Commit 1603f086 authored Jul 06, 2023 by Yu Kuai Committed by Greg Kroah-Hartman Sep 23, 2023

md/md-bitmap: hold 'reconfig_mutex' in backlog_store()



[ Upstream commit 44abfa6a95df425c0660d56043020b67e6d93ab8 ]

Several reasons why 'reconfig_mutex' should be held:

1) rdev_for_each() is not safe to be called without the lock, because
   rdev can be removed concurrently.
2) mddev_destroy_serial_pool() and mddev_create_serial_pool() should not
   be called concurrently.
3) mddev_suspend() from mddev_destroy/create_serial_pool() should be
   protected by the lock.

Fixes: 10c92fca ("md-bitmap: create and destroy wb_info_pool with the change of backlog")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20230706083727.608914-3-yukuai1@huaweicloud.com


Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 630be011

drivers/md/md-bitmap.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -2488,6 +2488,10 @@ backlog_store(struct mddev mddev, const char buf, size_t len)
		if (backlog > COUNTER_MAX)
		return -EINVAL;

		rv = mddev_lock(mddev);
		if (rv)
		return rv;

		/*
		* Without write mostly device, it doesn't make sense to set
		* backlog for max_write_behind.
		@@ -2501,6 +2505,7 @@ backlog_store(struct mddev mddev, const char buf, size_t len)
		if (!has_write_mostly) {
		pr_warn_ratelimited("%s: can't set backlog, no write mostly device available\n",
		mdname(mddev));
		mddev_unlock(mddev);
		return -EINVAL;
		}

		@@ -2518,6 +2523,8 @@ backlog_store(struct mddev mddev, const char buf, size_t len)
		}
		if (old_mwb != backlog)
		md_bitmap_update_sb(mddev->bitmap);

		mddev_unlock(mddev);
		return len;
		}