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audit: Factor out chunk replacement code

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Chunk replacement code is very similar for the cases where we grow or
shrink chunk. Factor the code out into a common helper function.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Jan Kara 2018-11-12 09:54:48 -05:00 committed by Paul Moore
parent 1635e57223
commit d31b326d3c
1 changed files with 40 additions and 46 deletions
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86
kernel/audit_tree.c
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@ -235,6 +235,38 @@ 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)
{
struct audit_tree *owner;
int i, j;
new->key = old->key;
list_splice_init(&old->trees, &new->trees);
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) {
i--;
continue;
}
owner = old->owners[j].owner;
new->owners[i].owner = owner;
new->owners[i].index = old->owners[j].index - j + i;
if (!owner) /* result of earlier fallback */
continue;
get_tree(owner);
list_replace_init(&old->owners[j].list, &new->owners[i].list);
}
/*
* Make sure chunk is fully initialized before making it visible in the
* hash. Pairs with a data dependency barrier in READ_ONCE() in
* audit_tree_lookup().
*/
smp_wmb();
list_replace_rcu(&old->hash, &new->hash);
}
static void untag_chunk(struct node *p)
{
struct audit_chunk *chunk = find_chunk(p);
@ -242,7 +274,6 @@ static void untag_chunk(struct node *p)
struct audit_chunk *new = NULL;
struct audit_tree *owner;
int size = chunk->count - 1;
int i, j;
fsnotify_get_mark(entry);
@ -291,38 +322,16 @@ static void untag_chunk(struct node *p)
chunk->dead = 1;
spin_lock(&hash_lock);
new->key = chunk->key;
list_replace_init(&chunk->trees, &new->trees);
if (owner->root == chunk) {
list_del_init(&owner->same_root);
owner->root = NULL;
}
for (i = j = 0; j <= size; i++, j++) {
struct audit_tree *s;
if (&chunk->owners[j] == p) {
list_del_init(&p->list);
i--;
continue;
}
s = chunk->owners[j].owner;
new->owners[i].owner = s;
new->owners[i].index = chunk->owners[j].index - j + i;
if (!s) /* result of earlier fallback */
continue;
get_tree(s);
list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
}
list_for_each_entry(owner, &new->trees, same_root)
owner->root = new;
list_del_init(&p->list);
/*
* Make sure chunk is fully initialized before making it visible in the
* hash. Pairs with a data dependency barrier in READ_ONCE() in
* audit_tree_lookup().
* This has to go last when updating chunk as once replace_chunk() is
* called, new RCU readers can see the new chunk.
*/
smp_wmb();
list_replace_rcu(&chunk->hash, &new->hash);
replace_chunk(new, chunk, p);
spin_unlock(&hash_lock);
fsnotify_detach_mark(entry);
mutex_unlock(&entry->group->mark_mutex);
@ -399,7 +408,6 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
static int tag_chunk(struct inode *inode, struct audit_tree *tree)
{
struct fsnotify_mark *old_entry, *chunk_entry;
struct audit_tree *owner;
struct audit_chunk *chunk, *old;
struct node *p;
int n;
@ -464,35 +472,21 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
fsnotify_put_mark(old_entry);
return 0;
}
chunk->key = old->key;
list_replace_init(&old->trees, &chunk->trees);
for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
struct audit_tree *s = old->owners[n].owner;
p->owner = s;
p->index = old->owners[n].index;
if (!s) /* result of fallback in untag */
continue;
get_tree(s);
list_replace_init(&old->owners[n].list, &p->list);
}
p = &chunk->owners[chunk->count - 1];
p->index = (chunk->count - 1) | (1U<<31);
p->owner = tree;
get_tree(tree);
list_add(&p->list, &tree->chunks);
list_for_each_entry(owner, &chunk->trees, same_root)
owner->root = chunk;
old->dead = 1;
if (!tree->root) {
tree->root = chunk;
list_add(&tree->same_root, &chunk->trees);
}
/*
* Make sure chunk is fully initialized before making it visible in the
* hash. Pairs with a data dependency barrier in READ_ONCE() in
* audit_tree_lookup().
* This has to go last when updating chunk as once replace_chunk() is
* called, new RCU readers can see the new chunk.
*/
smp_wmb();
list_replace_rcu(&old->hash, &chunk->hash);
replace_chunk(chunk, old, NULL);
spin_unlock(&hash_lock);
fsnotify_detach_mark(old_entry);
mutex_unlock(&audit_tree_group->mark_mutex);