[f2fs-dev] [PATCH] f2fs: fix crc endian conversion

[Jaegeuk Kim <jaegeuk.kim@samsung.com>]

>From ed1e92d596f5356ff2f8f8af2818d36ca31f5cf1 Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Date: Wed, 19 Jun 2013 20:47:19 +0900
Subject: [PATCH] f2fs: fix crc endian conversion
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net

While calculating CRC for the checkpoint block, we use __u32, but when storing
the crc value to the disk, we use __le32.

Let's fix the inconsistency.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
---
 fs/f2fs/checkpoint.c | 12 ++++++------
 fs/f2fs/f2fs.h       | 19 +++++++++++++++----
 2 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 9a77509..66a6b85 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -357,8 +357,8 @@ static struct page *validate_checkpoint(struct f2fs_sb_info *sbi,
 	unsigned long blk_size = sbi->blocksize;
 	struct f2fs_checkpoint *cp_block;
 	unsigned long long cur_version = 0, pre_version = 0;
-	unsigned int crc = 0;
 	size_t crc_offset;
+	__u32 crc = 0;
 
 	/* Read the 1st cp block in this CP pack */
 	cp_page_1 = get_meta_page(sbi, cp_addr);
@@ -369,7 +369,7 @@ static struct page *validate_checkpoint(struct f2fs_sb_info *sbi,
 	if (crc_offset >= blk_size)
 		goto invalid_cp1;
 
-	crc = *(unsigned int *)((unsigned char *)cp_block + crc_offset);
+	crc = le32_to_cpu(*((__u32 *)((unsigned char *)cp_block + crc_offset)));
 	if (!f2fs_crc_valid(crc, cp_block, crc_offset))
 		goto invalid_cp1;
 
@@ -384,7 +384,7 @@ static struct page *validate_checkpoint(struct f2fs_sb_info *sbi,
 	if (crc_offset >= blk_size)
 		goto invalid_cp2;
 
-	crc = *(unsigned int *)((unsigned char *)cp_block + crc_offset);
+	crc = le32_to_cpu(*((__u32 *)((unsigned char *)cp_block + crc_offset)));
 	if (!f2fs_crc_valid(crc, cp_block, crc_offset))
 		goto invalid_cp2;
 
@@ -648,7 +648,7 @@ static void do_checkpoint(struct f2fs_sb_info *sbi, bool is_umount)
 	block_t start_blk;
 	struct page *cp_page;
 	unsigned int data_sum_blocks, orphan_blocks;
-	unsigned int crc32 = 0;
+	__u32 crc32 = 0;
 	void *kaddr;
 	int i;
 
@@ -717,8 +717,8 @@ static void do_checkpoint(struct f2fs_sb_info *sbi, bool is_umount)
 	get_nat_bitmap(sbi, __bitmap_ptr(sbi, NAT_BITMAP));
 
 	crc32 = f2fs_crc32(ckpt, le32_to_cpu(ckpt->checksum_offset));
-	*(__le32 *)((unsigned char *)ckpt +
-				le32_to_cpu(ckpt->checksum_offset))
+	*((__le32 *)((unsigned char *)ckpt +
+				le32_to_cpu(ckpt->checksum_offset)))
 				= cpu_to_le32(crc32);
 
 	start_blk = __start_cp_addr(sbi);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 863a5e91..467d42d 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -47,14 +47,25 @@ struct f2fs_mount_info {
 	unsigned int	opt;
 };
 
-static inline __u32 f2fs_crc32(void *buff, size_t len)
+#define CRCPOLY_LE 0xedb88320
+
+static inline __u32 f2fs_crc32(void *buf, size_t len)
 {
-	return crc32_le(F2FS_SUPER_MAGIC, buff, len);
+	unsigned char *p = (unsigned char *)buf;
+	__u32 crc = F2FS_SUPER_MAGIC;
+	int i;
+
+	while (len--) {
+		crc ^= *p++;
+		for (i = 0; i < 8; i++)
+			crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
+	}
+	return crc;
 }
 
-static inline bool f2fs_crc_valid(__u32 blk_crc, void *buff, size_t buff_size)
+static inline bool f2fs_crc_valid(__u32 blk_crc, void *buf, size_t buf_size)
 {
-	return f2fs_crc32(buff, buff_size) == blk_crc;
+	return f2fs_crc32(buf, buf_size) == blk_crc;
 }
 
 /*
-- 
1.8.3.1.437.g0dbd812



-- 
Jaegeuk Kim
Samsung


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