linux-stable.git/fs/jbd2, branch v6.5.2

jbd2: remove __journal_try_to_free_buffer()

2023-07-11T03:09:21+00:00

__journal_try_to_free_buffer() has only one caller and it's logic is
much simple now, so just remove it and open code in
jbd2_journal_try_to_free_buffers().

Signed-off-by: Zhang Yi 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230606135928.434610-7-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o

jbd2: fix a race when checking checkpoint buffer busy

2023-07-11T03:09:21+00:00

Before removing checkpoint buffer from the t_checkpoint_list, we have to
check both BH_Dirty and BH_Lock bits together to distinguish buffers
have not been or were being written back. But __cp_buffer_busy() checks
them separately, it first check lock state and then check dirty, the
window between these two checks could be raced by writing back
procedure, which locks buffer and clears buffer dirty before I/O
completes. So it cannot guarantee checkpointing buffers been written
back to disk if some error happens later. Finally, it may clean
checkpoint transactions and lead to inconsistent filesystem.

jbd2_journal_forget() and __journal_try_to_free_buffer() also have the
same problem (journal_unmap_buffer() escape from this issue since it's
running under the buffer lock), so fix them through introducing a new
helper to try holding the buffer lock and remove really clean buffer.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217490
Cc: stable@vger.kernel.org
Suggested-by: Jan Kara 
Signed-off-by: Zhang Yi 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230606135928.434610-6-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o

jbd2: Fix wrongly judgement for buffer head removing while doing checkpoint

2023-07-11T03:09:21+00:00

Following process,

jbd2_journal_commit_transaction
// there are several dirty buffer heads in transaction->t_checkpoint_list
          P1                   wb_workfn
jbd2_log_do_checkpoint
 if (buffer_locked(bh)) // false
                            __block_write_full_page
                             trylock_buffer(bh)
                             test_clear_buffer_dirty(bh)
 if (!buffer_dirty(bh))
  __jbd2_journal_remove_checkpoint(jh)
   if (buffer_write_io_error(bh)) // false
                             >> bh IO error occurs <<
 jbd2_cleanup_journal_tail
  __jbd2_update_log_tail
   jbd2_write_superblock
   // The bh won't be replayed in next mount.
, which could corrupt the ext4 image, fetch a reproducer in [Link].

Since writeback process clears buffer dirty after locking buffer head,
we can fix it by try locking buffer and check dirtiness while buffer is
locked, the buffer head can be removed if it is neither dirty nor locked.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217490
Fixes: 470decc613ab ("[PATCH] jbd2: initial copy of files from jbd")
Signed-off-by: Zhihao Cheng 
Signed-off-by: Zhang Yi 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230606135928.434610-5-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o

jbd2: remove journal_clean_one_cp_list()

2023-07-11T03:09:21+00:00

journal_clean_one_cp_list() and journal_shrink_one_cp_list() are almost
the same, so merge them into journal_shrink_one_cp_list(), remove the
nr_to_scan parameter, always scan and try to free the whole checkpoint
list.

Signed-off-by: Zhang Yi 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230606135928.434610-4-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o

jbd2: remove t_checkpoint_io_list

2023-07-11T03:09:21+00:00

Since t_checkpoint_io_list was stop using in jbd2_log_do_checkpoint()
now, it's time to remove the whole t_checkpoint_io_list logic.

Signed-off-by: Zhang Yi 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230606135928.434610-3-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o

jbd2: recheck chechpointing non-dirty buffer

2023-07-11T03:09:21+00:00

There is a long-standing metadata corruption issue that happens from
time to time, but it's very difficult to reproduce and analyse, benefit
from the JBD2_CYCLE_RECORD option, we found out that the problem is the
checkpointing process miss to write out some buffers which are raced by
another do_get_write_access(). Looks below for detail.

jbd2_log_do_checkpoint() //transaction X
 //buffer A is dirty and not belones to any transaction
 __buffer_relink_io() //move it to the IO list
 __flush_batch()
  write_dirty_buffer()
                             do_get_write_access()
                             clear_buffer_dirty
                             __jbd2_journal_file_buffer()
                             //add buffer A to a new transaction Y
   lock_buffer(bh)
   //doesn't write out
 __jbd2_journal_remove_checkpoint()
 //finish checkpoint except buffer A
 //filesystem corrupt if the new transaction Y isn't fully write out.

Due to the t_checkpoint_list walking loop in jbd2_log_do_checkpoint()
have already handles waiting for buffers under IO and re-added new
transaction to complete commit, and it also removing cleaned buffers,
this makes sure the list will eventually get empty. So it's fine to
leave buffers on the t_checkpoint_list while flushing out and completely
stop using the t_checkpoint_io_list.

Cc: stable@vger.kernel.org
Suggested-by: Jan Kara 
Signed-off-by: Zhang Yi 
Tested-by: Zhihao Cheng 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230606135928.434610-2-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2023-06-29T20:18:36+00:00

Pull ext4 updates from Ted Ts'o:
 "Various cleanups and bug fixes in ext4's extent status tree,
  journalling, and block allocator subsystems.

