revert the revert of ext4: make __ext4_get_inode_loc plug

[Colin Ian King]

== SRU Justification Eoan ==

Now that 5.4 contains a fix to the bootup regression due to the lack of entropy at bootable we should apply this fix and also revert the revert of commit "Revert "ext4: make __ext4_get_inode_loc plug"".

== Fix ==

So, to clarify, apply the two upstream 5.4-rc commits:

commit 50ee7529ec4500c88f8664560770a7a1b65db72b
Author: Linus Torvalds <email address hidden>
Date: Sat Sep 28 16:53:52 2019 -0700

    random: try to actively add entropy rather than passively wait for it

commit 02f03c4206c1b2a7451d3b3546f86c9c783eac13
Author: Linus Torvalds <email address hidden>
Date: Sun Sep 29 17:59:23 2019 -0700

    Revert "Revert "ext4: make __ext4_get_inode_loc plug""

I've benchmarked the Eoan kernel with these two patches and found theo
following speed improvements on an i7-3770 CPU @ 3.40GHz with 8GB and a
WDC WD10EZEX-21WN4A HDD (7200RPM, 64MB cache).

git grep of the kernel: 0.14%
building fwts: 0.40%
build stress-ng 0.45%
tar up kernel source: 7.6%
boot time of eoan cloud image: 10.5%

So I think the speed improvements justify the SRU.

== Regression potential ==

minor change to ext4, which has been regression tested, so risk here is small. The entropy change will alter the random number generation, but I believe this does not change the cryptographical security of the random numbers being generated, so think this change is not security risk.

originally the ext4 change caused boot time user space regressions because of the entropy change of this fix, but the random fix addresses this, so I believe this risk is now zero.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-eoan' to 'verification-done-eoan'. If the problem still exists, change the tag 'verification-needed-eoan' to 'verification-failed-eoan'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Colin Ian King (colin-king)]

Verified, seeing same ball-park performance improvements.

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted linux-gcp-5.3 (5.3.0-1008.9~18.04.1) for bionic have finished running.
The following regressions have been reported in tests triggered by the package:

linux-gcp-5.3/unknown (amd64)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/bionic/update_excuses.html#linux-gcp-5.3

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.3.0-22.24

---------------
linux (5.3.0-22.24) eoan; urgency=medium

  * [REGRESSION] md/raid0: cannot assemble multi-zone RAID0 with default_layout
    setting (LP: #1849682)
    - Revert "md/raid0: avoid RAID0 data corruption due to layout confusion."

  * refcount underflow and type confusion in shiftfs (LP: #1850867) // CVE-2019-15793
    - SAUCE: shiftfs: Correct id translation for lower fs operations
    - SAUCE: shiftfs: prevent type confusion
    - SAUCE: shiftfs: Fix refcount underflow in btrfs ioctl handling

  * CVE-2018-12207
    - kvm: x86, powerpc: do not allow clearing largepages debugfs entry
    - SAUCE: KVM: vmx, svm: always run with EFER.NXE=1 when shadow paging is
      active
    - SAUCE: x86: Add ITLB_MULTIHIT bug infrastructure
    - SAUCE: kvm: mmu: ITLB_MULTIHIT mitigation
    - SAUCE: kvm: Add helper function for creating VM worker threads
    - SAUCE: kvm: x86: mmu: Recovery of shattered NX large pages
    - SAUCE: cpu/speculation: Uninline and export CPU mitigations helpers
    - SAUCE: kvm: x86: mmu: Apply global mitigations knob to ITLB_MULTIHIT

  * CVE-2019-11135
    - x86/msr: Add the IA32_TSX_CTRL MSR
    - x86/cpu: Add a helper function x86_read_arch_cap_msr()
    - x86/cpu: Add a "tsx=" cmdline option with TSX disabled by default
    - x86/speculation/taa: Add mitigation for TSX Async Abort
    - x86/speculation/taa: Add sysfs reporting for TSX Async Abort
    - kvm/x86: Export MDS_NO=0 to guests when TSX is enabled
    - x86/tsx: Add "auto" option to the tsx= cmdline parameter
    - x86/speculation/taa: Add documentation for TSX Async Abort
    - x86/tsx: Add config options to set tsx=on|off|auto
    - [Config] Disable TSX by default when possible

  * CVE-2019-0154
    - SAUCE: drm/i915: Lower RM timeout to avoid DSI hard hangs
    - SAUCE: drm/i915/gen8+: Add RC6 CTX corruption WA

  * CVE-2019-0155
    - SAUCE: drm/i915: Rename gen7 cmdparser tables
    - SAUCE: drm/i915: Disable Secure Batches for gen6+
    - SAUCE: drm/i915: Remove Master tables from cmdparser
    - SAUCE: drm/i915: Add support for mandatory cmdparsing
    - SAUCE: drm/i915: Support ro ppgtt mapped cmdparser shadow buffers
    - SAUCE: drm/i915: Allow parsing of unsized batches
    - SAUCE: drm/i915: Add gen9 BCS cmdparsing
    - SAUCE: drm/i915/cmdparser: Use explicit goto for error paths
    - SAUCE: drm/i915/cmdparser: Add support for backward jumps
    - SAUCE: drm/i915/cmdparser: Ignore Length operands during command matching

linux (5.3.0-21.22) eoan; urgency=medium

  * eoan/linux: 5.3.0-21.22 -proposed tracker (LP: #1850486)

  * Fix signing of staging modules in eoan (LP: #1850234)
    - [Packaging] Leave unsigned modules unsigned after adding .gnu_debuglink

linux (5.3.0-20.21) eoan; urgency=medium

  * eoan/linux: 5.3.0-20.21 -proposed tracker (LP: #1849064)

  * eoan: alsa/sof: Enable SOF_HDA link and codec (LP: #1848490)
    - [Config] Enable SOF_HDA link and codec

  * Eoan update: 5.3.7 upstream stable release (LP: #1848750)
    - panic: ensure preemption is disabled during panic()
    - [Config] updateconfigs for USB_RIO500
    - USB: rio500: Remove Rio 500 kernel driver
   ...