[f2fs-dev] [PATCH] fsck: Fix data loss issue observed during SPO

[Sahitya Tummala <stummala@codeaurora.org>]

With the commit <979b25727800> ("fsck.f2fs: check validity of nat journal"),
there is a serious data loss issue observed during sudden power off tests.

The reason is due to incorrect update of journal->n_nats in that patch.
When fsck encounters a nat journal entry with invalid blkaddr/nid, it
updates journal->n_nats with the index of such first entry and then continues
the for loop which scans all nats in journal in f2fs_init_nid_bitmap().
But that loop doesn't continue and doesn't update nm_i->nid_bitmap as well,
as it fails the for loop condition i < nats_in_cursum(journal).

There could be several other valid entries in the journal after this
invalid entry. Due to this invalid journal->n_nats, build_nat_area_bitmap()
could not be build properly for valid nat journal entries. It further results
into these fsck asserts/errors and causes data loss due to incorrect fsck fix.

[ASSERT] (sanity_check_nid: 372)  --> nid[0xfb01] ino is 0\x0a
[FIX] (__chk_dentries:1438)  --> Unlink [0xfb01] - _JeNcl242yB3Apz2MW,VOh6WmjsVht1W len[0x1c], type[0x1]\x0a
[ASSERT] (sanity_check_nid: 372)  --> nid[0xfa2d] ino is 0\x0a
[FIX] (__chk_dentries:1438)  --> Unlink [0xfa2d] - _++vN7axccjjGNI,TQEVmcOemY1EAAAA len[0x14], type[0x1]\x0a
...
NID[0xba5] is unreachable\x0a
NID[0xfa9] is unreachable\x0a
...
[FIX] (nullify_nat_entry:2089)  --> Remove nid [0xba5] in NAT\x0a
[FIX] (nullify_nat_entry:2089)  --> Remove nid [0xfa9] in NAT\x0a
...

Fixes: 979b25727800 ("fsck.f2fs: check validity of nat journal")
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
---
 fsck/mount.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fsck/mount.c b/fsck/mount.c
index 60e0e4a..1b93f49 100644
--- a/fsck/mount.c
+++ b/fsck/mount.c
@@ -1160,7 +1160,6 @@ static int f2fs_init_nid_bitmap(struct f2fs_sb_info *sbi)
 		addr = le32_to_cpu(nat_in_journal(journal, i).block_addr);
 		if (!IS_VALID_BLK_ADDR(sbi, addr)) {
 			MSG(0, "\tError: f2fs_init_nid_bitmap: addr(%u) is invalid!!!\n", addr);
-			journal->n_nats = cpu_to_le16(i);
 			c.fix_on = 1;
 			continue;
 		}
@@ -1168,7 +1167,6 @@ static int f2fs_init_nid_bitmap(struct f2fs_sb_info *sbi)
 		nid = le32_to_cpu(nid_in_journal(journal, i));
 		if (!IS_VALID_NID(sbi, nid)) {
 			MSG(0, "\tError: f2fs_init_nid_bitmap: nid(%u) is invalid!!!\n", nid);
-			journal->n_nats = cpu_to_le16(i);
 			c.fix_on = 1;
 			continue;
 		}
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.



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