linux-toradex.git/fs/aio.c, branch v3.18-rc5

percpu_ref: add PERCPU_REF_INIT_* flags

2014-09-24T17:31:50+00:00

With the recent addition of percpu_ref_reinit(), percpu_ref now can be
used as a persistent switch which can be turned on and off repeatedly
where turning off maps to killing the ref and waiting for it to drain;
however, there currently isn't a way to initialize a percpu_ref in its
off (killed and drained) state, which can be inconvenient for certain
persistent switch use cases.

Similarly, percpu_ref_switch_to_atomic/percpu() allow dynamic
selection of operation mode; however, currently a newly initialized
percpu_ref is always in percpu mode making it impossible to avoid the
latency overhead of switching to atomic mode.

This patch adds @flags to percpu_ref_init() and implements the
following flags.

* PERCPU_REF_INIT_ATOMIC	: start ref in atomic mode
* PERCPU_REF_INIT_DEAD		: start ref killed and drained

These flags should be able to serve the above two use cases.

v2: target_core_tpg.c conversion was missing.  Fixed.

Signed-off-by: Tejun Heo 
Reviewed-by: Kent Overstreet 
Cc: Jens Axboe 
Cc: Christoph Hellwig 
Cc: Johannes Weiner

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block into for-3.18

2014-09-24T17:00:21+00:00

This is to receive 0a30288da1ae ("blk-mq, percpu_ref: implement a
kludge for SCSI blk-mq stall during probe") which implements
__percpu_ref_kill_expedited() to work around SCSI blk-mq stall.  The
commit reverted and patches to implement proper fix will be added.

Signed-off-by: Tejun Heo 
Cc: Kent Overstreet 
Cc: Jens Axboe 
Cc: Christoph Hellwig

percpu-refcount: add @gfp to percpu_ref_init()

2014-09-08T00:51:30+00:00

Percpu allocator now supports allocation mask.  Add @gfp to
percpu_ref_init() so that !GFP_KERNEL allocation masks can be used
with percpu_refs too.

This patch doesn't make any functional difference.

v2: blk-mq conversion was missing.  Updated.

Signed-off-by: Tejun Heo 
Cc: Kent Overstreet 
Cc: Benjamin LaHaise 
Cc: Li Zefan 
Cc: Nicholas A. Bellinger 
Cc: Jens Axboe

aio: block exit_aio() until all context requests are completed

2014-09-04T20:54:47+00:00

It seems that exit_aio() also needs to wait for all iocbs to complete (like
io_destroy), but we missed the wait step in current implemention, so fix
it in the same way as we did in io_destroy.

Signed-off-by: Gu Zheng 
Signed-off-by: Benjamin LaHaise 
Cc: stable@vger.kernel.org

aio: add missing smp_rmb() in read_events_ring

2014-09-02T19:20:03+00:00

We ran into a case on ppc64 running mariadb where io_getevents would
return zeroed out I/O events.  After adding instrumentation, it became
clear that there was some missing synchronization between reading the
tail pointer and the events themselves.  This small patch fixes the
problem in testing.

Thanks to Zach for helping to look into this, and suggesting the fix.

Signed-off-by: Jeff Moyer 
Signed-off-by: Benjamin LaHaise 
Cc: stable@vger.kernel.org

aio: fix reqs_available handling

2014-08-24T22:47:27+00:00

As reported by Dan Aloni, commit f8567a3845ac ("aio: fix aio request
leak when events are reaped by userspace") introduces a regression when
user code attempts to perform io_submit() with more events than are
available in the ring buffer.  Reverting that commit would reintroduce a
regression when user space event reaping is used.

Fixing this bug is a bit more involved than the previous attempts to fix
this regression.  Since we do not have a single point at which we can
count events as being reaped by user space and io_getevents(), we have
to track event completion by looking at the number of events left in the
event ring.  So long as there are as many events in the ring buffer as
there have been completion events generate, we cannot call
put_reqs_available().  The code to check for this is now placed in
refill_reqs_available().

