block: loop: fix filesystem corruption in case of aio/dio

Starting from commit e36f620428(block: split bios to max possible length),
block core starts to split bio in the middle of bvec.

Unfortunately loop dio/aio doesn't consider this situation, and
always treat 'iter.iov_offset' as zero. Then filesystem corruption
is observed.

This patch figures out the offset of the base bvevc via
'bio->bi_iter.bi_bvec_done' and fixes the issue by passing the offset
to iov iterator.

Fixes: e36f6204288088f (block: split bios to max possible length)
Cc: Keith Busch <keith.busch@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org (4.5)
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/INSTALL b/INSTALL
index a6e2015..3b9b041 100644
--- a/INSTALL
+++ b/INSTALL
@@ -55,8 +55,9 @@ repository root directory:
 
   $ cd netsniff-ng/
 
-The installation (deinstallation) process done by make is fairly simple:
+The installation (deinstallation) process is fairly simple:
 
+  $ ./configure
   $ make
   # make install