[Ocfs2-devel] [PATCH]ocfs2: flush journal to update log tail info after journal recovery when mount

[Likai <li.kai4@h3c.com>]

Hi,  I meet a new problem that file may be lost althougth it is recorded in the jbd2 journal
with ocfs2 file system in one node scene. Can you give some suggestions for this problem
and modification patch?

Test method:
1. touch some files after mount
2. emergency restart
3. mount again, then log tail will not be updated
4. touch a new file and confirm that it is recorded in the journal area
5.emergency restart again
6. the new log will not be replayed becasuse its seq and blknum are not consistent with journal super block although it is an unbroken commit.

After analizing the codes, its cause is as follow:

Journal->j_flags will be set JBD2_ABORT in journal_init_common first.
if this flag is not cleared before journal_reset in journal recovery
scene, super log tail cannot be updated, then the new commit trans in
the journal may not be replayed because new commits recover old trans
area.

This exception happens when this lun is used by only one node. If it
is used by multi-nodes, other node will replay its journal and its
log tail info will be updated after recovery.

To fix this problem, use jbd2_journal_flush to update log tail as
ocfs2_replay_journal has done.

logdump:
Block 0: Journal Superblock
Seq: 0   Type: 4 (JBD2_SUPERBLOCK_V2)
Blocksize: 4096   Total Blocks: 32768   First Block: 1
First Commit ID: 13   Start Log Blknum: 1
Error: 0
Feature Compat: 0
Feature Incompat: 2 block64
Feature RO compat: 0
Journal UUID: 4ED3822C54294467A4F8E87D2BA4BC36
FS Share Cnt: 1   Dynamic Superblk Blknum: 0
Per Txn Block Limit    Journal: 0    Data: 0

Block 1: Journal Commit Block
Seq: 14   Type: 2 (JBD2_COMMIT_BLOCK)

Block 2: Journal Descriptor
Seq: 15   Type: 1 (JBD2_DESCRIPTOR_BLOCK)
No. Blocknum        Flags
0. 587             none
UUID: 00000000000000000000000000000000
1. 8257792         JBD2_FLAG_SAME_UUID
2. 619             JBD2_FLAG_SAME_UUID
3. 24772864        JBD2_FLAG_SAME_UUID
4. 8257802         JBD2_FLAG_SAME_UUID
5. 513             JBD2_FLAG_SAME_UUID JBD2_FLAG_LAST_TAG
...
Block 7: Inode
Inode: 8257802   Mode: 0640   Generation: 57157641 (0x3682809)
FS Generation: 2839773110 (0xa9437fb6)
CRC32: 00000000   ECC: 0000
Type: Regular   Attr: 0x0   Flags: Valid
Dynamic Features: (0x1) InlineData
User: 0 (root)   Group: 0 (root)   Size: 7
Links: 1   Clusters: 0
ctime: 0x5de5d870 0x11104c61 -- Tue Dec  3 11:37:20.286280801 2019
atime: 0x5de5d870 0x113181a1 -- Tue Dec  3 11:37:20.288457121 2019
mtime: 0x5de5d870 0x11104c61 -- Tue Dec  3 11:37:20.286280801 2019
dtime: 0x0 -- Thu Jan  1 08:00:00 1970
...
Block 9: Journal Commit Block
Seq: 15   Type: 2 (JBD2_COMMIT_BLOCK)

syslog:
Dec  3 11:41:05 cvknode02 kernel: [ 2265.648622] ocfs2: File system on device (252,1) was not unmounted cleanly, recovering it.
Dec  3 11:41:05 cvknode02 kernel: [ 2265.649695] fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 0
Dec  3 11:41:05 cvknode02 kernel: [ 2265.650407] fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 1
Dec  3 11:41:05 cvknode02 kernel: [ 2265.650409] fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 2
Dec  3 11:41:05 cvknode02 kernel: [ 2265.650410] fs/jbd2/recovery.c:(jbd2_journal_recover, 278): JBD2: recovery, exit status 0, recovered transactions 13 to 13

Seq 15 is an unbroken commit, but it cannot be replayed, inode 8257802
is a new file and it will be lost. After test, it is ok now.

Signed-off-by: Kai Li <li.kai4@h3c.com>
---
fs/ocfs2/journal.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 1afe57f425a0..b8b9d26fa731 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -1066,6 +1066,14 @@ int ocfs2_journal_load(struct ocfs2_journal *journal, int local, int replayed)
        ocfs2_clear_journal_error(osb->sb, journal->j_journal, osb->slot_num);
+       if (replayed) {
+                /* wipe the journal */
+                jbd2_journal_lock_updates(journal->j_journal);
+                status = jbd2_journal_flush(journal->j_journal);
+                jbd2_journal_unlock_updates(journal->j_journal);
+                mlog(ML_NOTICE, "journal recovery complete, status=%d", status);
+       }
+
       status = ocfs2_journal_toggle_dirty(osb, 1, replayed);
       if (status < 0) {
                mlog_errno(status);
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