kernfs: move struct kernfs_root out of the public view.

There is no need to have struct kernfs_root be part of kernfs.h for
the whole kernel to see and poke around it.  Move it internal to kernfs
code and provide a helper function, kernfs_root_to_node(), to handle the
one field that kernfs users were directly accessing from the structure.

Cc: Imran Khan <imran.f.khan@oracle.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220222070713.3517679-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index b57b3db..83f901e 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3221,13 +3221,13 @@ static int __init rdtgroup_setup_root(void)
 
        list_add(&rdtgroup_default.rdtgroup_list, &rdt_all_groups);
 
-       ret = rdtgroup_add_files(rdt_root->kn, RF_CTRL_BASE);
+       ret = rdtgroup_add_files(kernfs_root_to_node(rdt_root), RF_CTRL_BASE);
        if (ret) {
                kernfs_destroy_root(rdt_root);
                goto out;
        }
 
-       rdtgroup_default.kn = rdt_root->kn;
+       rdtgroup_default.kn = kernfs_root_to_node(rdt_root);
        kernfs_activate(rdtgroup_default.kn);
 
 out:

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index e6d9772..61a8edc 100644 (file)
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -970,6 +970,15 @@ void kernfs_destroy_root(struct kernfs_root *root)
        kernfs_put(root->kn); /* will also free @root */
 }
 
+/**
+ * kernfs_root_to_node - return the kernfs_node associated with a kernfs_root
+ * @root: root to use to lookup
+ */
+struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root)
+{
+       return root->kn;
+}
+
 /**
  * kernfs_create_dir_ns - create a directory
  * @parent: parent in which to create a new directory

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index fc3b32f..eeaa779 100644 (file)
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -31,6 +31,24 @@ struct kernfs_iattrs {
        atomic_t                user_xattr_size;
 };
 
+struct kernfs_root {
+       /* published fields */
+       struct kernfs_node      *kn;
+       unsigned int            flags;  /* KERNFS_ROOT_* flags */
+
+       /* private fields, do not use outside kernfs proper */
+       struct idr              ino_idr;
+       u32                     last_id_lowbits;
+       u32                     id_highbits;
+       struct kernfs_syscall_ops *syscall_ops;
+
+       /* list of kernfs_super_info of this root, protected by kernfs_rwsem */
+       struct list_head        supers;
+
+       wait_queue_head_t       deactivate_waitq;
+       struct rw_semaphore     kernfs_rwsem;
+};
+
 /* +1 to avoid triggering overflow warning when negating it */
 #define KN_DEACTIVATED_BIAS            (INT_MIN + 1)
 

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index e747c13..98467bb 100644 (file)
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -103,7 +103,7 @@ int __init sysfs_init(void)
        if (IS_ERR(sysfs_root))
                return PTR_ERR(sysfs_root);
 
-       sysfs_root_kn = sysfs_root->kn;
+       sysfs_root_kn = kernfs_root_to_node(sysfs_root);
 
        err = register_filesystem(&sysfs_fs_type);
        if (err) {

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 861c4f0..62aff08 100644 (file)
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -185,6 +185,7 @@ struct kernfs_syscall_ops {
                         struct kernfs_root *root);
 };
 
+#if 0
 struct kernfs_root {
        /* published fields */
        struct kernfs_node      *kn;
@@ -202,6 +203,9 @@ struct kernfs_root {
        wait_queue_head_t       deactivate_waitq;
        struct rw_semaphore     kernfs_rwsem;
 };
+#endif
+
+struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root);
 
 struct kernfs_open_file {
        /* published fields */

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index b31e146..a800c3b 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1302,7 +1302,7 @@ static struct css_set *find_css_set(struct css_set *old_cset,
 
 struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
 {
-       struct cgroup *root_cgrp = kf_root->kn->priv;
+       struct cgroup *root_cgrp = kernfs_root_to_node(kf_root)->priv;
 
        return root_cgrp->root;
 }
@@ -2025,7 +2025,7 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
                ret = PTR_ERR(root->kf_root);
                goto exit_root_id;
        }
-       root_cgrp->kn = root->kf_root->kn;
+       root_cgrp->kn = kernfs_root_to_node(root->kf_root);
        WARN_ON_ONCE(cgroup_ino(root_cgrp) != 1);
        root_cgrp->ancestor_ids[0] = cgroup_id(root_cgrp);