Commit 7d568a83 authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a798c10f

fs/kernfs/dir.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

fs/kernfs/kernfs-internal.h

+5 −0
Original line number Diff line number Diff line
@@ -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))

fs/kernfs/mount.c

+11 −0
Original line number Diff line number Diff line
@@ -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.

include/linux/kernfs.h

+4 −0
Original line number Diff line number Diff line
@@ -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;

};

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