refcount_t type should be used instead of atomic_t when the variable
is used as a reference counter. This is because the implementation of
refcount_t can prevent overflows and detect possible use-after-free.
Signed-off-by: Yejune Deng <yejune.d...@gmail.com>
---
fs/ceph/mds_client.h | 2 +-
fs/ceph/snap.c | 27 +++++++++++++++------------
fs/ceph/super.h | 2 +-
3 files changed, 17 insertions(+), 14 deletions(-)
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index eaa7c5422116..bf99c5ba47fc 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -351,7 +351,7 @@ struct ceph_pool_perm {
struct ceph_snapid_map {
struct rb_node node;
struct list_head lru;
- atomic_t ref;
+ refcount_t ref;
u64 snap;
dev_t dev;
unsigned long last_used;
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 0728b01d4d43..c0fbbb56b259 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -66,14 +66,15 @@ void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
struct ceph_snap_realm *realm)
{
dout("get_realm %p %d -> %d\n", realm,
- atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
+ refcount_read(&realm->nref), refcount_read(&realm->nref)+1);
/*
* since we _only_ increment realm refs or empty the empty
* list with snap_rwsem held, adjusting the empty list here is
* safe. we do need to protect against concurrent empty list
* additions, however.
*/
- if (atomic_inc_return(&realm->nref) == 1) {
+ refcount_inc(&realm->nref);
+ if (refcount_read(&realm->nref) == 1) {
spin_lock(&mdsc->snap_empty_lock);
list_del_init(&realm->empty_item);
spin_unlock(&mdsc->snap_empty_lock);
@@ -117,7 +118,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
if (!realm)
return ERR_PTR(-ENOMEM);
- atomic_set(&realm->nref, 1); /* for caller */
+ refcount_set(&realm->nref, 1); /* for caller */
realm->ino = ino;
INIT_LIST_HEAD(&realm->children);
INIT_LIST_HEAD(&realm->child_item);
@@ -199,8 +200,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
struct ceph_snap_realm *realm)
{
dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
- atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
- if (atomic_dec_and_test(&realm->nref))
+ refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
+ if (refcount_dec_and_test(&realm->nref))
__destroy_snap_realm(mdsc, realm);
}
@@ -211,8 +212,8 @@ void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
struct ceph_snap_realm *realm)
{
dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
- atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
- if (!atomic_dec_and_test(&realm->nref))
+ refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
+ if (!refcount_dec_and_test(&realm->nref))
return;
if (down_write_trylock(&mdsc->snap_rwsem)) {
@@ -1034,7 +1035,8 @@ struct ceph_snapid_map* ceph_get_snapid_map(struct
ceph_mds_client *mdsc,
} else if (snap < exist->snap) {
p = &(*p)->rb_right;
} else {
- if (atomic_inc_return(&exist->ref) == 1)
+ refcount_inc(&exist->ref);
+ if (refcount_read(&exist->ref) == 1)
list_del_init(&exist->lru);
break;
}
@@ -1057,7 +1059,7 @@ struct ceph_snapid_map* ceph_get_snapid_map(struct
ceph_mds_client *mdsc,
}
INIT_LIST_HEAD(&sm->lru);
- atomic_set(&sm->ref, 1);
+ refcount_set(&sm->ref, 1);
sm->snap = snap;
exist = NULL;
@@ -1076,7 +1078,8 @@ struct ceph_snapid_map* ceph_get_snapid_map(struct
ceph_mds_client *mdsc,
exist = NULL;
}
if (exist) {
- if (atomic_inc_return(&exist->ref) == 1)
+ refcount_inc(&exist->ref);
+ if (refcount_read(&exist->ref) == 1)
list_del_init(&exist->lru);
} else {
rb_link_node(&sm->node, parent, p);
@@ -1099,7 +1102,7 @@ void ceph_put_snapid_map(struct ceph_mds_client* mdsc,
{
if (!sm)
return;
- if (atomic_dec_and_lock(&sm->ref, &mdsc->snapid_map_lock)) {
+ if (refcount_dec_and_lock(&sm->ref, &mdsc->snapid_map_lock)) {
if (!RB_EMPTY_NODE(&sm->node)) {
sm->last_used = jiffies;
list_add_tail(&sm->lru, &mdsc->snapid_map_lru);
@@ -1161,7 +1164,7 @@ void ceph_cleanup_snapid_map(struct ceph_mds_client *mdsc)
sm = list_first_entry(&to_free, struct ceph_snapid_map, lru);
list_del(&sm->lru);
free_anon_bdev(sm->dev);
- if (WARN_ON_ONCE(atomic_read(&sm->ref))) {
+ if (WARN_ON_ONCE(refcount_read(&sm->ref))) {
pr_err("snapid map %llx -> %x still in use\n",
sm->snap, sm->dev);
}
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index c48bb30c8d70..062123a73ef1 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -835,7 +835,7 @@ struct ceph_readdir_cache_control {
struct ceph_snap_realm {
u64 ino;
struct inode *inode;
- atomic_t nref;
+ refcount_t nref;
struct rb_node node;
u64 created, seq;
--
2.29.0
