kernel_optimize_test/block
Tejun Heo 255bb490c8 block: blk-flush shouldn't call directly into q->request_fn() __blk_run_queue()
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 <tj@kernel.org>
Reported-by: Jan Beulich <JBeulich@novell.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-03-02 08:48:06 -05:00
..
blk-cgroup.c
blk-cgroup.h
blk-core.c
blk-exec.c
blk-flush.c
blk-integrity.c
blk-ioc.c
blk-iopoll.c
blk-lib.c
blk-map.c
blk-merge.c
blk-settings.c
blk-softirq.c
blk-sysfs.c
blk-tag.c
blk-throttle.c
blk-timeout.c
blk.h
bsg.c
cfq-iosched.c
cfq.h
compat_ioctl.c
deadline-iosched.c
elevator.c
genhd.c
ioctl.c
Kconfig
Kconfig.iosched
Makefile
noop-iosched.c
scsi_ioctl.c