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-rw-r--r--fs/kernfs/kernfs-internal.h22
-rw-r--r--fs/kernfs/mount.c156
2 files changed, 178 insertions, 0 deletions
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 0d949885389d..ced0d6dadc7d 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -134,6 +134,28 @@ struct sysfs_addrm_cxt {
#include "../sysfs/sysfs.h"
/*
+ * mount.c
+ */
+struct sysfs_super_info {
+ /*
+ * The root associated with this super_block. Each super_block is
+ * identified by the root and ns it's associated with.
+ */
+ struct kernfs_root *root;
+
+ /*
+ * Each sb is associated with one namespace tag, currently the network
+ * namespace of the task which mounted this sysfs instance. If multiple
+ * tags become necessary, make the following an array and compare
+ * sysfs_dirent tag against every entry.
+ */
+ const void *ns;
+};
+#define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
+
+extern struct kmem_cache *sysfs_dir_cachep;
+
+/*
* inode.c
*/
struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd);
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 872e262e5166..84c83e24bf25 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -7,3 +7,159 @@
*
* This file is released under the GPLv2.
*/
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/init.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+
+#include "kernfs-internal.h"
+
+struct kmem_cache *sysfs_dir_cachep;
+
+static const struct super_operations sysfs_ops = {
+ .statfs = simple_statfs,
+ .drop_inode = generic_delete_inode,
+ .evict_inode = sysfs_evict_inode,
+};
+
+static int sysfs_fill_super(struct super_block *sb)
+{
+ struct sysfs_super_info *info = sysfs_info(sb);
+ struct inode *inode;
+ struct dentry *root;
+
+ sb->s_blocksize = PAGE_CACHE_SIZE;
+ sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+ sb->s_magic = SYSFS_MAGIC;
+ sb->s_op = &sysfs_ops;
+ sb->s_time_gran = 1;
+
+ /* get root inode, initialize and unlock it */
+ mutex_lock(&sysfs_mutex);
+ inode = sysfs_get_inode(sb, info->root->sd);
+ mutex_unlock(&sysfs_mutex);
+ if (!inode) {
+ pr_debug("sysfs: could not get root inode\n");
+ return -ENOMEM;
+ }
+
+ /* instantiate and link root dentry */
+ root = d_make_root(inode);
+ if (!root) {
+ pr_debug("%s: could not get root dentry!\n", __func__);
+ return -ENOMEM;
+ }
+ kernfs_get(info->root->sd);
+ root->d_fsdata = info->root->sd;
+ sb->s_root = root;
+ sb->s_d_op = &sysfs_dentry_ops;
+ return 0;
+}
+
+static int sysfs_test_super(struct super_block *sb, void *data)
+{
+ struct sysfs_super_info *sb_info = sysfs_info(sb);
+ struct sysfs_super_info *info = data;
+
+ return sb_info->root == info->root && sb_info->ns == info->ns;
+}
+
+static int sysfs_set_super(struct super_block *sb, void *data)
+{
+ int error;
+ error = set_anon_super(sb, data);
+ if (!error)
+ sb->s_fs_info = data;
+ return error;
+}
+
+/**
+ * kernfs_super_ns - determine the namespace tag of a kernfs super_block
+ * @sb: super_block of interest
+ *
+ * Return the namespace tag associated with kernfs super_block @sb.
+ */
+const void *kernfs_super_ns(struct super_block *sb)
+{
+ struct sysfs_super_info *info = sysfs_info(sb);
+
+ return info->ns;
+}
+
+/**
+ * kernfs_mount_ns - kernfs mount helper
+ * @fs_type: file_system_type of the fs being mounted
+ * @flags: mount flags specified for the mount
+ * @root: kernfs_root of the hierarchy being mounted
+ * @ns: optional namespace tag of the mount
+ *
+ * This is to be called from each kernfs user's file_system_type->mount()
+ * implementation, which should pass through the specified @fs_type and
+ * @flags, and specify the hierarchy and namespace tag to mount via @root
+ * and @ns, respectively.
+ *
+ * The return value can be passed to the vfs layer verbatim.
+ */
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+ struct kernfs_root *root, const void *ns)
+{
+ struct super_block *sb;
+ struct sysfs_super_info *info;
+ int error;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return ERR_PTR(-ENOMEM);
+
+ info->root = root;
+ info->ns = ns;
+
+ sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
+ if (IS_ERR(sb) || sb->s_fs_info != info)
+ kfree(info);
+ if (IS_ERR(sb))
+ return ERR_CAST(sb);
+ if (!sb->s_root) {
+ error = sysfs_fill_super(sb);
+ if (error) {
+ deactivate_locked_super(sb);
+ return ERR_PTR(error);
+ }
+ sb->s_flags |= MS_ACTIVE;
+ }
+
+ return dget(sb->s_root);
+}
+
+/**
+ * kernfs_kill_sb - kill_sb for kernfs
+ * @sb: super_block being killed
+ *
+ * This can be used directly for file_system_type->kill_sb(). If a kernfs
+ * user needs extra cleanup, it can implement its own kill_sb() and call
+ * this function at the end.
+ */
+void kernfs_kill_sb(struct super_block *sb)
+{
+ struct sysfs_super_info *info = sysfs_info(sb);
+ struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
+
+ /*
+ * Remove the superblock from fs_supers/s_instances
+ * so we can't find it, before freeing sysfs_super_info.
+ */
+ kill_anon_super(sb);
+ kfree(info);
+ kernfs_put(root_sd);
+}
+
+void __init kernfs_init(void)
+{
+ sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
+ sizeof(struct sysfs_dirent),
+ 0, SLAB_PANIC, NULL);
+ sysfs_inode_init();
+}