_csum = true;
+		btrfs_set_file_extent_type(leaf, fi,
+					   BTRFS_FILE_EXTENT_PREALLOC);
+	} else {
+		btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
+		if (em->block_start == 0)
+			skip_csum = true;
+	}
+
+	block_len = max(em->block_len, em->orig_block_len);
+	if (em->compress_type != BTRFS_COMPRESS_NONE) {
+		btrfs_set_file_extent_disk_bytenr(leaf, fi, em->block_start);
+		btrfs_set_file_extent_disk_num_bytes(leaf, fi, block_len);
+	} else if (em->block_start < EXTENT_MAP_LAST_BYTE) {
+		btrfs_set_file_extent_disk_bytenr(leaf, fi,
+						  em->block_start -
+						  extent_offset);
+		btrfs_set_file_extent_disk_num_bytes(leaf, fi, block_len);
+	} else {
+		btrfs_set_file_extent_disk_bytenr(leaf, fi, 0);
+		btrfs_set_file_extent_disk_num_bytes(leaf, fi, 0);
 	}
 
-	while (len) {
-		if (args->nr)
-			goto next_slot;
-again:
-		key.objectid = btrfs_ino(inode);
-		key.type = BTRFS_EXTENT_DATA_KEY;
-		key.offset = search_start;
-
-		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
-		if (ret < 0)
-			return ret;
-
-		if (ret) {
-			/*
-			 * A rare case were we can have an em for a section of a
-			 * larger extent so we need to make sure that this em
-			 * falls within the extent we've found.  If not we just
-			 * bail and go back to ye-olde way of doing things but
-			 * it happens often enough in testing that we need to do
-			 * this dance to make sure.
-			 */
-			do {
-				if (path->slots[0] == 0) {
-					btrfs_release_path(path);
-					if (search_start == 0)
-						return -ENOENT;
-					search_start--;
-					goto again;
-				}
+	btrfs_set_file_extent_offset(leaf, fi, em->start - em->orig_start);
+	btrfs_set_file_extent_num_bytes(leaf, fi, em->len);
+	btrfs_set_file_extent_ram_bytes(leaf, fi, em->len);
+	btrfs_set_file_extent_compression(leaf, fi, em->compress_type);
+	btrfs_set_file_extent_encryption(leaf, fi, 0);
+	btrfs_set_file_extent_other_encoding(leaf, fi, 0);
+	btrfs_mark_buffer_dirty(leaf);
 
-				path->slots[0]--;
-				btrfs_item_key_to_cpu(path->nodes[0], &key,
-						      path->slots[0]);
-				if (key.objectid != btrfs_ino(inode) ||
-				    key.type != BTRFS_EXTENT_DATA_KEY) {
-					btrfs_release_path(path);
-					return -ENOENT;
-				}
-			} while (key.offset > start);
+	/*
+	 * Have to check the extent to the right of us to make sure it doesn't
+	 * fall in our current range.  We're ok if the previous extent is in our
+	 * range since the recovery stuff will run us in key order and thus just
+	 * drop the part we overwrote.
+	 */
+	ret = drop_adjacent_extents(trans, log, inode, em, path);
+	btrfs_release_path(path);
+	path->really_keep_locks = 0;
+	if (ret) {
+		return ret;
+	}
 
-			num_bytes = btrfs_file_extent_length(path);
-			if (key.offset + num_bytes <= start) {
-				btrfs_release_path(path);
-				return -ENOENT;
-			}
-		}
-		args->src = path->nodes[0];
-next_slot:
-		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
-		num_bytes = btrfs_file_extent_length(path);
-		if (args->nr &&
-		    args->start_slot + args->nr == path->slots[0]) {
-			args->nr++;
-		} else if (args->nr) {
-			ret = copy_items(trans, inode, dst_path, args->src,
-					 args->start_slot, args->nr,
-					 LOG_INODE_ALL);
-			if (ret)
-				return ret;
-			args->nr = 1;
-			args->start_slot = path->slots[0];
-		} else if (!args->nr) {
-			args->nr = 1;
-			args->start_slot = path->slots[0];
-		}
-		nritems = btrfs_header_nritems(path->nodes[0]);
-		path->slots[0]++;
-		if (len < num_bytes) {
-			/* I _think_ this is ok, envision we write to a
-			 * preallocated space that is adjacent to a previously
-			 * written preallocated space that gets merged when we
-			 * mark this preallocated space written.  If we do not
-			 * have the adjacent extent in cache then when we copy
-			 * this extent it could end up being larger than our EM
-			 * thinks it is, which is a-ok, so just set len to 0.
-			 */
-			len = 0;
-		} else {
-			len -= num_bytes;
-		}
-		start = key.offset + num_bytes;
-		args->next_offset = start;
-		search_start = start;
+	if (skip_csum)
+		return 0;
 
