lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Wed, 23 May 2012 10:43:22 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Minchan Kim <minchan@...nel.org>,
	Nitin Gupta <ngupta@...are.org>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>
Subject: [PATCH 2/2 v2] zram: clean up handle

zram's handle variable can store handle of zsmalloc in case of
compressing efficiently. Otherwise, it stores point of page descriptor.
This patch clean up the mess by union struct.

changelog
  * from v1
	- none(new add in v2)

Cc: Nitin Gupta <ngupta@...are.org>
Cc: Seth Jennings <sjenning@...ux.vnet.ibm.com>
Signed-off-by: Minchan Kim <minchan@...nel.org>
---
 drivers/staging/zram/zram_drv.c |   77 ++++++++++++++++++++-------------------
 drivers/staging/zram/zram_drv.h |    5 ++-
 2 files changed, 44 insertions(+), 38 deletions(-)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index abd69d1..ceab5ca 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -150,7 +150,7 @@ static void zram_free_page(struct zram *zram, size_t index)
 	}
 
 	if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
-		__free_page((struct page *)handle);
+		__free_page(zram->table[index].page);
 		zram_clear_flag(zram, index, ZRAM_UNCOMPRESSED);
 		zram_stat_dec(&zram->stats.pages_expand);
 		goto out;
@@ -189,7 +189,7 @@ static void handle_uncompressed_page(struct zram *zram, struct bio_vec *bvec,
 	unsigned char *user_mem, *cmem;
 
 	user_mem = kmap_atomic(page);
-	cmem = kmap_atomic((struct page *)zram->table[index].handle);
+	cmem = kmap_atomic(zram->table[index].page);
 
 	memcpy(user_mem + bvec->bv_offset, cmem + offset, bvec->bv_len);
 	kunmap_atomic(cmem);
@@ -315,7 +315,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 			   int offset)
 {
 	int ret;
-	u32 store_offset;
 	size_t clen;
 	unsigned long handle;
 	struct zobj_header *zheader;
@@ -396,25 +395,33 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 			goto out;
 		}
 
-		store_offset = 0;
-		zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
-		zram_stat_inc(&zram->stats.pages_expand);
-		handle = (unsigned long)page_store;
 		src = kmap_atomic(page);
 		cmem = kmap_atomic(page_store);
-		goto memstore;
-	}
+		memcpy(cmem, src, clen);
+		kunmap_atomic(cmem);
+		kunmap_atomic(src);
 
-	handle = zs_malloc(zram->mem_pool, clen + sizeof(*zheader));
-	if (!handle) {
-		pr_info("Error allocating memory for compressed "
-			"page: %u, size=%zu\n", index, clen);
-		ret = -ENOMEM;
-		goto out;
-	}
-	cmem = zs_map_object(zram->mem_pool, handle);
+		zram->table[index].page = page_store;
+		zram->table[index].size = PAGE_SIZE;
+
+		zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
+		zram_stat_inc(&zram->stats.pages_expand);
+	} else {
+		handle = zs_malloc(zram->mem_pool, clen + sizeof(*zheader));
+		if (!handle) {
+			pr_info("Error allocating memory for "
+				"compressed page: %u, size=%zu\n", index, clen);
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		zram->table[index].handle = handle;
+		zram->table[index].size = clen;
 
-memstore:
+		cmem = zs_map_object(zram->mem_pool, handle);
+		memcpy(cmem, src, clen);
+		zs_unmap_object(zram->mem_pool, handle);
+	}
 #if 0
 	/* Back-reference needed for memory defragmentation */
 	if (!zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)) {
@@ -424,18 +431,6 @@ memstore:
 	}
 #endif
 
-	memcpy(cmem, src, clen);
-
-	if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
-		kunmap_atomic(cmem);
-		kunmap_atomic(src);
-	} else {
-		zs_unmap_object(zram->mem_pool, handle);
-	}
-
-	zram->table[index].handle = handle;
-	zram->table[index].size = clen;
-
 	/* Update stats */
 	zram_stat64_add(zram, &zram->stats.compr_size, clen);
 	zram_stat_inc(&zram->stats.pages_stored);
@@ -580,6 +575,8 @@ error:
 void __zram_reset_device(struct zram *zram)
 {
 	size_t index;
+	unsigned long handle;
+	struct page *page;
 
 	zram->init_done = 0;
 
@@ -592,14 +589,17 @@ void __zram_reset_device(struct zram *zram)
 
 	/* Free all pages that are still in this zram device */
 	for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
-		unsigned long handle = zram->table[index].handle;
-		if (!handle)
-			continue;
-
-		if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
-			__free_page((struct page *)handle);
-		else
+		if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
+			page = zram->table[index].page;
+			if (!page)
+				continue;
+			__free_page(page);
+		} else {
+			handle = zram->table[index].handle;
+			if (!handle)
+				continue;
 			zs_free(zram->mem_pool, handle);
+		}
 	}
 
 	vfree(zram->table);
@@ -788,6 +788,9 @@ static int __init zram_init(void)
 {
 	int ret, dev_id;
 
+	BUILD_BUG_ON(sizeof(((struct table *)0)->page) !=
+		sizeof(((struct table *)0)->handle));
+
 	if (num_devices > max_num_devices) {
 		pr_warning("Invalid value for num_devices: %u\n",
 				num_devices);
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 7a7e256..54d082f 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -81,7 +81,10 @@ enum zram_pageflags {
 
 /* Allocated for each disk page */
 struct table {
-	unsigned long handle;
+	union {
+		unsigned long handle; /* compressible */
+		struct page *page; /* incompressible */
+	};
 	u16 size;	/* object size (excluding header) */
 	u8 count;	/* object ref count (not yet used) */
 	u8 flags;
-- 
1.7.9.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists