forked from Minki/linux
mainlining shenanigans
397eac17f8
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.com Signed-off-by: Kai Li <li.kai4@h3c.com> Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> Reviewed-by: Changwei 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.