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  1. 16 6月, 2020 1 次提交
  3. 18 3月, 2020 1 次提交
    • X
      alinux: jbd2: track slow handle which is preventing transaction committing · 83cd9d23
      由 Xiaoguang Wang 提交于 
      While transaction is going to commit, it first sets its state to be
T_LOCKED and waits all outstanding handles to complete, and the
committing transaction will always be in locked state so long as it
has outstanding handles, also the whole fs will be locked and all later
fs modification operations will be stucked in wait_transaction_locked().

It's hard to tell why handles are that slow, so here we add a new staic
tracepoint to track such slow handle, and show io wait time and sched
wait time, output likes below:
  fsstress-20347 [024] ....  1570.305454: jbd2_slow_handle_stats: dev 254,17
tid 15853 type 4 line_no 3101 interval 126 sync 0 requested_blocks 24
dirtied_blocks 0 trans_wait 122 space_wait 0 sched_wait 0 io_wait 126

"trans_wait 122" means that this current committing transaction has been
locked for 122ms, due to this handle is not completed quickly.

From "io_wait 126", we can see that io is the major reason.

In this patch, we also add a per fs control file used to determine
whether a handle can be considered to be slow.
    /proc/fs/jbd2/vdb1-8/stall_thresh
default value is 100ms, users can set new threshold by echoing new value
to this file.

Later I also plan to add a proc file fs per fs to record these info.
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
      83cd9d23
  5. 17 1月, 2020 1 次提交
  7. 15 1月, 2020 3 次提交
    • X
      alinux: jbd2: add proc entry to control whether doing buffer copy-out · 1ced8a5c
      由 Xiaoguang Wang 提交于 
      When jbd2 tries to get write access to one buffer, and if this buffer
is under writeback with BH_Shadow flag, jbd2 will wait until this buffer
has been written to disk, but sometimes the time taken to wait may be
much long, especially disk capacity is almost full.

Here add a proc entry "force-copy", if its value is not zero, jbd2 will
always do meta buffer copy-cout, then we can eliminate the unnecessary
wating time here, and reduce long tail latency for buffered-write.

I construct such test case below:

$cat offline.fio
; fio-rand-RW.job for fiotest

[global]
name=fio-rand-RW
filename=fio-rand-RW
rw=randrw
rwmixread=60
rwmixwrite=40
bs=4K
direct=0
numjobs=4
time_based=1
runtime=900

[file1]
size=60G
ioengine=sync
iodepth=16

$cat online.fio
; fio-seq-write.job for fiotest

[global]
name=fio-seq-write
filename=fio-seq-write
rw=write
bs=256K
direct=0
numjobs=1
time_based=1
runtime=60

[file1]
rate=50m
size=10G
ioengine=sync
iodepth=16

With this patch:
$cat /proc/fs/jbd2/sda5-8/force_copy
0

online fio almost always get such long tail latency:

Jobs: 1 (f=1), 0B/s-0B/s: [W(1)][100.0%][w=50.0MiB/s][w=200 IOPS][eta
00m:00s]
file1: (groupid=0, jobs=1): err= 0: pid=17855: Thu Nov 15 09:45:57 2018
  write: IOPS=200, BW=50.0MiB/s (52.4MB/s)(3000MiB/60001msec)
    clat (usec): min=135, max=4086.6k, avg=867.21, stdev=50338.22
     lat (usec): min=139, max=4086.6k, avg=871.16, stdev=50338.22
    clat percentiles (usec):
     |  1.00th=[    141],  5.00th=[    143], 10.00th=[    145],
     | 20.00th=[    147], 30.00th=[    147], 40.00th=[    149],
     | 50.00th=[    149], 60.00th=[    151], 70.00th=[    153],
     | 80.00th=[    155], 90.00th=[    159], 95.00th=[    163],
     | 99.00th=[    255], 99.50th=[    273], 99.90th=[    429],
     | 99.95th=[    441], 99.99th=[3640656]

$cat /proc/fs/jbd2/sda5-8/force_copy
1

online fio latency is much better.

