diff options
| -rw-r--r-- | fs/configfs/dir.c | 104 |
1 files changed, 72 insertions, 32 deletions
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 810c1395d6b2..5f952187fc53 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -505,13 +505,15 @@ static int populate_groups(struct config_group *group) int i; if (group->default_groups) { - /* FYI, we're faking mkdir here + /* + * FYI, we're faking mkdir here * I'm not sure we need this semaphore, as we're called * from our parent's mkdir. That holds our parent's * i_mutex, so afaik lookup cannot continue through our * parent to find us, let alone mess with our tree. * That said, taking our i_mutex is closer to mkdir - * emulation, and shouldn't hurt. */ + * emulation, and shouldn't hurt. + */ mutex_lock(&dentry->d_inode->i_mutex); for (i = 0; group->default_groups[i]; i++) { @@ -546,20 +548,34 @@ static void unlink_obj(struct config_item *item) item->ci_group = NULL; item->ci_parent = NULL; + + /* Drop the reference for ci_entry */ config_item_put(item); + /* Drop the reference for ci_parent */ config_group_put(group); } } static void link_obj(struct config_item *parent_item, struct config_item *item) { - /* Parent seems redundant with group, but it makes certain - * traversals much nicer. */ + /* + * Parent seems redundant with group, but it makes certain + * traversals much nicer. + */ item->ci_parent = parent_item; + + /* + * We hold a reference on the parent for the child's ci_parent + * link. + */ item->ci_group = config_group_get(to_config_group(parent_item)); list_add_tail(&item->ci_entry, &item->ci_group->cg_children); + /* + * We hold a reference on the child for ci_entry on the parent's + * cg_children + */ config_item_get(item); } @@ -684,6 +700,10 @@ static void client_drop_item(struct config_item *parent_item, type = parent_item->ci_type; BUG_ON(!type); + /* + * If ->drop_item() exists, it is responsible for the + * config_item_put(). + */ if (type->ct_group_ops && type->ct_group_ops->drop_item) type->ct_group_ops->drop_item(to_config_group(parent_item), item); @@ -694,14 +714,14 @@ static void client_drop_item(struct config_item *parent_item, static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) { - int ret; + int ret, module_got = 0; struct config_group *group; struct config_item *item; struct config_item *parent_item; struct configfs_subsystem *subsys; struct configfs_dirent *sd; struct config_item_type *type; - struct module *owner; + struct module *owner = NULL; char *name; if (dentry->d_parent == configfs_sb->s_root) { @@ -754,43 +774,63 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) kfree(name); if (!item) { + /* + * If item == NULL, then link_obj() was never called. + * There are no extra references to clean up. + */ ret = -ENOMEM; goto out_put; } - ret = -EINVAL; + /* + * link_obj() has been called (via link_group() for groups). + * From here on out, errors must clean that up. + */ + type = item->ci_type; - if (type) { - owner = type->ct_owner; - if (try_module_get(owner)) { - if (group) { - ret = configfs_attach_group(parent_item, - item, - dentry); - } else { - ret = configfs_attach_item(parent_item, - item, - dentry); - } + if (!type) { + ret = -EINVAL; + goto out_unlink; + } - if (ret) { - down(&subsys->su_sem); - if (group) - unlink_group(group); - else - unlink_obj(item); - client_drop_item(parent_item, item); - up(&subsys->su_sem); + owner = type->ct_owner; + if (!try_module_get(owner)) { + ret = -EINVAL; + goto out_unlink; + } - module_put(owner); - } - } + /* + * I hate doing it this way, but if there is + * an error, module_put() probably should + * happen after any cleanup. + */ + module_got = 1; + + if (group) + ret = configfs_attach_group(parent_item, item, dentry); + else + ret = configfs_attach_item(parent_item, item, dentry); + +out_unlink: + if (ret) { + /* Tear down everything we built up */ + down(&subsys->su_sem); + if (group) + unlink_group(group); + else + unlink_obj(item); + client_drop_item(parent_item, item); + up(&subsys->su_sem); + + if (module_got) + module_put(owner); } out_put: /* - * link_obj()/link_group() took a reference from child->parent. - * Drop our working ref + * link_obj()/link_group() took a reference from child->parent, + * so the parent is safely pinned. We can drop our working + * reference. */ config_item_put(parent_item); |