A test program from Dan and modified by me for verifying this bug is available
at http://www.kvack.org/~bcrl/20140824-aio_bug.c .

Reported-by: Dan Aloni 
Signed-off-by: Benjamin LaHaise 
Acked-by: Dan Aloni 
Cc: Kent Overstreet 
Cc: Mateusz Guzik 
Cc: Petr Matousek 
Cc: stable@vger.kernel.org      # v3.16 and anything that f8567a3845ac was backported to
Signed-off-by: Linus Torvalds

Merge git://git.kvack.org/~bcrl/aio-next

2014-08-16T14:56:27+00:00

Pull aio updates from Ben LaHaise.

* git://git.kvack.org/~bcrl/aio-next:
  aio: use iovec array rather than the single one
  aio: fix some comments
  aio: use the macro rather than the inline magic number
  aio: remove the needless registration of ring file's private_data
  aio: remove no longer needed preempt_disable()
  aio: kill the misleading rcu read locks in ioctx_add_table() and kill_ioctx()
  aio: change exit_aio() to load mm->ioctx_table once and avoid rcu_read_lock()

Merge branch 'for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

2014-08-04T17:09:27+00:00

Pull percpu updates from Tejun Heo:

 - Major reorganization of percpu header files which I think makes
   things a lot more readable and logical than before.

 - percpu-refcount is updated so that it requires explicit destruction
   and can be reinitialized if necessary.  This was pulled into the
   block tree to replace the custom percpu refcnting implemented in
   blk-mq.

 - In the process, percpu and percpu-refcount got cleaned up a bit

* 'for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (21 commits)
  percpu-refcount: implement percpu_ref_reinit() and percpu_ref_is_zero()
  percpu-refcount: require percpu_ref to be exited explicitly
  percpu-refcount: use unsigned long for pcpu_count pointer
  percpu-refcount: add helpers for ->percpu_count accesses
  percpu-refcount: one bit is enough for REF_STATUS
  percpu-refcount, aio: use percpu_ref_cancel_init() in ioctx_alloc()
  workqueue: stronger test in process_one_work()
  workqueue: clear POOL_DISASSOCIATED in rebind_workers()
  percpu: Use ALIGN macro instead of hand coding alignment calculation
  percpu: invoke __verify_pcpu_ptr() from the generic part of accessors and operations
  percpu: preffity percpu header files
  percpu: use raw_cpu_*() to define __this_cpu_*()
  percpu: reorder macros in percpu header files
  percpu: move {raw|this}_cpu_*() definitions to include/linux/percpu-defs.h
  percpu: move generic {raw|this}_cpu_*_N() definitions to include/asm-generic/percpu.h
  percpu: only allow sized arch overrides for {raw|this}_cpu_*() ops
  percpu: reorganize include/linux/percpu-defs.h
  percpu: move accessors from include/linux/percpu.h to percpu-defs.h
  percpu: include/asm-generic/percpu.h should contain only arch-overridable parts
  percpu: introduce arch_raw_cpu_ptr()
  ...

aio: use iovec array rather than the single one

2014-07-24T14:59:40+00:00

Previously, we only offer a single iovec to handle all the read/write cases, so
the PREADV/PWRITEV request always need to alloc more iovec buffer when copying
user vectors.
If we use a tmp iovec array rather than the single one, some small PREADV/PWRITEV
workloads(vector size small than the tmp buffer) will not need to alloc more
iovec buffer when copying user vectors.

Reviewed-by: Jeff Moyer 
Signed-off-by: Gu Zheng 
Signed-off-by: Benjamin LaHaise

aio: fix some comments

2014-07-24T14:59:40+00:00

The function comments of aio_run_iocb and aio_read_events are out of date, so
fix them here.

Reviewed-by: Jeff Moyer 
Signed-off-by: Gu Zheng 
Signed-off-by: Benjamin LaHaise