From: Li Nan <linan122@huawei.com>
Factor out a helper to get 'rdev' and 'replacement' from config->mirrors.
Just to make code cleaner and prepare to fix the bug of io loss while
'replacement' replace 'rdev'.
There is no functional change.
Signed-off-by: Li Nan <linan122@huawei.com>
---
drivers/md/raid10.c | 30 +++++++++++++++++++++---------
1 file changed, 21 insertions(+), 9 deletions(-)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 3e6a09aaaba6..eaaf6307ddda 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1346,6 +1346,26 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
}
}
+static void get_rdev_repl_from_mirror(struct raid10_info *mirror,
+ struct md_rdev **prdev,
+ struct md_rdev **prrdev)
+{
+ struct md_rdev *rdev, *rrdev;
+
+ rrdev = rcu_dereference(mirror->replacement);
+ /*
+ * Read replacement first to prevent reading both rdev and
+ * replacement as NULL during replacement replace rdev.
+ */
+ smp_mb();
+ rdev = rcu_dereference(mirror->rdev);
+ if (rdev == rrdev)
+ rrdev = NULL;
+
+ *prrdev = rrdev;
+ *prdev = rdev;
+}
+
static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)
{
int i;
@@ -1489,15 +1509,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
int d = r10_bio->devs[i].devnum;
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;
+ get_rdev_repl_from_mirror(&conf->mirrors[d], &rdev, &rrdev);
if (rdev && (test_bit(Faulty, &rdev->flags)))
rdev = NULL;
if (rrdev && (test_bit(Faulty, &rrdev->flags)))
--
2.39.2On Tue, Jun 27, 2023 at 6:58 PM <linan666@huaweicloud.com> wrote:
>
[...]
>
> +static void get_rdev_repl_from_mirror(struct raid10_info *mirror,
> + struct md_rdev **prdev,
> + struct md_rdev **prrdev)
> +{
> + struct md_rdev *rdev, *rrdev;
> +
> + rrdev = rcu_dereference(mirror->replacement);
> + /*
> + * Read replacement first to prevent reading both rdev and
> + * replacement as NULL during replacement replace rdev.
> + */
> + smp_mb();
> + rdev = rcu_dereference(mirror->rdev);
> + if (rdev == rrdev)
> + rrdev = NULL;
> +
> + *prrdev = rrdev;
> + *prdev = rdev;
I don't think the reduction in duplicated code justifies two output arguments.
How about
static struct md_rdev *dereference_rdev_and_rrdev(struct raid10_info *mirror,
struct md_rdev **prrdev)
{
...
*prrdev = xxx;
return rdev;
}
So we only have one argument for output.
Also, "from_mirror" in the function name doesn't really add more value.
Thanks,
Song
在 2023/7/1 7:53, Song Liu 写道:
> On Tue, Jun 27, 2023 at 6:58 PM <linan666@huaweicloud.com> wrote:
>>
> [...]
>
>>
>> +static void get_rdev_repl_from_mirror(struct raid10_info *mirror,
>> + struct md_rdev **prdev,
>> + struct md_rdev **prrdev)
>> +{
>> + struct md_rdev *rdev, *rrdev;
>> +
>> + rrdev = rcu_dereference(mirror->replacement);
>> + /*
>> + * Read replacement first to prevent reading both rdev and
>> + * replacement as NULL during replacement replace rdev.
>> + */
>> + smp_mb();
>> + rdev = rcu_dereference(mirror->rdev);
>> + if (rdev == rrdev)
>> + rrdev = NULL;
>> +
>> + *prrdev = rrdev;
>> + *prdev = rdev;
>
> I don't think the reduction in duplicated code justifies two output arguments.
>
> How about
>
> static struct md_rdev *dereference_rdev_and_rrdev(struct raid10_info *mirror,
> struct md_rdev **prrdev)
> {
> ...
> *prrdev = xxx;
> return rdev;
> }
>
> So we only have one argument for output.
>
> Also, "from_mirror" in the function name doesn't really add more value.
>
> Thanks,
> Song
> .
I agree. Let me improve this.
--
Thanks,
Nan
Hi,
在 2023/06/28 9:57, linan666@huaweicloud.com 写道:
> From: Li Nan <linan122@huawei.com>
>
> Factor out a helper to get 'rdev' and 'replacement' from config->mirrors.
> Just to make code cleaner and prepare to fix the bug of io loss while
> 'replacement' replace 'rdev'.
>
> There is no functional change.
>
> Signed-off-by: Li Nan <linan122@huawei.com>
> ---
> drivers/md/raid10.c | 30 +++++++++++++++++++++---------
> 1 file changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 3e6a09aaaba6..eaaf6307ddda 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -1346,6 +1346,26 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
> }
> }
>
> +static void get_rdev_repl_from_mirror(struct raid10_info *mirror,
> + struct md_rdev **prdev,
> + struct md_rdev **prrdev)
I don't like this name, but I can live with this for now, related code
will be removed eventually.
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
> +{
> + struct md_rdev *rdev, *rrdev;
> +
> + rrdev = rcu_dereference(mirror->replacement);
> + /*
> + * Read replacement first to prevent reading both rdev and
> + * replacement as NULL during replacement replace rdev.
> + */
> + smp_mb();
> + rdev = rcu_dereference(mirror->rdev);
> + if (rdev == rrdev)
> + rrdev = NULL;
> +
> + *prrdev = rrdev;
> + *prdev = rdev;
> +}
> +
> static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)
> {
> int i;
> @@ -1489,15 +1509,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
> int d = r10_bio->devs[i].devnum;
> 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;
> + get_rdev_repl_from_mirror(&conf->mirrors[d], &rdev, &rrdev);
> if (rdev && (test_bit(Faulty, &rdev->flags)))
> rdev = NULL;
> if (rrdev && (test_bit(Faulty, &rrdev->flags)))
>
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