Jobs: 1 (f=1), 0B/s-0B/s: [W(1)][100.0%][w=50.0MiB/s][w=200 IOPS][eta
00m:00s]
file1: (groupid=0, jobs=1): err= 0: pid=8084: Thu Nov 15 09:31:15 2018
  write: IOPS=200, BW=50.0MiB/s (52.4MB/s)(3000MiB/60001msec)
    clat (usec): min=137, max=545, avg=151.35, stdev=16.22
     lat (usec): min=140, max=548, avg=155.31, stdev=16.65
    clat percentiles (usec):
     |  1.00th=[  143],  5.00th=[  145], 10.00th=[  145], 20.00th=[
147],
     | 30.00th=[  147], 40.00th=[  147], 50.00th=[  149], 60.00th=[
149],
     | 70.00th=[  151], 80.00th=[  155], 90.00th=[  157], 95.00th=[
161],
     | 99.00th=[  239], 99.50th=[  269], 99.90th=[  420], 99.95th=[
429],
     | 99.99th=[  537]

As to the cost: because we'll always need to copy meta buffer, will
consume minor cpu time and some memory(at most 32MB for 128MB journal
size).
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      1ced8a5c
    • X
      alinux: jbd2: add new "stats" proc file · 7e2e7b9a
      由 Xiaoguang Wang 提交于 
      /proc/fs/jbd2/${device}/info only shows whole average statistical
info about jbd2's life cycle, but it can not show jbd2 info in
specified time interval and sometimes this capability is very useful
for trouble shooting. For example, we can not see how rs_locked and
rs_flushing grows in specified time interval, but these two indexes
can explain some reasons for app's behaviours.

Here we add a new "stats" proc file like /proc/diskstats, then we can
implement a simple tool jbd2_stats which'll display detailed jbd2 info
in specified time interval. Like below(time interval 5s):

[lege@localhost ~]$ cat /proc/fs/jbd2/vdb1-8/stats
51 30 8192 0 1 241616 0 0 22 0 47158 891 942 1000 1000

[lege@localhost ~]$ gcc -o jbd2_stat jbd2_stat.c ; ./jbd2_stat

Device              tid     trans   handles    locked  flushing
logging
vdb1-8             1861       158       359     13.00      0.00
2.00

Device              tid     trans   handles    locked  flushing
logging
vdb1-8             1974       113       389     26.00      0.00
5.00

Device              tid     trans   handles    locked  flushing
logging
vdb1-8             2188       214       308     10.00      0.00
7.00

Device              tid     trans   handles    locked  flushing
logging
vdb1-8             2344       156       332     19.00      0.00
4.00
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      7e2e7b9a
    • J
      alinux: jbd2: create jbd2-ckpt thread for journal checkpoint · 3999cdd9
      由 Joseph Qi 提交于 
      This is trying to do jbd2 checkpoint in a specific kernel thread, then
checkpoint won't be under io throttle control.
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Nzhangliguang <zhangliguang@linux.alibaba.com>
Reviewed by: Baoyou Xie <baoyou.xie@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      3999cdd9
  9. 27 12月, 2019 1 次提交
  11. 28 7月, 2019 1 次提交
    • R
      jbd2: introduce jbd2_inode dirty range scoping · af3812b6
      由 Ross Zwisler 提交于 
      commit 6ba0e7dc64a5adcda2fbe65adc466891795d639e upstream.

Currently both journal_submit_inode_data_buffers() and
journal_finish_inode_data_buffers() operate on the entire address space
of each of the inodes associated with a given journal entry.  The
consequence of this is that if we have an inode where we are constantly
appending dirty pages we can end up waiting for an indefinite amount of
time in journal_finish_inode_data_buffers() while we wait for all the
pages under writeback to be written out.

The easiest way to cause this type of workload is do just dd from
/dev/zero to a file until it fills the entire filesystem.  This can
cause journal_finish_inode_data_buffers() to wait for the duration of
the entire dd operation.

We can improve this situation by scoping each of the inode dirty ranges
associated with a given transaction.  We do this via the jbd2_inode
structure so that the scoping is contained within jbd2 and so that it
follows the lifetime and locking rules for that structure.

This allows us to limit the writeback & wait in
journal_submit_inode_data_buffers() and
journal_finish_inode_data_buffers() respectively to the dirty range for
a given struct jdb2_inode, keeping us from waiting forever if the inode
in question is still being appended to.
Signed-off-by: NRoss Zwisler <zwisler@google.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      af3812b6
  13. 22 5月, 2019 2 次提交
  15. 06 4月, 2019 1 次提交
    • T
      jbd2: fix race when writing superblock · 91544201
      由 Theodore Ts'o 提交于 
      [ Upstream commit 538bcaa6261b77e71d37f5596c33127c1a3ec3f7 ]

The jbd2 superblock is lockless now, so there is probably a race
condition between writing it so disk and modifing contents of it, which
may lead to checksum error. The following race is the one case that we
have captured.

jbd2                                fsstress
jbd2_journal_commit_transaction
 jbd2_journal_update_sb_log_tail
  jbd2_write_superblock
   jbd2_superblock_csum_set         jbd2_journal_revoke
                                     jbd2_journal_set_features(revork)
                                     modify superblock
   submit_bh(checksum incorrect)

Fix this by locking the buffer head before modifing it.  We always
write the jbd2 superblock after we modify it, so this just means
calling the lock_buffer() a little earlier.

