[PATCH 0/5] Preallocate flush bio, sysfs tunable

[David Sterba <dsterba@suse.com>]

This patchset follows the updates in the write_dev_flush function. The flush
bio can be preallocated at the device creation time, so we avoid repeated
alloc/free.

Next, there's a new sysfs tunable to enable forced dev flushes for devices that
do not support the barriers. This helps to test the new code but is not meant
for any non-debugging use.

I've tested lightly with some workloads and toggled the sysfs knob during that,
all fine.

David Sterba (5):
  btrfs: preallocate device flush bio
  btrfs: account as waiting for IO, while waiting fot the flush bio
    completion
  btrfs: move dev stats accounting out of wait_dev_flush
  btrfs: add fs flag to force device flushing
  btrfs: sysfs: export the force_dev_flush flag

 fs/btrfs/ctree.h   |  1 +
 fs/btrfs/disk-io.c | 41 +++++++++++++----------------------------
 fs/btrfs/sysfs.c   | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.c | 12 ++++++++++++
 fs/btrfs/volumes.h |  1 +
 5 files changed, 74 insertions(+), 28 deletions(-)

-- 
2.13.0