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Paul Lawrence 0ce3eb37e9 ANDROID: dm-bow: Add dm-bow feature
Based on https://www.redhat.com/archives/dm-devel/2019-March/msg00025.html

Third version of dm-bow. Key changes:

Free list added
Support for block sizes other than 4k
Handles writes during trim phase, and overlapping trims
Integer overflow error
Support trims even if underlying device doesn't
Numerous small bug fixes

bow == backup on write

USE CASE:

dm-bow takes a snapshot of an existing file system before mounting.
The user may, before removing the device, commit the snapshot.
Alternatively the user may remove the device and then run a command
line utility to restore the device to its original state.

dm-bow does not require an external device

dm-bow efficiently uses all the available free space on the file system.

IMPLEMENTATION:

dm-bow can be in one of three states.

In state one, the free blocks on the device are identified by issuing
an FSTRIM to the filesystem.

In state two, any writes cause the overwritten data to be backup up
to the available free space. While in this state, the device can be
restored by unmounting the filesystem, removing the dm-bow device
and running a usermode tool over the underlying device.

In state three, the changes are committed, dm-bow is in pass-through
mode and the drive can no longer be restored.

It is planned to use this driver to enable restoration of a failed
update attempt on Android devices using ext4.

Test: Can boot Android with userdata mounted on this device. Can commit
userdata after SUW has run. Can then reboot, make changes and roll back.

Known issues:

Mutex is held around entire flush operation, including lengthy I/O. Plan
is to convert to state machine with pending queues.

Interaction with block encryption is unknown, especially with respect
to sector 0.

Bug: 119769411
Bug: 129280212
Test: Dogfooded on Wahoo.
      Ran under Cuttlefish, running VtsKernelBowTest &
      VtsKernelCheckpointTest tests against 4.19, 4.14 & 4.9 kernels
Change-Id: Id70988bbd797ebe3e76fc175094388b423c8da8c
Signed-off-by: Paul Lawrence <paullawrence@google.com>
2019-05-03 10:44:54 -07:00
arch ANDROID: cuttlefish_defconfig: Enable CONFIG_INPUT_MOUSEDEV 2019-05-03 10:44:54 -07:00
block block: don't deal with discard limit in blkdev_issue_discard() 2018-10-18 07:23:40 -06:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
Documentation ANDROID: dm-bow: Add dm-bow feature 2019-05-03 10:44:54 -07:00
drivers ANDROID: dm-bow: Add dm-bow feature 2019-05-03 10:44:54 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs ANDROID: cpufreq: Add time_in_state to /proc/uid directories 2019-05-03 10:44:50 -07:00
include ANDROID: cpufreq: times: record fast switch frequency transitions 2019-05-03 10:44:51 -07:00
init Kbuild updates for v4.19 (2nd) 2018-08-25 13:40:38 -07:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel ANDROID: proc: Add /proc/uid directory 2019-05-03 10:44:50 -07:00
lib test_ida: Fix lockdep warning 2018-10-15 16:31:29 -04:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm ANDROID: add extra free kbytes tunable 2019-05-03 10:40:06 -07:00
net ANDROID: net: ipv6: autoconf routes into per-device tables 2019-05-03 10:42:46 -07:00
samples samples: disable CONFIG_SAMPLES for UML 2018-10-11 02:15:46 +09:00
scripts ANDROID: Kbuild, LLVMLinux: allow overriding clang target triple 2019-05-03 10:39:56 -07:00
security ANDROID: security,perf: Allow further restriction of perf_event_open 2019-05-03 10:42:45 -07:00
sound ALSA: hda/realtek - Cannot adjust speaker's volume on Dell XPS 27 7760 2018-10-04 07:50:48 +02:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-20 15:02:51 +02:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: Remove obsolete kvm_unmap_hva notifier backend 2018-09-07 15:06:02 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
build.config.cuttlefish.aarch64 ANDROID: Move from clang r346389b to r349610. 2019-05-03 10:44:48 -07:00
build.config.cuttlefish.x86_64 ANDROID: Move from clang r346389b to r349610. 2019-05-03 10:44:48 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Add an entry for the code of conduct 2018-10-22 07:33:36 +01:00
Makefile ANDROID: Kbuild, LLVMLinux: allow overriding clang target triple 2019-05-03 10:39:56 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.