This checksum corruption problem can be reproduced by xfstests
generic/475.
Reported-by: Nzhangyi (F) <yi.zhang@huawei.com>
Suggested-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      91544201
  17. 21 5月, 2018 2 次提交
  19. 20 2月, 2018 1 次提交
  21. 19 2月, 2018 1 次提交
    • T
      ext4: pass -ESHUTDOWN code to jbd2 layer · fb7c0244
      由 Theodore Ts'o 提交于 
      Previously the jbd2 layer assumed that a file system check would be
required after a journal abort.  In the case of the deliberate file
system shutdown, this should not be necessary.  Allow the jbd2 layer
to distinguish between these two cases by using the ESHUTDOWN errno.

Also add proper locking to __journal_abort_soft().
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
      fb7c0244
  23. 18 12月, 2017 1 次提交
    • T
      ext4: fix up remaining files with SPDX cleanups · f5166768
      由 Theodore Ts'o 提交于 
      A number of ext4 source files were skipped due because their copyright
permission statements didn't match the expected text used by the
automated conversion utilities.  I've added SPDX tags for the rest.

While looking at some of these files, I've noticed that we have quite
a bit of variation on the licenses that were used --- in particular
some of the Red Hat licenses on the jbd2 files use a GPL2+ license,
and we have some files that have a LGPL-2.1 license (which was quite
surprising).

I've not attempted to do any license changes.  Even if it is perfectly
legal to relicense to GPL 2.0-only for consistency's sake, that should
be done with ext4 developer community discussion.
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      f5166768
  25. 03 11月, 2017 1 次提交
    • J
      ext4: Support for synchronous DAX faults · b8a6176c
      由 Jan Kara 提交于 
      We return IOMAP_F_DIRTY flag from ext4_iomap_begin() when asked to
prepare blocks for writing and the inode has some uncommitted metadata
changes. In the fault handler ext4_dax_fault() we then detect this case
(through VM_FAULT_NEEDDSYNC return value) and call helper
dax_finish_sync_fault() to flush metadata changes and insert page table
entry. Note that this will also dirty corresponding radix tree entry
which is what we want - fsync(2) will still provide data integrity
guarantees for applications not using userspace flushing. And
applications using userspace flushing can avoid calling fsync(2) and
thus avoid the performance overhead.
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
      b8a6176c
  27. 19 10月, 2017 1 次提交
  29. 20 6月, 2017 1 次提交
  31. 04 5月, 2017 2 次提交
  33. 30 4月, 2017 2 次提交
    • J
      jbd2: fix dbench4 performance regression for 'nobarrier' mounts · 5052b069
      由 Jan Kara 提交于 
      Commit b685d3d6 "block: treat REQ_FUA and REQ_PREFLUSH as
synchronous" removed REQ_SYNC flag from WRITE_FUA implementation. Since
JBD2 strips REQ_FUA and REQ_FLUSH flags from submitted IO when the
filesystem is mounted with nobarrier mount option, journal superblock
writes ended up being async writes after this patch and that caused
heavy performance regression for dbench4 benchmark with high number of
processes. In my test setup with HP RAID array with non-volatile write
cache and 32 GB ram, dbench4 runs with 8 processes regressed by ~25%.

Fix the problem by making sure journal superblock writes are always
treated as synchronous since they generally block progress of the
journalling machinery and thus the whole filesystem.

Fixes: b685d3d6
CC: stable@vger.kernel.org
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      5052b069
    • J
      jbd2: Fix lockdep splat with generic/270 test · c52c47e4
      由 Jan Kara 提交于 
      I've hit a lockdep splat with generic/270 test complaining that:

3216.fsstress.b/3533 is trying to acquire lock:
 (jbd2_handle){++++..}, at: [<ffffffff813152e0>] jbd2_log_wait_commit+0x0/0x150

but task is already holding lock:
 (jbd2_handle){++++..}, at: [<ffffffff8130bd3b>] start_this_handle+0x35b/0x850

The underlying problem is that jbd2_journal_force_commit_nested()
(called from ext4_should_retry_alloc()) may get called while a
transaction handle is started. In such case it takes care to not wait
for commit of the running transaction (which would deadlock) but only
for a commit of a transaction that is already committing (which is safe
as that doesn't wait for any filesystem locks).

