[PATCH 11/14] audit: Drop all unused chunk nodes during deletion

Jan Kara
2018-10-17T10:15:02Z

When deleting chunk from a tree, drop all unused nodes in a chunk
instead of just the one used by the tree. This gets rid of possibly
lingering unused nodes (created due to fallback path in untag_chunk())
and also removes some special cases and will allow us to simplify
locking in untag_chunk().

Signed-off-by: Jan Kara <jack@suse.cz>
---
kernel/audit_tree.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index ca2b6baff7aa..145e8c92dd31 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -277,8 +277,7 @@ static struct audit_chunk *find_chunk(struct node *p)
return container_of(p, struct audit_chunk, owners[0]);
}

-static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old,
- struct node *skip)
+static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old)
{
struct audit_tree *owner;
int i, j;
@@ -288,7 +287,7 @@ static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old,
list_for_each_entry(owner, &new->trees, same_root)
owner->root = new;
for (i = j = 0; j < old->count; i++, j++) {
- if (&old->owners[j] == skip) {
+ if (!old->owners[j].owner) {
i--;
continue;
}
@@ -322,20 +321,28 @@ static void remove_chunk_node(struct audit_chunk *chunk, struct node *p)
put_tree(owner);
}

+static int chunk_count_trees(struct audit_chunk *chunk)
+{
+ int i;
+ int ret = 0;
+
+ for (i = 0; i < chunk->count; i++)
+ if (chunk->owners[i].owner)
+ ret++;
+ return ret;
+}
+
static void untag_chunk(struct node *p)
{
struct audit_chunk *chunk = find_chunk(p);
struct fsnotify_mark *entry = chunk->mark;
struct audit_chunk *new = NULL;
- int size = chunk->count - 1;
+ int size;

remove_chunk_node(chunk, p);
fsnotify_get_mark(entry);
spin_unlock(&hash_lock);

- if (size)
- new = alloc_chunk(size);
-
mutex_lock(&entry->group->mark_mutex);
/*
* mark_mutex protects mark from getting detached and thus also from
@@ -348,6 +355,7 @@ static void untag_chunk(struct node *p)
goto out;
}

+ size = chunk_count_trees(chunk);
if (!size) {
chunk->dead = 1;
spin_lock(&hash_lock);
@@ -360,6 +368,7 @@ static void untag_chunk(struct node *p)
goto out;
}

+ new = alloc_chunk(size);
if (!new)
goto out_mutex;

@@ -375,7 +384,7 @@ static void untag_chunk(struct node *p)
* This has to go last when updating chunk as once replace_chunk() is
* called, new RCU readers can see the new chunk.
*/
- replace_chunk(new, chunk, p);
+ replace_chunk(new, chunk);
spin_unlock(&hash_lock);
fsnotify_detach_mark(entry);
mutex_unlock(&entry->group->mark_mutex);
@@ -520,7 +529,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
* This has to go last when updating chunk as once replace_chunk() is
* called, new RCU readers can see the new chunk.
*/
- replace_chunk(chunk, old, NULL);
+ replace_chunk(chunk, old);
spin_unlock(&hash_lock);
fsnotify_detach_mark(old_entry);
mutex_unlock(&audit_tree_group->mark_mutex);
--
2.16.4