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Nikos Tsironis ac0a5f701f dm era: commit metadata in postsuspend after worker stops
commit 9ae6e8b1c9 upstream.

During postsuspend dm-era does the following:

1. Archives the current era
2. Commits the metadata, as part of the RPC call for archiving the
   current era
3. Stops the worker

Until the worker stops, it might write to the metadata again. Moreover,
these writes are not flushed to disk immediately, but are cached by the
dm-bufio client, which writes them back asynchronously.

As a result, the committed metadata of a suspended dm-era device might
not be consistent with the in-core metadata.

In some cases, this can result in the corruption of the on-disk
metadata. Suppose the following sequence of events:

1. Load a new table, e.g. a snapshot-origin table, to a device with a
   dm-era table
2. Suspend the device
3. dm-era commits its metadata, but the worker does a few more metadata
   writes until it stops, as part of digesting an archived writeset
4. These writes are cached by the dm-bufio client
5. Load the dm-era table to another device.
6. The new instance of the dm-era target loads the committed, on-disk
   metadata, which don't include the extra writes done by the worker
   after the metadata commit.
7. Resume the new device
8. The new dm-era target instance starts using the metadata
9. Resume the original device
10. The destructor of the old dm-era target instance is called and
    destroys the dm-bufio client, which results in flushing the cached
    writes to disk
11. These writes might overwrite the writes done by the new dm-era
    instance, hence corrupting its metadata.

Fix this by committing the metadata after the worker stops running.

stop_worker uses flush_workqueue to flush the current work. However, the
work item may re-queue itself and flush_workqueue doesn't wait for
re-queued works to finish.

This could result in the worker changing the metadata after they have
been committed, or writing to the metadata concurrently with the commit
in the postsuspend thread.

Use drain_workqueue instead, which waits until the work and all
re-queued works finish.

Fixes: eec40579d8 ("dm: add era target")
Cc: stable@vger.kernel.org # v3.15+
Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-06-29 09:03:20 +02:00
Documentation x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data 2022-06-16 13:30:33 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch arm64: mm: Don't invalidate FROM_DEVICE buffers at start of DMA transfer 2022-06-25 15:18:40 +02:00
block block: Fix handling of offline queues in blk_mq_alloc_request_hctx() 2022-06-22 14:22:02 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: memneq - move into lib/ 2022-06-22 14:22:03 +02:00
drivers dm era: commit metadata in postsuspend after worker stops 2022-06-29 09:03:20 +02:00
fs btrfs: add error messages to all unrecognized mount options 2022-06-29 09:03:19 +02:00
include ata: libata: add qc->flags in ata_qc_complete_template tracepoint 2022-06-29 09:03:20 +02:00
init Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug 2022-06-09 10:23:26 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:23:10 +02:00
kernel bpf: Fix calling global functions from BPF_PROG_TYPE_EXT programs 2022-06-25 15:18:40 +02:00
lib crypto: memneq - move into lib/ 2022-06-22 14:22:03 +02:00
mm init: Initialize noop_backing_dev_info early 2022-06-22 14:22:02 +02:00
net net: openvswitch: fix parsing of nw_proto for IPv6 fragments 2022-06-29 09:03:18 +02:00
samples samples/landlock: Format with clang-format 2022-06-09 10:23:23 +02:00
scripts faddr2line: Fix overlapping text section failures, the sequel 2022-06-22 14:22:02 +02:00
security KEYS: trusted: tpm2: Fix migratable logic 2022-06-14 18:36:25 +02:00
sound ALSA: hda/realtek: Add quirk for Clevo NS50PU 2022-06-29 09:03:18 +02:00
tools selftests/bpf: Add selftest for calling global functions from freplace 2022-06-25 15:18:40 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: avoid NULL pointer dereference in kvm_dirty_ring_push 2022-04-13 20:59:26 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Add new IOMMU development mailing list 2022-06-29 09:03:20 +02:00
Makefile Linux 5.15.50 2022-06-25 15:18:40 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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.

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.