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kernfs: implement kernfs_root->supers list 

Currently, there's no way to find out which super_blocks are
associated with a given kernfs_root.  Let's implement it - the planned
inotify extension to kernfs_notify() needs it.

Make kernfs_super_info point back to the super_block and chain it at
kernfs_root->supers.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo 2014-04-09 11:07:30 -04:00 committed by Greg Kroah-Hartman
parent a798c10faf
commit 7d568a8383
4 changed files with 21 additions and 0 deletions
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1
fs/kernfs/dir.c
View File

@ -711,6 +711,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
return ERR_PTR(-ENOMEM);
ida_init(&root->ino_ida);
INIT_LIST_HEAD(&root->supers);
kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
KERNFS_DIR);

5
fs/kernfs/kernfs-internal.h
View File

@ -49,6 +49,8 @@ static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn)
* mount.c
*/
struct kernfs_super_info {
struct super_block *sb;
/*
* The root associated with this super_block. Each super_block is
* identified by the root and ns it's associated with.
@ -62,6 +64,9 @@ struct kernfs_super_info {
* an array and compare kernfs_node tag against every entry.
*/
const void *ns;
/* anchored at kernfs_root->supers, protected by kernfs_mutex */
struct list_head node;
};
#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))

11
fs/kernfs/mount.c
View File

@ -68,6 +68,7 @@ static int kernfs_fill_super(struct super_block *sb)
struct inode *inode;
struct dentry *root;
info->sb = sb;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = SYSFS_MAGIC;
@ -166,12 +167,18 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
*new_sb_created = !sb->s_root;
if (!sb->s_root) {
struct kernfs_super_info *info = kernfs_info(sb);
error = kernfs_fill_super(sb);
if (error) {
deactivate_locked_super(sb);
return ERR_PTR(error);
}
sb->s_flags |= MS_ACTIVE;
mutex_lock(&kernfs_mutex);
list_add(&info->node, &root->supers);
mutex_unlock(&kernfs_mutex);
}
return dget(sb->s_root);
@ -190,6 +197,10 @@ void kernfs_kill_sb(struct super_block *sb)
struct kernfs_super_info *info = kernfs_info(sb);
struct kernfs_node *root_kn = sb->s_root->d_fsdata;
mutex_lock(&kernfs_mutex);
list_del(&info->node);
mutex_unlock(&kernfs_mutex);
/*
* Remove the superblock from fs_supers/s_instances
* so we can't find it, before freeing kernfs_super_info.

4
include/linux/kernfs.h
View File

@ -144,6 +144,10 @@ struct kernfs_root {
/* private fields, do not use outside kernfs proper */
struct ida ino_ida;
struct kernfs_syscall_ops *syscall_ops;
/* list of kernfs_super_info of this root, protected by kernfs_mutex */
struct list_head supers;
wait_queue_head_t deactivate_waitq;
};