696b50bbf6
[ Upstream commit 6a5cb53aaa4ef515ddeffa04ce18b771121127b4 ] We have a test case as follow: mdadm -CR /dev/md1 -l 1 -n 4 /dev/sd[a-d] \ --assume-clean --bitmap=internal mdadm -S /dev/md1 mdadm -A /dev/md1 /dev/sd[b-c] --run --force mdadm --zero /dev/sda mdadm /dev/md1 -a /dev/sda echo offline > /sys/block/sdc/device/state echo offline > /sys/block/sdb/device/state sleep 5 mdadm -S /dev/md1 echo running > /sys/block/sdb/device/state echo running > /sys/block/sdc/device/state mdadm -A /dev/md1 /dev/sd[a-c] --run --force When we readd /dev/sda to the array, it started to do recovery. After offline the other two disks in md1, the recovery have been interrupted and superblock update info cannot be written to the offline disks. While the spare disk (/dev/sda) can continue to update superblock info. After stopping the array and assemble it, we found the array run fail, with the follow kernel message: [ 172.986064] md: kicking non-fresh sdb from array! [ 173.004210] md: kicking non-fresh sdc from array! [ 173.022383] md/raid1:md1: active with 0 out of 4 mirrors [ 173.022406] md1: failed to create bitmap (-5) [ 173.023466] md: md1 stopped. Since both sdb and sdc have the value of 'sb->events' smaller than that in sda, they have been kicked from the array. However, the only remained disk sda is in 'spare' state before stop and it cannot be added to conf->mirrors[] array. In the end, raid array assemble and run fail. In fact, we can use the older disk sdb or sdc to assemble the array. That means we should not choose the 'spare' disk as the fresh disk in analyze_sbs(). To fix the problem, we do not compare superblock events when it is a spare disk, as same as validate_super. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.