f2fs: Add a new CP flag to help fsck fix resize SPO issues

Add and set a new CP flag CP_RESIZEFS_FLAG during
online resize FS to help fsck fix the metadata mismatch
that may happen due to SPO during resize, where SB
got updated but CP data couldn't be written yet.

fsck errors -
Info: CKPT version = 6ed7bccb
        Wrong user_block_count(2233856)
[f2fs_do_mount:3365] Checkpoint is polluted
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -1298,10 +1298,14 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	else
 		__clear_ckpt_flags(ckpt, CP_ORPHAN_PRESENT_FLAG);
 
-	if (is_sbi_flag_set(sbi, SBI_NEED_FSCK) ||
-		is_sbi_flag_set(sbi, SBI_IS_RESIZEFS))
+	if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
 		__set_ckpt_flags(ckpt, CP_FSCK_FLAG);
 
+	if (is_sbi_flag_set(sbi, SBI_IS_RESIZEFS))
+		__set_ckpt_flags(ckpt, CP_RESIZEFS_FLAG);
+	else
+		__clear_ckpt_flags(ckpt, CP_RESIZEFS_FLAG);
+
 	if (is_sbi_flag_set(sbi, SBI_CP_DISABLED))
 		__set_ckpt_flags(ckpt, CP_DISABLED_FLAG);
 	else

include/linux/f2fs_fs.h

@@ -125,6 +125,7 @@ struct f2fs_super_block {
 /*
  * For checkpoint
  */
+#define CP_RESIZEFS_FLAG		0x00004000
 #define CP_DISABLED_QUICK_FLAG		0x00002000
 #define CP_DISABLED_FLAG		0x00001000
 #define CP_QUOTA_NEED_FSCK_FLAG		0x00000800