On mon, 29 Jul 2013 19:35:49 +0100, Filipe David Borba Manana wrote:
> After reading all device items from the chunk tree, don't
> exit the loop and then navigate down the tree again to find
> the chunk items. Instead just read all device items and
> chunk items with a single tree search. This is possible
> because all device items are found before any chunk item in
> the chunks tree.
>
> This is a port of the corresponding kernel patch to keep both
> kernel and btrfs-progs identical:
>
> https://patchwork.kernel.org/patch/2835105/
>
> Signed-off-by: Filipe David Borba Manana <fdman...@gmail.com>
> ---
>
> V2: Simplified logic inside the loop
> (suggested by Josef Bacik on irc).
The comment is the same to the kernel side(Coding style problem of the comment).
Reviewed-by: Miao Xie <mi...@cn.fujitsu.com>
>
> volumes.c | 28 +++++++++-------------------
> 1 file changed, 9 insertions(+), 19 deletions(-)
>
> diff --git a/volumes.c b/volumes.c
> index 0ff2283..2c69f28 100644
> --- a/volumes.c
> +++ b/volumes.c
> @@ -1718,14 +1718,13 @@ int btrfs_read_chunk_tree(struct btrfs_root *root)
> if (!path)
> return -ENOMEM;
>
> - /* first we search for all of the device items, and then we
> - * read in all of the chunk items. This way we can create chunk
> - * mappings that reference all of the devices that are afound
> - */
> + /* Read all device items, and then all the chunk items. All
> + device items are found before any chunk item (their object id
> + is smaller than the lowest possible object id for a chunk
> + item - BTRFS_FIRST_CHUNK_TREE_OBJECTID). */
> key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
> key.offset = 0;
> key.type = 0;
> -again:
> ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
> while(1) {
> leaf = path->nodes[0];
> @@ -1739,16 +1738,12 @@ again:
> break;
> }
> btrfs_item_key_to_cpu(leaf, &found_key, slot);
> - if (key.objectid == BTRFS_DEV_ITEMS_OBJECTID) {
> - if (found_key.objectid != BTRFS_DEV_ITEMS_OBJECTID)
> - break;
> - if (found_key.type == BTRFS_DEV_ITEM_KEY) {
> - struct btrfs_dev_item *dev_item;
> - dev_item = btrfs_item_ptr(leaf, slot,
> + if (found_key.type == BTRFS_DEV_ITEM_KEY) {
> + struct btrfs_dev_item *dev_item;
> + dev_item = btrfs_item_ptr(leaf, slot,
> struct btrfs_dev_item);
> - ret = read_one_dev(root, leaf, dev_item);
> - BUG_ON(ret);
> - }
> + ret = read_one_dev(root, leaf, dev_item);
> + BUG_ON(ret);
> } else if (found_key.type == BTRFS_CHUNK_ITEM_KEY) {
> struct btrfs_chunk *chunk;
> chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
> @@ -1757,11 +1752,6 @@ again:
> }
> path->slots[0]++;
> }
> - if (key.objectid == BTRFS_DEV_ITEMS_OBJECTID) {
> - key.objectid = 0;
> - btrfs_release_path(root, path);
> - goto again;
> - }
>
> ret = 0;
> error:
>
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