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From: "Gaoxiang (OS)" <gaoxiang25@huawei.com>
To: Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>,
	"Yuchao (T)" <yuchao0@huawei.com>
Cc: "linux-f2fs-devel@lists.sourceforge.net"
	<linux-f2fs-devel@lists.sourceforge.net>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	heyunlei <heyunlei@huawei.com>, Gao Xiang <hsiangkao@aol.com>
Subject: [f2fs-dev] [PATCH] f2fs: use crc ^ cp_ver instead of crc | cp_ver for recovery
Date: Wed, 31 Jan 2018 16:16:25 +0000	[thread overview]
Message-ID: <9047C53C18267742AB12E43B65C7F9F70BCE5C21@dggemi505-mbx.china.huawei.com> (raw)

This patch add a flag CP_CRC_RECOVERY_XOR_FLAG to use XORed crc ^ cp_ver
since crc | cp_ver is more likely to get a collision or become 11..1111 | cp_ver.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
 fs/f2fs/checkpoint.c    |  4 ++--
 fs/f2fs/node.h          | 16 +++++++++++-----
 fs/f2fs/segment.c       |  3 ++-
 include/linux/f2fs_fs.h |  1 +
 4 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 8b0945b..9e7e63b 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1157,8 +1157,8 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
 		__set_ckpt_flags(ckpt, CP_FSCK_FLAG);
 
-	/* set this flag to activate crc|cp_ver for recovery */
-	__set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG);
+	/* set this flag to activate crc^cp_ver for recovery */
+	__set_ckpt_flags(ckpt, CP_CRC_RECOVERY_XOR_FLAG);
 	__clear_ckpt_flags(ckpt, CP_NOCRC_RECOVERY_FLAG);
 
 	spin_unlock_irqrestore(&sbi->cp_lock, flags);
diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index 081ef0d..7b9489f 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -293,8 +293,11 @@ static inline void fill_node_footer_blkaddr(struct page *page, block_t blkaddr)
 	struct f2fs_node *rn = F2FS_NODE(page);
 	__u64 cp_ver = cur_cp_version(ckpt);
 
-	if (__is_set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG))
-		cp_ver |= (cur_cp_crc(ckpt) << 32);
+	if (__is_set_ckpt_flags(ckpt, CP_CRC_RECOVERY_XOR_FLAG))
+		cp_ver ^= cur_cp_crc(ckpt) << 32;
+	/* for backward compatibility */
+	else if (unlikely(__is_set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG)))
+		cp_ver |= cur_cp_crc(ckpt) << 32;
 
 	rn->footer.cp_ver = cpu_to_le64(cp_ver);
 	rn->footer.next_blkaddr = cpu_to_le32(blkaddr);
@@ -307,10 +310,13 @@ static inline bool is_recoverable_dnode(struct page *page)
 
 	/* Don't care crc part, if fsck.f2fs sets it. */
 	if (__is_set_ckpt_flags(ckpt, CP_NOCRC_RECOVERY_FLAG))
-		return (cp_ver << 32) == (cpver_of_node(page) << 32);
+		return (__u32)cp_ver == (__u32)cpver_of_node(page);
 
-	if (__is_set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG))
-		cp_ver |= (cur_cp_crc(ckpt) << 32);
+	if (__is_set_ckpt_flags(ckpt, CP_CRC_RECOVERY_XOR_FLAG))
+		cp_ver ^= cur_cp_crc(ckpt) << 32;
+	/* for backward compatibility */
+	else if (unlikely(__is_set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG)))
+		cp_ver |= cur_cp_crc(ckpt) << 32;
 
 	return cp_ver == cpver_of_node(page);
 }
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 205b0d9..64d0c1f 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2316,7 +2316,8 @@ static void allocate_segment_by_default(struct f2fs_sb_info *sbi,
 
 	if (force)
 		new_curseg(sbi, type, true);
-	else if (!is_set_ckpt_flags(sbi, CP_CRC_RECOVERY_FLAG) &&
+	else if (!(is_set_ckpt_flags(sbi, CP_CRC_RECOVERY_FLAG) ||
+		is_set_ckpt_flags(sbi, CP_CRC_RECOVERY_XOR_FLAG)) &&
 					type == CURSEG_WARM_NODE)
 		new_curseg(sbi, type, false);
 	else if (curseg->alloc_type == LFS && is_next_segment_free(sbi, type))
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index f7f0990..07ddf4b 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -117,6 +117,7 @@ struct f2fs_super_block {
 /*
  * For checkpoint
  */
+#define CP_CRC_RECOVERY_XOR_FLAG	0x00000800
 #define CP_LARGE_NAT_BITMAP_FLAG	0x00000400
 #define CP_NOCRC_RECOVERY_FLAG	0x00000200
 #define CP_TRIMMED_FLAG		0x00000100
-- 
2.1.4

             reply	other threads:[~2018-01-31 16:16 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-31 16:16 Gaoxiang (OS) [this message]
2018-02-01 13:27 ` [f2fs-dev] [PATCH] f2fs: use crc ^ cp_ver instead of crc | cp_ver for recovery Chao Yu
2018-02-01 13:57   ` Gao Xiang
2018-02-01 13:57     ` Gao Xiang
2018-02-01 14:06     ` [f2fs-dev] " Gao Xiang
2018-02-01 14:29       ` Chao Yu
2018-02-01 14:29         ` Chao Yu
2018-02-01 14:30         ` [f2fs-dev] " Chao Yu
2018-02-01 14:30           ` Chao Yu
2018-02-01 14:38           ` [f2fs-dev] " Gao Xiang
2018-02-01 14:38             ` Gao Xiang

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