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Commit 8e31748d authored by Daniel Rosenberg's avatar Daniel Rosenberg Committed by Alistair Delva
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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
Bug: 122428178
Change-Id: Ie769d7b3bb2f5972afe05c1bf16cf88c91647ab2
Signed-off-by: default avatarDaniel Rosenberg <drosen@google.com>
[astrachan: Folded 89a54ed3bf68 ("ANDROID: mnt: Fix next_descendent")
            into this patch]
[drosen: Folded 138993ea820 ("Android: mnt: Propagate remount
         correctly") into this patch, integrated fs_context things
	 Now has update_mnt_data instead of needing remount2
Signed-off-by: default avatarAlistair Strachan <astrachan@google.com>
parent 4d53a040

fs/namespace.c

+27 −1
Original line number Diff line number Diff line
@@ -203,6 +203,7 @@ 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);
@@ -962,6 +964,15 @@ struct vfsmount *vfs_create_mount(struct fs_context *fc) 
	if (!mnt)

		return ERR_PTR(-ENOMEM);



	if (fc->fs_type->alloc_mnt_data) {

		mnt->mnt.data = fc->fs_type->alloc_mnt_data();

		if (!mnt->mnt.data) {

			mnt_free_id(mnt);

			free_vfsmnt(mnt);

			return ERR_PTR(-ENOMEM);

		}

		fc->root->d_sb->s_op->update_mnt_data(mnt->mnt.data, fc);

	}

	if (fc->sb_flags & SB_KERNMOUNT)

		mnt->mnt.mnt_flags = MNT_INTERNAL;
@@ -1045,6 +1056,14 @@ 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
@@ -2531,8 +2550,15 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags, 
		err = -EPERM;

		if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) {

			err = reconfigure_super(fc);

			if (!err)

			if (!err) {

				sb->s_op->update_mnt_data(mnt->mnt.data, fc);

				set_mount_attributes(mnt, mnt_flags);

				namespace_lock();

				lock_mount_hash();

				propagate_remount(mnt);

				unlock_mount_hash();

				namespace_unlock();

			}

		}

		up_write(&sb->s_umount);

	}

fs/pnode.c

+16 −0
Original line number Diff line number Diff line
@@ -601,3 +601,19 @@ int propagate_umount(struct list_head *list) 


	return 0;

}



void propagate_remount(struct mount *mnt)

{

	struct mount *parent = mnt->mnt_parent;

	struct mount *p = mnt, *m;

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



	if (!sb->s_op->copy_mnt_data)

		return;

	for (p = propagation_next(parent, parent); p;

				p = propagation_next(p, parent)) {

		m = __lookup_mnt(&p->mnt, mnt->mnt_mountpoint);

		if (m)

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

	}

}

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 *, 
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

+4 −0
Original line number Diff line number Diff line
@@ -1936,6 +1936,9 @@ 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 (*update_mnt_data) (void *, struct fs_context *);

	void (*umount_begin) (struct super_block *);



	int (*show_options)(struct seq_file *, struct dentry *);
@@ -2203,6 +2206,7 @@ struct file_system_type { 
	const struct fs_parameter_description *parameters;

	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
@@ -69,6 +69,7 @@ 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 */