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Commit c9b3c815 authored by Daniel Rosenberg's avatar Daniel Rosenberg
Browse files

mnt: Add filesystem private data to mount points 



This starts to add private data associated directly
to mount points. The intent is to give filesystems
a sense of where they have come from, as a means of
letting a filesystem take different actions based on
this information.

Change-Id: Ie769d7b3bb2f5972afe05c1bf16cf88c91647ab2
Signed-off-by: default avatarDaniel Rosenberg <drosen@google.com>
parent 1aa4b87d

fs/namespace.c

+27 −1
Original line number Diff line number Diff line
@@ -568,6 +568,7 @@ int sb_prepare_remount_readonly(struct super_block *sb) 


static void free_vfsmnt(struct mount *mnt)

{

	kfree(mnt->mnt.data);

	kfree(mnt->mnt_devname);

#ifdef CONFIG_SMP

	free_percpu(mnt->mnt_pcp);
@@ -901,11 +902,21 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void 
	if (!mnt)

		return ERR_PTR(-ENOMEM);



	mnt->mnt.data = NULL;

	if (type->alloc_mnt_data) {

		mnt->mnt.data = type->alloc_mnt_data();

		if (!mnt->mnt.data) {

			mnt_free_id(mnt);

			free_vfsmnt(mnt);

			return ERR_PTR(-ENOMEM);

		}

	}

	if (flags & MS_KERNMOUNT)

		mnt->mnt.mnt_flags = MNT_INTERNAL;



	root = mount_fs(type, flags, name, data);

	if (IS_ERR(root)) {

		kfree(mnt->mnt.data);

		mnt_free_id(mnt);

		free_vfsmnt(mnt);

		return ERR_CAST(root);
@@ -933,6 +944,14 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, 
	if (!mnt)

		return ERR_PTR(-ENOMEM);



	if (sb->s_op->clone_mnt_data) {

		mnt->mnt.data = sb->s_op->clone_mnt_data(old->mnt.data);

		if (!mnt->mnt.data) {

			err = -ENOMEM;

			goto out_free;

		}

	}



	if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE))

		mnt->mnt_group_id = 0; /* not a peer of original */

	else
@@ -1000,6 +1019,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, 
	return mnt;



 out_free:

	kfree(mnt->mnt.data);

	mnt_free_id(mnt);

	free_vfsmnt(mnt);

	return ERR_PTR(err);
@@ -2122,8 +2142,14 @@ static int do_remount(struct path *path, int flags, int mnt_flags, 
		err = change_mount_flags(path->mnt, flags);

	else if (!capable(CAP_SYS_ADMIN))

		err = -EPERM;

	else

	else {

		err = do_remount_sb(sb, flags, data, 0);

		namespace_lock();

		lock_mount_hash();

		propagate_remount(mnt);

		unlock_mount_hash();

		namespace_unlock();

	}

	if (!err) {

		lock_mount_hash();

		mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;

fs/pnode.c

+14 −0
Original line number Diff line number Diff line
@@ -403,3 +403,17 @@ int propagate_umount(struct hlist_head *list) 
		__propagate_umount(mnt);

	return 0;

}



int propagate_remount(struct mount *mnt) {

	struct mount *m;

	struct super_block *sb = mnt->mnt.mnt_sb;

	int ret = 0;



	if (sb->s_op->copy_mnt_data) {

		for (m = first_slave(mnt); m->mnt_slave.next != &mnt->mnt_slave_list; m = next_slave(m)) {

			sb->s_op->copy_mnt_data(m->mnt.data, mnt->mnt.data);

		}

	}



	return ret;

}

fs/pnode.h

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ int propagate_mnt(struct mount *, struct mountpoint *, struct mount *, 
		struct hlist_head *);

int propagate_umount(struct hlist_head *);

int propagate_mount_busy(struct mount *, int);

int propagate_remount(struct mount *);

void mnt_release_group_id(struct mount *);

int get_dominating_id(struct mount *mnt, const struct path *root);

unsigned int mnt_get_count(struct mount *mnt);

include/linux/fs.h

+3 −0
Original line number Diff line number Diff line
@@ -1581,6 +1581,8 @@ struct super_operations { 
	int (*unfreeze_fs) (struct super_block *);

	int (*statfs) (struct dentry *, struct kstatfs *);

	int (*remount_fs) (struct super_block *, int *, char *);

	void *(*clone_mnt_data) (void *);

	void (*copy_mnt_data) (void *, void *);

	void (*umount_begin) (struct super_block *);



	int (*show_options)(struct seq_file *, struct dentry *);
@@ -1794,6 +1796,7 @@ struct file_system_type { 
#define FS_RENAME_DOES_D_MOVE	32768	/* FS will handle d_move() during rename() internally. */

	struct dentry *(*mount) (struct file_system_type *, int,

		       const char *, void *);

	void *(*alloc_mnt_data) (void);

	void (*kill_sb) (struct super_block *);

	struct module *owner;

	struct file_system_type * next;

include/linux/mount.h

+1 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ struct vfsmount { 
	struct dentry *mnt_root;	/* root of the mounted tree */

	struct super_block *mnt_sb;	/* pointer to superblock */

	int mnt_flags;

	void *data;

};



struct file; /* forward dec */