Improve the loop driver

Hi Jens,

This patch series fixes two bugs and enables lock context analysis in the loop driver. While I am aware that the merge window is open, I'm posting this patch series anyway such that reviewing of this patch series can start.

This series of patches is a reworked version of a subset of the series "[PATCH v2 00/12] Enable lock context analysis in drivers/block/". In this version Nilay's feedback has been addressed.

Thanks,

Bart.

Bart Van Assche (13):
loop: Fix the code for recursion detection
loop: Reorder checks in loop_validate_file()
loop: Enable context analysis
loop: Assign a unique lockdep key to each lo_mutex instance
loop: Add more __must_hold() annotations
loop: Protect all lo_backing_file accesses with lo->lo_mutex
loop: Fix race conditions in loop_validate_file()
loop: Remove memory barriers
loop: Split loop_change_fd()
loop: Split loop_configure()
loop: Remove the "bool global" function argument
loop: Modify the loop_process_work() calling convention
loop: Add __guarded_by() annotations

 drivers/block/Makefile |   2 +
 drivers/block/loop.c   | 382 ++++++++++++++++++++++++-----------------
 2 files changed, 230 insertions(+), 154 deletions(-)