In fact there are also other callers of jbd2_log_wait_commit() that take
care to pass tid of a transaction that is already committing and for
those cases, the lockdep instrumentation is too restrictive and leading
to false positive reports. Fix the problem by calling
jbd2_might_wait_for_commit() from jbd2_log_wait_commit() only if the
transaction isn't already committing.

Fixes: 1eaa566dSigned-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      c52c47e4
  35. 19 4月, 2017 1 次提交
    • P
      mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU · 5f0d5a3a
      由 Paul E. McKenney 提交于 
      A group of Linux kernel hackers reported chasing a bug that resulted
from their assumption that SLAB_DESTROY_BY_RCU provided an existence
guarantee, that is, that no block from such a slab would be reallocated
during an RCU read-side critical section.  Of course, that is not the
case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
slab of blocks.

However, there is a phrase for this, namely "type safety".  This commit
therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order
to avoid future instances of this sort of confusion.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <linux-mm@kvack.org>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
[ paulmck: Add comments mentioning the old name, as requested by Eric
  Dumazet, in order to help people familiar with the old name find
  the new one. ]
Acked-by: NDavid Rientjes <rientjes@google.com>
      5f0d5a3a
  37. 16 3月, 2017 1 次提交
  39. 02 2月, 2017 1 次提交
    • S
      jbd2: fix use after free in kjournald2() · dbfcef6b
      由 Sahitya Tummala 提交于 
      Below is the synchronization issue between unmount and kjournald2
contexts, which results into use after free issue in kjournald2().
Fix this issue by using journal->j_state_lock to synchronize the
wait_event() done in journal_kill_thread() and the wake_up() done
in kjournald2().

TASK 1:
umount cmd:
   |--jbd2_journal_destroy() {
       |--journal_kill_thread() {
            write_lock(&journal->j_state_lock);
	    journal->j_flags |= JBD2_UNMOUNT;
	    ...
	    write_unlock(&journal->j_state_lock);
	    wake_up(&journal->j_wait_commit);	   TASK 2 wakes up here:
	    					   kjournald2() {
						     ...
						     checks JBD2_UNMOUNT flag and calls goto end-loop;
						     ...
						     end_loop:
						       write_unlock(&journal->j_state_lock);
						       journal->j_task = NULL; --> If this thread gets
						       pre-empted here, then TASK 1 wait_event will
						       exit even before this thread is completely
						       done.
	    wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
	    ...
	    write_lock(&journal->j_state_lock);
	    write_unlock(&journal->j_state_lock);
	  }
       |--kfree(journal);
     }
}
						       wake_up(&journal->j_wait_done_commit); --> this step
						       now results into use after free issue.
						   }
Signed-off-by: NSahitya Tummala <stummala@codeaurora.org>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      dbfcef6b
  41. 14 1月, 2017 1 次提交
    • T
      fs/jbd2, locking/mutex, sched/wait: Use mutex_lock_io() for journal->j_checkpoint_mutex · 6fa7aa50
      由 Tejun Heo 提交于 
      When an ext4 fs is bogged down by a lot of metadata IOs (in the
reported case, it was deletion of millions of files, but any massive
amount of journal writes would do), after the journal is filled up,
tasks which try to access the filesystem and aren't currently
performing the journal writes end up waiting in
__jbd2_log_wait_for_space() for journal->j_checkpoint_mutex.

Because those mutex sleeps aren't marked as iowait, this condition can
lead to misleadingly low iowait and /proc/stat:procs_blocked.  While
iowait propagation is far from strict, this condition can be triggered
fairly easily and annotating these sleeps correctly helps initial
diagnosis quite a bit.

Use the new mutex_lock_io() for journal->j_checkpoint_mutex so that
these sleeps are properly marked as iowait.
Reported-by: NMingbo Wan <mingbo@fb.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/1477673892-28940-5-git-send-email-tj@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6fa7aa50
  43. 25 12月, 2016 1 次提交
  45. 01 11月, 2016 1 次提交
  47. 16 9月, 2016 1 次提交
  49. 30 6月, 2016 2 次提交
    • J
      jbd2: track more dependencies on transaction commit · 1eaa566d
      由 Jan Kara 提交于 
      So far we were tracking only dependency on transaction commit due to
starting a new handle (which may require commit to start a new
transaction). Now add tracking also for other cases where we wait for
transaction commit. This way lockdep can catch deadlocks e. g. because we
call jbd2_journal_stop() for a synchronous handle with some locks held
which rank below transaction start.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      1eaa566d
    • J
      jbd2: move lockdep tracking to journal_s · ab714aff
      由 Jan Kara 提交于 
      Currently lockdep map is tracked in each journal handle. To be able to
expand lockdep support to cover also other cases where we depend on
transaction commit and where handle is not available, move lockdep map
into struct journal_s. Since this makes the lockdep map shared for all
handles, we have to use rwsem_acquire_read() for acquisitions now.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      ab714aff
  51. 25 6月, 2016 1 次提交
    • M
      jbd2: get rid of superfluous __GFP_REPEAT · f2db1971
      由 Michal Hocko 提交于 
      jbd2_alloc is explicit about its allocation preferences wrt.  the
allocation size.  Sub page allocations go to the slab allocator and
larger are using either the page allocator or vmalloc.  This is all good
but the logic is unnecessarily complex.

