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Diffstat (limited to 'fs/notify/mark.c')
-rw-r--r--fs/notify/mark.c152
1 files changed, 112 insertions, 40 deletions
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index bfb415d0d757..824095db5a3b 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -89,10 +89,14 @@ struct kmem_cache *fsnotify_mark_connector_cachep;
static DEFINE_SPINLOCK(destroy_lock);
static LIST_HEAD(destroy_list);
+static struct fsnotify_mark_connector *connector_destroy_list;
static void fsnotify_mark_destroy_workfn(struct work_struct *work);
static DECLARE_DELAYED_WORK(reaper_work, fsnotify_mark_destroy_workfn);
+static void fsnotify_connector_destroy_workfn(struct work_struct *work);
+static DECLARE_WORK(connector_reaper_work, fsnotify_connector_destroy_workfn);
+
void fsnotify_get_mark(struct fsnotify_mark *mark)
{
atomic_inc(&mark->refcnt);
@@ -139,22 +143,73 @@ void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
__fsnotify_update_child_dentry_flags(conn->inode);
}
+/* Free all connectors queued for freeing once SRCU period ends */
+static void fsnotify_connector_destroy_workfn(struct work_struct *work)
+{
+ struct fsnotify_mark_connector *conn, *free;
+
+ spin_lock(&destroy_lock);
+ conn = connector_destroy_list;
+ connector_destroy_list = NULL;
+ spin_unlock(&destroy_lock);
+
+ synchronize_srcu(&fsnotify_mark_srcu);
+ while (conn) {
+ free = conn;
+ conn = conn->destroy_next;
+ kmem_cache_free(fsnotify_mark_connector_cachep, free);
+ }
+}
+
+
+static struct inode *fsnotify_detach_connector_from_object(
+ struct fsnotify_mark_connector *conn)
+{
+ struct inode *inode = NULL;
+
+ if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE) {
+ inode = conn->inode;
+ rcu_assign_pointer(inode->i_fsnotify_marks, NULL);
+ inode->i_fsnotify_mask = 0;
+ conn->inode = NULL;
+ conn->flags &= ~FSNOTIFY_OBJ_TYPE_INODE;
+ } else if (conn->flags & FSNOTIFY_OBJ_TYPE_VFSMOUNT) {
+ rcu_assign_pointer(real_mount(conn->mnt)->mnt_fsnotify_marks,
+ NULL);
+ real_mount(conn->mnt)->mnt_fsnotify_mask = 0;
+ conn->mnt = NULL;
+ conn->flags &= ~FSNOTIFY_OBJ_TYPE_VFSMOUNT;
+ }
+
+ return inode;
+}
+
static struct inode *fsnotify_detach_from_object(struct fsnotify_mark *mark)
{
struct fsnotify_mark_connector *conn;
struct inode *inode = NULL;
+ bool free_conn = false;
conn = mark->connector;
spin_lock(&conn->lock);
hlist_del_init_rcu(&mark->obj_list);
if (hlist_empty(&conn->list)) {
- if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE)
- inode = conn->inode;
+ inode = fsnotify_detach_connector_from_object(conn);
+ free_conn = true;
+ } else {
+ __fsnotify_recalc_mask(conn);
}
- __fsnotify_recalc_mask(conn);
mark->connector = NULL;
spin_unlock(&conn->lock);
+ if (free_conn) {
+ spin_lock(&destroy_lock);
+ conn->destroy_next = connector_destroy_list;
+ connector_destroy_list = conn;
+ spin_unlock(&destroy_lock);
+ queue_work(system_unbound_wq, &connector_reaper_work);
+ }
+
return inode;
}
@@ -259,14 +314,6 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark,
fsnotify_free_mark(mark);
}
-void fsnotify_connector_free(struct fsnotify_mark_connector **connp)
-{
- if (*connp) {
- kmem_cache_free(fsnotify_mark_connector_cachep, *connp);
- *connp = NULL;
- }
-}
-
void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask)
{
assert_spin_locked(&mark->lock);
@@ -318,9 +365,9 @@ int fsnotify_compare_groups(struct fsnotify_group *a, struct fsnotify_group *b)
}
static int fsnotify_attach_connector_to_object(
- struct fsnotify_mark_connector **connp,
- struct inode *inode,
- struct vfsmount *mnt)
+ struct fsnotify_mark_connector __rcu **connp,
+ struct inode *inode,
+ struct vfsmount *mnt)
{
struct fsnotify_mark_connector *conn;
@@ -331,7 +378,7 @@ static int fsnotify_attach_connector_to_object(
INIT_HLIST_HEAD(&conn->list);
if (inode) {
conn->flags = FSNOTIFY_OBJ_TYPE_INODE;
- conn->inode = inode;
+ conn->inode = igrab(inode);
} else {
conn->flags = FSNOTIFY_OBJ_TYPE_VFSMOUNT;
conn->mnt = mnt;
@@ -342,6 +389,8 @@ static int fsnotify_attach_connector_to_object(
*/
if (cmpxchg(connp, NULL, conn)) {
/* Someone else created list structure for us */
+ if (inode)
+ iput(inode);
kmem_cache_free(fsnotify_mark_connector_cachep, conn);
}
@@ -349,6 +398,34 @@ static int fsnotify_attach_connector_to_object(
}
/*
+ * Get mark connector, make sure it is alive and return with its lock held.
