Commit e2342ca8 authored Dec 05, 2016 by NeilBrown Committed by Shaohua Li Dec 05, 2016

md: fix refcount problem on mddev when stopping array.



md_open() gets a counted reference on an mddev using mddev_find().
If it ends up returning an error, it must drop this reference.

There are two error paths where the reference is not dropped.
One only happens if the process is signalled and an awkward time,
which is quite unlikely.
The other was introduced recently in commit af8d8e6f.

Change the code to ensure the drop the reference when returning an error,
and make it harded to re-introduce this sort of bug in the future.

Reported-by: Marc Smith <marc.smith@mcc.edu>
Fixes: af8d8e6f ("md: changes for MD_STILL_CLOSED flag")
Signed-off-by: NeilBrown <neilb@suse.com>
Acked-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

parent 3d7e7e1d

drivers/md/md.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -7112,7 +7112,8 @@ static int md_open(struct block_device *bdev, fmode_t mode)

		if (test_bit(MD_CLOSING, &mddev->flags)) {
		mutex_unlock(&mddev->open_mutex);
		return -ENODEV;
		err = -ENODEV;
		goto out;
		}

		err = 0;
		@@ -7121,6 +7122,8 @@ static int md_open(struct block_device *bdev, fmode_t mode)

		check_disk_change(bdev);
		out:
		if (err)
		mddev_put(mddev);
		return err;
		}

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