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Jason Baron 4f61488541 md/raid0: add discard support for the 'original' layout
commit e836007089 upstream.

We've found that using raid0 with the 'original' layout and discard
enabled with different disk sizes (such that at least two zones are
created) can result in data corruption. This is due to the fact that
the discard handling in 'raid0_handle_discard()' assumes the 'alternate'
layout. We've seen this corruption using ext4 but other filesystems are
likely susceptible as well.

More specifically, while multiple zones are necessary to create the
corruption, the corruption may not occur with multiple zones if they
layout in such a way the layout matches what the 'alternate' layout
would have produced. Thus, not all raid0 devices with the 'original'
layout, different size disks and discard enabled will encounter this
corruption.

The 3.14 kernel inadvertently changed the raid0 disk layout for different
size disks. Thus, running a pre-3.14 kernel and post-3.14 kernel on the
same raid0 array could corrupt data. This lead to the creation of the
'original' layout (to match the pre-3.14 layout) and the 'alternate' layout
(to match the post 3.14 layout) in the 5.4 kernel time frame and an option
to tell the kernel which layout to use (since it couldn't be autodetected).
However, when the 'original' layout was added back to 5.4 discard support
for the 'original' layout was not added leading this issue.

I've been able to reliably reproduce the corruption with the following
test case:

1. create raid0 array with different size disks using original layout
2. mkfs
3. mount -o discard
4. create lots of files
5. remove 1/2 the files
6. fstrim -a (or just the mount point for the raid0 array)
7. umount
8. fsck -fn /dev/md0 (spews all sorts of corruptions)

Let's fix this by adding proper discard support to the 'original' layout.
The fix 'maps' the 'original' layout disks to the order in which they are
read/written such that we can compare the disks in the same way that the
current 'alternate' layout does. A 'disk_shift' field is added to
'struct strip_zone'. This could be computed on the fly in
raid0_handle_discard() but by adding this field, we save some computation
in the discard path.

Note we could also potentially fix this by re-ordering the disks in the
zones that follow the first one, and then always read/writing them using
the 'alternate' layout. However, that is seen as a more substantial change,
and we are attempting the least invasive fix at this time to remedy the
corruption.

I've verified the change using the reproducer mentioned above. Typically,
the corruption is seen after less than 3 iterations, while the patch has
run 500+ iterations.

Cc: NeilBrown <neilb@suse.de>
Cc: Song Liu <song@kernel.org>
Fixes: c84a1372df ("md/raid0: avoid RAID0 data corruption due to layout confusion.")
Cc: stable@vger.kernel.org
Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230623180523.1901230-1-jbaron@akamai.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-07-23 13:47:51 +02:00
Documentation arm64: errata: Add detection for TRBE overwrite in FILL mode 2023-07-23 13:47:48 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch MIPS: KVM: Fix NULL pointer dereference 2023-07-23 13:47:48 +02:00
block block/partition: fix signedness issue for Amiga partitions 2023-07-23 13:47:37 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto KEYS: asymmetric: Copy sig and digest in public_key_verify_signature() 2023-06-09 10:32:34 +02:00
drivers md/raid0: add discard support for the 'original' layout 2023-07-23 13:47:51 +02:00
fs jfs: jfs_dmap: Validate db_l2nbperpage while mounting 2023-07-23 13:47:49 +02:00
include net/sched: make psched_mtu() RTNL-less safe 2023-07-23 13:47:45 +02:00
init kbuild: Add CONFIG_PAHOLE_VERSION 2023-02-25 12:06:45 +01:00
io_uring io_uring: add reschedule point to handle_tw_list() 2023-07-23 13:47:38 +02:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel bpf: cpumap: Fix memory leak in cpu_map_update_elem 2023-07-23 13:47:45 +02:00
lib test_firmware: return ENOMEM instead of ENOSPC on failed memory allocation 2023-07-23 13:47:25 +02:00
mm mm/damon/ops-common: atomically test and clear young on ptes and pmds 2023-07-23 13:47:47 +02:00
net net/sched: sch_qfq: account for stab overhead in qfq_enqueue 2023-07-23 13:47:45 +02:00
samples samples/bpf: Fix buffer overflow in tcp_basertt 2023-07-23 13:46:49 +02:00
scripts kbuild: Disable GCOV for *.mod.o 2023-07-23 13:47:17 +02:00
security integrity: Fix possible multiple allocation in integrity_inode_get() 2023-07-23 13:47:33 +02:00
sound ASoC: mediatek: mt8173: Fix snd_soc_component_initialize error path 2023-07-23 13:47:35 +02:00
tools wireguard: netlink: send staged packets when setting initial private key 2023-07-23 13:47:37 +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 illegal stage2 mapping on invalid memory slot 2023-06-28 10:29:42 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.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
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild
Kconfig
MAINTAINERS Remove DECnet support from kernel 2023-06-21 15:59:15 +02:00
Makefile Linux 5.15.120 2023-07-05 18:25:05 +01:00
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