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    SubjectRe: [Ocfs2-devel] [PATCH v3] ocfs2: call journal flush to mark journal as empty after journal recovery when mount
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    On 2019/12/17 10:01, Kai Li wrote:
    > If journal is dirty when mount, it will be replayed but jbd2 sb
    > log tail cannot be updated to mark a new start because
    > journal->j_flag has already been set with JBD2_ABORT first
    > in journal_init_common. When a new transaction is committed, it
    > will be recored in block 1 first(journal->j_tail is set to 1 in
    > journal_reset).If emergency restart happens again before journal
    > super block is updated unfortunately, the new recorded trans will
    > not be replayed in the next mount.
    >
    > The following steps describe this procedure in detail.
    > 1. mount and touch some files
    > 2. these transactions are committed to journal area but not checkpointed
    > 3. emergency restart
    > 4. mount again and its journals are replayed
    > 5. journal super block's first s_start is 1, but its s_seq is not updated
    > 6. touch a new file and its trans is committed but not checkpointed
    > 7. emergency restart again
    > 8. mount and journal is dirty, but trans committed in 6 will not be
    > replayed.
    >
    > This exception happens easily when this lun is used by only one node. If it
    > is used by multi-nodes, other node will replay its journal and its
    > journal super block will be updated after recovery like what this patch
    > does.
    >
    > ocfs2_recover_node->ocfs2_replay_journal.
    >
    > The following jbd2 journal can be generated by touching a new file after
    > journal is replayed, and seq 15 is the first valid commit, but first seq
    > is 13 in journal super block.
    > 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)
    >
    > The following is jouranl recovery log when recovering the upper jbd2
    > journal when mount again.
    > syslog:
    > [ 2265.648622] ocfs2: File system on device (252,1) was not unmounted cleanly, recovering it.
    > [ 2265.649695] fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 0
    > [ 2265.650407] fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 1
    > [ 2265.650409] fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 2
    > [ 2265.650410] fs/jbd2/recovery.c:(jbd2_journal_recover, 278): JBD2: recovery, exit status 0, recovered transactions 13 to 13
    >
    > Due to first commit seq 13 recorded in journal super is not consistent
    > with the value recorded in block 1(seq is 14), journal recovery will be
    > terminated before seq 15 even though it is an unbroken commit, inode
    > 8257802 is a new file and it will be lost.
    >
    > 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..68ba354cf361 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) {
    > + jbd2_journal_lock_updates(journal->j_journal);
    > + status = jbd2_journal_flush(journal->j_journal);

    What if jbd2_journal_flush gets failed? The 's_sequence' and 's_start'
    won't be reset, and I wonder if the problem still remains.

    Thanks,
    Jun

    > + jbd2_journal_unlock_updates(journal->j_journal);
    > + if (status < 0)
    > + mlog_errno(status);
    > + }
    > +
    > status = ocfs2_journal_toggle_dirty(osb, 1, replayed);
    > if (status < 0) {
    > mlog_errno(status);
    >

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