-		if (path->slots[0] < nritems) {
-			if (len)
-				goto next_slot;
-			break;
-		}
+	/* block start is already adjusted for the file extent offset. */
+	ret = btrfs_lookup_csums_range(log->fs_info->csum_root,
+				       em->block_start + csum_offset,
+				       em->block_start + csum_offset +
+				       csum_len - 1, &ordered_sums, 0);
+	if (ret)
+		return ret;
 
-		if (args->nr) {
-			ret = copy_items(trans, inode, dst_path, args->src,
-					 args->start_slot, args->nr,
-					 LOG_INODE_ALL);
-			if (ret)
-				return ret;
-			args->nr = 0;
-			btrfs_release_path(path);
-		}
+	while (!list_empty(&ordered_sums)) {
+		struct btrfs_ordered_sum *sums = list_entry(ordered_sums.next,
+						   struct btrfs_ordered_sum,
+						   list);
+		if (!ret)
+			ret = btrfs_csum_file_blocks(trans, log, sums);
+		list_del(&sums->list);
+		kfree(sums);
 	}
 
-	return 0;
+	return ret;
 }
 
 static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
 				     struct btrfs_root *root,
 				     struct inode *inode,
-				     struct btrfs_path *path,
-				     struct btrfs_path *dst_path)
+				     struct btrfs_path *path)
 {
-	struct log_args args;
 	struct extent_map *em, *n;
 	struct list_head extents;
 	struct extent_map_tree *tree = &BTRFS_I(inode)->extent_tree;
@@ -3297,8 +3372,6 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
 
 	INIT_LIST_HEAD(&extents);
 
-	memset(&args, 0, sizeof(args));
-
 	write_lock(&tree->lock);
 	test_gen = root->fs_info->last_trans_committed;
 
@@ -3331,34 +3404,13 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
 
 		write_unlock(&tree->lock);
 
-		/*
-		 * If the previous EM and the last extent we left off on aren't
-		 * sequential then we need to copy the items we have and redo
-		 * our search
-		 */
-		if (args.nr && em->mod_start != args.next_offset) {
-			ret = copy_items(trans, inode, dst_path, args.src,
-					 args.start_slot, args.nr,
-					 LOG_INODE_ALL);
-			if (ret) {
-				free_extent_map(em);
-				write_lock(&tree->lock);
-				continue;
-			}
-			btrfs_release_path(path);
-			args.nr = 0;
-		}
-
-		ret = log_one_extent(trans, inode, root, em, path, dst_path, &args);
+		ret = log_one_extent(trans, inode, root, em, path);
 		free_extent_map(em);
 		write_lock(&tree->lock);
 	}
 	WARN_ON(!list_empty(&extents));
 	write_unlock(&tree->lock);
 
-	if (!ret && args.nr)
-		ret = copy_items(trans, inode, dst_path, args.src,
-				 args.start_slot, args.nr, LOG_INODE_ALL);
 	btrfs_release_path(path);
 	return ret;
 }
@@ -3551,10 +3603,8 @@ next_slot:
 
 log_extents:
 	if (fast_search) {
-		btrfs_release_path(path);
 		btrfs_release_path(dst_path);
-		ret = btrfs_log_changed_extents(trans, root, inode, path,
-						dst_path);
+		ret = btrfs_log_changed_extents(trans, root, inode, dst_path);
 		if (ret) {
 			err = ret;
 			goto out_unlock;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 886f4ba0f71d..d79b5b620e94 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4983,6 +4983,7 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
 	em->bdev = (struct block_device *)map;
 	em->start = logical;
 	em->len = length;
+	em->orig_start = 0;
 	em->block_start = 0;
 	em->block_len = em->len;