Btrfs: make send's file extent item search more efficient (7fdd29d0) · Commits · 戴 / test

Instead of looking for a file extent item, process it, release the path and do a btree search for the next file extent item, just process all file extent items in a leaf without intermediate btree searches. This way we save cpu and we're not blocking other tasks or affecting concurrency on the btree, because send's paths use the commit root and skip btree node/leaf locking. Signed-off-by:

Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by:

Josef Bacik <jbacik@fb.com> Signed-off-by:

Chris Mason <clm@fb.com>

fs/btrfs/send.c

+17 −10

Original line number	Diff line number	Diff line
		@@ -4573,17 +4573,25 @@ static int process_all_extents(struct send_ctx *sctx)
		key.objectid = sctx->cmp_key->objectid;
		key.type = BTRFS_EXTENT_DATA_KEY;
		key.offset = 0;
		while (1) {
		ret = btrfs_search_slot_for_read(root, &key, path, 1, 0);
		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
		if (ret < 0)
		goto out;
		if (ret) {
		ret = 0;
		goto out;
		}

		while (1) {
		eb = path->nodes[0];
		slot = path->slots[0];

		if (slot >= btrfs_header_nritems(eb)) {
		ret = btrfs_next_leaf(root, path);
		if (ret < 0) {
		goto out;
		} else if (ret > 0) {
		ret = 0;
		break;
		}
		continue;
		}

		btrfs_item_key_to_cpu(eb, &found_key, slot);

		if (found_key.objectid != key.objectid \|\|
		@@ -4596,8 +4604,7 @@ static int process_all_extents(struct send_ctx *sctx)
		if (ret < 0)
		goto out;

		btrfs_release_path(path);
		key.offset = found_key.offset + 1;
		path->slots[0]++;
		}

		out:

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