Re: [PATCH RFC 0/3] md/raid1: data corruption with serialization

Hi,

在 2026/2/4 22:58, Xiao Ni 写道:
> A data corruption can happen when using serialization for raid1.
> Serialization is not enabled by default. But it looks like there
> is a data corruption risk if serialization is closed. Because the
> lower driver can't guarantee the sequence which io is written first.
> So it's possible that different member disks will have different
> data for nvme devices. This patch set doesn't open serialization
> by default.

An important idea is that if there are filesystem on top of raid1/10/5, there
is no need to consider overlap bio. The only case for serialization is WriteMostly,
that bio can be returned to user while it's not done for slow disks. And that is
the reason why serialization is for rdev.

We definitely will not enable serialization by default, because there will
be huge performance degradation. And I don't think we'll handle the case user
manage data with raw disk, and write to the same area concurrently. At last, if
there are still problem with WriteMostly case, please rebase and keep serialization
for rdev.

>
> Xiao Ni (3):
>    md: add return value of mddev_create_serial_pool
>    md/raid1: fix data corruption by moving serialization to mddev level
>    md/raid1: fix incorrect sector range in serialization
>
>   drivers/md/md-bitmap.c |  28 +++++--
>   drivers/md/md.c        | 171 ++++++++++++++---------------------------
>   drivers/md/md.h        |  30 ++++----
>   drivers/md/raid1.c     |  47 ++++++-----
>   4 files changed, 115 insertions(+), 161 deletions(-)
>
-- 
Thansk,
Kuai