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Subject[PATCH 4.14 076/193] md: fix deadlock error in recent patch.
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: NeilBrown <neilb@suse.com>

commit d47c8ad261f787af22a220ffcc2d07afba809223 upstream.

A recent patch aimed to cause md_write_start() to fail (rather than
block) when the mddev was suspending, so as to avoid deadlocks.
Unfortunately the test in wait_event() was wrong, and it didn't change
behaviour at all.

We wait_event() must wait until the metadata is written OR the array is
suspending.

Fixes: cc27b0c78c79 ("md: fix deadlock between mddev_suspend() and md_write_start()")
Reported-by: Xiao Ni <xni@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/md.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8039,7 +8039,8 @@ bool md_write_start(struct mddev *mddev,
if (did_change)
sysfs_notify_dirent_safe(mddev->sysfs_state);
wait_event(mddev->sb_wait,
- !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) && !mddev->suspended);
+ !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
+ mddev->suspended);
if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
percpu_ref_put(&mddev->writes_pending);
return false;

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