Btrfs: early work to file_write in big extents

Signed-off-by: Chris Mason <chris.mason@oracle.com>

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))