If no metadata devices are configured on raid1/4/5/6/10
(e.g. via dm-raid), md_write_start() unconditionally waits
for superblocks to be written thus deadlocking.
Fix introduces mddev->has_superblocks bool, defines it in md_run()
and checks for it in md_write_start() to conditionally avoid waiting.
Once on it, check for non-existing superblocks in md_super_write().
Link: https://bugzilla.kernel.org/show_bug.cgi?id=198647
Fixes: cc27b0c78c796 ("md: fix deadlock between mddev_suspend() and md_write_start()")
Signed-off-by: Heinz Mauelshagen <[email protected]>
---
drivers/md/md.c | 10 ++++++++++
drivers/md/md.h | 2 ++
2 files changed, 12 insertions(+)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 0081ace39a64..8a7e7034962c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -801,6 +801,9 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
struct bio *bio;
int ff = 0;
+ if (!page)
+ return;
+
if (test_bit(Faulty, &rdev->flags))
return;
@@ -5452,6 +5455,7 @@ int md_run(struct mddev *mddev)
* the only valid external interface is through the md
* device.
*/
+ mddev->has_superblocks = false;
rdev_for_each(rdev, mddev) {
if (test_bit(Faulty, &rdev->flags))
continue;
@@ -5465,6 +5469,9 @@ int md_run(struct mddev *mddev)
set_disk_ro(mddev->gendisk, 1);
}
+ if (rdev->sb_page)
+ mddev->has_superblocks = true;
+
/* perform some consistency tests on the device.
* We don't want the data to overlap the metadata,
* Internal Bitmap issues have been handled elsewhere.
@@ -8049,6 +8056,7 @@ EXPORT_SYMBOL(md_done_sync);
bool md_write_start(struct mddev *mddev, struct bio *bi)
{
int did_change = 0;
+
if (bio_data_dir(bi) != WRITE)
return true;
@@ -8081,6 +8089,8 @@ bool md_write_start(struct mddev *mddev, struct bio *bi)
rcu_read_unlock();
if (did_change)
sysfs_notify_dirent_safe(mddev->sysfs_state);
+ if (!mddev->has_superblocks)
+ return true;
wait_event(mddev->sb_wait,
!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
mddev->suspended);
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 58cd20a5e85e..fbc925cce810 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -468,6 +468,8 @@ struct mddev {
void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
struct md_cluster_info *cluster_info;
unsigned int good_device_nr; /* good device num within cluster raid */
+
+ bool has_superblocks:1;
};
enum recovery_flags {
--
2.14.3
On Fri, Feb 02, 2018 at 11:13:19PM +0100, Heinz Mauelshagen wrote:
> If no metadata devices are configured on raid1/4/5/6/10
> (e.g. via dm-raid), md_write_start() unconditionally waits
> for superblocks to be written thus deadlocking.
>
> Fix introduces mddev->has_superblocks bool, defines it in md_run()
> and checks for it in md_write_start() to conditionally avoid waiting.
>
> Once on it, check for non-existing superblocks in md_super_write().
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=198647
> Fixes: cc27b0c78c796 ("md: fix deadlock between mddev_suspend() and md_write_start()")
Applied, thanks!
> Signed-off-by: Heinz Mauelshagen <[email protected]>
> ---
> drivers/md/md.c | 10 ++++++++++
> drivers/md/md.h | 2 ++
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 0081ace39a64..8a7e7034962c 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -801,6 +801,9 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
> struct bio *bio;
> int ff = 0;
>
> + if (!page)
> + return;
> +
> if (test_bit(Faulty, &rdev->flags))
> return;
>
> @@ -5452,6 +5455,7 @@ int md_run(struct mddev *mddev)
> * the only valid external interface is through the md
> * device.
> */
> + mddev->has_superblocks = false;
> rdev_for_each(rdev, mddev) {
> if (test_bit(Faulty, &rdev->flags))
> continue;
> @@ -5465,6 +5469,9 @@ int md_run(struct mddev *mddev)
> set_disk_ro(mddev->gendisk, 1);
> }
>
> + if (rdev->sb_page)
> + mddev->has_superblocks = true;
> +
> /* perform some consistency tests on the device.
> * We don't want the data to overlap the metadata,
> * Internal Bitmap issues have been handled elsewhere.
> @@ -8049,6 +8056,7 @@ EXPORT_SYMBOL(md_done_sync);
> bool md_write_start(struct mddev *mddev, struct bio *bi)
> {
> int did_change = 0;
> +
> if (bio_data_dir(bi) != WRITE)
> return true;
>
> @@ -8081,6 +8089,8 @@ bool md_write_start(struct mddev *mddev, struct bio *bi)
> rcu_read_unlock();
> if (did_change)
> sysfs_notify_dirent_safe(mddev->sysfs_state);
> + if (!mddev->has_superblocks)
> + return true;
> wait_event(mddev->sb_wait,
> !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
> mddev->suspended);
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 58cd20a5e85e..fbc925cce810 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -468,6 +468,8 @@ struct mddev {
> void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
> struct md_cluster_info *cluster_info;
> unsigned int good_device_nr; /* good device num within cluster raid */
> +
> + bool has_superblocks:1;
> };
>
> enum recovery_flags {
> --
> 2.14.3
>