From dc2e4982cb018306f0699cd460a9033467f07be5 Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Tue, 13 Jan 2026 12:46:45 +0900 Subject: 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 Acked-by: Herbert Xu Tested-by: Yosry Ahmed Cc: Herbert Xu Cc: Brian Geffon Cc: Johannes Weiner Cc: Minchan Kim Cc: Nhat Pham Signed-off-by: Andrew Morton --- include/linux/zsmalloc.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/zsmalloc.h b/include/linux/zsmalloc.h index 5565c3171007..478410c880b1 100644 --- a/include/linux/zsmalloc.h +++ b/include/linux/zsmalloc.h @@ -22,6 +22,7 @@ struct zs_pool_stats { }; struct zs_pool; +struct scatterlist; struct zs_pool *zs_create_pool(const char *name); void zs_destroy_pool(struct zs_pool *pool); @@ -43,6 +44,9 @@ 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); -- cgit v1.2.3