zram: factor out different page types read

Similarly to write, split the page read code into ZRAM_HUGE read,
ZRAM_SAME read and compressed page read to simplify the code.

Link: https://lkml.kernel.org/r/20241218063513.297475-6-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 2a5ecaf292e0f83dd52daece303d0d132836c485..c4454ceee4ddc407003aaf3c9107475cb8a68f8a 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1531,54 +1531,73 @@ out:
        zram_set_obj_size(zram, index, 0);
 }
 
-/*
- * Reads (decompresses if needed) a page from zspool (zsmalloc).
- * Corresponding ZRAM slot should be locked.
- */
-static int zram_read_from_zspool(struct zram *zram, struct page *page,
+static int read_same_filled_page(struct zram *zram, struct page *page,
                                 u32 index)
 {
-       struct zcomp_strm *zstrm;
+       void *mem;
+
+       mem = kmap_local_page(page);
+       zram_fill_page(mem, PAGE_SIZE, zram_get_handle(zram, index));
+       kunmap_local(mem);
+       return 0;
+}
+
+static int read_incompressible_page(struct zram *zram, struct page *page,
+                                   u32 index)
+{
        unsigned long handle;
-       unsigned int size;
        void *src, *dst;
-       u32 prio;
-       int ret;
 
        handle = zram_get_handle(zram, index);
-       if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) {
-               void *mem;
+       src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
+       dst = kmap_local_page(page);
+       copy_page(dst, src);
+       kunmap_local(dst);
+       zs_unmap_object(zram->mem_pool, handle);
 
-               mem = kmap_local_page(page);
-               zram_fill_page(mem, PAGE_SIZE, handle);
-               kunmap_local(mem);
-               return 0;
-       }
+       return 0;
+}
 
-       size = zram_get_obj_size(zram, index);
+static int read_compressed_page(struct zram *zram, struct page *page, u32 index)
+{
+       struct zcomp_strm *zstrm;
+       unsigned long handle;
+       unsigned int size;
+       void *src, *dst;
+       int ret, prio;
 
-       if (size != PAGE_SIZE) {
-               prio = zram_get_priority(zram, index);
-               zstrm = zcomp_stream_get(zram->comps[prio]);
-       }
+       handle = zram_get_handle(zram, index);
+       size = zram_get_obj_size(zram, index);
+       prio = zram_get_priority(zram, index);
 
+       zstrm = zcomp_stream_get(zram->comps[prio]);
        src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
-       if (size == PAGE_SIZE) {
-               dst = kmap_local_page(page);
-               copy_page(dst, src);
-               kunmap_local(dst);
-               ret = 0;
-       } else {
-               dst = kmap_local_page(page);
-               ret = zcomp_decompress(zram->comps[prio], zstrm,
-                                      src, size, dst);
-               kunmap_local(dst);
-               zcomp_stream_put(zram->comps[prio]);
-       }
+       dst = kmap_local_page(page);
+       ret = zcomp_decompress(zram->comps[prio], zstrm, src, size, dst);
+       kunmap_local(dst);
        zs_unmap_object(zram->mem_pool, handle);
+       zcomp_stream_put(zram->comps[prio]);
+
        return ret;
 }
 
+/*
+ * Reads (decompresses if needed) a page from zspool (zsmalloc).
+ * Corresponding ZRAM slot should be locked.
+ */
+static int zram_read_from_zspool(struct zram *zram, struct page *page,
+                                u32 index)
+{
+       if (zram_test_flag(zram, index, ZRAM_SAME) ||
+           !zram_get_handle(zram, index))
+               return read_same_filled_page(zram, page, index);
+
+       if (!zram_test_flag(zram, index, ZRAM_HUGE))
+               return read_compressed_page(zram, page, index);
+       else
+               return read_incompressible_page(zram, page, index);
+}
+
 static int zram_read_page(struct zram *zram, struct page *page, u32 index,
                          struct bio *parent)
 {