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authorHeinz Mauelshagen <heinzm@redhat.com>2018-02-02 23:13:19 +0100
committerShaohua Li <sh.li@alibaba-inc.com>2018-02-18 10:11:59 -0800
commit4b6c1060eaa6495aa5b0032e8f2d51dd936b1257 (patch)
tree6060f030df613e4b68d18bc6c150bdfa02077444 /drivers/md
parentb126194cbb799f9980b92a77e58db6ad794c8082 (diff)
md: fix md_write_start() deadlock w/o metadata devices
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 <heinzm@redhat.com> Signed-off-by: Shaohua Li <sh.li@alibaba-inc.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/md.c10
-rw-r--r--drivers/md/md.h2
2 files changed, 12 insertions, 0 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index bcf4ab9ab3df..9b73cf139b80 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.
@@ -8065,6 +8072,7 @@ 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;
@@ -8097,6 +8105,8 @@ 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 {