Files
linux-torvalds-mirror/include/linux/zsmalloc.h
Sergey Senozhatsky dc2e4982cb zsmalloc: introduce SG-list based object read API
Currently, zsmalloc performs address linearization on read (which
sometimes requires memcpy() to a local buffer).  Not all zsmalloc users
need a linear address.  For example, Crypto API supports SG-list,
performing linearization under the hood, if needed.  In addition, some
compressors can have native SG-list support, completely avoiding the
linearization step.

Provide an SG-list based zsmalloc read API:
- zs_obj_read_sg_begin()
- zs_obj_read_sg_end()

This API allows callers to obtain an SG representation of the object (one
entry for objects that are contained in a single page and two entries for
spanning objects), avoiding the need for a bounce buffer and memcpy.

[senozhatsky@chromium.org: make zs_obj_read_sg_begin() return void, per Yosry]
  Link: https://lkml.kernel.org/r/20260117024900.792237-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20260113034645.2729998-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-01-26 20:02:32 -08:00

56 lines
1.7 KiB
C

/*
* zsmalloc memory allocator
*
* Copyright (C) 2011 Nitin Gupta
* Copyright (C) 2012, 2013 Minchan Kim
*
* This code is released using a dual license strategy: BSD/GPL
* You can choose the license that better fits your requirements.
*
* Released under the terms of 3-clause BSD License
* Released under the terms of GNU General Public License Version 2.0
*/
#ifndef _ZS_MALLOC_H_
#define _ZS_MALLOC_H_
#include <linux/types.h>
struct zs_pool_stats {
/* How many pages were migrated (freed) */
atomic_long_t pages_compacted;
};
struct zs_pool;
struct scatterlist;
struct zs_pool *zs_create_pool(const char *name);
void zs_destroy_pool(struct zs_pool *pool);
unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t flags,
const int nid);
void zs_free(struct zs_pool *pool, unsigned long obj);
size_t zs_huge_class_size(struct zs_pool *pool);
unsigned long zs_get_total_pages(struct zs_pool *pool);
unsigned long zs_compact(struct zs_pool *pool);
unsigned int zs_lookup_class_index(struct zs_pool *pool, unsigned int size);
void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats);
void *zs_obj_read_begin(struct zs_pool *pool, unsigned long handle,
size_t mem_len, void *local_copy);
void zs_obj_read_end(struct zs_pool *pool, unsigned long handle,
size_t mem_len, void *handle_mem);
void zs_obj_read_sg_begin(struct zs_pool *pool, unsigned long handle,
struct scatterlist *sg, size_t mem_len);
void zs_obj_read_sg_end(struct zs_pool *pool, unsigned long handle);
void zs_obj_write(struct zs_pool *pool, unsigned long handle,
void *handle_mem, size_t mem_len);
extern const struct movable_operations zsmalloc_mops;
#endif