Verification with bionic-proposed of xfstests results.

No regressions introduced by this bcache patchset.

The comparison between -updates and -proposed is not directly possible
because -proposed introduced failures via other components in I/O path
(e.g., block, ext4).

This is described below, and just to make sure, the -proposed kernel
has been rebuilt with the bcache patchset reverted, and test results
are the same (same failures with/without the patchset; no regression).

It's also been confirmed (below) that tests with a raw block device
(sda) instead of bcache device (thus eliminating the bcache code)
shows the new/introduced failures (ext4/035, generic/553, generic/554).

(the output below does look better on a very wide screen. :-)


proposed kernel: 4.15.0-55.62 (with patchset)
---

xfstests.test.none.log:		Failures: ext4/032 ext4/035 generic/371 ----------- generic/484 generic/491 ----------- generic/537 ----------- ----------- generic/553 generic/554
xfstests.test.writearound.log:	Failures: ext4/032 ext4/035 ----------- generic/451 generic/484 generic/491 ----------- generic/537 ----------- ----------- generic/553 generic/554
xfstests.test.writeback.log:	Failures: -------- ext4/035 ----------- ----------- generic/484 generic/491 ----------- generic/537 ----------- ----------- generic/553 generic/554
xfstests.test.writethrough.log:	Failures: ext4/032 ext4/035 ----------- ----------- generic/484 generic/491 ----------- generic/537 ----------- ----------- generic/553 generic/554

sda-only (no bcache)		Failures: ext4/032 ext4/035 generic/371 ----------- generic/484 generic/491 ----------- ----------- generic/538 ----------- generic/553 generic/554


proposed kernel (4.15.0-56 without patchset)
---

$ uname -rv
4.15.0-56-generic #62+test20190730b1 SMP Tue Jul 30 18:25:01 -03 2019


xfstests.test.none.log:		Failures: ext4/032 ext4/035 generic/371 ----------- generic/484 generic/491 ----------- generic/537 ----------- ----------- generic/553 generic/554
xfstests.test.writearound.log:	Failures: ext4/032 ext4/035 ----------- generic/451 generic/484 generic/491 ----------- generic/537 ----------- generic/547 generic/553 generic/554
xfstests.test.writeback.log:	Failures: -------- ext4/035 ----------- ----------- generic/484 generic/491 ----------- generic/537 ----------- ----------- generic/553 generic/554
xfstests.test.writethrough.log:	Failures: ext4/032 ext4/035 ----------- ----------- generic/484 generic/491 ----------- generic/537 ----------- ----------- generic/553 generic/554


test kernel (4.15.0-55 with patchset)
---

xfstests.test.none.log:		Failures: ext4/032 -------- ----------- ----------- generic/484 generic/491 generic/504 generic/537 ----------- ----------- ----------- -----------
xfstests.test.writearound.log:	Failures: ext4/032 -------- ----------- generic/451 generic/484 generic/491 generic/504 generic/537 ----------- ----------- ----------- ----------- 
xfstests.test.writeback.log:	Failures: -------- -------- ----------- ----------- generic/484 generic/491 generic/504 generic/537 ----------- ----------- ----------- ----------- 
xfstests.test.writethrough.log:	Failures: ext4/032 -------- ----------- ----------- generic/484 generic/491 generic/504 generic/537 ----------- ----------- ----------- ----------- 

orig kernel (4.15.0-55)
---

xfstests.test.none.log:		Failures: ext4/032 -------- ----------- ----------- generic/484 generic/491 generic/504 generic/537 ----------- ----------- ----------- ----------- 
xfstests.test.writearound.log:	Failures: ext4/032 -------- generic/371 generic/451 generic/484 generic/491 generic/504 generic/537 ----------- ----------- ----------- ----------- 
xfstests.test.writeback.log:	Failures: -------- -------- ----------- ----------- generic/484 generic/491 generic/504 generic/537 ----------- ----------- ----------- ----------- 
xfstests.test.writethrough.log:	Failures: ext4/032 -------- ----------- ----------- generic/484 generic/491 generic/504 generic/537 ----------- ----------- ----------- -----------