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authorTejun Heo <tj@kernel.org>2013-11-28 14:54:40 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-11-29 18:10:48 -0800
commitba7443bc656e5236c316b2acacc8b551f872910f (patch)
tree08b9a7a0504ae77abc634419167958ce4e6c4e64 /fs/sysfs/mount.c
parent061447a496b915f1dc8f8c645c6825f856d2bbac (diff)
downloadlinux-ba7443bc656e5236c316b2acacc8b551f872910f.tar.bz2
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 <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/sysfs/mount.c')
-rw-r--r--fs/sysfs/mount.c29
1 files changed, 18 insertions, 11 deletions
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;