From 79a059e47c054608d51abce1297bfce1d1d063be Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Thu, 16 Jun 2022 13:19:33 -0600 Subject: [PATCH] md/raid5: Refactor raid5_make_request loop Break immediately if raid5_get_active_stripe() returns NULL and deindent the rest of the loop. Annotate this check with an unlikely(). This makes the code easier to read and reduces the indentation level. No functional changes intended. Signed-off-by: Logan Gunthorpe Reviewed-by: Christoph Hellwig Reviewed-by: Guoqing Jiang Signed-off-by: Song Liu Signed-off-by: Jens Axboe --- drivers/md/raid5.c | 109 +++++++++++++++++++++++---------------------- 1 file changed, 55 insertions(+), 54 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 61dffe5b2aa69..ee7c1af8dcdb2 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -5902,68 +5902,69 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) sh = raid5_get_active_stripe(conf, new_sector, previous, (bi->bi_opf & REQ_RAHEAD), 0); - if (sh) { - if (unlikely(previous)) { - /* expansion might have moved on while waiting for a - * stripe, so we must do the range check again. - * Expansion could still move past after this - * test, but as we are holding a reference to - * 'sh', we know that if that happens, - * STRIPE_EXPANDING will get set and the expansion - * won't proceed until we finish with the stripe. - */ - int must_retry = 0; - spin_lock_irq(&conf->device_lock); - if (!ahead_of_reshape(mddev, logical_sector, - conf->reshape_progress)) - /* mismatch, need to try again */ - must_retry = 1; - spin_unlock_irq(&conf->device_lock); - if (must_retry) { - raid5_release_stripe(sh); - schedule(); - do_prepare = true; - goto retry; - } - } - if (read_seqcount_retry(&conf->gen_lock, seq)) { - /* Might have got the wrong stripe_head - * by accident - */ - raid5_release_stripe(sh); - goto retry; - } + if (unlikely(!sh)) { + /* cannot get stripe, just give-up */ + bi->bi_status = BLK_STS_IOERR; + break; + } - if (test_bit(STRIPE_EXPANDING, &sh->state) || - !add_stripe_bio(sh, bi, dd_idx, rw, previous)) { - /* Stripe is busy expanding or - * add failed due to overlap. Flush everything - * and wait a while - */ - md_wakeup_thread(mddev->thread); + if (unlikely(previous)) { + /* expansion might have moved on while waiting for a + * stripe, so we must do the range check again. + * Expansion could still move past after this + * test, but as we are holding a reference to + * 'sh', we know that if that happens, + * STRIPE_EXPANDING will get set and the expansion + * won't proceed until we finish with the stripe. + */ + int must_retry = 0; + spin_lock_irq(&conf->device_lock); + if (!ahead_of_reshape(mddev, logical_sector, + conf->reshape_progress)) + /* mismatch, need to try again */ + must_retry = 1; + spin_unlock_irq(&conf->device_lock); + if (must_retry) { raid5_release_stripe(sh); schedule(); do_prepare = true; goto retry; } - if (do_flush) { - set_bit(STRIPE_R5C_PREFLUSH, &sh->state); - /* we only need flush for one stripe */ - do_flush = false; - } + } - set_bit(STRIPE_HANDLE, &sh->state); - clear_bit(STRIPE_DELAYED, &sh->state); - if ((!sh->batch_head || sh == sh->batch_head) && - (bi->bi_opf & REQ_SYNC) && - !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) - atomic_inc(&conf->preread_active_stripes); - release_stripe_plug(mddev, sh); - } else { - /* cannot get stripe for read-ahead, just give-up */ - bi->bi_status = BLK_STS_IOERR; - break; + if (read_seqcount_retry(&conf->gen_lock, seq)) { + /* Might have got the wrong stripe_head by accident */ + raid5_release_stripe(sh); + goto retry; + } + + if (test_bit(STRIPE_EXPANDING, &sh->state) || + !add_stripe_bio(sh, bi, dd_idx, rw, previous)) { + /* + * Stripe is busy expanding or add failed due to + * overlap. Flush everything and wait a while. + */ + md_wakeup_thread(mddev->thread); + raid5_release_stripe(sh); + schedule(); + do_prepare = true; + goto retry; } + + if (do_flush) { + set_bit(STRIPE_R5C_PREFLUSH, &sh->state); + /* we only need flush for one stripe */ + do_flush = false; + } + + set_bit(STRIPE_HANDLE, &sh->state); + clear_bit(STRIPE_DELAYED, &sh->state); + if ((!sh->batch_head || sh == sh->batch_head) && + (bi->bi_opf & REQ_SYNC) && + !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) + atomic_inc(&conf->preread_active_stripes); + + release_stripe_plug(mddev, sh); } finish_wait(&conf->wait_for_overlap, &w); -- 2.39.5