Re: [PATCH 2/2] dm-raid1: don't fail the mirror for invalid I/O errors

[Keith Busch <kbusch@kernel.org>]

On Tue, Jun 16, 2026 at 05:54:28PM +0000, Dr. David Alan Gilbert wrote:
> OK, for this pair I think would be fair for a Tested-by me as well;
> they certainly resolve the hang and the WARN/BUGs.
> I still see the errors as EIO on my tests, and on the older mirror type

Could you share your reproducer? I'm just using the original recipe you
sent here:

https://lore.kernel.org/linux-block/ai7rnH20IYeSmY8s@gallifrey/

And I'm seeing EINVAL instead EIO.

> get the stuck resync on write, and on the newer mirror I see the write
> apparently succeed (did it really?)

There was a time when ext4 used to fallback to buffered io for writes
but not for reads, but looks like that was fixed since 6.18, so should
be returning error.

I tried testing it with a modification to your original read test, and
it is still failing with EINVAL for me:

  pread of 4096 said: -1 (Invalid argument)
  pwrite of 4096 said: -1 (Invalid argument)

---
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

const char* path="/mnt/tmp/testfile";
static char buf[8192];

int main()
{
  int fd=open(path, O_RDWR|O_DIRECT|O_CLOEXEC);

  errno=0;
  int res3=pread(fd, buf, 4096, 0);
  printf("pread of 4096 said: %d (%m)\n", res3);
  res3=pwrite(fd, buf, 4096, 0);
  printf("pwrite of 4096 said: %d (%m)\n", res3);
}
--