linux-kernel - Re: [PATCH 1/2 v2] f2fs: allow to recover node blocks given updated checkpoint

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Message-ID: <20180120220528.GB28167@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Sat, 20 Jan 2018 14:05:28 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH 1/2 v2] f2fs: allow to recover node blocks given updated
 checkpoint

If fsck.f2fs changes crc, we have no way to recover some inode blocks by roll-
forward recovery. Let's relax the condition to recover them.

Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---

Change log from v1:
 - add a new checkpoint flag to handle this

 fs/f2fs/checkpoint.c    | 1 +
 fs/f2fs/node.h          | 4 ++++
 include/linux/f2fs_fs.h | 1 +
 3 files changed, 6 insertions(+)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 9c7596f7daae..512dca8abc7d 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1157,6 +1157,7 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 
 	/* set this flag to activate crc|cp_ver for recovery */
 	__set_ckpt_flags(ckpt, CP_CRC_RECOVERY_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 0ee3e5ff49a3..081ef0d672bf 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -305,6 +305,10 @@ static inline bool is_recoverable_dnode(struct page *page)
 	struct f2fs_checkpoint *ckpt = F2FS_CKPT(F2FS_P_SB(page));
 	__u64 cp_ver = cur_cp_version(ckpt);
 
+	/* 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);
+
 	if (__is_set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG))
 		cp_ver |= (cur_cp_crc(ckpt) << 32);
 
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index cfb522e6affc..6eed677b6d9a 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_NOCRC_RECOVERY_FLAG	0x00000200
 #define CP_TRIMMED_FLAG		0x00000100
 #define CP_NAT_BITS_FLAG	0x00000080
 #define CP_CRC_RECOVERY_FLAG	0x00000040
-- 
2.15.0.531.g2ccb3012c9-goog