4.2.8-ckt2 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: NeilBrown <neilb@xxxxxxxx>
commit 312045eef985b61d74c28047ecd8eca6719d9516 upstream.
md currently doesn't allow a 'sync_action' such as 'reshape' to be set
while MD_RECOVERY_NEEDED is set.
This s a problem, particularly since commit 738a273806ee as that can
cause ->check_shape to call mddev_resume() which sets
MD_RECOVERY_NEEDED. So by the time we come to start 'reshape' it is
very likely that MD_RECOVERY_NEEDED is still set.
Testing for this flag is not really needed and is in any case very
racy as it can be set at any moment - asynchronously. Any race
between setting a sync_action and setting MD_RECOVERY_NEEDED must
already be handled properly in some locked code, probably
md_check_recovery(), so remove the test here.
The test on MD_RECOVERY_RUNNING is also racy in the 'reshape' case
so we should test it again after getting mddev_lock().
As this fixes a race and a regression which can cause 'reshape' to
fail, it is suitable for -stable kernels since 4.1
Reported-by: Xiao Ni <xni@xxxxxxxxxx>
Fixes: 738a273806ee ("md/raid5: fix allocation of 'scribble' array.")
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
drivers/md/md.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 95e7b72..3d49672 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4235,8 +4235,7 @@ action_store(struct mddev *mddev, const char *page, size_t len)
}
mddev_unlock(mddev);
}
- } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
- test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
+ } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
return -EBUSY;
else if (cmd_match(page, "resync"))
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
@@ -4249,8 +4248,12 @@ action_store(struct mddev *mddev, const char *page, size_t len)
return -EINVAL;
err = mddev_lock(mddev);
if (!err) {
- clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
- err = mddev->pers->start_reshape(mddev);
+ if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+ err = -EBUSY;
+ else {
+ clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+ err = mddev->pers->start_reshape(mddev);
+ }
mddev_unlock(mddev);
}
if (err)
--
1.9.1
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