From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 2/8] kernfs: implement kernfs_walk_and_get() Date: Mon, 7 Dec 2015 17:38:49 -0500 Message-ID: <1449527935-27056-3-git-send-email-tj@kernel.org> References: <1449527935-27056-1-git-send-email-tj@kernel.org> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=qhXc2pO6dnLasc3zbmNEnnLz59gTEFE2wIOp07blT4M=; b=iMMUQ2orL7CcORexLHBJHdWzzJjljv/bjnzXfZqYTtKgMZLx7n+AG3MlVuUo+4j1PF jE8zeNwb5TEtrYCj/DYW4yAAXuxLeKcz9TbPhUVEa07QV6XCWtD+8w+Afa2JZHhb2NA2 SbGUWhv0NE64ogMM+3JA14TuT+5aQVW+rD7LBmJps3/QYZnpBk9LEXxillmPp++dVO+e ISaG/S/vMTgcbBEnXXZIlS7dktDly5QvvGCdeDALCiEyRNrsJOttvYmqZcPJKmSP8PtV In6/4lTA3WqXSEGxG1cPB0ijzauuBDF0P6Tg9KLPxOBc4XdJ7jZlY2DnUhYjhRYJxc1+ swZA== In-Reply-To: <1449527935-27056-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: davem@davemloft.net, pablo@netfilter.org, kaber@trash.net, kadlec@blackhole.kfki.hu, daniel@iogearbox.net, daniel.wagner@bmw-carit.de, nhorman@tuxdriver.com Cc: lizefan@huawei.com, hannes@cmpxchg.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, ninasc@fb.com, Tejun Heo 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 91e0045..742bf4a 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 @@ -719,6 +742,29 @@ 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 * @flags: KERNFS_ROOT_* flags diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 5d4e9c4..af51df3 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) { } @@ -431,6 +437,12 @@ kernfs_find_and_get(struct kernfs_node *kn, const char *name) } 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) { -- 2.5.0