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@xxxxxxxxxx>
---
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
