Commit afc567a4 authored Nov 25, 2017 by Mike Snitzer

dm table: fix regression from improper dm_dev_internal.count refcount_t conversion

Multiple refcounts are needed if the device was already added. The
micro-optimization of setting the refcount to 1 on first added (rather
than fall thru to a common refcount_inc) lost sight of the fact that the
refcount_inc is also needed for the case when the device already exists
and the mode need not be upgraded.

Fixes: 2a0b4682 ("dm: convert dm_dev_internal.count from atomic_t to refcount_t")
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

parent ae64f9bd

drivers/md/dm-table.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -453,14 +453,15 @@ int dm_get_device(struct dm_target ti, const char path, fmode_t mode,

		refcount_set(&dd->count, 1);
		list_add(&dd->list, &t->devices);
		goto out;

		} else if (dd->dm_dev->mode != (mode \| dd->dm_dev->mode)) {
		r = upgrade_mode(dd, mode, t->md);
		if (r)
		return r;
		refcount_inc(&dd->count);
		}

		refcount_inc(&dd->count);
		out:
		*result = dd->dm_dev;
		return 0;
		}

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