1) as per Ted, the vmalloc fallback is a left-over:

 : jbd2_alloc is only passed in the bh->b_size, which can't be PAGE_SIZE, so
 : the code path that calls vmalloc() should never get called.  When we
 : conveted jbd2_alloc() to suppor sub-page size allocations in commit
 : d2eecb03, there was an assumption that it could be called with a size
 : greater than PAGE_SIZE, but that's certaily not true today.

Moreover vmalloc allocation might even lead to a deadlock because the
callers expect GFP_NOFS context while vmalloc is GFP_KERNEL.

2) __GFP_REPEAT for requests <= PAGE_ALLOC_COSTLY_ORDER is ignored
   since the flag was introduced.

Let's simplify the code flow and use the slab allocator for sub-page
requests and the page allocator for others.  Even though order > 0 is
not currently used as per above leave that option open.

Link: http://lkml.kernel.org/r/1464599699-30131-18-git-send-email-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f2db1971
  53. 08 6月, 2016 3 次提交
  55. 24 4月, 2016 1 次提交
    • J
      jbd2: add support for avoiding data writes during transaction commits · 41617e1a
      由 Jan Kara 提交于 
      Currently when filesystem needs to make sure data is on permanent
storage before committing a transaction it adds inode to transaction's
inode list. During transaction commit, jbd2 writes back all dirty
buffers that have allocated underlying blocks and waits for the IO to
finish. However when doing writeback for delayed allocated data, we
allocate blocks and immediately submit the data. Thus asking jbd2 to
write dirty pages just unnecessarily adds more work to jbd2 possibly
writing back other redirtied blocks.

Add support to jbd2 to allow filesystem to ask jbd2 to only wait for
outstanding data writes before committing a transaction and thus avoid
unnecessary writes.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      41617e1a
  57. 05 4月, 2016 1 次提交
    • K
      mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros · 09cbfeaf
      由 Kirill A. Shutemov 提交于 
      PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      09cbfeaf
  59. 10 3月, 2016 1 次提交
    • O
      jbd2: fix FS corruption possibility in jbd2_journal_destroy() on umount path · c0a2ad9b
      由 OGAWA Hirofumi 提交于 
      On umount path, jbd2_journal_destroy() writes latest transaction ID
(->j_tail_sequence) to be used at next mount.

The bug is that ->j_tail_sequence is not holding latest transaction ID
in some cases. So, at next mount, there is chance to conflict with
remaining (not overwritten yet) transactions.

	mount (id=10)
	write transaction (id=11)
	write transaction (id=12)
	umount (id=10) <= the bug doesn't write latest ID

	mount (id=10)
	write transaction (id=11)
	crash

	mount
	[recovery process]
		transaction (id=11)
		transaction (id=12) <= valid transaction ID, but old commit
                                       must not replay

Like above, this bug become the cause of recovery failure, or FS
corruption.

So why ->j_tail_sequence doesn't point latest ID?

Because if checkpoint transactions was reclaimed by memory pressure
(i.e. bdev_try_to_free_page()), then ->j_tail_sequence is not updated.
(And another case is, __jbd2_journal_clean_checkpoint_list() is called
with empty transaction.)

So in above cases, ->j_tail_sequence is not pointing latest
transaction ID at umount path. Plus, REQ_FLUSH for checkpoint is not
done too.

So, to fix this problem with minimum changes, this patch updates
->j_tail_sequence, and issue REQ_FLUSH.  (With more complex changes,
some optimizations would be possible to avoid unnecessary REQ_FLUSH
for example though.)

BTW,

	journal->j_tail_sequence =
		++journal->j_transaction_sequence;

Increment of ->j_transaction_sequence seems to be unnecessary, but
ext3 does this.
Signed-off-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
      c0a2ad9b
  61. 23 2月, 2016 1 次提交