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SubjectRe: [PATCH] jbd2: update log tail info after journal recovery
Hello!

On Wed 04-12-19 03:47:52, Likai wrote:
> 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(like ext4). 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 when mount.
> 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 commit recover old trans area.
>
> 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.
>
>
> To fix this problem, I clear JBD2_ABORT flag before journal_reset so that jbd2_journal_update_sb_log_tail
> can update log tail later. After test, it is ok now.

Thanks for the report and the patch! I agree with the analysis and the fix.
This seems to be a bug introduced by commit 85e0c4e89c1b8 "jbd2: if the
journal is aborted then don't allow update of the log tail". So can you
please create a patch with proper changelog, your signed-off-by, unmangled
white-spaces, and also

Fixes: 85e0c4e89c1b "jbd2: if the journal is aborted then don't allow update of the log tail"

tag and resubmit it? Thank you!

Honza

>
> ---
> fs/jbd2/journal.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 593f3e31fb21..6fc9fd41830e 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1685,6 +1685,11 @@ int jbd2_journal_load(journal_t *journal)
> journal->j_devname);
> return -EFSCORRUPTED;
> }
> + /*
> + * clear JBD2_ABORT flag which was initialized in journal_init_common
> + * here to update log tail information with the newest seq.
> + */
> + journal->j_flags &= ~JBD2_ABORT;
> /* OK, we've finished with the dynamic journal bits:
> * reinitialise the dynamic contents of the superblock in memory
> @@ -1692,7 +1697,6 @@ int jbd2_journal_load(journal_t *journal)
> if (journal_reset(journal))
> goto recovery_error;
> - journal->j_flags &= ~JBD2_ABORT;
> journal->j_flags |= JBD2_LOADED;
> return 0;
> -------------------------------------------------------------------------------------------------------------------------------------
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--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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