4.14-stable review patch. If anyone has any objections, please let me know.
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From: Heinz Mauelshagen heinzm@redhat.com
[ Upstream commit 4b6c1060eaa6495aa5b0032e8f2d51dd936b1257 ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/md.c | 10 ++++++++++ drivers/md/md.h | 2 ++ 2 files changed, 12 insertions(+)
--- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -779,6 +779,9 @@ void md_super_write(struct mddev *mddev, struct bio *bio; int ff = 0;
+ if (!page) + return; + if (test_bit(Faulty, &rdev->flags)) return;
@@ -5434,6 +5437,7 @@ 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; @@ -5447,6 +5451,9 @@ 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. @@ -8022,6 +8029,7 @@ 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;
@@ -8054,6 +8062,8 @@ bool md_write_start(struct mddev *mddev, 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); --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -462,6 +462,8 @@ 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 {