Commit 819829f0 authored by Amir Goldstein's avatar Amir Goldstein
Browse files

ovl: refactor layer parsing helpers 



In preparation for new mount options to add lowerdirs one by one,
generalize ovl_parse_param_upperdir() into helper ovl_parse_layer()
that will be used for parsing a single lower layers.

Suggested-by: default avatarMiklos Szeredi <miklos@szeredi.hu>
Link: https://lore.kernel.org/r/CAJfpegt7VC94KkRtb1dfHG8+4OzwPBLYqhtc8=QFUxpFJE+=RQ@mail.gmail.com/


Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
parent 0cea4c09

fs/overlayfs/params.c

+67 −54
Original line number Diff line number Diff line
@@ -43,7 +43,7 @@ module_param_named(metacopy, ovl_metacopy_def, bool, 0644); 
MODULE_PARM_DESC(metacopy,

		 "Default to on or off for the metadata only copy up feature");



enum {

enum ovl_opt {

	Opt_lowerdir,

	Opt_upperdir,

	Opt_workdir,
@@ -238,19 +238,8 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path) 
		pr_err("failed to resolve '%s': %i\n", name, err);

		goto out;

	}

	err = -EINVAL;

	if (ovl_dentry_weird(path->dentry)) {

		pr_err("filesystem on '%s' not supported\n", name);

		goto out_put;

	}

	if (!d_is_dir(path->dentry)) {

		pr_err("'%s' not a directory\n", name);

		goto out_put;

	}

	return 0;



out_put:

	path_put_init(path);

out:

	return err;

}
@@ -268,7 +257,7 @@ static void ovl_unescape(char *s) 
	}

}



static int ovl_mount_dir(const char *name, struct path *path, bool upper)

static int ovl_mount_dir(const char *name, struct path *path)

{

	int err = -ENOMEM;

	char *tmp = kstrdup(name, GFP_KERNEL);
@@ -276,60 +265,82 @@ static int ovl_mount_dir(const char *name, struct path *path, bool upper) 
	if (tmp) {

		ovl_unescape(tmp);

		err = ovl_mount_dir_noesc(tmp, path);



		if (!err && upper && path->dentry->d_flags & DCACHE_OP_REAL) {

			pr_err("filesystem on '%s' not supported as upperdir\n",

			       tmp);

			path_put_init(path);

			err = -EINVAL;

		}

		kfree(tmp);

	}

	return err;

}



static int ovl_parse_param_upperdir(const char *name, struct fs_context *fc,

				    bool workdir)

static int ovl_mount_dir_check(struct fs_context *fc, const struct path *path,

			       enum ovl_opt layer, const char *name, bool upper)

{

	int err;

	struct ovl_fs *ofs = fc->s_fs_info;

	struct ovl_config *config = &ofs->config;

	struct ovl_fs_context *ctx = fc->fs_private;

	struct path path;

	char *dup;

	if (ovl_dentry_weird(path->dentry))

		return invalfc(fc, "filesystem on %s not supported", name);



	err = ovl_mount_dir(name, &path, true);

	if (err)

		return err;

	if (!d_is_dir(path->dentry))

		return invalfc(fc, "%s is not a directory", name);



	/*

	 * Check whether upper path is read-only here to report failures

	 * early. Don't forget to recheck when the superblock is created

	 * as the mount attributes could change.

	 */

	if (__mnt_is_readonly(path.mnt)) {

		path_put(&path);

		return -EINVAL;

	if (upper) {

		if (path->dentry->d_flags & DCACHE_OP_REAL)

			return invalfc(fc, "filesystem on %s not supported as upperdir", name);

		if (__mnt_is_readonly(path->mnt))

			return invalfc(fc, "filesystem on %s is read-only", name);

	}



	dup = kstrdup(name, GFP_KERNEL);

	if (!dup) {

		path_put(&path);

		return -ENOMEM;

	return 0;

}



	if (workdir) {

		kfree(config->workdir);

		config->workdir = dup;

		path_put(&ctx->work);

		ctx->work = path;

	} else {

		kfree(config->upperdir);

		config->upperdir = dup;

		path_put(&ctx->upper);

		ctx->upper = path;

static void ovl_add_layer(struct fs_context *fc, enum ovl_opt layer,

			 struct path *path, char **pname)

{

	struct ovl_fs *ofs = fc->s_fs_info;

	struct ovl_config *config = &ofs->config;

	struct ovl_fs_context *ctx = fc->fs_private;



	switch (layer) {

	case Opt_workdir:

		swap(config->workdir, *pname);

		swap(ctx->work, *path);

		break;

	case Opt_upperdir:

		swap(config->upperdir, *pname);

		swap(ctx->upper, *path);

		break;

	default:

		WARN_ON(1);

	}

	return 0;

}



static int ovl_parse_layer(struct fs_context *fc, struct fs_parameter *param,

			   enum ovl_opt layer)

{

	char *name = kstrdup(param->string, GFP_KERNEL);

	bool upper = (layer == Opt_upperdir || layer == Opt_workdir);

	struct path path;

	int err;



	if (!name)

		return -ENOMEM;



	err = ovl_mount_dir(name, &path);

	if (err)

		goto out_free;



	err = ovl_mount_dir_check(fc, &path, layer, name, upper);

	if (err)

		goto out_put;



	/* Store the user provided path string in ctx to show in mountinfo */

	ovl_add_layer(fc, layer, &path, &name);



out_put:

	path_put(&path);

out_free:

	kfree(name);

	return err;

}



static void ovl_reset_lowerdirs(struct ovl_fs_context *ctx)
@@ -417,7 +428,11 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
	for (nr = 0; nr < nr_lower; nr++, l++) {

		memset(l, 0, sizeof(*l));



		err = ovl_mount_dir(iter, &l->path, false);

		err = ovl_mount_dir(iter, &l->path);

		if (err)

			goto out_put;



		err = ovl_mount_dir_check(fc, &l->path, Opt_lowerdir, iter, false);

		if (err)

			goto out_put;
@@ -505,10 +520,8 @@ static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param) 
		err = ovl_parse_param_lowerdir(param->string, fc);

		break;

	case Opt_upperdir:

		fallthrough;

	case Opt_workdir:

		err = ovl_parse_param_upperdir(param->string, fc,

					       (Opt_workdir == opt));

		err = ovl_parse_layer(fc, param, opt);

		break;

	case Opt_default_permissions:

		config->default_permissions = true;