On 12/9/21 7:16 PM, Song Liu wrote:
On Wed, Nov 10, 2021 at 10:15 AM Vishal Verma <vverma@xxxxxxxxxxxxxxxx> wrote:Returns EAGAIN in case the raid456 driver would block waiting for situations like: - Reshape operation, - Discard operation. Signed-off-by: Vishal Verma <vverma@xxxxxxxxxxxxxxxx> --- drivers/md/raid5.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 9c1a5877cf9f..fa64ee315241 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -5710,6 +5710,11 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) int d; again: sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0); + /* Bail out if REQ_NOWAIT is set */ + if (bi->bi_opf & REQ_NOWAIT) { + bio_wouldblock_error(bi); + return; + }This is not right. raid5_get_active_stripe() gets refcount on the sh, we cannot simply return here. I think we need the logic after raid5_release_stripe() and before schedule().prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags); @@ -5820,6 +5825,15 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) bi->bi_next = NULL; md_account_bio(mddev, &bi); + /* Bail out if REQ_NOWAIT is set */ + if (bi->bi_opf & REQ_NOWAIT && + conf->reshape_progress != MaxSector && + mddev->reshape_backwards + ? logical_sector < conf->reshape_safe + : logical_sector >= conf->reshape_safe) { + bio_wouldblock_error(bi); + return true; + }This is also problematic, and is the trigger of those error messages. We only want to trigger -EAGAIN when logical_sector is between reshape_progress and reshape_safe. Just to clarify, did you mean doing something like: if (bi->bi_opf & REQ_NOWAIT && + conf->reshape_progress != MaxSector && + (mddev->reshape_backwards + ? (logical_sector > conf->reshape_progress && logical_sector < conf->reshape_safe) + : logical_sector >= conf->reshape_safe)) { + bio_wouldblock_error(bi); + return true; + Please let me know if these make sense. Thanks, Song Makes sense. Thanks for your feedback. I'll incorporate it and test.
