From be08a107d9f40b84c736044e1e6b4271730de7df Mon Sep 17 00:00:00 2001
From: Zhao Heming <heming.zhao@suse.com>
Date: Wed, 30 Jun 2021 21:02:57 +0800
Subject: [PATCH] md: md_open returns -EBUSY when entering racing area
stable inclusion
from linux-4.19.191
commit 5db6e4c5c1284cec6720afe27f202a3dca697def
--------------------------------
commit 6a4db2a60306eb65bfb14ccc9fde035b74a4b4e7 upstream.
commit d3374825ce57 ("md: make devices disappear when they are no longer
needed.") introduced protection between mddev creating & removing. The
md_open shouldn't create mddev when all_mddevs list doesn't contain
mddev. With currently code logic, there will be very easy to trigger
soft lockup in non-preempt env.
This patch changes md_open returning from -ERESTARTSYS to -EBUSY, which
will break the infinitely retry when md_open enter racing area.
This patch is partly fix soft lockup issue, full fix needs mddev_find
is split into two functions: mddev_find & mddev_find_or_alloc. And
md_open should call new mddev_find (it only does searching job).
For more detail, please refer with Christoph's "split mddev_find" patch
in later commits.
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
drivers/md/md.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 60682ba9ae55..4045aa610336 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7550,8 +7550,7 @@ static int md_open(struct block_device *bdev, fmode_t mode)
/* Wait until bdev->bd_disk is definitely gone */
if (work_pending(&mddev->del_work))
flush_workqueue(md_misc_wq);
- /* Then retry the open from the top */
- return -ERESTARTSYS;
+ return -EBUSY;
}
BUG_ON(mddev != bdev->bd_disk->private_data);
--
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