| Message ID | 20230522115449.2203939-4-linan666@huaweicloud.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | raid10 bugfix | expand |
Hi, 在 2023/05/22 19:54, linan666@huaweicloud.com 写道: > From: Li Nan <linan122@huawei.com> > > When we remove a disk which has replacement, first set rdev to NULL > and then set replacement to rdev, finally set replacement to NULL (see > raid10_remove_disk()). If io is submitted during the same time, it might > read both rdev and replacement as NULL, and io will not be submitted. > > rdev -> NULL > read rdev > replacement -> NULL > read replacement > > Fix it by reading replacement first and rdev later, meanwhile, use smp_mb() > to prevent memory reordering. Looks good, feel free to add: Reviewed-by: Yu Kuai <yukuai3@huawei.com> > > Fixes: 475b0321a4df ("md/raid10: writes should get directed to replacement as well as original.") > Signed-off-by: Li Nan <linan122@huawei.com> > --- > drivers/md/raid10.c | 22 ++++++++++++++++++---- > 1 file changed, 18 insertions(+), 4 deletions(-) > > diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c > index 70cc87c7ee57..25a5a7b1e95c 100644 > --- a/drivers/md/raid10.c > +++ b/drivers/md/raid10.c > @@ -779,8 +779,16 @@ static struct md_rdev *read_balance(struct r10conf *conf, > disk = r10_bio->devs[slot].devnum; > rdev = rcu_dereference(conf->mirrors[disk].replacement); > if (rdev == NULL || test_bit(Faulty, &rdev->flags) || > - r10_bio->devs[slot].addr + sectors > rdev->recovery_offset) > + r10_bio->devs[slot].addr + sectors > > + rdev->recovery_offset) { > + /* > + * Read replacement first to prevent reading both rdev > + * and replacement as NULL during replacement replace > + * rdev. > + */ > + smp_mb(); > rdev = rcu_dereference(conf->mirrors[disk].rdev); > + } > if (rdev == NULL || > test_bit(Faulty, &rdev->flags)) > continue; > @@ -1479,9 +1487,15 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio, > > for (i = 0; i < conf->copies; i++) { > int d = r10_bio->devs[i].devnum; > - struct md_rdev *rdev = rcu_dereference(conf->mirrors[d].rdev); > - struct md_rdev *rrdev = rcu_dereference( > - conf->mirrors[d].replacement); > + struct md_rdev *rdev, *rrdev; > + > + rrdev = rcu_dereference(conf->mirrors[d].replacement); > + /* > + * Read replacement first to Prevent reading both rdev and > + * replacement as NULL during replacement replace rdev. > + */ > + smp_mb(); > + rdev = rcu_dereference(conf->mirrors[d].rdev); > if (rdev == rrdev) > rrdev = NULL; > if (rdev && (test_bit(Faulty, &rdev->flags))) >
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 70cc87c7ee57..25a5a7b1e95c 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -779,8 +779,16 @@ static struct md_rdev *read_balance(struct r10conf *conf, disk = r10_bio->devs[slot].devnum; rdev = rcu_dereference(conf->mirrors[disk].replacement); if (rdev == NULL || test_bit(Faulty, &rdev->flags) || - r10_bio->devs[slot].addr + sectors > rdev->recovery_offset) + r10_bio->devs[slot].addr + sectors > + rdev->recovery_offset) { + /* + * Read replacement first to prevent reading both rdev + * and replacement as NULL during replacement replace + * rdev. + */ + smp_mb(); rdev = rcu_dereference(conf->mirrors[disk].rdev); + } if (rdev == NULL || test_bit(Faulty, &rdev->flags)) continue; @@ -1479,9 +1487,15 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio, for (i = 0; i < conf->copies; i++) { int d = r10_bio->devs[i].devnum; - struct md_rdev *rdev = rcu_dereference(conf->mirrors[d].rdev); - struct md_rdev *rrdev = rcu_dereference( - conf->mirrors[d].replacement); + struct md_rdev *rdev, *rrdev; + + rrdev = rcu_dereference(conf->mirrors[d].replacement); + /* + * Read replacement first to Prevent reading both rdev and + * replacement as NULL during replacement replace rdev. + */ + smp_mb(); + rdev = rcu_dereference(conf->mirrors[d].rdev); if (rdev == rrdev) rrdev = NULL; if (rdev && (test_bit(Faulty, &rdev->flags)))