dm thin metadata: fix bug in dm_thin_remove_range()
dm_btree_remove_leaves() only unmaps a contiguous region so we need a
loop, in __remove_range(), to handle ranges that contain multiple
regions.
A new btree function, dm_btree_lookup_next(), is introduced which is
more efficiently able to skip over regions of the thin device which
aren't mapped. __remove_range() uses dm_btree_lookup_next() for each
iteration of __remove_range()'s loop.
Also, improve description of dm_btree_remove_leaves().
Fixes: 6550f075 ("dm thin metadata: add dm_thin_remove_range()")
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 4.1+
diff --git a/drivers/md/persistent-data/dm-btree.h b/drivers/md/persistent-data/dm-btree.h
index 11d8cf7..c74301f 100644
--- a/drivers/md/persistent-data/dm-btree.h
+++ b/drivers/md/persistent-data/dm-btree.h
@@ -110,6 +110,13 @@
uint64_t *keys, void *value_le);
/*
+ * Tries to find the first key where the bottom level key is >= to that
+ * given. Useful for skipping empty sections of the btree.
+ */
+int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, uint64_t *rkey, void *value_le);
+
+/*
* Insertion (or overwrite an existing value). O(ln(n))
*/
int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
@@ -135,9 +142,10 @@
uint64_t *keys, dm_block_t *new_root);
/*
- * Removes values between 'keys' and keys2, where keys2 is keys with the
- * final key replaced with 'end_key'. 'end_key' is the one-past-the-end
- * value. 'keys' may be altered.
+ * Removes a _contiguous_ run of values starting from 'keys' and not
+ * reaching keys2 (where keys2 is keys with the final key replaced with
+ * 'end_key'). 'end_key' is the one-past-the-end value. 'keys' may be
+ * altered.
*/
int dm_btree_remove_leaves(struct dm_btree_info *info, dm_block_t root,
uint64_t *keys, uint64_t end_key,