diff options
| -rw-r--r-- | fs/kernfs/dir.c | 71 | ||||
| -rw-r--r-- | fs/sysfs/mount.c | 2 | ||||
| -rw-r--r-- | include/linux/kernfs.h | 15 |
3 files changed, 78 insertions, 10 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 89f8462f337e..3cff0a233cd1 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -435,7 +435,7 @@ int kernfs_add_one(struct kernfs_node *kn) goto out_unlock; ret = -ENOENT; - if (!kernfs_active(parent)) + if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent)) goto out_unlock; kn->hash = kernfs_name_hash(kn->name, kn->ns); @@ -451,9 +451,19 @@ int kernfs_add_one(struct kernfs_node *kn) ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; } - /* Mark the entry added into directory tree */ - atomic_sub(KN_DEACTIVATED_BIAS, &kn->active); - ret = 0; + mutex_unlock(&kernfs_mutex); + + /* + * Activate the new node unless CREATE_DEACTIVATED is requested. + * If not activated here, the kernfs user is responsible for + * activating the node with kernfs_activate(). A node which hasn't + * been activated is not visible to userland and its removal won't + * trigger deactivation. + */ + if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) + kernfs_activate(kn); + return 0; + out_unlock: mutex_unlock(&kernfs_mutex); return ret; @@ -528,13 +538,14 @@ EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); /** * kernfs_create_root - create a new kernfs hierarchy * @scops: optional syscall operations for the hierarchy + * @flags: KERNFS_ROOT_* flags * @priv: opaque data associated with the new directory * * Returns the root of the new hierarchy on success, ERR_PTR() value on * failure. */ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, - void *priv) + unsigned int flags, void *priv) { struct kernfs_root *root; struct kernfs_node *kn; @@ -553,14 +564,17 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, return ERR_PTR(-ENOMEM); } - atomic_sub(KN_DEACTIVATED_BIAS, &kn->active); kn->priv = priv; kn->dir.root = root; root->syscall_ops = scops; + root->flags = flags; root->kn = kn; init_waitqueue_head(&root->deactivate_waitq); + if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) + kernfs_activate(kn); + return root; } @@ -783,6 +797,40 @@ static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos, return pos->parent; } +/** + * kernfs_activate - activate a node which started deactivated + * @kn: kernfs_node whose subtree is to be activated + * + * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node + * needs to be explicitly activated. A node which hasn't been activated + * isn't visible to userland and deactivation is skipped during its + * removal. This is useful to construct atomic init sequences where + * creation of multiple nodes should either succeed or fail atomically. + * + * The caller is responsible for ensuring that this function is not called + * after kernfs_remove*() is invoked on @kn. + */ +void kernfs_activate(struct kernfs_node *kn) +{ + struct kernfs_node *pos; + + mutex_lock(&kernfs_mutex); + + pos = NULL; + while ((pos = kernfs_next_descendant_post(pos, kn))) { + if (!pos || (pos->flags & KERNFS_ACTIVATED)) + continue; + + WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb)); + WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS); + + atomic_sub(KN_DEACTIVATED_BIAS, &pos->active); + pos->flags |= KERNFS_ACTIVATED; + } + + mutex_unlock(&kernfs_mutex); +} + static void __kernfs_remove(struct kernfs_node *kn) { struct kernfs_node *pos; @@ -817,7 +865,16 @@ static void __kernfs_remove(struct kernfs_node *kn) */ kernfs_get(pos); - kernfs_drain(pos); + /* + * Drain iff @kn was activated. This avoids draining and + * its lockdep annotations for nodes which have never been + * activated and allows embedding kernfs_remove() in create + * error paths without worrying about draining. + */ + if (kn->flags & KERNFS_ACTIVATED) + kernfs_drain(pos); + else + WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS); /* * kernfs_unlink_sibling() succeeds once per node. Use it diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index 6211230814fd..5c7fdd9c6811 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -62,7 +62,7 @@ int __init sysfs_init(void) { int err; - sysfs_root = kernfs_create_root(NULL, NULL); + sysfs_root = kernfs_create_root(NULL, 0, NULL); if (IS_ERR(sysfs_root)) return PTR_ERR(sysfs_root); diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 5d5b7e947294..4520c86f5cb4 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -38,6 +38,7 @@ enum kernfs_node_type { #define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK enum kernfs_node_flag { + KERNFS_ACTIVATED = 0x0010, KERNFS_NS = 0x0020, KERNFS_HAS_SEQ_SHOW = 0x0040, KERNFS_HAS_MMAP = 0x0080, @@ -47,6 +48,11 @@ enum kernfs_node_flag { KERNFS_SUICIDED = 0x0800, }; +/* @flags for kernfs_create_root() */ +enum kernfs_root_flag { + KERNFS_ROOT_CREATE_DEACTIVATED = 0x0001, +}; + /* type-specific structures for kernfs_node union members */ struct kernfs_elem_dir { unsigned long subdirs; @@ -128,6 +134,7 @@ struct kernfs_syscall_ops { struct kernfs_root { /* published fields */ struct kernfs_node *kn; + unsigned int flags; /* KERNFS_ROOT_* flags */ /* private fields, do not use outside kernfs proper */ struct ida ino_ida; @@ -223,7 +230,7 @@ void kernfs_get(struct kernfs_node *kn); void kernfs_put(struct kernfs_node *kn); struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, - void *priv); + unsigned int flags, void *priv); void kernfs_destroy_root(struct kernfs_root *root); struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, @@ -239,6 +246,7 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent, struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, const char *name, struct kernfs_node *target); +void kernfs_activate(struct kernfs_node *kn); void kernfs_remove(struct kernfs_node *kn); void kernfs_break_active_protection(struct kernfs_node *kn); void kernfs_unbreak_active_protection(struct kernfs_node *kn); @@ -276,7 +284,8 @@ static inline void kernfs_get(struct kernfs_node *kn) { } static inline void kernfs_put(struct kernfs_node *kn) { } static inline struct kernfs_root * -kernfs_create_root(struct kernfs_syscall_ops *scops, void *priv) +kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags, + void *priv) { return ERR_PTR(-ENOSYS); } static inline void kernfs_destroy_root(struct kernfs_root *root) { } @@ -298,6 +307,8 @@ kernfs_create_link(struct kernfs_node *parent, const char *name, struct kernfs_node *target) { return ERR_PTR(-ENOSYS); } +static inline void kernfs_activate(struct kernfs_node *kn) { } + static inline void kernfs_remove(struct kernfs_node *kn) { } static inline bool kernfs_remove_self(struct kernfs_node *kn) |