On Fri, Jan 29, 2016 at 01:03:25PM +0800, Qu Wenruo wrote:
> Use new function, create_convert_image_v2() to create snapshot of old
> filesystem.
>
> Unlike old function which is called after copying all inodes, this
> function need to be called before copying inodes.
>
> Signed-off-by: Qu Wenruo <[email protected]>
> Signed-off-by: David Sterba <[email protected]>
> ---
> btrfs-convert.c | 184
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 184 insertions(+)
>
> diff --git a/btrfs-convert.c b/btrfs-convert.c
> index 102953a..16e2309 100644
> --- a/btrfs-convert.c
> +++ b/btrfs-convert.c
> @@ -1412,6 +1412,7 @@ static int create_image_file_range(struct
> btrfs_trans_handle *trans,
> fail:
> return ret;
> }
> +
> /*
> * Create the fs image file.
> */
> @@ -1605,6 +1606,189 @@ fail:
> return ret;
> }
>
> +static int create_image_file_range_v2(struct btrfs_trans_handle *trans,
> + struct btrfs_root *root,
> + struct cache_tree *used,
> + struct btrfs_inode_item *inode,
> + u64 ino, u64 bytenr, u64 *ret_len,
> + int datacsum)
> +{
> + struct cache_extent *cache;
> + struct btrfs_block_group_cache *bg_cache;
> + u64 len = *ret_len;
> + u64 disk_bytenr;
> + int ret;
> +
> + BUG_ON(bytenr != round_down(bytenr, root->sectorsize));
> + BUG_ON(len != round_down(len, root->sectorsize));
> + len = min_t(u64, len, BTRFS_MAX_EXTENT_SIZE);
> +
> + cache = search_cache_extent(used, bytenr);
> + if (cache) {
> + if (cache->start <= bytenr) {
> + /*
> + * |///////Used///////|
> + * |<--insert--->|
> + * bytenr
> + */
> + len = min_t(u64, len, cache->start + cache->size -
> + bytenr);
> + disk_bytenr = bytenr;
> + } else {
> + /*
> + * |//Used//|
> + * |<-insert-->|
> + * bytenr
> + */
> + len = min(len, cache->start - bytenr);
> + disk_bytenr = 0;
> + datacsum = 0;
> + }
> + } else {
> + /*
> + * |//Used//| |EOF
> + * |<-insert-->|
> + * bytenr
> + */
> + disk_bytenr = 0;
> + datacsum = 0;
> + }
> +
> + if (disk_bytenr) {
> + /* Check if the range is in a data block group */
> + bg_cache = btrfs_lookup_block_group(root->fs_info, bytenr);
> + if (!bg_cache)
> + return -ENOENT;
> + if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_DATA))
> + return -EINVAL;
> +
> + /* The extent should never cross block group boundary */
> + len = min_t(u64, len, bg_cache->key.objectid +
> + bg_cache->key.offset - bytenr);
> + }
> +
> + BUG_ON(len != round_down(len, root->sectorsize));
> + ret = btrfs_record_file_extent(trans, root, ino, inode, bytenr,
> + disk_bytenr, len);
> + if (ret < 0)
> + return ret;
> +
> + if (datacsum)
> + ret = csum_disk_extent(trans, root, bytenr, len);
> + *ret_len = len;
> + return ret;
> +}
> +
> +static int wipe_reserved_ranges(struct cache_tree *tree, u64 min_stripe_size,
> + int ensure_size);
> +
> +/*
> + * Create the fs image file of old filesystem.
> + *
> + * This is completely fs independent as we have cctx->used, only
> + * need to create file extents point to all the posistions.
s/posistions/positions/g
> + * TODO: Add handler for reserved ranges in next patch
> + */
> +static int create_image_v2(struct btrfs_root *root,
> + struct btrfs_mkfs_config *cfg,
> + struct btrfs_convert_context *cctx,
> + u64 size, char *name, int datacsum)
> +{
> + struct btrfs_inode_item buf;
> + struct btrfs_trans_handle *trans;
> + struct btrfs_path *path = NULL;
> + struct btrfs_key key;
> + struct cache_extent *cache;
> + struct cache_tree used_tmp;
> + u64 cur;
> + u64 ino;
> + int ret;
> +
> + trans = btrfs_start_transaction(root, 1);
> + if (!trans)
> + return -ENOMEM;
> +
> + cache_tree_init(&used_tmp);
> +
> + ret = btrfs_find_free_objectid(trans, root, BTRFS_FIRST_FREE_OBJECTID,
> + &ino);
> + if (ret < 0)
> + goto out;
> + ret = btrfs_new_inode(trans, root, ino, 0600 | S_IFREG);
> + if (ret < 0)
> + goto out;
> + ret = btrfs_add_link(trans, root, ino, BTRFS_FIRST_FREE_OBJECTID, name,
> + strlen(name), BTRFS_FT_REG_FILE, NULL, 1);
> + if (ret < 0)
> + goto out;
> +
> + path = btrfs_alloc_path();
> + if (!path) {
> + ret = -ENOMEM;
> + goto out;
> + }
> + key.objectid = ino;
> + key.type = BTRFS_INODE_ITEM_KEY;
> + key.offset = 0;
> +
> + ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
> + if (ret) {
> + ret = (ret > 0 ? -ENOENT : ret);
> + goto out;
> + }
> + read_extent_buffer(path->nodes[0], &buf,
> + btrfs_item_ptr_offset(path->nodes[0], path->slots[0]),
> + sizeof(buf));
> + btrfs_release_path(path);
It seems unnecessary to search for inode_item, inode_item is
initialized by fill_inode_item(), so fill_inode_item(...&buf...) is fine.
> +
> + /*
> + * Create a new used space cache, which doesn't contain the reserved
> + * range
> + */
> + for (cache = first_cache_extent(&cctx->used); cache;
> + cache = next_cache_extent(cache)) {
> + ret = add_cache_extent(&used_tmp, cache->start, cache->size);
> + if (ret < 0)
> + goto out;
> + }
It's not clear why we need used_tmp.
Thanks,
-liubo
> + ret = wipe_reserved_ranges(&used_tmp, 0, 0);
> + if (ret < 0)
> + goto out;
> +
> + /*
> + * Start from 1M, as 0~1M is reserved, and create_image_file_range_v2()
> + * can't handle bytenr 0(will consider it as a hole)
> + */
> + cur = 1024 * 1024;
> + while (cur < size) {
> + u64 len = size - cur;
> +
> + ret = create_image_file_range_v2(trans, root, &used_tmp,
> + &buf, ino, cur, &len, datacsum);
> + if (ret < 0)
> + goto out;
> + cur += len;
> + }
> +
> + key.objectid = ino;
> + key.type = BTRFS_INODE_ITEM_KEY;
> + key.offset = 0;
> + ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
> + if (ret) {
> + ret = (ret > 0 ? -ENOENT : ret);
> + goto out;
> + }
> + btrfs_set_stack_inode_size(&buf, cfg->num_bytes);
> + write_extent_buffer(path->nodes[0], &buf,
> + btrfs_item_ptr_offset(path->nodes[0], path->slots[0]),
> + sizeof(buf));
> +out:
> + free_extent_cache_tree(&used_tmp);
> + btrfs_free_path(path);
> + btrfs_commit_transaction(trans, root);
> + return ret;
> +}
> +
> static struct btrfs_root * link_subvol(struct btrfs_root *root,
> const char *base, u64 root_objectid)
> {
> --
> 2.7.0
>
>
>
> --
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