From 2871c69e025e8bc507651d5a9cf81a8a7da9d24b Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Wed, 21 Oct 2015 18:36:49 +0100 Subject: dm btree remove: fix a bug when rebalancing nodes after removal Commit 4c7e309340ff ("dm btree remove: fix bug in redistribute3") wasn't a complete fix for redistribute3(). The redistribute3 function takes 3 btree nodes and shares out the entries evenly between them. If the three nodes in total contained (MAX_ENTRIES * 3) - 1 entries between them then this was erroneously getting rebalanced as (MAX_ENTRIES - 1) on the left and right, and (MAX_ENTRIES + 1) in the center. Fix this issue by being more careful about calculating the target number of entries for the left and right nodes. Unit tested in userspace using this program: https://github.com/jthornber/redistribute3-test/blob/master/redistribute3_t.c Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org diff --git a/drivers/md/persistent-data/dm-btree-remove.c b/drivers/md/persistent-data/dm-btree-remove.c index 421a36c..2e4c4cb 100644 --- a/drivers/md/persistent-data/dm-btree-remove.c +++ b/drivers/md/persistent-data/dm-btree-remove.c @@ -301,11 +301,16 @@ static void redistribute3(struct dm_btree_info *info, struct btree_node *parent, { int s; uint32_t max_entries = le32_to_cpu(left->header.max_entries); - unsigned target = (nr_left + nr_center + nr_right) / 3; - BUG_ON(target > max_entries); + unsigned total = nr_left + nr_center + nr_right; + unsigned target_right = total / 3; + unsigned remainder = (target_right * 3) != total; + unsigned target_left = target_right + remainder; + + BUG_ON(target_left > max_entries); + BUG_ON(target_right > max_entries); if (nr_left < nr_right) { - s = nr_left - target; + s = nr_left - target_left; if (s < 0 && nr_center < -s) { /* not enough in central node */ @@ -316,10 +321,10 @@ static void redistribute3(struct dm_btree_info *info, struct btree_node *parent, } else shift(left, center, s); - shift(center, right, target - nr_right); + shift(center, right, target_right - nr_right); } else { - s = target - nr_right; + s = target_right - nr_right; if (s > 0 && nr_center < s) { /* not enough in central node */ shift(center, right, nr_center); @@ -329,7 +334,7 @@ static void redistribute3(struct dm_btree_info *info, struct btree_node *parent, } else shift(center, right, s); - shift(left, center, nr_left - target); + shift(left, center, nr_left - target_left); } *key_ptr(parent, c->index) = center->keys[0]; -- cgit v0.10.2 From 4dcb8b57df3593dcb20481d9d6cf79d1dc1534be Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 22 Oct 2015 10:56:40 -0400 Subject: dm btree: fix leak of bufio-backed block in btree_split_beneath error path btree_split_beneath()'s error path had an outstanding FIXME that speaks directly to the potential for _not_ cleaning up a previously allocated bufio-backed block. Fix this by releasing the previously allocated bufio block using unlock_block(). Reported-by: Mikulas Patocka Signed-off-by: Mike Snitzer Acked-by: Joe Thornber Cc: stable@vger.kernel.org diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c index b6cec25..0e09aef 100644 --- a/drivers/md/persistent-data/dm-btree.c +++ b/drivers/md/persistent-data/dm-btree.c @@ -523,7 +523,7 @@ static int btree_split_beneath(struct shadow_spine *s, uint64_t key) r = new_block(s->info, &right); if (r < 0) { - /* FIXME: put left */ + unlock_block(s->info, left); return r; } -- cgit v0.10.2 From 3201ac452e84a8a368197d648c9b7011e061804a Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Thu, 22 Oct 2015 18:10:55 +0100 Subject: dm cache: the CLEAN_SHUTDOWN flag was not being set If the CLEAN_SHUTDOWN flag is not set when a cache is loaded then all cache blocks are marked as dirty and a full writeback occurs. __commit_transaction() is responsible for setting/clearing CLEAN_SHUTDOWN (based the flags_mutator that is passed in). Fix this issue, of the cache's on-disk flags being wrong, by making sure __commit_transaction() does not reset the flags after the mutator has altered the flags in preparation for them being serialized to disk. before: sb_flags = mutator(le32_to_cpu(disk_super->flags)); disk_super->flags = cpu_to_le32(sb_flags); disk_super->flags = cpu_to_le32(cmd->flags); after: disk_super->flags = cpu_to_le32(cmd->flags); sb_flags = mutator(le32_to_cpu(disk_super->flags)); disk_super->flags = cpu_to_le32(sb_flags); Reported-by: Bogdan Vasiliev Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c index 20cc36b..0a17d1b 100644 --- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -634,10 +634,10 @@ static int __commit_transaction(struct dm_cache_metadata *cmd, disk_super = dm_block_data(sblock); + disk_super->flags = cpu_to_le32(cmd->flags); if (mutator) update_flags(disk_super, mutator); - disk_super->flags = cpu_to_le32(cmd->flags); disk_super->mapping_root = cpu_to_le64(cmd->root); disk_super->hint_root = cpu_to_le64(cmd->hint_root); disk_super->discard_root = cpu_to_le64(cmd->discard_root); -- cgit v0.10.2