linux-toradex.git/include/linux/jbd2.h, branch v3.10.2

jbd2: use kmem_cache_zalloc instead of kmem_cache_alloc/memset

2013-04-19T21:49:23+00:00

The jbd2_alloc_handle() function is only called by new_handle().  So
this commit uses kmem_cache_zalloc() instead of
kmem_cache_alloc()/memset().

Signed-off-by: Zheng Liu 
Signed-off-by: "Theodore Ts'o"

jbd2: fix race between jbd2_journal_remove_checkpoint and ->j_commit_callback

2013-04-04T02:06:52+00:00

The following race is possible:

[kjournald2]                              other_task
jbd2_journal_commit_transaction()
  j_state = T_FINISHED;
  spin_unlock(&journal->j_list_lock);
                                         ->jbd2_journal_remove_checkpoint()
					   ->jbd2_journal_free_transaction();
					     ->kmem_cache_free(transaction)
  ->j_commit_callback(journal, transaction);
    -> USE_AFTER_FREE

WARNING: at lib/list_debug.c:62 __list_del_entry+0x1c0/0x250()
Hardware name:
list_del corruption. prev->next should be ffff88019a4ec198, but was 6b6b6b6b6b6b6b6b
Modules linked in: cpufreq_ondemand acpi_cpufreq freq_table mperf coretemp kvm_intel kvm crc32c_intel ghash_clmulni_intel microcode sg xhci_hcd button sd_mod crc_t10dif aesni_intel ablk_helper cryptd lrw aes_x86_64 xts gf128mul ahci libahci pata_acpi ata_generic dm_mirror dm_region_hash dm_log dm_mod
Pid: 16400, comm: jbd2/dm-1-8 Tainted: G        W    3.8.0-rc3+ #107
Call Trace:
 [] warn_slowpath_common+0xad/0xf0
 [] warn_slowpath_fmt+0x46/0x50
 [] ? ext4_journal_commit_callback+0x99/0xc0
 [] __list_del_entry+0x1c0/0x250
 [] ext4_journal_commit_callback+0x6f/0xc0
 [] jbd2_journal_commit_transaction+0x23a6/0x2570
 [] ? try_to_del_timer_sync+0x82/0xa0
 [] ? del_timer_sync+0x91/0x1e0
 [] kjournald2+0x19f/0x6a0
 [] ? wake_up_bit+0x40/0x40
 [] ? bit_spin_lock+0x80/0x80
 [] kthread+0x10e/0x120
 [] ? __init_kthread_worker+0x70/0x70
 [] ret_from_fork+0x7c/0xb0
 [] ? __init_kthread_worker+0x70/0x70

In order to demonstrace this issue one should mount ext4 with mount -o
discard option on SSD disk.  This makes callback longer and race
window becomes wider.

In order to fix this we should mark transaction as finished only after
callbacks have completed

Signed-off-by: Dmitry Monakhov 
Signed-off-by: "Theodore Ts'o" 
Cc: stable@vger.kernel.org

ext4/jbd2: don't wait (forever) for stale tid caused by wraparound

2013-04-04T02:02:52+00:00

In the case where an inode has a very stale transaction id (tid) in
i_datasync_tid or i_sync_tid, it's possible that after a very large
(2**31) number of transactions, that the tid number space might wrap,
causing tid_geq()'s calculations to fail.

Commit deeeaf13 "jbd2: fix fsync() tid wraparound bug", later modified
by commit e7b04ac0 "jbd2: don't wake kjournald unnecessarily",
attempted to fix this problem, but it only avoided kjournald spinning
forever by fixing the logic in jbd2_log_start_commit().

Unfortunately, in the codepaths in fs/ext4/fsync.c and fs/ext4/inode.c
that might call jbd2_log_start_commit() with a stale tid, those
functions will subsequently call jbd2_log_wait_commit() with the same
stale tid, and then wait for a very long time.  To fix this, we
replace the calls to jbd2_log_start_commit() and
jbd2_log_wait_commit() with a call to a new function,
jbd2_complete_transaction(), which will correctly handle stale tid's.

