linux-kernel - [PATCH 6/6] zram: factor out different page types read

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Message-ID: <20241210105420.1888790-7-senozhatsky@chromium.org>
Date: Tue, 10 Dec 2024 19:54:00 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Minchan Kim <minchan@...nel.org>,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH 6/6] 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.

Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 drivers/block/zram/zram_drv.c | 85 +++++++++++++++++++++--------------
 1 file changed, 52 insertions(+), 33 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 18263e4c208e..e4a7191ec13c 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1528,54 +1528,73 @@ static void zram_free_page(struct zram *zram, size_t index)
 	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)
 {
-- 
2.47.1.613.gc27f4b7a9f-goog