zram: move immutable comp params away from per-CPU context

Immutable params never change once comp has been allocated and setup, so
we don't need to store multiple copies of them in each per-CPU backend
context.  Move those to per-comp zcomp_params and pass it to backends
callbacks for requests execution.  Basically, this means parameters
sharing between different contexts.

Also introduce two new backends callbacks: setup_params() and
release_params().  First, we need to validate params in a driver-specific
way; second, driver may want to allocate its specific representation of
the params which is needed to execute requests.

Link: https://lkml.kernel.org/r/20240902105656.1383858-20-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 16 insertions, 4 deletions

diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index 1d8920c2d449..ad5762813842 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -7,10 +7,18 @@
 
 #define ZCOMP_PARAM_NO_LEVEL	INT_MIN
 
+/*
+ * Immutable driver (backend) parameters. The driver may attach private
+ * data to it (e.g. driver representation of the dictionary, etc.).
+ *
+ * This data is kept per-comp and is shared among execution contexts.
+ */
 struct zcomp_params {
 	void *dict;
 	size_t dict_sz;
 	s32 level;
+
+	void *drv_data;
 };
 
 /*
@@ -38,13 +46,17 @@ struct zcomp_req {
 };
 
 struct zcomp_ops {
-	int (*compress)(struct zcomp_ctx *ctx, struct zcomp_req *req);
-	int (*decompress)(struct zcomp_ctx *ctx, struct zcomp_req *req);
+	int (*compress)(struct zcomp_params *params, struct zcomp_ctx *ctx,
+			struct zcomp_req *req);
+	int (*decompress)(struct zcomp_params *params, struct zcomp_ctx *ctx,
+			  struct zcomp_req *req);
 
-	int (*create_ctx)(struct zcomp_params *params,
-			  struct zcomp_ctx *ctx);
+	int (*create_ctx)(struct zcomp_params *params, struct zcomp_ctx *ctx);
 	void (*destroy_ctx)(struct zcomp_ctx *ctx);
 
+	int (*setup_params)(struct zcomp_params *params);
+	void (*release_params)(struct zcomp_params *params);
+
 	const char *name;
 };