mm: zpool: add interfaces for object read/write APIs

Patch series "Switch zswap to object read/write APIs".

This patch series updates zswap to use the new object read/write APIs
defined by zsmalloc in [1], and remove the old object mapping APIs and the
related code from zpool and zsmalloc.

This patch (of 5):

Zsmalloc introduced new APIs to read/write objects besides mapping them.
Add the necessary zpool interfaces.

Link: https://lkml.kernel.org/r/20250305061134.4105762-1-yosry.ahmed@linux.dev
Link: https://lkml.kernel.org/r/20250305061134.4105762-2-yosry.ahmed@linux.dev
Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/zpool.h b/include/linux/zpool.h
index 5e6dc46b8cc4cb5f423ad29f65d868a18edf262f..1784e735ee049d3ebf6e521aa4aa779dde28a5e0 100644 (file)
--- a/include/linux/zpool.h
+++ b/include/linux/zpool.h
@@ -52,6 +52,16 @@ void *zpool_map_handle(struct zpool *pool, unsigned long handle,
 
 void zpool_unmap_handle(struct zpool *pool, unsigned long handle);
 
+
+void *zpool_obj_read_begin(struct zpool *zpool, unsigned long handle,
+                          void *local_copy);
+
+void zpool_obj_read_end(struct zpool *zpool, unsigned long handle,
+                       void *handle_mem);
+
+void zpool_obj_write(struct zpool *zpool, unsigned long handle,
+                    void *handle_mem, size_t mem_len);
+
 u64 zpool_get_total_pages(struct zpool *pool);
 
 
@@ -90,6 +100,13 @@ struct zpool_driver {
                                enum zpool_mapmode mm);
        void (*unmap)(void *pool, unsigned long handle);
 
+       void *(*obj_read_begin)(void *pool, unsigned long handle,
+                               void *local_copy);
+       void (*obj_read_end)(void *pool, unsigned long handle,
+                            void *handle_mem);
+       void (*obj_write)(void *pool, unsigned long handle,
+                         void *handle_mem, size_t mem_len);
+
        u64 (*total_pages)(void *pool);
 };
 

diff --git a/mm/zpool.c b/mm/zpool.c
index 4bbd12d4b65992af6ea06f480fc07a5f23ca9e47..378c2d1e5638f6a6d8d1af6a7d0f16f872279476 100644 (file)
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -320,6 +320,54 @@ void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
        zpool->driver->unmap(zpool->pool, handle);
 }
 
+/**
+ * zpool_obj_read_begin() - Start reading from a previously allocated handle.
+ * @zpool:     The zpool that the handle was allocated from
+ * @handle:    The handle to read from
+ * @local_copy:        A local buffer to use if needed.
+ *
+ * This starts a read operation of a previously allocated handle. The passed
+ * @local_copy buffer may be used if needed by copying the memory into.
+ * zpool_obj_read_end() MUST be called after the read is completed to undo any
+ * actions taken (e.g. release locks).
+ *
+ * Returns: A pointer to the handle memory to be read, if @local_copy is used,
+ * the returned pointer is @local_copy.
+ */
+void *zpool_obj_read_begin(struct zpool *zpool, unsigned long handle,
+                          void *local_copy)
+{
+       return zpool->driver->obj_read_begin(zpool->pool, handle, local_copy);
+}
+
+/**
+ * zpool_obj_read_end() - Finish reading from a previously allocated handle.
+ * @zpool:     The zpool that the handle was allocated from
+ * @handle:    The handle to read from
+ * @handle_mem:        The pointer returned by zpool_obj_read_begin()
+ *
+ * Finishes a read operation previously started by zpool_obj_read_begin().
+ */
+void zpool_obj_read_end(struct zpool *zpool, unsigned long handle,
+                       void *handle_mem)
+{
+       zpool->driver->obj_read_end(zpool->pool, handle, handle_mem);
+}
+
+/**
+ * zpool_obj_write() - Write to a previously allocated handle.
+ * @zpool:     The zpool that the handle was allocated from
+ * @handle:    The handle to read from
+ * @handle_mem:        The memory to copy from into the handle.
+ * @mem_len:   The length of memory to be written.
+ *
+ */
+void zpool_obj_write(struct zpool *zpool, unsigned long handle,
+                    void *handle_mem, size_t mem_len)
+{
+       zpool->driver->obj_write(zpool->pool, handle, handle_mem, mem_len);
+}
+
 /**
  * zpool_get_total_pages() - The total size of the pool
  * @zpool:     The zpool to check

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 63c99db71dc1f31a08bd1b39818f05f8a2772d1a..d84b300db64e7181139b6ae7b2c4b2be99900b5d 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -507,6 +507,24 @@ static void zs_zpool_unmap(void *pool, unsigned long handle)
        zs_unmap_object(pool, handle);
 }
 
+static void *zs_zpool_obj_read_begin(void *pool, unsigned long handle,
+                                    void *local_copy)
+{
+       return zs_obj_read_begin(pool, handle, local_copy);
+}
+
+static void zs_zpool_obj_read_end(void *pool, unsigned long handle,
+                                 void *handle_mem)
+{
+       zs_obj_read_end(pool, handle, handle_mem);
+}
+
+static void zs_zpool_obj_write(void *pool, unsigned long handle,
+                              void *handle_mem, size_t mem_len)
+{
+       zs_obj_write(pool, handle, handle_mem, mem_len);
+}
+
 static u64 zs_zpool_total_pages(void *pool)
 {
        return zs_get_total_pages(pool);
@@ -522,6 +540,9 @@ static struct zpool_driver zs_zpool_driver = {
        .free =                   zs_zpool_free,
        .map =                    zs_zpool_map,
        .unmap =                  zs_zpool_unmap,
+       .obj_read_begin =         zs_zpool_obj_read_begin,
+       .obj_read_end  =          zs_zpool_obj_read_end,
+       .obj_write =              zs_zpool_obj_write,
        .total_pages =            zs_zpool_total_pages,
 };