• Kai Li's avatar
    ocfs2: call journal flush to mark journal as empty after journal recovery when mount · 397eac17
    Kai Li authored
    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 journal recovery log when recovering the upper jbd2
    journal when mount again.
    
    syslog:
      ocfs2: File system on device (252,1) was not unmounted cleanly, recovering it.
      fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 0
      fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 1
      fs/jbd2/recovery.c:(do_one_pass, 449): Starting recovery pass 2
      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.
    
    Link: http://lkml.kernel.org/r/20191217020140.2197-1-li.kai4@h3c.comSigned-off-by: default avatarKai Li <li.kai4@h3c.com>
    Reviewed-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
    Reviewed-by: default avatarChangwei Ge <gechangwei@live.cn>
    Cc: Mark Fasheh <mark@fasheh.com>
    Cc: Joel Becker <jlbec@evilplan.org>
    Cc: Junxiao Bi <junxiao.bi@oracle.com>
    Cc: Gang He <ghe@suse.com>
    Cc: Jun Piao <piaojun@huawei.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    397eac17
journal.c 61.6 KB