+ * This is for users that get connector pointer from inode or mount. Users that
+ * hold reference to a mark on the list may directly lock connector->lock as
+ * they are sure list cannot go away under them.
+ */
+static struct fsnotify_mark_connector *fsnotify_grab_connector(
+ struct fsnotify_mark_connector __rcu **connp)
+{
+ struct fsnotify_mark_connector *conn;
+ int idx;
+
+ idx = srcu_read_lock(&fsnotify_mark_srcu);
+ conn = srcu_dereference(*connp, &fsnotify_mark_srcu);
+ if (!conn)
+ goto out;
+ spin_lock(&conn->lock);
+ if (!(conn->flags & (FSNOTIFY_OBJ_TYPE_INODE |
+ FSNOTIFY_OBJ_TYPE_VFSMOUNT))) {
+ spin_unlock(&conn->lock);
+ srcu_read_unlock(&fsnotify_mark_srcu, idx);
+ return NULL;
+ }
+out:
+ srcu_read_unlock(&fsnotify_mark_srcu, idx);
+ return conn;
+}
+
+/*
* Add mark into proper place in given list of marks. These marks may be used
* for the fsnotify backend to determine which event types should be delivered
* to which group and for which inodes. These marks are ordered according to
@@ -360,7 +437,7 @@ static int fsnotify_add_mark_list(struct fsnotify_mark *mark,
{
struct fsnotify_mark *lmark, *last = NULL;
struct fsnotify_mark_connector *conn;
- struct fsnotify_mark_connector **connp;
+ struct fsnotify_mark_connector __rcu **connp;
int cmp;
int err = 0;
@@ -370,21 +447,20 @@ static int fsnotify_add_mark_list(struct fsnotify_mark *mark,
connp = &inode->i_fsnotify_marks;
else
connp = &real_mount(mnt)->mnt_fsnotify_marks;
-
- if (!*connp) {
+restart:
+ spin_lock(&mark->lock);
+ conn = fsnotify_grab_connector(connp);
+ if (!conn) {
+ spin_unlock(&mark->lock);
err = fsnotify_attach_connector_to_object(connp, inode, mnt);
if (err)
return err;
+ goto restart;
}
- spin_lock(&mark->lock);
- conn = *connp;
- spin_lock(&conn->lock);
/* is mark the first mark? */
if (hlist_empty(&conn->list)) {
hlist_add_head_rcu(&mark->obj_list, &conn->list);
- if (inode)
- igrab(inode);
goto added;
}
@@ -486,15 +562,17 @@ int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
* Given a list of marks, find the mark associated with given group. If found
* take a reference to that mark and return it, else return NULL.
*/
-struct fsnotify_mark *fsnotify_find_mark(struct fsnotify_mark_connector *conn,
- struct fsnotify_group *group)
+struct fsnotify_mark *fsnotify_find_mark(
+ struct fsnotify_mark_connector __rcu **connp,
+ struct fsnotify_group *group)
{
+ struct fsnotify_mark_connector *conn;
struct fsnotify_mark *mark;
+ conn = fsnotify_grab_connector(connp);
if (!conn)
return NULL;
- spin_lock(&conn->lock);
hlist_for_each_entry(mark, &conn->list, obj_list) {
if (mark->group == group) {
fsnotify_get_mark(mark);
@@ -572,26 +650,20 @@ void fsnotify_detach_group_marks(struct fsnotify_group *group)
}
}
-void fsnotify_destroy_marks(struct fsnotify_mark_connector *conn)
+/* Destroy all marks attached to inode / vfsmount */
+void fsnotify_destroy_marks(struct fsnotify_mark_connector __rcu **connp)
{
+ struct fsnotify_mark_connector *conn;
struct fsnotify_mark *mark;
- if (!conn)
- return;
-
- while (1) {
+ while ((conn = fsnotify_grab_connector(connp))) {
/*
* We have to be careful since we can race with e.g.
- * fsnotify_clear_marks_by_group() and once we drop 'lock',
- * mark can get removed from the obj_list and destroyed. But
- * we are holding mark reference so mark cannot be freed and
- * calling fsnotify_destroy_mark() more than once is fine.
+ * fsnotify_clear_marks_by_group() and once we drop the list
+ * lock, mark can get removed from the obj_list and destroyed.
+ * But we are holding mark reference so mark cannot be freed
+ * and calling fsnotify_destroy_mark() more than once is fine.
*/
- spin_lock(&conn->lock);
- if (hlist_empty(&conn->list)) {
- spin_unlock(&conn->lock);
- break;
- }
mark = hlist_entry(conn->list.first, struct fsnotify_mark,
obj_list);
fsnotify_get_mark(mark);