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

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[ 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: 10c92fca63 ("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>
This commit is contained in:
Yu Kuai 2023-07-06 16:37:27 +08:00 committed by Greg Kroah-Hartman
parent e970bc3828
commit f9b9c6b0d4
1 changed files with 7 additions and 0 deletions
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7
drivers/md/md-bitmap.c
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@ -2481,6 +2481,10 @@ backlog_store(struct mddev *mddev, const char *buf, size_t len)
if (backlog > COUNTER_MAX) if (backlog > COUNTER_MAX)
return -EINVAL; return -EINVAL;
rv = mddev_lock(mddev);
if (rv)
return rv;
/* /*
* Without write mostly device, it doesn't make sense to set * Without write mostly device, it doesn't make sense to set
* backlog for max_write_behind. * backlog for max_write_behind.
@ -2494,6 +2498,7 @@ backlog_store(struct mddev *mddev, const char *buf, size_t len)
if (!has_write_mostly) { if (!has_write_mostly) {
pr_warn_ratelimited("%s: can't set backlog, no write mostly device available\n", pr_warn_ratelimited("%s: can't set backlog, no write mostly device available\n",
mdname(mddev)); mdname(mddev));
mddev_unlock(mddev);
return -EINVAL; return -EINVAL;
} }
@ -2509,6 +2514,8 @@ backlog_store(struct mddev *mddev, const char *buf, size_t len)
} }
if (old_mwb != backlog) if (old_mwb != backlog)
md_bitmap_update_sb(mddev->bitmap); md_bitmap_update_sb(mddev->bitmap);
mddev_unlock(mddev);
return len; return len;
} }