linux-stable.git/block, branch linux-2.6.38.y

block: always allocate genhd->ev if check_events is implemented

2011-06-03T01:33:46+00:00

commit 75e3f3ee3c64968d42f4843ec49e579f84b5aa0c upstream.

9fd097b149 (block: unexport DISK_EVENT_MEDIA_CHANGE for legacy/fringe
drivers) removed DISK_EVENT_MEDIA_CHANGE from legacy/fringe block
drivers which have inadequate ->check_events().  Combined with earlier
change 7c88a168da (block: don't propagate unlisted DISK_EVENTs to
userland), this enables using ->check_events() for internal processing
while avoiding enabling in-kernel block event polling which can lead
to infinite event loop.

Unfortunately, this made many drivers including floppy without any bit
set in disk->events and ->async_events in which case disk_add_events()
simply skipped allocation of disk->ev, which disables whole event
handling.  As ->check_events() is still used during open processing
for revalidation, this can lead to open failure.

This patch always allocates disk->ev if ->check_events is implemented.
In the long term, it would make sense to simply include the event
structure inline into genhd as it's now used by virtually all block
devices.

Signed-off-by: Tejun Heo 
Reported-by: Ondrej Zary 
Reported-by: Alex Villacis Lasso 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: add proper state guards to __elv_next_request

2011-06-03T01:33:46+00:00

commit 0a58e077eb600d1efd7e54ad9926a75a39d7f8ae upstream.

blk_cleanup_queue() calls elevator_exit() and after this, we can't
touch the elevator without oopsing.  __elv_next_request() must check
for this state because in the refcounted queue model, we can still
call it after blk_cleanup_queue() has been called.

This was reported as causing an oops attributable to scsi.

Signed-off-by: James Bottomley 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: Fix discard topology stacking and reporting

2011-06-03T01:33:44+00:00

commit a934a00a69e940b126b9bdbf83e630ef5fe43523 upstream.

In some cases we would end up stacking discard_zeroes_data incorrectly.
Fix this by enabling the feature by default for stacking drivers and
clearing it for low-level drivers. Incorporating a device that does not
support dzd will then cause the feature to be disabled in the stacking
driver.

Also ensure that the maximum discard value does not overflow when
exported in sysfs and return 0 in the alignment and dzd fields for
devices that don't support discard.

Reported-by: Lukas Czerner 
Signed-off-by: Martin K. Petersen 
Acked-by: Mike Snitzer 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block, blk-sysfs: Fix an err return path in blk_register_queue()

2011-05-02T16:19:32+00:00

commit ed5302d3c25006a9edc7a7fbea97a30483f89ef7 upstream.

We do not call blk_trace_remove_sysfs() in err return path
if kobject_add() fails. This path fixes it.

Signed-off-by: Liu Yuan 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: fix mis-synchronisation in blkdev_issue_zeroout()

2011-03-11T14:36:08+00:00

BZ29402
https://bugzilla.kernel.org/show_bug.cgi?id=29402

We can hit serious mis-synchronization in bio completion path of
blkdev_issue_zeroout() leading to a panic.

The problem is that when we are going to wait_for_completion() in
blkdev_issue_zeroout() we check if the bb.done equals issued (number of
submitted bios). If it does, we can skip the wait_for_completition()
and just out of the function since there is nothing to wait for.
However, there is a ordering problem because bio_batch_end_io() is
calling atomic_inc(&bb->done) before complete(), hence it might seem to
blkdev_issue_zeroout() that all bios has been completed and exit. At
this point when bio_batch_end_io() is going to call complete(bb->wait),
bb and wait does not longer exist since it was allocated on stack in
blkdev_issue_zeroout() ==> panic!

(thread 1)                      (thread 2)
bio_batch_end_io()              blkdev_issue_zeroout()
  if(bb) {                      ...
    if (bb->end_io)             ...
      bb->end_io(bio, err);     ...
    atomic_inc(&bb->done);      ...
    ...                         while (issued != atomic_read(&bb.done))
    ...                         (let issued == bb.done)
    ...                         (do the rest of the function)
    ...                         return ret;
    complete(bb->wait);
    ^^^^^^^^
    panic

We can fix this easily by simplifying bio_batch and completion counting.

