Jiangyiwen
2019-Dec-20 12:52 UTC
[Ocfs2-devel] [PATCH v3] ocfs2: call journal flush to mark journal as empty after journal recovery when mount
On 2019/12/20 17:33, Likai wrote:> On 2019/12/20 17:14, piaojun wrote: >> On 2019/12/20 9:11, Joseph Qi wrote: >>> On 19/12/19 22:15, piaojun wrote: >>>> 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 checkpointedHi, I wonder that in this step, does the function jbd2_journal_commit_transaction() return? I understand only jbd2_journal_commit_transaction() return it means the transaction is committed completely, and the s_seq can be updated in jbd2_journal_commit_transaction()->jbd2_update_log_tail(), so I don't know how this scenario happened. If emergency restart happens in before jbd2_journal_commit_transaction() return, I think this transaction shouldn't be a valid transaction. Can you explain where the specific function is executed? Thanks, Yiwen.>>>>> 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 at 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. >>>> >>> Yes, but we don't want this to fail the mount process, instead we just log >>> an error and system administrator should know the result. >>> >> Thanks for your reply and I have another question about this issue. IMO >> the second trans is not complete as jbd2 sb has not been updated, so we >> do not need to replay it when mount again. >> >> Jun >> >> > I don't think so. The problem is that jbd2 sb should be updated to mark > a new start after mount rather than whether trans committed later is > complete or not. > > In fact , the trans is complete too as the commit log described. > > Thanks > > > _______________________________________________ > Ocfs2-devel mailing list > Ocfs2-devel at oss.oracle.com > https://oss.oracle.com/mailman/listinfo/ocfs2-devel > > . >
Changwei Ge
2019-Dec-21 07:24 UTC
[Ocfs2-devel] [PATCH v3] ocfs2: call journal flush to mark journal as empty after journal recovery when mount
On 12/20/19 8:52 PM, Jiangyiwen wrote:> On 2019/12/20 17:33, Likai wrote: >> On 2019/12/20 17:14, piaojun wrote: >>> On 2019/12/20 9:11, Joseph Qi wrote: >>>> On 19/12/19 22:15, piaojun wrote: >>>>> 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 > > Hi, > > I wonder that in this step, does the function > jbd2_journal_commit_transaction() return? > I understand only jbd2_journal_commit_transaction() return it means the > transaction > is committed completely, and the s_seq can be updated in > jbd2_journal_commit_transaction()->jbd2_update_log_tail(), so I don't > know how > this scenario happened. > > If emergency restart happens in before jbd2_journal_commit_transaction()The trick is that jbd2 kernel thread even doesn't have a chance to to update tail. Assuming that a timepoint sits between *mount completion* and the *first iteration* of committing work that jbd2 thread. -Changwei> return, > I think this transaction shouldn't be a valid transaction. > > Can you explain where the specific function is executed? > > Thanks, > Yiwen. > >>>>>> 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 at 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. >>>>> >>>> Yes, but we don't want this to fail the mount process, instead we >>>> just log >>>> an error and system administrator should know the result. >>>> >>> Thanks for your reply and I have another question about this issue. IMO >>> the second trans is not complete as jbd2 sb has not been updated, so we >>> do not need to replay it when mount again. >>> >>> Jun >>> >>> >> I don't think so. The problem is that jbd2 sb should be updated to mark >> a new start after mount rather than whether trans committed later is >> complete or not. >> >> In fact , the trans is complete too as the commit log described. >> >> Thanks >> >> >> _______________________________________________ >> Ocfs2-devel mailing list >> Ocfs2-devel at oss.oracle.com >> https://oss.oracle.com/mailman/listinfo/ocfs2-devel >> >> . >> >