On 23/09/2024 07:15, Yu Kuai wrote:
This way, BLK_STS_IOERR will always be returned, perhaps what you want
is to return the error code from bio_split()?
Yeah, I would like to return that error code, so maybe I can encode it
in the master_bio directly or pass as an arg to raid_end_bio_io().
That's fine, however, I think the change can introduce problems in some
corner cases, for example there is a rdev with badblocks and a slow rdev
with full copy. Currently raid1_read_request() will split this bio to
read some from fast rdev, and read the badblocks region from slow rdev.
We need a new branch in read_balance() to choose a rdev with full copy.
Sure, I do realize that the mirror'ing personalities need more
sophisticated error handling changes (than what I presented).
However, in raid1_read_request() we do the read_balance() and then the
bio_split() attempt. So what are you suggesting we do for the
bio_split() error? Is it to retry without the bio_split()?
To me bio_split() should not fail. If it does, it is likely ENOMEM or
some other bug being exposed, so I am not sure that retrying with
skipping bio_split() is the right approach (if that is what you are
suggesting).
Thanks,
John
