Btrfs: bulk delete checksum items in the same leaf (6f546216) · Commits · 戴 / test

Very often we have the checksums for an extent spread in multiple items in the checksums tree, and currently the algorithm to delete them starts by looking for them one by one and then deleting them one by one, which is not optimal since each deletion involves shifting all the other items in the leaf and when the leaf reaches some low threshold, to move items off the leaf into its left and right neighbor leafs. Also, after each item deletion we release our search path and start a new search for other checksums items. So optimize this by deleting in bulk all the items in the same leaf that contain checksums for the extent being freed. Signed-off-by:

Filipe Manana <fdmanana@suse.com> Reviewed-by:

Liu Bo <bo.li.liu@oracle.com>

fs/btrfs/file-item.c

+27 −1

Original line number	Diff line number	Diff line
		@@ -643,7 +643,33 @@ int btrfs_del_csums(struct btrfs_trans_handle *trans,

		/* delete the entire item, it is inside our range */
		if (key.offset >= bytenr && csum_end <= end_byte) {
		ret = btrfs_del_item(trans, root, path);
		int del_nr = 1;

		/*
		* Check how many csum items preceding this one in this
		* leaf correspond to our range and then delete them all
		* at once.
		*/
		if (key.offset > bytenr && path->slots[0] > 0) {
		int slot = path->slots[0] - 1;

		while (slot >= 0) {
		struct btrfs_key pk;

		btrfs_item_key_to_cpu(leaf, &pk, slot);
		if (pk.offset < bytenr \|\|
		pk.type != BTRFS_EXTENT_CSUM_KEY \|\|
		pk.objectid !=
		BTRFS_EXTENT_CSUM_OBJECTID)
		break;
		path->slots[0] = slot;
		del_nr++;
		key.offset = pk.offset;
		slot--;
		}
		}
		ret = btrfs_del_items(trans, root, path,
		path->slots[0], del_nr);
		if (ret)
		goto out;
		if (key.offset == bytenr)

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