LU-4416 osd-ldiskfs: limit trans size to match reservations

LU-4416 osd-ldiskfs: limit trans size to match reservations

Linux commit 8f7d89f36 (jbd2: transaction reservation support)
shrunk the limit of a transaction size to be
j_max_transaction_buffers / 2 to accomodate the reservations.
This can have a perforamce impact so we limit this change to
3.10+ kernels. The same commit that changed this is the same
one that changed the number of arguments to ext4_journal_start
function so we use that test for this. This patch adjusts the
limit in osd_trans_start to match depending on the kernel
version.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: I10a65474dbaf7b67fe7cd59cc2544759d1e3270d
Reviewed-on: http://review.whamcloud.com/10376
Tested-by: Jenkins
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>