linux-toradex.git/fs/jbd2/checkpoint.c, branch v3.2.17

jbd2: use WRITE_SYNC in journal checkpoint

2011-06-27T16:36:29+00:00

In journal checkpoint, we write the buffer and wait for its finish.
But in cfq, the async queue has a very low priority, and in our test,
if there are too many sync queues and every queue is filled up with
requests, the write request will be delayed for quite a long time and
all the tasks which are waiting for journal space will end with errors like:

INFO: task attr_set:3816 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
attr_set      D ffff880028393480     0  3816      1 0x00000000
 ffff8802073fbae8 0000000000000086 ffff8802140847c8 ffff8800283934e8
 ffff8802073fb9d8 ffffffff8103e456 ffff8802140847b8 ffff8801ed728080
 ffff8801db4bc080 ffff8801ed728450 ffff880028393480 0000000000000002
Call Trace:
 [] ? __dequeue_entity+0x33/0x38
 [] ? need_resched+0x23/0x2d
 [] ? thread_return+0xa2/0xbc
 [] ? jbd2_journal_dirty_metadata+0x116/0x126 [jbd2]
 [] ? jbd2_journal_dirty_metadata+0x116/0x126 [jbd2]
 [] __mutex_lock_common+0x14e/0x1a9
 [] ? brelse+0x13/0x15 [ext4]
 [] __mutex_lock_slowpath+0x19/0x1b
 [] mutex_lock+0x1b/0x32
 [] __jbd2_journal_insert_checkpoint+0xe3/0x20c [jbd2]
 [] start_this_handle+0x438/0x527 [jbd2]
 [] ? autoremove_wake_function+0x0/0x3e
 [] jbd2_journal_start+0xa1/0xcc [jbd2]
 [] ext4_journal_start_sb+0x57/0x81 [ext4]
 [] ext4_xattr_set+0x6c/0xe3 [ext4]
 [] ext4_xattr_user_set+0x42/0x4b [ext4]
 [] generic_setxattr+0x6b/0x76
 [] __vfs_setxattr_noperm+0x47/0xc0
 [] vfs_setxattr+0x7f/0x9a
 [] setxattr+0xb5/0xe8
 [] ? do_filp_open+0x571/0xa6e
 [] sys_fsetxattr+0x6b/0x91
 [] system_call_fastpath+0x16/0x1b

So this patch tries to use WRITE_SYNC in __flush_batch so that the request will
be moved into sync queue and handled by cfq timely. We also use the new plug,
sot that all the WRITE_SYNC requests can be given as a whole when we unplug it.

Signed-off-by: Tao Ma 
Signed-off-by: "Theodore Ts'o" 
Cc: Jan Kara 
Reported-by: Robin Dong

jbd2: Fix oops in jbd2_journal_remove_journal_head()

2011-06-13T19:38:22+00:00

jbd2_journal_remove_journal_head() can oops when trying to access
journal_head returned by bh2jh(). This is caused for example by the
following race:

	TASK1					TASK2
  jbd2_journal_commit_transaction()
    ...
    processing t_forget list
      __jbd2_journal_refile_buffer(jh);
      if (!jh->b_transaction) {
        jbd_unlock_bh_state(bh);
					jbd2_journal_try_to_free_buffers()
					  jbd2_journal_grab_journal_head(bh)
					  jbd_lock_bh_state(bh)
					  __journal_try_to_free_buffer()
					  jbd2_journal_put_journal_head(jh)
        jbd2_journal_remove_journal_head(bh);

jbd2_journal_put_journal_head() in TASK2 sees that b_jcount == 0 and
buffer is not part of any transaction and thus frees journal_head
before TASK1 gets to doing so. Note that even buffer_head can be
released by try_to_free_buffers() after
jbd2_journal_put_journal_head() which adds even larger opportunity for
oops (but I didn't see this happen in reality).

Fix the problem by making transactions hold their own journal_head
reference (in b_jcount). That way we don't have to remove journal_head
explicitely via jbd2_journal_remove_journal_head() and instead just
remove journal_head when b_jcount drops to zero. The result of this is
that [__]jbd2_journal_refile_buffer(),
[__]jbd2_journal_unfile_buffer(), and
__jdb2_journal_remove_checkpoint() can free journal_head which needs
modification of a few callers. Also we have to be careful because once
journal_head is removed, buffer_head might be freed as well. So we
have to get our own buffer_head reference where it matters.

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

Merge branch 'next' into upstream-merge

2010-10-28T03:44:47+00:00

Conflicts:
	fs/ext4/inode.c
	fs/ext4/mballoc.c
	include/trace/events/ext4.h

jbd2: Add sanity check for attempts to start handle during umount

2010-10-28T01:30:04+00:00

An attempt to modify the file system during the call to
jbd2_destroy_journal() can lead to a system lockup.  So add some
checking to make it much more obvious when this happens to and to
determine where the offending code is located.

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

block: remove BLKDEV_IFL_WAIT

2010-09-16T18:52:58+00:00

All the blkdev_issue_* helpers can only sanely be used for synchronous
caller.  To issue cache flushes or barriers asynchronously the caller needs
to set up a bio by itself with a completion callback to move the asynchronous
state machine ahead.  So drop the BLKDEV_IFL_WAIT flag that is always
specified when calling blkdev_issue_* and also remove the now unused flags
argument to blkdev_issue_flush and blkdev_issue_zeroout.  For
blkdev_issue_discard we need to keep it for the secure discard flag, which
gains a more descriptive name and loses the bitops vs flag confusion.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

remove SWRITE* I/O types

2010-08-18T05:09:01+00:00

These flags aren't real I/O types, but tell ll_rw_block to always
lock the buffer instead of giving up on a failed trylock.

Instead add a new write_dirty_buffer helper that implements this semantic
and use it from the existing SWRITE* callers.  Note that the ll_rw_block
code had a bug where it didn't promote WRITE_SYNC_PLUG properly, which
this patch fixes.

In the ufs code clean up the helper that used to call ll_rw_block
to mirror sync_dirty_buffer, which is the function it implements for
compound buffers.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

jbd2: Change j_state_lock to be a rwlock_t

2010-08-04T01:35:12+00:00

Lockstat reports have shown that j_state_lock is a major source of
lock contention, especially on systems with more than 4 CPU cores.  So
change it to be a read/write spinlock.

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

jbd2: Use atomic variables to avoid taking t_handle_lock in jbd2_journal_stop

2010-08-02T12:43:25+00:00

By using an atomic_t for t_updates and t_outstanding credits, this
should allow us to not need to take transaction t_handle_lock in
jbd2_journal_stop().

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

blkdev: generalize flags for blkdev_issue_fn functions

2010-04-28T17:47:36+00:00

The patch just convert all blkdev_issue_xxx function to common
set of flags. Wait/allocation semantics preserved.

Signed-off-by: Dmitry Monakhov 
Signed-off-by: Jens Axboe

ext4: Add new tracepoint for jbd2_cleanup_journal_tail

2009-12-23T12:45:44+00:00

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