t_max_wait is added in commit 8e85fb3f to indicate how long we
were waiting for new transaction to start. In commit 6d0bf005,
it is moved to another function named update_t_max_wait to
avoid a build warning. But the wrong thing is that the original
'ts' is initialized in the start of function start_this_handle
and we can calculate t_max_wait in the right way. while with
this change, ts is initialized within the function and t_max_wait
can never be calculated right.

This patch moves the initialization of ts to the original beginning
of start_this_handle and pass it to function update_t_max_wait so
that it can be calculated right and the build warning is avoided also.

Cc: Jan Kara <jack@suse.cz>
Signed-off-by: NTao Ma <boyu.mt@taobao.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: NEric Sandeen <sandeen@redhat.com>

If we somehow wrap, we don't want to keep printing the warning message
over and over again.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

In do_get_write_access() we wait on BH_Unshadow bit for buffer to get
from shadow state. The waking code in journal_commit_transaction() has
a bug because it does not issue a memory barrier after the buffer is
moved from the shadow state and before wake_up_bit() is called. Thus a
waitqueue check can happen before the buffer is actually moved from
the shadow state and waiting process may never be woken. Fix the
problem by issuing proper barrier.
Reported-by: NTao Ma <boyu.mt@taobao.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

If an application program does not make any changes to the indirect
blocks or extent tree, i_datasync_tid will not get updated.  If there
are enough commits (i.e., 2**31) such that tid_geq()'s calculations
wrap, and there isn't a currently active transaction at the time of
the fdatasync() call, this can end up triggering a BUG_ON in
fs/jbd2/commit.c:

	J_ASSERT(journal->j_running_transaction != NULL);

It's pretty rare that this can happen, since it requires the use of
fdatasync() plus *very* frequent and excessive use of fsync().  But
with the right workload, it can.

We fix this by replacing the use of tid_geq() with an equality test,
since there's only one valid transaction id that we is valid for us to
wait until it is commited: namely, the currently running transaction
(if it exists).
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

There is potential memory leak of journal head in function
jbd2_journal_commit_transaction. The problem is that JBD2 will not
reclaim the journal head of commit record if error occurs or journal
is abotred.

I use the following script to reproduce this issue, on a RHEL6
system. I found it very easy to reproduce with async commit enabled.

mount /dev/sdb /mnt -o journal_checksum,journal_async_commit
touch /mnt/xxx
echo offline > /sys/block/sdb/device/state
sync
umount /mnt
rmmod ext4
rmmod jbd2

Removal of the jbd2 module will make slab complaining that
"cache `jbd2_journal_head': can't free all objects".
Signed-off-by: NZhang Huan <zhhuan@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

bdget() should not be called when we hold spinlocks since
it might sleep.
Reviewed-by: NJan Kara <jack@suse.cz>
Signed-off-by: NZhu Yanhai <gaoyang.zyh@taobao.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

'write_op' was still used, even though it was always WRITE_SYNC now.
Add plugging around the cases where it submits IO, and flush them
before we end up waiting for that IO.
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

With the plugging now being explicitly controlled by the
submitter, callers need not pass down unplugging hints
to the block layer. If they want to unplug, it's because they
manually plugged on their own - in which case, they should just
unplug at will.
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

The Patch below removes one to many "n's" in a word..
Signed-off-by: NJustin P. Mattock <justinmattock@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: linux-ext4@vger.kernel.org
Acked-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NJan Kara <jack@suse.cz>

On an SMP ARM system running ext4, I've received a report that the
first J_ASSERT in jbd2_journal_commit_transaction has been triggering:

	J_ASSERT(journal->j_running_transaction != NULL);

While investigating possible causes for this problem, I noticed that
__jbd2_log_start_commit() is getting called with j_state_lock only
read-locked, in spite of the fact that it's possible for it might
j_commit_request.  Fix this by grabbing the necessary information so
we can test to see if we need to start a new transaction before
dropping the read lock, and then calling jbd2_log_start_commit() which
will grab the write lock.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Replace the jbd2_inode structure (which is 48 bytes) with a pointer
and only allocate the jbd2_inode when it is needed --- that is, when
the file system has a journal present and the inode has been opened
for writing.  This allows us to further slim down the ext4_inode_info
structure.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This is a port to jbd2 of a patch which Namhyung Kim <namhyung@gmail.com>
originally made to fs/jbd.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This is a port to jbd2 of a patch which Namhyung Kim <namhyung@gmail.com>
originally made to fs/jbd.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This is a port to jbd2 of a patch which Namhyung Kim <namhyung@gmail.com>
originally made to fs/jbd.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

'buffer_head' should be 'journal_head'

This is a port of a patch which Namhyung Kim <namhyung@gmail.com> made
to fs/jbd to jbd2.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

We had an open-coded version of printk_ratelimited(); use the provided
abstraction to make the code cleaner and easier to understand.

Based on a similar patch for fs/jbd from Namhyung Kim <namhyung@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

In jbd2_journal_init_dev(), we need make sure the journal structure is
fully initialzied before calling jbd2_stats_proc_init().
Reviewed-by: NAndreas Dilger <andreas.dilger@oracle.com>
Signed-off-by: Nyangsheng <sheng.yang@oracle.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

jbd2_slab_create_sem is used as a mutex, so make it one.

