+ zram-factor-out-different-page-types-read.patch added to mm-unstable branch

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The patch titled
     Subject: zram: factor out different page types read
has been added to the -mm mm-unstable branch.  Its filename is
     zram-factor-out-different-page-types-read.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-factor-out-different-page-types-read.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: zram: factor out different page types read
Date: Tue, 10 Dec 2024 19:54:00 +0900

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/20241210105420.1888790-7-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 drivers/block/zram/zram_drv.c |   85 +++++++++++++++++++-------------
 1 file changed, 52 insertions(+), 33 deletions(-)

--- a/drivers/block/zram/zram_drv.c~zram-factor-out-different-page-types-read
+++ a/drivers/block/zram/zram_drv.c
@@ -1532,54 +1532,73 @@ 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)
 {
_

Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are

zram-panic-when-use-ext4-over-zram-fix.patch
zram-cond_resched-in-writeback-loop.patch
zram-free-slot-memory-early-during-write.patch
zram-remove-entry-element-member.patch
zram-factor-out-zram_same-write.patch
zram-factor-out-zram_huge-write.patch
zram-factor-out-different-page-types-read.patch





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