From ba7443bc656e5236c316b2acacc8b551f872910f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 28 Nov 2013 14:54:40 -0500 Subject: sysfs, kernfs: implement kernfs_create/destroy_root() There currently is single kernfs hierarchy in the whole system which is used for sysfs. kernfs needs to support multiple hierarchies to allow other users. This patch introduces struct kernfs_root which serves as the root of each kernfs hierarchy and implements kernfs_create/destroy_root(). * Each kernfs_root is associated with a root sd (sysfs_dentry). The root is freed when the root sd is released and kernfs_destory_root() simply invokes kernfs_remove() on the root sd. sysfs_remove_one() is updated to handle release of the root sd. Note that ps_iattr update in sysfs_remove_one() is trivially updated for readability. * Root sd's are now dynamically allocated using sysfs_new_dirent(). Update sysfs_alloc_ino() so that it gives out ino from 1 so that the root sd still gets ino 1. * While kernfs currently only points to the root sd, it'll soon grow fields which are specific to each hierarchy. As determining a given sd's root will be necessary, sd->s_dir.root is added. This backlink fits better as a separate field in sd; however, sd->s_dir is inside union with space to spare, so use it to save space and provide kernfs_root() accessor to determine the root sd. * As hierarchies may be destroyed now, each mount needs to hold onto the hierarchy it's attached to. Update sysfs_fill_super() and sysfs_kill_sb() so that they get and put the kernfs_root respectively. * sysfs_root is replaced with kernfs_root which is dynamically created by invoking kernfs_create_root() from sysfs_init(). This patch doesn't introduce any visible behavior changes. v2: kernfs_create_root() forgot to set @sd->priv. Fixed. Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/mount.c | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) (limited to 'fs/sysfs/mount.c') diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index 7cbd1fce2826..0b5661b462f7 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -32,15 +32,8 @@ static const struct super_operations sysfs_ops = { .evict_inode = sysfs_evict_inode, }; -static struct sysfs_dirent sysfs_root = { - .s_name = "", - .s_count = ATOMIC_INIT(1), - .s_flags = SYSFS_DIR, - .s_mode = S_IFDIR | S_IRUGO | S_IXUGO, - .s_ino = 1, -}; - -struct sysfs_dirent *sysfs_root_sd = &sysfs_root; +static struct kernfs_root *sysfs_root; +struct sysfs_dirent *sysfs_root_sd; static int sysfs_fill_super(struct super_block *sb) { @@ -68,6 +61,7 @@ static int sysfs_fill_super(struct super_block *sb) pr_debug("%s: could not get root dentry!\n", __func__); return -ENOMEM; } + kernfs_get(sysfs_root_sd); root->d_fsdata = sysfs_root_sd; sb->s_root = root; sb->s_d_op = &sysfs_dentry_ops; @@ -138,11 +132,15 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type, static void sysfs_kill_sb(struct super_block *sb) { struct sysfs_super_info *info = sysfs_info(sb); - /* Remove the superblock from fs_supers/s_instances + 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); free_sysfs_super_info(info); + kernfs_put(root_sd); } static struct file_system_type sysfs_fs_type = { @@ -166,12 +164,21 @@ int __init sysfs_init(void) if (err) goto out_err; + sysfs_root = kernfs_create_root(NULL); + if (IS_ERR(sysfs_root)) { + err = PTR_ERR(sysfs_root); + goto out_err; + } + sysfs_root_sd = sysfs_root->sd; + err = register_filesystem(&sysfs_fs_type); if (err) - goto out_err; + goto out_destroy_root; return 0; +out_destroy_root: + kernfs_destroy_root(sysfs_root); out_err: kmem_cache_destroy(sysfs_dir_cachep); sysfs_dir_cachep = NULL; -- cgit v1.2.3-59-g8ed1b