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.h | 169 ++++++++++++++++++++++++++++++ 1 file changed, 169 insertions(+) create mode 100644 drivers/md/persistent-data/dm-space-map.h (limited to 'drivers/md/persistent-data/dm-space-map.h') diff --git a/drivers/md/persistent-data/dm-space-map.h b/drivers/md/persistent-data/dm-space-map.h new file mode 100644 index 000000000..6bf69922b --- /dev/null +++ b/drivers/md/persistent-data/dm-space-map.h @@ -0,0 +1,169 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2011 Red Hat, Inc. + * + * This file is released under the GPL. + */ + +#ifndef _LINUX_DM_SPACE_MAP_H +#define _LINUX_DM_SPACE_MAP_H + +#include "dm-block-manager.h" + +typedef void (*dm_sm_threshold_fn)(void *context); + +/* + * struct dm_space_map keeps a record of how many times each block in a device + * is referenced. It needs to be fixed on disk as part of the transaction. + */ +struct dm_space_map { + void (*destroy)(struct dm_space_map *sm); + + /* + * You must commit before allocating the newly added space. + */ + int (*extend)(struct dm_space_map *sm, dm_block_t extra_blocks); + + /* + * Extensions do not appear in this count until after commit has + * been called. + */ + int (*get_nr_blocks)(struct dm_space_map *sm, dm_block_t *count); + + /* + * Space maps must never allocate a block from the previous + * transaction, in case we need to rollback. This complicates the + * semantics of get_nr_free(), it should return the number of blocks + * that are available for allocation _now_. For instance you may + * have blocks with a zero reference count that will not be + * available for allocation until after the next commit. + */ + int (*get_nr_free)(struct dm_space_map *sm, dm_block_t *count); + + int (*get_count)(struct dm_space_map *sm, dm_block_t b, uint32_t *result); + int (*count_is_more_than_one)(struct dm_space_map *sm, dm_block_t b, + int *result); + int (*set_count)(struct dm_space_map *sm, dm_block_t b, uint32_t count); + + int (*commit)(struct dm_space_map *sm); + + int (*inc_blocks)(struct dm_space_map *sm, dm_block_t b, dm_block_t e); + int (*dec_blocks)(struct dm_space_map *sm, dm_block_t b, dm_block_t e); + + /* + * new_block will increment the returned block. + */ + int (*new_block)(struct dm_space_map *sm, dm_block_t *b); + + /* + * The root contains all the information needed to fix the space map. + * Generally this info is small, so squirrel it away in a disk block + * along with other info. + */ + int (*root_size)(struct dm_space_map *sm, size_t *result); + int (*copy_root)(struct dm_space_map *sm, void *copy_to_here_le, size_t len); + + /* + * You can register one threshold callback which is edge-triggered + * when the free space in the space map drops below the threshold. + */ + int (*register_threshold_callback)(struct dm_space_map *sm, + dm_block_t threshold, + dm_sm_threshold_fn fn, + void *context); +}; + +/*----------------------------------------------------------------*/ + +static inline void dm_sm_destroy(struct dm_space_map *sm) +{ + if (sm) + sm->destroy(sm); +} + +static inline int dm_sm_extend(struct dm_space_map *sm, dm_block_t extra_blocks) +{ + return sm->extend(sm, extra_blocks); +} + +static inline int dm_sm_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count) +{ + return sm->get_nr_blocks(sm, count); +} + +static inline int dm_sm_get_nr_free(struct dm_space_map *sm, dm_block_t *count) +{ + return sm->get_nr_free(sm, count); +} + +static inline int dm_sm_get_count(struct dm_space_map *sm, dm_block_t b, + uint32_t *result) +{ + return sm->get_count(sm, b, result); +} + +static inline int dm_sm_count_is_more_than_one(struct dm_space_map *sm, + dm_block_t b, int *result) +{ + return sm->count_is_more_than_one(sm, b, result); +} + +static inline int dm_sm_set_count(struct dm_space_map *sm, dm_block_t b, + uint32_t count) +{ + return sm->set_count(sm, b, count); +} + +static inline int dm_sm_commit(struct dm_space_map *sm) +{ + return sm->commit(sm); +} + +static inline int dm_sm_inc_blocks(struct dm_space_map *sm, dm_block_t b, dm_block_t e) +{ + return sm->inc_blocks(sm, b, e); +} + +static inline int dm_sm_inc_block(struct dm_space_map *sm, dm_block_t b) +{ + return dm_sm_inc_blocks(sm, b, b + 1); +} + +static inline int dm_sm_dec_blocks(struct dm_space_map *sm, dm_block_t b, dm_block_t e) +{ + return sm->dec_blocks(sm, b, e); +} + +static inline int dm_sm_dec_block(struct dm_space_map *sm, dm_block_t b) +{ + return dm_sm_dec_blocks(sm, b, b + 1); +} + +static inline int dm_sm_new_block(struct dm_space_map *sm, dm_block_t *b) +{ + return sm->new_block(sm, b); +} + +static inline int dm_sm_root_size(struct dm_space_map *sm, size_t *result) +{ + return sm->root_size(sm, result); +} + +static inline int dm_sm_copy_root(struct dm_space_map *sm, void *copy_to_here_le, size_t len) +{ + return sm->copy_root(sm, copy_to_here_le, len); +} + +static inline int dm_sm_register_threshold_callback(struct dm_space_map *sm, + dm_block_t threshold, + dm_sm_threshold_fn fn, + void *context) +{ + if (sm->register_threshold_callback) + return sm->register_threshold_callback(sm, threshold, fn, context); + + return -EINVAL; +} + + +#endif /* _LINUX_DM_SPACE_MAP_H */ -- cgit v1.3.1