From: Yu Kuai <yukuai3@huawei.com> mainline inclusion from mainline-v6.9-rc1 commit ba58f57fdf98af642c57654599823640ffe8334c category: bugfix bugzilla: 190197 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- There is no functional change for now, make read_balance() cleaner and prepare to fix problems and refactor the handler of sequential IO. Co-developed-by: Paul Luse <paul.e.luse@linux.intel.com> Signed-off-by: Paul Luse <paul.e.luse@linux.intel.com> Signed-off-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Xiao Ni <xni@redhat.com> Signed-off-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20240229095714.926789-11-yukuai1@huaweicloud.com Signed-off-by: Li Nan <linan122@huawei.com> --- drivers/md/raid1.c | 71 ++++++++++++++++++++++++---------------------- 1 file changed, 37 insertions(+), 34 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 78173321d099..f89968d5d0d0 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -701,6 +701,31 @@ static int choose_slow_rdev(struct r1conf *conf, struct r1bio *r1_bio, return bb_disk; } +static bool is_sequential(struct r1conf *conf, int disk, struct r1bio *r1_bio) +{ + /* TODO: address issues with this check and concurrency. */ + return conf->mirrors[disk].next_seq_sect == r1_bio->sector || + conf->mirrors[disk].head_position == r1_bio->sector; +} + +/* + * If buffered sequential IO size exceeds optimal iosize, check if there is idle + * disk. If yes, choose the idle disk. + */ +static bool should_choose_next(struct r1conf *conf, int disk) +{ + struct raid1_info *mirror = &conf->mirrors[disk]; + int opt_iosize; + + if (!test_bit(Nonrot, &mirror->rdev->flags)) + return false; + + opt_iosize = bdev_io_opt(mirror->rdev->bdev) >> 9; + return opt_iosize > 0 && mirror->seq_start != MaxSector && + mirror->next_seq_sect > opt_iosize && + mirror->next_seq_sect - opt_iosize >= mirror->seq_start; +} + /* * This routine returns the disk from which the requested read should * be done. There is a per-array 'next expected sequential IO' sector @@ -764,43 +789,21 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect pending = atomic_read(&rdev->nr_pending); dist = abs(this_sector - conf->mirrors[disk].head_position); /* Don't change to another disk for sequential reads */ - if (conf->mirrors[disk].next_seq_sect == this_sector - || dist == 0) { - int opt_iosize = bdev_io_opt(rdev->bdev) >> 9; - struct raid1_info *mirror = &conf->mirrors[disk]; - - /* - * If buffered sequential IO size exceeds optimal - * iosize, check if there is idle disk. If yes, choose - * the idle disk. read_balance could already choose an - * idle disk before noticing it's a sequential IO in - * this disk. This doesn't matter because this disk - * will idle, next time it will be utilized after the - * first disk has IO size exceeds optimal iosize. In - * this way, iosize of the first disk will be optimal - * iosize at least. iosize of the second disk might be - * small, but not a big deal since when the second disk - * starts IO, the first disk is likely still busy. - */ - if (test_bit(Nonrot, &rdev->flags) && opt_iosize > 0 && - mirror->seq_start != MaxSector && - mirror->next_seq_sect > opt_iosize && - mirror->next_seq_sect - opt_iosize >= - mirror->seq_start) { - /* - * Add 'pending' to avoid choosing this disk if - * there is other idle disk. - */ - pending++; - /* - * If there is no other idle disk, this disk - * will be chosen. - */ - sequential_disk = disk; - } else { + if (is_sequential(conf, disk, r1_bio)) { + if (!should_choose_next(conf, disk)) { best_disk = disk; break; } + /* + * Add 'pending' to avoid choosing this disk if + * there is other idle disk. + */ + pending++; + /* + * If there is no other idle disk, this disk + * will be chosen. + */ + sequential_disk = disk; } if (min_pending > pending) { -- 2.39.2