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Filename Latest commit message Latest commit date
Ming-Hung Tsai e231d03907 dm array: fix cursor index when skipping across block boundaries
[ Upstream commit 0bb1968da2737ba68fd63857d1af2b301a18d3bf ]

dm_array_cursor_skip() seeks to the target position by loading array
blocks iteratively until the specified number of entries to skip is
reached. When seeking across block boundaries, it uses
dm_array_cursor_next() to step into the next block.
dm_array_cursor_skip() must first move the cursor index to the end
of the current block; otherwise, the cursor position could incorrectly
remain in the same block, causing the actual number of skipped entries
to be much smaller than expected.

This bug affects cache resizing in v2 metadata and could lead to data
loss if the fast device is shrunk during the first-time resume. For
example:

1. create a cache metadata consists of 32768 blocks, with a dirty block
   assigned to the second bitmap block. cache_restore v1.0 is required.

cat <<EOF >> cmeta.xml
<superblock uuid="" block_size="64" nr_cache_blocks="32768" \
policy="smq" hint_width="4">
  <mappings>
    <mapping cache_block="32767" origin_block="0" dirty="true"/>
  </mappings>
</superblock>
EOF
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2

2. bring up the cache while attempt to discard all the blocks belonging
   to the second bitmap block (block# 32576 to 32767). The last command
   is expected to fail, but it actually succeeds.

dmsetup create cdata --table "0 2084864 linear /dev/sdc 8192"
dmsetup create corig --table "0 65536 linear /dev/sdc 2105344"
dmsetup create cache --table "0 65536 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 64 2 metadata2 writeback smq \
2 migration_threshold 0"

In addition to the reproducer described above, this fix can be
verified using the "array_cursor/skip" tests in dm-unit:
  dm-unit run /pdata/array_cursor/skip/ --kernel-dir <KERNEL_DIR>

Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Fixes: 9b696229aa ("dm persistent data: add cursor skip functions to the cursor APIs")
Reviewed-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-02-01 18:18:44 +01:00
arch ARC: build: Try to guess GCC variant of cross compiler 2025-01-09 13:23:36 +01:00
block blk-iocost: Avoid using clamp() on inuse in __propagate_weights() 2024-12-19 18:05:04 +01:00
certs
crypto crypto: pcrypt - Call crypto layer directly when padata_do_parallel() return -EBUSY 2024-12-14 19:44:23 +01:00
Documentation PCI: Add 'reset_subordinate' to reset hierarchy below bridge 2024-12-14 19:44:54 +01:00
drivers dm array: fix cursor index when skipping across block boundaries 2025-02-01 18:18:44 +01:00
fs jbd2: flush filesystem device before updating tail sequence 2025-02-01 18:18:44 +01:00
include af_packet: fix vlan_get_protocol_dgram() vs MSG_PEEK 2025-01-09 13:23:35 +01:00
init initramfs: avoid filename buffer overrun 2024-12-14 19:44:21 +01:00
ipc ipc: replace costly bailout check in sysvipc_find_ipc() 2024-09-04 13:15:02 +02:00
kernel ftrace: use preempt_enable/disable notrace macros to avoid double fault 2025-01-09 13:23:37 +01:00
lib lib: string_helpers: silence snprintf() output truncation warning 2024-12-14 19:44:39 +01:00
LICENSES
mm mm: vmscan: account for free pages to prevent infinite Loop in throttle_direct_reclaim() 2025-01-09 13:23:37 +01:00
net net/sctp: Prevent autoclose integer overflow in sctp_association_init() 2025-01-09 13:23:37 +01:00
samples samples/bpf: Fix a resource leak 2024-12-14 19:44:50 +01:00
scripts modpost: fix the missed iteration for the max bit in do_input() 2025-01-09 13:23:36 +01:00
security selinux: ignore unknown extended permissions 2025-01-09 13:23:33 +01:00
sound sound: usb: format: don't warn that raw DSD is unsupported 2025-01-09 13:23:36 +01:00
tools perf trace: Avoid garbage when not printing a syscall's arguments 2024-12-14 19:44:32 +01:00
usr
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS iio: stx104: Move to addac subdirectory 2023-08-30 16:27:12 +02:00
Makefile Linux 5.4.289 2025-01-09 13:23:37 +01:00
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.