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Commit a618d31a authored by Daniel Rosenberg's avatar Daniel Rosenberg Committed by Alistair Strachan
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ANDROID: 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.

Bug: 62094374
Bug: 120446149
Change-Id: Ie769d7b3bb2f5972afe05c1bf16cf88c91647ab2
Signed-off-by: default avatarDaniel Rosenberg <drosen@google.com>
[astrachan: Folded 89a54ed3bf68 ("ANDROID: mnt: Fix next_descendent")
            into this patch]
Signed-off-by: default avatarAlistair Strachan <astrachan@google.com>
parent 50f0dd43

fs/namespace.c

+25 −1
Original line number Diff line number Diff line
@@ -200,6 +200,7 @@ static struct mount *alloc_vfsmnt(const char *name) 
		mnt->mnt_count = 1;

		mnt->mnt_writers = 0;

#endif

		mnt->mnt.data = NULL;



		INIT_HLIST_NODE(&mnt->mnt_hash);

		INIT_LIST_HEAD(&mnt->mnt_child);
@@ -552,6 +553,7 @@ int sb_prepare_remount_readonly(struct super_block *sb) 


static void free_vfsmnt(struct mount *mnt)

{

	kfree(mnt->mnt.data);

	kfree_const(mnt->mnt_devname);

#ifdef CONFIG_SMP

	free_percpu(mnt->mnt_pcp);
@@ -955,6 +957,14 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void 
	if (!mnt)

		return ERR_PTR(-ENOMEM);



	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 & SB_KERNMOUNT)

		mnt->mnt.mnt_flags = MNT_INTERNAL;
@@ -1002,6 +1012,14 @@ 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
@@ -2286,8 +2304,14 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags, 
		err = change_mount_flags(path->mnt, ms_flags);

	else if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))

		err = -EPERM;

	else

	else {

		err = do_remount_sb(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

+34 −0
Original line number Diff line number Diff line
@@ -607,3 +607,37 @@ int propagate_umount(struct list_head *list) 


	return 0;

}



/*

 *  Iterates over all slaves, and slaves of slaves.

 */

static struct mount *next_descendent(struct mount *root, struct mount *cur)

{

	if (!IS_MNT_NEW(cur) && !list_empty(&cur->mnt_slave_list))

		return first_slave(cur);

	do {

		struct mount *master = cur->mnt_master;



		if (!master || cur->mnt_slave.next != &master->mnt_slave_list) {

			struct mount *next = next_slave(cur);



			return (next == root) ? NULL : next;

		}

		cur = master;

	} while (cur != root);

	return NULL;

}



void propagate_remount(struct mount *mnt)

{

	struct mount *m = mnt;

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



	if (sb->s_op->copy_mnt_data) {

		m = next_descendent(mnt, m);

		while (m) {

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

			m = next_descendent(mnt, m);

		}

	}

}

fs/pnode.h

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ int propagate_mnt(struct mount *, struct mountpoint *, struct mount *, 
int propagate_umount(struct list_head *);

int propagate_mount_busy(struct mount *, int);

void propagate_mount_unlock(struct mount *);

void 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
@@ -1861,6 +1861,8 @@ 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 *);
@@ -2123,6 +2125,7 @@ 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
@@ -68,6 +68,7 @@ struct vfsmount { 
	struct dentry *mnt_root;	/* root of the mounted tree */

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

	int mnt_flags;

	void *data;

} __randomize_layout;



struct file; /* forward dec */