xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

sysfs, kernfs: implement kernfs_create/destroy_root()

Browse Source 
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>
This commit is contained in:
Tejun Heo
2013-11-28 14:54:40 -05:00
committed by Greg Kroah-Hartman
parent 061447a496
commit ba7443bc65
4 changed files with 113 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
fs/sysfs/mount.c
View File

@@ -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;