Re: [PATCH] md/raid1,raid10: fix IO handle for REQ_NOWAIT
From: zhengqixing
Date: Sat Jun 14 2025 - 02:40:02 EST
Hello Paul,
在 2025/6/13 16:02, Paul Menzel 写道:
> Dear Zheng,
>
>
> Thank you for the patch.
>
> Am 12.06.25 um 15:21 schrieb Zheng Qixing:
>> From: Zheng Qixing <zhengqixing@xxxxxxxxxx>
>>
>> IO with REQ_NOWAIT should not set R1BIO_Uptodate when it fails,
>> and bad blocks should also be cleared when REQ_NOWAIT IO succeeds.
>
> It’d be great if you could add an explanation for the *should*. Why
> should it not be done?
>
> Do you have a reproducer for this?
>
If we set R1BIO_Uptodate when IO with REQ_NOWAIT fails, the request will
return a success.
But actually it should return BLK_STS_IOERR or BLK_STS_AGAIN, right?
>> Fixes: 9f346f7d4ea7 ("md/raid1,raid10: don't handle IO error for
>> REQ_RAHEAD and REQ_NOWAIT")
>> Signed-off-by: Zheng Qixing <zhengqixing@xxxxxxxxxx>
>> ---
>> drivers/md/raid1.c | 11 ++++++-----
>> drivers/md/raid10.c | 9 +++++----
>> 2 files changed, 11 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
>> index 19c5a0ce5a40..a1cddd24b178 100644
>> --- a/drivers/md/raid1.c
>> +++ b/drivers/md/raid1.c
>> @@ -455,13 +455,13 @@ static void raid1_end_write_request(struct bio
>> *bio)
>> struct md_rdev *rdev = conf->mirrors[mirror].rdev;
>> sector_t lo = r1_bio->sector;
>> sector_t hi = r1_bio->sector + r1_bio->sectors;
>> - bool ignore_error = !raid1_should_handle_error(bio) ||
>> - (bio->bi_status && bio_op(bio) == REQ_OP_DISCARD);
>> + bool discard_error = bio->bi_status && bio_op(bio) ==
>> REQ_OP_DISCARD;
>
> Excuse my ignorance. What is the difference between ignore and discard?
REQ_OP_DISCARD is a operation type while REQ_NOWAIT is just a request flag.
These two can be combined together. IO with REQ_NOWAIT can fail early, even
though the storage medium is fine. So, we better handle this type of
error specially.
I hope this clarifies your doubts.
>
>> /*
>> * 'one mirror IO has finished' event handler:
>> */
>> - if (bio->bi_status && !ignore_error) {
>> + if (bio->bi_status && !discard_error &&
>> + raid1_should_handle_error(bio)) {
>> set_bit(WriteErrorSeen, &rdev->flags);
>> if (!test_and_set_bit(WantReplacement, &rdev->flags))
>> set_bit(MD_RECOVERY_NEEDED, &
>> @@ -507,12 +507,13 @@ static void raid1_end_write_request(struct bio
>> *bio)
>> * check this here.
>> */
>> if (test_bit(In_sync, &rdev->flags) &&
>> - !test_bit(Faulty, &rdev->flags))
>> + !test_bit(Faulty, &rdev->flags) &&
>> + (!bio->bi_status || discard_error))
>> set_bit(R1BIO_Uptodate, &r1_bio->state);
>> /* Maybe we can clear some bad blocks. */
>> if (rdev_has_badblock(rdev, r1_bio->sector,
>> r1_bio->sectors) &&
>> - !ignore_error) {
>> + !bio->bi_status) {
>> r1_bio->bios[mirror] = IO_MADE_GOOD;
>> set_bit(R1BIO_MadeGood, &r1_bio->state);
>> }
>> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
>> index b74780af4c22..1848947b0a6d 100644
>> --- a/drivers/md/raid10.c
>> +++ b/drivers/md/raid10.c
>> @@ -458,8 +458,8 @@ static void raid10_end_write_request(struct bio
>> *bio)
>> int slot, repl;
>> struct md_rdev *rdev = NULL;
>> struct bio *to_put = NULL;
>> - bool ignore_error = !raid1_should_handle_error(bio) ||
>> - (bio->bi_status && bio_op(bio) == REQ_OP_DISCARD);
>> + bool discard_error = bio->bi_status && bio_op(bio) ==
>> REQ_OP_DISCARD;
>> + bool ignore_error = !raid1_should_handle_error(bio) ||
>> discard_error;
>> dev = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
>> @@ -522,13 +522,14 @@ static void raid10_end_write_request(struct
>> bio *bio)
>> * check this here.
>> */
>> if (test_bit(In_sync, &rdev->flags) &&
>> - !test_bit(Faulty, &rdev->flags))
>> + !test_bit(Faulty, &rdev->flags) &&
>> + (!bio->bi_status || discard_error))
>> set_bit(R10BIO_Uptodate, &r10_bio->state);
>> /* Maybe we can clear some bad blocks. */
>> if (rdev_has_badblock(rdev, r10_bio->devs[slot].addr,
>> r10_bio->sectors) &&
>> - !ignore_error) {
>> + !bio->bi_status) {
>> bio_put(bio);
>> if (repl)
>> r10_bio->devs[slot].repl_bio = IO_MADE_GOOD;
>
>
> Kind regards,
>
> Paul
Regards,
Zheng
</zhengqixing@xxxxxxxxxx></zhengqixing@xxxxxxxxxx>