From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- drivers/md/persistent-data/dm-space-map-metadata.h | 45 ++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 drivers/md/persistent-data/dm-space-map-metadata.h (limited to 'drivers/md/persistent-data/dm-space-map-metadata.h') diff --git a/drivers/md/persistent-data/dm-space-map-metadata.h b/drivers/md/persistent-data/dm-space-map-metadata.h new file mode 100644 index 000000000..ca5c3e532 --- /dev/null +++ b/drivers/md/persistent-data/dm-space-map-metadata.h @@ -0,0 +1,45 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2011 Red Hat, Inc. + * + * This file is released under the GPL. + */ + +#ifndef DM_SPACE_MAP_METADATA_H +#define DM_SPACE_MAP_METADATA_H + +#include "dm-transaction-manager.h" + +#define DM_SM_METADATA_BLOCK_SIZE (4096 >> SECTOR_SHIFT) + +/* + * The metadata device is currently limited in size. + * + * We have one block of index, which can hold 255 index entries. Each + * index entry contains allocation info about ~16k metadata blocks. + */ +#define DM_SM_METADATA_MAX_BLOCKS (255 * ((1 << 14) - 64)) +#define DM_SM_METADATA_MAX_SECTORS (DM_SM_METADATA_MAX_BLOCKS * DM_SM_METADATA_BLOCK_SIZE) + +/* + * Unfortunately we have to use two-phase construction due to the cycle + * between the tm and sm. + */ +struct dm_space_map *dm_sm_metadata_init(void); + +/* + * Create a fresh space map. + */ +int dm_sm_metadata_create(struct dm_space_map *sm, + struct dm_transaction_manager *tm, + dm_block_t nr_blocks, + dm_block_t superblock); + +/* + * Open from a previously-recorded root. + */ +int dm_sm_metadata_open(struct dm_space_map *sm, + struct dm_transaction_manager *tm, + void *root_le, size_t len); + +#endif /* DM_SPACE_MAP_METADATA_H */ -- cgit v1.3.1