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[v4,52/53] btrfs: fix reloc root leak with 0 ref reloc roots on recovery

Message ID ff8b458f78b382790ac48a668d141d07d3a61a08.1607019557.git.josef@toxicpanda.com (mailing list archive)
State New, archived
Headers show
Series Cleanup error handling in relocation | expand

Commit Message

Josef Bacik Dec. 3, 2020, 6:22 p.m. UTC 
When recovering a relocation, if we run into a reloc root that has 0
refs we simply add it to the reloc_control->reloc_roots list, and then
clean it up later.  The problem with this is __del_reloc_root() doesn't
do anything if the root isn't in the radix tree, which in this case it
won't be because we never call __add_reloc_root() on the reloc_root.

This exit condition simply isn't correct really.  During normal
operation we can remove ourselves from the rb tree and then we're meant
to clean up later at merge_reloc_roots() time, and this happens
correctly.  During recovery we're depending on free_reloc_roots() to
drop our references, but we're short-circuiting.

Fix this by continuing to check if we're on the list and dropping
ourselves from the reloc_control root list and dropping our reference
appropriately.  Change the corresponding BUG_ON() to an ASSERT() that
does the correct thing if we aren't in the rb tree.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/relocation.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
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Patch

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 38002f47e962..01b7b35be3f3 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -671,9 +671,7 @@  static void __del_reloc_root(struct btrfs_root *root)
 			RB_CLEAR_NODE(&node->rb_node);
 		}
 		spin_unlock(&rc->reloc_root_tree.lock);
-		if (!node)
-			return;
-		BUG_ON((struct btrfs_root *)node->data != root);
+		ASSERT(!node || (struct btrfs_root *)node->data == root);
 	}
 
 	/*