diff options
| -rw-r--r-- | fs/kernfs/dir.c | 175 | ||||
| -rw-r--r-- | fs/sysfs/dir.c | 44 | ||||
| -rw-r--r-- | include/linux/kernfs.h | 26 |
3 files changed, 203 insertions, 42 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 42a250f83b98..a347792c2e5a 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -19,6 +19,8 @@ #include "kernfs-internal.h" DEFINE_MUTEX(kernfs_mutex); +static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */ +static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by rename_lock */ #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) @@ -37,6 +39,141 @@ static bool kernfs_lockdep(struct kernfs_node *kn) #endif } +static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) +{ + return strlcpy(buf, kn->parent ? kn->name : "/", buflen); +} + +static char * __must_check kernfs_path_locked(struct kernfs_node *kn, char *buf, + size_t buflen) +{ + char *p = buf + buflen; + int len; + + *--p = '\0'; + + do { + len = strlen(kn->name); + if (p - buf < len + 1) { + buf[0] = '\0'; + p = NULL; + break; + } + p -= len; + memcpy(p, kn->name, len); + *--p = '/'; + kn = kn->parent; + } while (kn && kn->parent); + + return p; +} + +/** + * kernfs_name - obtain the name of a given node + * @kn: kernfs_node of interest + * @buf: buffer to copy @kn's name into + * @buflen: size of @buf + * + * Copies the name of @kn into @buf of @buflen bytes. The behavior is + * similar to strlcpy(). It returns the length of @kn's name and if @buf + * isn't long enough, it's filled upto @buflen-1 and nul terminated. + * + * This function can be called from any context. + */ +int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) +{ + unsigned long flags; + int ret; + + spin_lock_irqsave(&kernfs_rename_lock, flags); + ret = kernfs_name_locked(kn, buf, buflen); + spin_unlock_irqrestore(&kernfs_rename_lock, flags); + return ret; +} + +/** + * kernfs_path - build full path of a given node + * @kn: kernfs_node of interest + * @buf: buffer to copy @kn's name into + * @buflen: size of @buf + * + * Builds and returns the full path of @kn in @buf of @buflen bytes. The + * path is built from the end of @buf so the returned pointer usually + * doesn't match @buf. If @buf isn't long enough, @buf is nul terminated + * and %NULL is returned. + */ +char *kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen) +{ + unsigned long flags; + char *p; + + spin_lock_irqsave(&kernfs_rename_lock, flags); + p = kernfs_path_locked(kn, buf, buflen); + spin_unlock_irqrestore(&kernfs_rename_lock, flags); + return p; +} + +/** + * pr_cont_kernfs_name - pr_cont name of a kernfs_node + * @kn: kernfs_node of interest + * + * This function can be called from any context. + */ +void pr_cont_kernfs_name(struct kernfs_node *kn) +{ + unsigned long flags; + + spin_lock_irqsave(&kernfs_rename_lock, flags); + + kernfs_name_locked(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf)); + pr_cont("%s", kernfs_pr_cont_buf); + + spin_unlock_irqrestore(&kernfs_rename_lock, flags); +} + +/** + * pr_cont_kernfs_path - pr_cont path of a kernfs_node + * @kn: kernfs_node of interest + * + * This function can be called from any context. + */ +void pr_cont_kernfs_path(struct kernfs_node *kn) +{ + unsigned long flags; + char *p; + + spin_lock_irqsave(&kernfs_rename_lock, flags); + + p = kernfs_path_locked(kn, kernfs_pr_cont_buf, + sizeof(kernfs_pr_cont_buf)); + if (p) + pr_cont("%s", p); + else + pr_cont("<name too long>"); + + spin_unlock_irqrestore(&kernfs_rename_lock, flags); +} + +/** + * kernfs_get_parent - determine the parent node and pin it + * @kn: kernfs_node of interest + * + * Determines @kn's parent, pins and returns it. This function can be + * called from any context. + */ +struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn) +{ + struct kernfs_node *parent; + unsigned long flags; + + spin_lock_irqsave(&kernfs_rename_lock, flags); + parent = kn->parent; + kernfs_get(parent); + spin_unlock_irqrestore(&kernfs_rename_lock, flags); + + return parent; +} + /** * kernfs_name_hash * @name: Null terminated string to hash @@ -1103,8 +1240,14 @@ int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, const char *new_name, const void *new_ns) { + struct kernfs_node *old_parent; + const char *old_name = NULL; int error; + /* can't move or rename root */ + if (!kn->parent) + return -EINVAL; + mutex_lock(&kernfs_mutex); error = -ENOENT; @@ -1126,13 +1269,8 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, new_name = kstrdup(new_name, GFP_KERNEL); if (!new_name) goto out; - - if (kn->flags & KERNFS_STATIC_NAME) - kn->flags &= ~KERNFS_STATIC_NAME; - else - kfree(kn->name); - - kn->name = new_name; + } else { + new_name = NULL; } /* @@ -1140,12 +1278,29 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, */ kernfs_unlink_sibling(kn); kernfs_get(new_parent); - kernfs_put(kn->parent); - kn->ns = new_ns; - kn->hash = kernfs_name_hash(kn->name, kn->ns); + + /* rename_lock protects ->parent and ->name accessors */ + spin_lock_irq(&kernfs_rename_lock); + + old_parent = kn->parent; kn->parent = new_parent; + + kn->ns = new_ns; + if (new_name) { + if (!