Commit 1e7a1421 authored Apr 11, 2018 by Nikolay Borisov Committed by David Sterba May 28, 2018

btrfs: Fix lock release order



Locks should generally be released in the oppposite order they are
acquired. Generally lock acquisiton ordering is used to ensure
deadlocks don't happen. However, as becomes more complicated it's
best to also maintain proper unlock order so as to avoid possible dead
locks. This was found by code inspection and doesn't necessarily lead
to a deadlock scenario.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent b25f0d00

fs/btrfs/extent-tree.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2597,8 +2597,8 @@ static int cleanup_ref_head(struct btrfs_trans_handle *trans,
		delayed_refs->num_heads--;
		rb_erase(&head->href_node, &delayed_refs->href_root);
		RB_CLEAR_NODE(&head->href_node);
		spin_unlock(&delayed_refs->lock);
		spin_unlock(&head->lock);
		spin_unlock(&delayed_refs->lock);
		atomic_dec(&delayed_refs->num_entries);

		trace_run_delayed_ref_head(fs_info, head, 0);

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