Commit 89876f27 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'for-4.15-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "We have two more fixes for 4.15, both aimed for stable.

  The leak fix is obvious, the second patch fixes a bug revealed by the
  refcount API, when it behaves differently than previous atomic_t and
  reports refs going from 0 to 1 in one case"

* tag 'for-4.15-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix refcount_t usage when deleting btrfs_delayed_nodes
  btrfs: Fix flush bio leak
parents 12e971b6 ec35e48b
......@@ -87,6 +87,7 @@ static struct btrfs_delayed_node *btrfs_get_delayed_node(
spin_lock(&root->inode_lock);
node = radix_tree_lookup(&root->delayed_nodes_tree, ino);
if (node) {
if (btrfs_inode->delayed_node) {
refcount_inc(&node->refs); /* can be accessed */
......@@ -94,9 +95,30 @@ static struct btrfs_delayed_node *btrfs_get_delayed_node(
spin_unlock(&root->inode_lock);
return node;
}
btrfs_inode->delayed_node = node;
/* can be accessed and cached in the inode */
refcount_add(2, &node->refs);
/*
* It's possible that we're racing into the middle of removing
* this node from the radix tree. In this case, the refcount
* was zero and it should never go back to one. Just return
* NULL like it was never in the radix at all; our release
* function is in the process of removing it.
*
* Some implementations of refcount_inc refuse to bump the
* refcount once it has hit zero. If we don't do this dance
* here, refcount_inc() may decide to just WARN_ONCE() instead
* of actually bumping the refcount.
*
* If this node is properly in the radix, we want to bump the
* refcount twice, once for the inode and once for this get
* operation.
*/
if (refcount_inc_not_zero(&node->refs)) {
refcount_inc(&node->refs);
btrfs_inode->delayed_node = node;
} else {
node = NULL;
}
spin_unlock(&root->inode_lock);
return node;
}
......@@ -254,17 +276,18 @@ static void __btrfs_release_delayed_node(
mutex_unlock(&delayed_node->mutex);
if (refcount_dec_and_test(&delayed_node->refs)) {
bool free = false;
struct btrfs_root *root = delayed_node->root;
spin_lock(&root->inode_lock);
if (refcount_read(&delayed_node->refs) == 0) {
radix_tree_delete(&root->delayed_nodes_tree,
delayed_node->inode_id);
free = true;
}
/*
* Once our refcount goes to zero, nobody is allowed to bump it
* back up. We can delete it now.
*/
ASSERT(refcount_read(&delayed_node->refs) == 0);
radix_tree_delete(&root->delayed_nodes_tree,
delayed_node->inode_id);
spin_unlock(&root->inode_lock);
if (free)
kmem_cache_free(delayed_node_cache, delayed_node);
kmem_cache_free(delayed_node_cache, delayed_node);
}
}
......
......@@ -237,7 +237,6 @@ static struct btrfs_device *__alloc_device(void)
kfree(dev);
return ERR_PTR(-ENOMEM);
}
bio_get(dev->flush_bio);
INIT_LIST_HEAD(&dev->dev_list);
INIT_LIST_HEAD(&dev->dev_alloc_list);
......
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