(kn->flags & KERNFS_STATIC_NAME)) + old_name = kn->name; + kn->flags &= ~KERNFS_STATIC_NAME; + kn->name = new_name; + } + + spin_unlock_irq(&kernfs_rename_lock); + + kn->hash = kernfs_name_hash(new_name, new_ns); kernfs_link_sibling(kn); + kernfs_put(old_parent); + kfree(old_name); + error = 0; out: mutex_unlock(&kernfs_mutex); diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index ee0d761c3179..0b45ff42f374 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -19,39 +19,18 @@ DEFINE_SPINLOCK(sysfs_symlink_target_lock); -/** - * sysfs_pathname - return full path to sysfs dirent - * @kn: kernfs_node whose path we want - * @path: caller allocated buffer of size PATH_MAX - * - * Gives the name "/" to the sysfs_root entry; any path returned - * is relative to wherever sysfs is mounted. - */ -static char *sysfs_pathname(struct kernfs_node *kn, char *path) -{ - if (kn->parent) { - sysfs_pathname(kn->parent, path); - strlcat(path, "/", PATH_MAX); - } - strlcat(path, kn->name, PATH_MAX); - return path; -} - void sysfs_warn_dup(struct kernfs_node *parent, const char *name) { - char *path; + char *buf, *path = NULL; - path = kzalloc(PATH_MAX, GFP_KERNEL); - if (path) { - sysfs_pathname(parent, path); - strlcat(path, "/", PATH_MAX); - strlcat(path, name, PATH_MAX); - } + buf = kzalloc(PATH_MAX, GFP_KERNEL); + if (buf) + path = kernfs_path(parent, buf, PATH_MAX); - WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s'\n", - path ? path : name); + WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s/%s'\n", + path, name); - kfree(path); + kfree(buf); } /** @@ -122,9 +101,13 @@ void sysfs_remove_dir(struct kobject *kobj) int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name, const void *new_ns) { - struct kernfs_node *parent = kobj->sd->parent; + struct kernfs_node *parent; + int ret; - return kernfs_rename_ns(kobj->sd, parent, new_name, new_ns); + parent = kernfs_get_parent(kobj->sd); + ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns); + kernfs_put(parent); + return ret; } int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj, @@ -133,7 +116,6 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj, struct kernfs_node *kn = kobj->sd; struct kernfs_node *new_parent; - BUG_ON(!kn->parent); new_parent = new_parent_kobj && new_parent_kobj->sd ? new_parent_kobj->sd : sysfs_root_kn; diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 9c899040c05e..8736ee86a1d6 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -91,7 +91,12 @@ struct kernfs_node { #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; #endif - /* the following two fields are published */ + /* + * Use kernfs_get_parent() and kernfs_name/path() instead of + * accessing the following two fields directly. If the node is + * never moved to a different parent, it is safe to access the + * parent directly. + */ struct kernfs_node *parent; const char *name; @@ -229,6 +234,12 @@ static inline bool kernfs_ns_enabled(struct kernfs_node *kn) return kn->flags & KERNFS_NS; } +int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen); +char * __must_check kernfs_path(struct kernfs_node *kn, char *buf, + size_t buflen); +void pr_cont_kernfs_name(struct kernfs_node *kn); +void pr_cont_kernfs_path(struct kernfs_node *kn); +struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn); struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name, const void *ns); void kernfs_get(struct kernfs_node *kn); @@ -283,6 +294,19 @@ static inline void kernfs_enable_ns(struct kernfs_node *kn) { } static inline bool kernfs_ns_enabled(struct kernfs_node *kn) { return false; } +static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) +{ return -ENOSYS; } + +static inline char * __must_check kernfs_path(struct kernfs_node *kn, char *buf, + size_t buflen) +{ return NULL; } + +static inline void pr_cont_kernfs_name(struct kernfs_node *kn) { } +static inline void pr_cont_kernfs_path(struct kernfs_node *kn) { } + +static inline struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn) +{ return NULL; } + static inline struct kernfs_node * kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name, const void *ns) |