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Commit a0c9a8b8 authored by Al Viro's avatar Al Viro
Browse files

teach vfs_get_tree() to handle subtype, switch do_new_mount() to it 



Roll the handling of subtypes into do_new_mount() and vfs_get_tree().  The
former determines any subtype string and hangs it off the fs_context; the
latter applies it.

Make do_new_mount() create, parameterise and commit an fs_context and
create a mount for itself rather than calling vfs_kern_mount().

[AV -- missing kstrdup()]
[AV -- ... and no kstrdup() if we get to setting ->s_submount - we
simply transfer it from fc, leaving NULL behind]
[AV -- constify ->s_submount, while we are at it]

Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 8f291889

fs/namespace.c

+46 −31
Original line number Diff line number Diff line
@@ -2479,29 +2479,6 @@ static int do_move_mount(struct path *path, const char *old_name) 
	return err;

}



static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)

{

	int err;

	const char *subtype = strchr(fstype, '.');

	if (subtype) {

		subtype++;

		err = -EINVAL;

		if (!subtype[0])

			goto err;

	} else

		subtype = "";



	mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);

	err = -ENOMEM;

	if (!mnt->mnt_sb->s_subtype)

		goto err;

	return mnt;



 err:

	mntput(mnt);

	return ERR_PTR(err);

}



/*

 * add a mount into a namespace's mount tree

 */
@@ -2557,7 +2534,9 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, 
{

	struct file_system_type *type;

	struct vfsmount *mnt;

	int err;

	struct fs_context *fc;

	const char *subtype = NULL;

	int err = 0;



	if (!fstype)

		return -EINVAL;
@@ -2566,23 +2545,59 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, 
	if (!type)

		return -ENODEV;



	mnt = vfs_kern_mount(type, sb_flags, name, data);

	if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&

	    !mnt->mnt_sb->s_subtype)

		mnt = fs_set_subtype(mnt, fstype);

	if (type->fs_flags & FS_HAS_SUBTYPE) {

		subtype = strchr(fstype, '.');

		if (subtype) {

			subtype++;

			if (!*subtype) {

				put_filesystem(type);

				return -EINVAL;

			}

		} else {

			subtype = "";

		}

	}



	fc = fs_context_for_mount(type, sb_flags);

	put_filesystem(type);

	if (IS_ERR(mnt))

		return PTR_ERR(mnt);

	if (IS_ERR(fc))

		return PTR_ERR(fc);



	if (subtype) {

		fc->subtype = kstrdup(subtype, GFP_KERNEL);

		if (!fc->subtype)

			err = -ENOMEM;

	}

	if (!err && name) {

		fc->source = kstrdup(name, GFP_KERNEL);

		if (!fc->source)

			err = -ENOMEM;

	}

	if (!err)

		err = parse_monolithic_mount_data(fc, data);

	if (!err)

		err = vfs_get_tree(fc);

	if (err)

		goto out;



	up_write(&fc->root->d_sb->s_umount);

	mnt = vfs_create_mount(fc);

	if (IS_ERR(mnt)) {

		err = PTR_ERR(mnt);

		goto out;

	}



	if (mount_too_revealing(mnt, &mnt_flags)) {

		mntput(mnt);

		return -EPERM;

		err = -EPERM;

		goto out;

	}



	err = do_add_mount(real_mount(mnt), path, mnt_flags);

	if (err)

		mntput(mnt);

out:

	put_fs_context(fc);

	return err;

}

fs/super.c

+5 −0
Original line number Diff line number Diff line
@@ -1262,6 +1262,11 @@ int vfs_get_tree(struct fs_context *fc) 
	sb = fc->root->d_sb;

	WARN_ON(!sb->s_bdi);



	if (fc->subtype && !sb->s_subtype) {

		sb->s_subtype = fc->subtype;

		fc->subtype = NULL;

	}



	/*

	 * Write barrier is for super_cache_count(). We place it before setting

	 * SB_BORN as the data dependency between the two functions is the

include/linux/fs.h

+1 −1
Original line number Diff line number Diff line
@@ -1447,7 +1447,7 @@ struct super_block { 
	 * Filesystem subtype.  If non-empty the filesystem type field

	 * in /proc/mounts will be "type.subtype"

	 */

	char *s_subtype;

	const char *s_subtype;



	const struct dentry_operations *s_d_op; /* default d_op for dentries */