ext4: keep uniform naming convention for io & io_end variables

Let's keep uniform naming convention for ext4_submit_io (io)
& ext4_end_io_t (io_end) structures, to avoid any confusion.
No functionality change in this patch.

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20191016073711.4141-2-riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
BUG=b:144741353
TEST=xfstests/smoke, no new failures introduced
SOURCE=UPSTREAM(821ff38d192a42a95fe33b5928ce5ed15cbe8564)

Change-Id: I219fb8c87231e0ee13f44cbcbf42020899a89597
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/lakitu-kernel/+/2113631
Commit-Queue: Vaibhav Rustagi <vaibhavrustagi@google.com>
Commit-Queue: Harshad Shirwadkar <harshads@google.com>
Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Reviewed-by: Roy Yang <royyang@google.com>
1 file changed