As a bonus, jbd2_complete_transaction() will avoid locking
j_state_lock for writing unless a commit needs to be started.  This
should have a small (but probably not measurable) improvement for
ext4's scalability.

Signed-off-by: "Theodore Ts'o" 
Reported-by: Ben Hutchings 
Reported-by: George Barnett 
Cc: stable@vger.kernel.org

jbd2: use module parameters instead of debugfs for jbd_debug

2013-02-09T21:29:20+00:00

There are multiple reasons to move away from debugfs.  First of all,
we are only using it for a single parameter, and it is much more
complicated to set up (some 30 lines of code compared to 3), and one
more thing that might fail while loading the jbd2 module.

Secondly, as a module paramter it can be specified as a boot option if
jbd2 is built into the kernel, or as a parameter when the module is
loaded, and it can also be manipulated dynamically under
/sys/module/jbd2/parameters/jbd2_debug.  So it is more flexible.

Ultimately we want to move away from using jbd_debug() towards
tracepoints, but for now this is still a useful simplification of the
code base.

Signed-off-by: "Theodore Ts'o"

jbd2: add tracepoints which provide per-handle statistics

2013-02-08T18:00:22+00:00

Handles which stay open a long time are problematic when it comes time
to close down a transaction so it can be committed.  These tracepoints
will help us determine which ones are the problematic ones, and to
validate whether changes makes things better or worse.

Signed-off-by: "Theodore Ts'o"

jbd2: revert "jbd2: add COW fields to struct jbd2_journal_handle"

2013-02-07T05:02:15+00:00

This reverts commit 93737456d68ddcb86232f669b83da673dd12e351.

The cow-snapshots effort is no longer active, so remove these extra
fields to shrink down the handle structure.

Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Jan Kara

jbd2: track request delay statistics

2013-02-07T03:30:23+00:00

Track the delay between when we first request that the commit begin
and when it actually begins, so we can see how much of a gap exists.
In theory, this should just be the remaining scheduling quantuum of
the thread which requested the commit (assuming it was not a
synchronous operation which triggered the commit request) plus
scheduling overhead; however, it's possible that real time processes
might get in the way of letting the kjournald thread from executing.

Signed-off-by: "Theodore Ts'o"

ext4: fix deadlock in journal_unmap_buffer()

2012-12-25T18:29:52+00:00

We cannot wait for transaction commit in journal_unmap_buffer()
because we hold page lock which ranks below transaction start.  We
solve the issue by bailing out of journal_unmap_buffer() and
jbd2_journal_invalidatepage() with -EBUSY.  Caller is then responsible
for waiting for transaction commit to finish and try invalidation
again. Since the issue can happen only for page stradding i_size, it
is simple enough to manually call jbd2_journal_invalidatepage() for
such page from ext4_setattr(), check the return value and wait if
necessary.

Signed-off-by: Jan Kara 
Signed-off-by: "Theodore Ts'o"

jbd2: remove VLAIS usage from JBD2 code

2012-11-08T16:24:46+00:00

The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). Since ctx is always a 32-bit CRC, hard coding a size of 4
bytes accomplishes the same thing without the use of VLAIS. This is the same
technique already employed in fs/ext4/ext4.h

Signed-off-by: Mark Charlebois 
Signed-off-by: Behan Webster 
Signed-off-by: "Theodore Ts'o"

ext4: remove ext4_handle_release_buffer()

2012-11-08T16:22:46+00:00

ext4_handle_release_buffer() was intended to remove journal
write access from a buffer, but it doesn't actually do anything
at all other than add a BUFFER_TRACE point, but it's not reliably
used for that either.  Remove all the associated dead code.

Signed-off-by: Eric Sandeen 
Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Carlos Maiolino