  Also improve performance for parallel DIO overwrites"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (55 commits)
  ext4: avoid updating the superblock on a r/o mount if not needed
  jbd2: skip reading super block if it has been verified
  ext4: fix to check return value of freeze_bdev() in ext4_shutdown()
  ext4: refactoring to use the unified helper ext4_quotas_off()
  ext4: turn quotas off if mount failed after enabling quotas
  ext4: update doc about journal superblock description
  ext4: add journal cycled recording support
  jbd2: continue to record log between each mount
  jbd2: remove j_format_version
  jbd2: factor out journal initialization from journal_get_superblock()
  jbd2: switch to check format version in superblock directly
  jbd2: remove unused feature macros
  ext4: ext4_put_super: Remove redundant checking for 'sbi->s_journal_bdev'
  ext4: Fix reusing stale buffer heads from last failed mounting
  ext4: allow concurrent unaligned dio overwrites
  ext4: clean up mballoc criteria comments
  ext4: make ext4_zeroout_es() return void
  ext4: make ext4_es_insert_extent() return void
  ext4: make ext4_es_insert_delayed_block() return void
  ext4: make ext4_es_remove_extent() return void
  ...

jbd2: skip reading super block if it has been verified

2023-06-26T23:36:45+00:00

We got a NULL pointer dereference issue below while running generic/475
I/O failure pressure test.

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 #PF: supervisor write access in kernel mode
 #PF: error_code(0x0002) - not-present page
 PGD 0 P4D 0
 Oops: 0002 [#1] PREEMPT SMP PTI
 CPU: 1 PID: 15600 Comm: fsstress Not tainted 6.4.0-rc5-xfstests-00055-gd3ab1bca26b4 #190
 RIP: 0010:jbd2_journal_set_features+0x13d/0x430
 ...
 Call Trace:
  
  ? __die+0x23/0x60
  ? page_fault_oops+0xa4/0x170
  ? exc_page_fault+0x67/0x170
  ? asm_exc_page_fault+0x26/0x30
  ? jbd2_journal_set_features+0x13d/0x430
  jbd2_journal_revoke+0x47/0x1e0
  __ext4_forget+0xc3/0x1b0
  ext4_free_blocks+0x214/0x2f0
  ext4_free_branches+0xeb/0x270
  ext4_ind_truncate+0x2bf/0x320
  ext4_truncate+0x1e4/0x490
  ext4_handle_inode_extension+0x1bd/0x2a0
  ? iomap_dio_complete+0xaf/0x1d0

The root cause is the journal super block had been failed to write out
due to I/O fault injection, it's uptodate bit was cleared by
end_buffer_write_sync() and didn't reset yet in jbd2_write_superblock().
And it raced by journal_get_superblock()->bh_read(), unfortunately, the
read IO is also failed, so the error handling in
journal_fail_superblock() unexpectedly clear the journal->j_sb_buffer,
finally lead to above NULL pointer dereference issue.

If the journal super block had been read and verified, there is no need
to call bh_read() read it again even if it has been failed to written
out. So the fix could be simply move buffer_verified(bh) in front of
bh_read(). Also remove a stale comment left in
jbd2_journal_check_used_features().

Fixes: 51bacdba23d8 ("jbd2: factor out journal initialization from journal_get_superblock()")
Reported-by: Theodore Ts'o 
Signed-off-by: Zhang Yi 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230616015547.3155195-1-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o

jbd2: continue to record log between each mount

2023-06-26T23:35:13+00:00

For a newly mounted file system, the journal committing thread always
record new transactions from the start of the journal area, no matter
whether the journal was clean or just has been recovered. So the logdump
code in debugfs cannot dump continuous logs between each mount, it is
disadvantageous to analysis corrupted file system image and locate the
file system inconsistency bugs.

If we get a corrupted file system in the running products and want to
find out what has happened, besides lookup the system log, one effective
way is to backtrack the journal log. But we may not always run e2fsck
before each mount and the default fsck -a mode also cannot always
checkout all inconsistencies, so it could left over some inconsistencies
into the next mount until we detect it. Finally, transactions in the
journal may probably discontinuous and some relatively new transactions
has been covered, it becomes hard to analyse. If we could record
transactions continuously between each mount, we could acquire more
useful info from the journal. Like this:

 |Previous mount checkpointed/recovered logs|Current mount logs         |
 |{------}{---}{--------} ... {------}| ... |{======}{========}...000000|

And yes the journal area is limited and cannot record everything, the
problematic transaction may also be covered even if we do this, but
this is still useful for fuzzy tests and short-running products.

This patch save the head blocknr in the superblock after flushing the
journal or unmounting the file system, let the next mount could continue
to record new transaction behind it. This change is backward compatible
because the old kernel does not care about the head blocknr of the
journal. It is also fine if we mount a clean old image without valid
head blocknr, we fail back to set it to s_first just like before.
Finally, for the case of mount an unclean file system, we could also get
the journal head easily after scanning/replaying the journal, it will
continue to record new transaction after the recovered transactions.

Signed-off-by: Zhang Yi 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230322013353.1843306-2-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o

jbd2: remove j_format_version

2023-06-26T23:35:13+00:00

journal->j_format_version is no longer used, remove it.

Signed-off-by: Zhang Yi 
Signed-off-by: Zhihao Cheng 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230315013128.3911115-7-chengzhihao1@huawei.com
Signed-off-by: Theodore Ts'o