Merge tag 'configfs-for-4.12' of git://git.infradead.org/users/hch/configfs
Pull configfs updates from Christoph Hellwig:
"A fix from Nic for a race seen in production (including a stable tag).
And while I'm sending you this I'm also sneaking in a trivial new
helper from Bart so that we don't need inter-tree dependencies for the
next merge window"
* tag 'configfs-for-4.12' of git://git.infradead.org/users/hch/configfs:
configfs: Introduce config_item_get_unless_zero()
configfs: Fix race between create_link and configfs_rmdir
diff --git a/fs/configfs/item.c b/fs/configfs/item.c
index 8b2a994..a66f662 100644
--- a/fs/configfs/item.c
+++ b/fs/configfs/item.c
@@ -138,6 +138,14 @@ struct config_item *config_item_get(struct config_item *item)
}
EXPORT_SYMBOL(config_item_get);
+struct config_item *config_item_get_unless_zero(struct config_item *item)
+{
+ if (item && kref_get_unless_zero(&item->ci_kref))
+ return item;
+ return NULL;
+}
+EXPORT_SYMBOL(config_item_get_unless_zero);
+
static void config_item_cleanup(struct config_item *item)
{
struct config_item_type *t = item->ci_type;
diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c
index a6ab012..c8aabba 100644
--- a/fs/configfs/symlink.c
+++ b/fs/configfs/symlink.c
@@ -83,14 +83,13 @@ static int create_link(struct config_item *parent_item,
ret = -ENOMEM;
sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);
if (sl) {
- sl->sl_target = config_item_get(item);
spin_lock(&configfs_dirent_lock);
if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
spin_unlock(&configfs_dirent_lock);
- config_item_put(item);
kfree(sl);
return -ENOENT;
}
+ sl->sl_target = config_item_get(item);
list_add(&sl->sl_list, &target_sd->s_links);
spin_unlock(&configfs_dirent_lock);
ret = configfs_create_link(sl, parent_item->ci_dentry,
diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index 2319b8c..c967090 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -74,7 +74,8 @@ extern void config_item_init_type_name(struct config_item *item,
const char *name,
struct config_item_type *type);
-extern struct config_item * config_item_get(struct config_item *);
+extern struct config_item *config_item_get(struct config_item *);
+extern struct config_item *config_item_get_unless_zero(struct config_item *);
extern void config_item_put(struct config_item *);
struct config_item_type {
