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authorTejun Heo <tj@kernel.org>2015-11-20 15:55:52 -0500
committerTejun Heo <tj@kernel.org>2015-11-20 15:55:52 -0500
commitbd96f76a2454c6b97d70945902e30b4c31510678 (patch)
tree6700838f83e76e2558f9a36742acf81b589d3d38 /fs/kernfs/dir.c
parentcgroup: record ancestor IDs and reimplement cgroup_is_descendant() using it (diff)
downloadlinux-dev-bd96f76a2454c6b97d70945902e30b4c31510678.tar.xz
linux-dev-bd96f76a2454c6b97d70945902e30b4c31510678.zip
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 <tj@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: David Miller <davem@davemloft.net>
Diffstat (limited to '')
-rw-r--r--fs/kernfs/dir.c46
1 files changed, 46 insertions, 0 deletions
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
@@ -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