[ akpm muttered: We may as well make it local to
jbd2_journal_create_slab() also. ]
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <alpine.LFD.2.00.1010162231480.2496@localhost6.localdomain6>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

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: N"Theodore Ts'o" <tytso@mit.edu>

This fixes a hang seen in jbd2_journal_release_jbd_inode
on a lot of Power 6 systems running with ext4. When we get
in the hung state, all I/O to the disk in question gets blocked
where we stay indefinitely. Looking at the task list, I can see
we are stuck in jbd2_journal_release_jbd_inode waiting on a
wake up. I added some debug code to detect this scenario and
dump additional data if we were stuck in jbd2_journal_release_jbd_inode
for longer than 30 minutes. When it hit, I was able to see that
i_flags was 0, suggesting we missed the wake up.

This patch changes i_flags to be an unsigned long, uses bit operators
to access it, and adds barriers around the accesses. Prior to applying
this patch, we were regularly hitting this hang on numerous systems
in our test environment. After applying the patch, the hangs no longer
occur.
Signed-off-by: NBrian King <brking@linux.vnet.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

"wakup"
Signed-off-by: NAndrea Gelmini <andrea.gelmini@gelma.net>
Signed-off-by: NJan Kara <jack@suse.cz>

Fsync performance for small files achieved by cfq on high-end disks is
lower than what deadline can achieve, due to idling introduced between
the sync write happening in process context and the journal commit.

Moreover, when competing with a sequential reader, a process writing
small files and fsync-ing them is starved.

This patch fixes the two problems by:
- marking journal commits as WRITE_SYNC, so that they get the REQ_NOIDLE
  flag set,
- force all queues that have REQ_NOIDLE requests to be put in the noidle
  tree.

Having the queue associated to the fsync-ing process and the one associated
 to journal commits in the noidle tree allows:
- switching between them without idling,
- fairness vs. competing idling queues, since they will be serviced only
  after the noidle tree expires its slice.
Acked-by: NVivek Goyal <vgoyal@redhat.com>
Reviewed-by: NJeff Moyer <jmoyer@redhat.com>
Tested-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

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: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

Before we start accessing a huge (> 16 TiB) OCFS2 volume, we need to
confirm that its journal supports 64-bit offsets.  In particular, we
need to check the journal's feature bits before recovering the journal.

This is not possible with JBD2 at present, because the journal
superblock (where the feature bits reside) is not loaded from disk until
the journal is recovered.

This patch loads the journal superblock in
jbd2_journal_check_used_features() if it has not already been loaded,
allowing us to check the feature bits before journal recovery.
Signed-off-by: NPatrick LoPresti <lopresti@gmail.com>
Cc: linux-ext4@vger.kernel.org
Acked-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Switch to the WRITE_FLUSH_FUA flag for journal commits and remove the
EOPNOTSUPP detection for barriers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

Currently JBD2 relies blkdev_issue_flush() draining the queue when ASYNC_COMMIT
feature is set. This property is going away so make JBD2 wait for buffers it
needs on its own before submitting the cache flush.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

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: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Instead of abusing a buffer_head flag just add a variant of
sync_dirty_buffer which allows passing the exact type of write
flag required.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Fix the compiler warning:

  fs/jbd2/transaction.c: In function ‘start_this_handle’:
  fs/jbd2/transaction.c:98: warning: unused variable ‘ts’
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This should remove the last exclusive lock from start_this_handle(),
so that we should now be able to start multiple transactions at the
same time on large SMP systems.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

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: N"Theodore Ts'o" <tytso@mit.edu>

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: N"Theodore Ts'o" <tytso@mit.edu>

Saying things like "sync failed" when a device does
not support barriers makes users slightly more worried than
they need to be; rather than talking about sync failures,
let's just state the barrier-based facts.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

__GFP_NOFAIL is going away, so add our own retry loop.  Also add
jbd2__journal_start() and jbd2__journal_restart() which take a gfp
mask, so that file systems can optionally (re)start transaction
handles using GFP_KERNEL.  If they do this, then they need to be
prepared to handle receiving an PTR_ERR(-ENOMEM) error, and be ready
to reflect that error up to userspace.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

OCFS2 uses t_commit trigger to compute and store checksum of the just
committed blocks. When a buffer has b_frozen_data, checksum is computed
for it instead of b_data but this can result in an old checksum being
written to the filesystem in the following scenario:

1) transaction1 is opened
2) handle1 is opened
3) journal_access(handle1, bh)
    - This sets jh->b_transaction to transaction1
4) modify(bh)
5) journal_dirty(handle1, bh)
6) handle1 is closed
7) start committing transaction1, opening transaction2
8) handle2 is opened
9) journal_access(handle2, bh)
    - This copies off b_frozen_data to make it safe for transaction1 to commit.
      jh->b_next_transaction is set to transaction2.
10) jbd2_journal_write_metadata() checksums b_frozen_data
11) the journal correctly writes b_frozen_data to the disk journal
12) handle2 is closed
    - There was no dirty call for the bh on handle2, so it is never queued for
      any more journal operation
13) Checkpointing finally happens, and it just spools the bh via normal buffer
writeback.  This will write b_data, which was never triggered on and thus
contains a wrong (old) checksum.

This patch fixes the problem by calling the trigger at the moment data is
frozen for journal commit - i.e., either when b_frozen_data is created by
do_get_write_access or just before we write a buffer to the log if
b_frozen_data does not exist. We also rename the trigger to t_frozen as
that better describes when it is called.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

No real bugs found, just removed some dead code.

Found by gcc 4.6's new warnings.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

One of the most contended locks in the jbd2 layer is j_state_lock when
running dbench.  This is especially true if using the real-time kernel
with its "sleeping spinlocks" patch that replaces spinlocks with
priority inheriting mutexes --- but it also shows up on large SMP
benchmarks.

Thanks to John Stultz for pointing this out.

Reviewed by Mingming Cao and Jan Kara.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>