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

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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: 2a0b4682e0 ("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>
This commit is contained in:
Mike Snitzer 2017-11-25 00:27:26 -05:00
parent ae64f9bd1d
commit afc567a497
1 changed files with 3 additions and 2 deletions
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5
drivers/md/dm-table.c
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@ -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;
}