fs/btrfs/ctree.c

315 	struct extent_buffer *cow;
334 	cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
337 	if (IS_ERR(cow))
338 		return PTR_ERR(cow);
340 	copy_extent_buffer_full(cow, buf);
341 	btrfs_set_header_bytenr(cow, cow->start);
342 	btrfs_set_header_generation(cow, trans->transid);
343 	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
344 	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
347 		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
349 		btrfs_set_header_owner(cow, new_root_objectid);
351 	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
355 		ret = btrfs_inc_ref(trans, root, cow, 1);
357 		ret = btrfs_inc_ref(trans, root, cow, 0);
359 		btrfs_tree_unlock(cow);
360 		free_extent_buffer(cow);
365 	btrfs_mark_buffer_dirty(trans, cow);
366 	*cow_ret = cow;
413 				       struct extent_buffer *cow,
481 				ret = btrfs_inc_ref(trans, root, cow, 1);
490 				ret = btrfs_inc_ref(trans, root, cow, 1);
492 				ret = btrfs_inc_ref(trans, root, cow, 0);
505 				ret = btrfs_inc_ref(trans, root, cow, 1);
507 				ret = btrfs_inc_ref(trans, root, cow, 0);
521  * does the dirty work in cow of a single block.  The parent block (if
522  * supplied) is updated to point to the new cow copy.  The new buffer is marked
528  * empty_size -- a hint that you plan on doing more cow.  This is the size in
542 	struct extent_buffer *cow;
571 	cow = btrfs_alloc_tree_block(trans, root, parent_start,
574 	if (IS_ERR(cow))
575 		return PTR_ERR(cow);
577 	/* cow is set to blocking by btrfs_init_new_buffer */
579 	copy_extent_buffer_full(cow, buf);
580 	btrfs_set_header_bytenr(cow, cow->start);
581 	btrfs_set_header_generation(cow, trans->transid);
582 	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
583 	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
586 		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
588 		btrfs_set_header_owner(cow, root->root_key.objectid);
590 	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
592 	ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
594 		btrfs_tree_unlock(cow);
595 		free_extent_buffer(cow);
601 		ret = btrfs_reloc_cow_block(trans, root, buf, cow);
603 			btrfs_tree_unlock(cow);
604 			free_extent_buffer(cow);
616 		ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
618 			btrfs_tree_unlock(cow);
619 			free_extent_buffer(cow);
623 		atomic_inc(&cow->refs);
624 		rcu_assign_pointer(root->node, cow);
635 			btrfs_tree_unlock(cow);
636 			free_extent_buffer(cow);
641 					cow->start);
648 				btrfs_tree_unlock(cow);
649 				free_extent_buffer(cow);
660 	btrfs_mark_buffer_dirty(trans, cow);
661 	*cow_ret = cow;
676 	 * We do not need to cow a block if
1138 			/* left was locked after cow */
1982  * @cow:	boolean should CoW operations be performed. Must always be 1
1999 		      int ins_len, int cow)
2019 	BUG_ON(!cow && ins_len);
2026 	ASSERT(!p->nowait || !cow);
2044 	if (!cow)
2047 	if (cow && (p->keep_locks || p->lowest_level))
2075 		if (cow) {
2079 			 * if we don't really need to cow this block
2243  * Naturally, there is no support for insert, delete or cow operations.
2246  * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
4600  * This does not cow, but it does stuff the starting key it finds back
4601  * into min_key, so you can call btrfs_search_slot with cow=1 on the