4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mike Snitzer <[email protected]>

commit 687cf4412a343a63928a5c9d91bdc0f522939d43 upstream.

Otherwise dm_bitset_cursor_begin() return -ENODATA.  Other calls to
dm_bitset_cursor_begin() have similar negative checks.

Fixes inability to create a cache in passthrough mode (even though doing
so makes no sense).

Fixes: 0d963b6e65 ("dm cache metadata: fix metadata2 format's 
blocks_are_clean_separate_dirty")
Cc: [email protected]
Reported-by: David Teigland <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/md/dm-cache-metadata.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -929,6 +929,10 @@ static int blocks_are_clean_separate_dir
        bool dirty_flag;
        *result = true;
 
+       if (from_cblock(cmd->cache_blocks) == 0)
+               /* Nothing to do */
+               return 0;
+
        r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
                                   from_cblock(cmd->cache_blocks), 
&cmd->dirty_cursor);
        if (r) {


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