[PATCH 4.19 25/44] dm cache metadata: verify cache has blocks in blocks_are_clean_separate_dirty()

Greg Kroah-Hartman
2018-12-18T16:42:04Z

From: Mike Snitzer <snitzer@redhat.com>

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: stable@vger.kernel.org
Reported-by: David Teigland <teigland@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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
@@ -930,6 +930,10 @@ 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) {