Also remove bio_end_io_t *end_io since it is not used.

Signed-off-by: Lukas Czerner 
Reported-by: Eric Whitney 
Tested-by: Eric Whitney 
Reviewed-by: Jeff Moyer 
CC: Dmitry Monakhov 
Signed-off-by: Jens Axboe

block: blk-flush shouldn't call directly into q->request_fn() __blk_run_queue()

2011-03-02T13:48:06+00:00

blk-flush decomposes a flush into sequence of multiple requests.  On
completion of a request, the next one is queued; however, block layer
must not implicitly call into q->request_fn() directly from completion
path.  This makes the queue behave unexpectedly when seen from the
drivers and violates the assumption that q->request_fn() is called
with process context + queue_lock.

This patch makes blk-flush the following two changes to make sure
q->request_fn() is not called directly from request completion path.

- blk_flush_complete_seq_end_io() now asks __blk_run_queue() to always
  use kblockd instead of calling directly into q->request_fn().

- queue_next_fseq() uses ELEVATOR_INSERT_REQUEUE instead of
  ELEVATOR_INSERT_FRONT so that elv_insert() doesn't try to unplug the
  request queue directly.

Reported by Jan in the following threads.

 http://thread.gmane.org/gmane.linux.ide/48778
 http://thread.gmane.org/gmane.linux.ide/48786

stable: applicable to v2.6.37.

Signed-off-by: Tejun Heo 
Reported-by: Jan Beulich 
Cc: "David S. Miller" 
Cc: stable@kernel.org
Signed-off-by: Jens Axboe

block: add @force_kblockd to __blk_run_queue()

2011-03-02T13:48:05+00:00

__blk_run_queue() automatically either calls q->request_fn() directly
or schedules kblockd depending on whether the function is recursed.
blk-flush implementation needs to be able to explicitly choose
kblockd.  Add @force_kblockd.

All the current users are converted to specify %false for the
parameter and this patch doesn't introduce any behavior change.

stable: This is prerequisite for fixing ide oops caused by the new
        blk-flush implementation.

Signed-off-by: Tejun Heo 
Cc: Jan Beulich 
Cc: James Bottomley 
Cc: stable@kernel.org
Signed-off-by: Jens Axboe

block: fix kernel-doc format for blkdev_issue_zeroout

2011-03-01T18:45:24+00:00

Signed-off-by: Ben Hutchings 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

blk-throttle: Do not use kblockd workqueue for throtl work

2011-03-01T18:41:53+00:00

o Dominik Klein reported a system hang issue while doing some blkio
  throttling testing.

  https://lkml.org/lkml/2011/2/24/173

o Some tracing revealed that CFQ was not dispatching any more jobs as
  queue unplug was not happening. And queue unplug was not happening
  because unplug work was not being called as there was one throttling
  work on same cpu which as not finished yet. And throttling work had not
  finished as it was tyring to dispatch a bio to CFQ but all the request
  descriptors were consume to it was put to sleep.

o So basically it is a cyclic dependecny between CFQ unplug work and
  throtl dispatch work. Tejun suggested that use separate workqueue for
  such cases.

o This patch uses a separate workqueue for throttle related work and
  does not rely on kblockd workqueue anymore.

Cc: stable@kernel.org
Reported-by: Dominik Klein 
Signed-off-by: Vivek Goyal 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe

Merge branch 'for-linus' of git://neil.brown.name/md

2011-02-25T19:13:26+00:00

* 'for-linus' of git://neil.brown.name/md:
  md: Fix - again - partition detection when array becomes active
  Fix over-zealous flush_disk when changing device size.
  md: avoid spinlock problem in blk_throtl_exit
  md: correctly handle probe of an 'mdp' device.
  md: don't set_capacity before array is active.
  md: Fix raid1->raid0 takeover