From bd96f76a2454c6b97d70945902e30b4c31510678 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 20 Nov 2015 15:55:52 -0500 Subject: [PATCH] kernfs: implement kernfs_walk_and_get() Implement kernfs_walk_and_get() which is similar to kernfs_find_and_get() but can walk a path instead of just a name. v2: Use strlcpy() instead of strlen() + memcpy() as suggested by David. Signed-off-by: Tejun Heo Acked-by: Greg Kroah-Hartman Cc: David Miller --- fs/kernfs/dir.c | 46 ++++++++++++++++++++++++++++++++++++++++++ include/linux/kernfs.h | 12 +++++++++++ 2 files changed, 58 insertions(+) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 91e004518237..742bf4a230e8 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -694,6 +694,29 @@ static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, return NULL; } +static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, + const unsigned char *path, + const void *ns) +{ + static char path_buf[PATH_MAX]; /* protected by kernfs_mutex */ + size_t len = strlcpy(path_buf, path, PATH_MAX); + char *p = path_buf; + char *name; + + lockdep_assert_held(&kernfs_mutex); + + if (len >= PATH_MAX) + return NULL; + + while ((name = strsep(&p, "/")) && parent) { + if (*name == '\0') + continue; + parent = kernfs_find_ns(parent, name, ns); + } + + return parent; +} + /** * kernfs_find_and_get_ns - find and get kernfs_node with the given name * @parent: kernfs_node to search under @@ -718,6 +741,29 @@ struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, } EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); +/** + * kernfs_walk_and_get_ns - find and get kernfs_node with the given path + * @parent: kernfs_node to search under + * @path: path to look for + * @ns: the namespace tag to use + * + * Look for kernfs_node with path @path under @parent and get a reference + * if found. This function may sleep and returns pointer to the found + * kernfs_node on success, %NULL on failure. + */ +struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent, + const char *path, const void *ns) +{ + struct kernfs_node *kn; + + mutex_lock(&kernfs_mutex); + kn = kernfs_walk_ns(parent, path, ns); + kernfs_get(kn); + mutex_unlock(&kernfs_mutex); + + return kn; +} + /** * kernfs_create_root - create a new kernfs hierarchy * @scops: optional syscall operations for the hierarchy diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 5d4e9c4b821d..af51df35d749 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -274,6 +274,8 @@ 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); +struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent, + const char *path, const void *ns); void kernfs_get(struct kernfs_node *kn); void kernfs_put(struct kernfs_node *kn); @@ -350,6 +352,10 @@ static inline struct kernfs_node * kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name, const void *ns) { return NULL; } +static inline struct kernfs_node * +kernfs_walk_and_get_ns(struct kernfs_node *parent, const char *path, + const void *ns) +{ return NULL; } static inline void kernfs_get(struct kernfs_node *kn) { } static inline void kernfs_put(struct kernfs_node *kn) { } @@ -430,6 +436,12 @@ kernfs_find_and_get(struct kernfs_node *kn, const char *name) return kernfs_find_and_get_ns(kn, name, NULL); } +static inline struct kernfs_node * +kernfs_walk_and_get(struct kernfs_node *kn, const char *path) +{ + return kernfs_walk_and_get_ns(kn, path, NULL); +} + static inline struct kernfs_node * kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode, void *priv) -- 2.20.1