Commit c835110b authored by Amir Goldstein's avatar Amir Goldstein
Browse files

ovl: remove unused code in lowerdir param parsing 



Commit beae836e ("ovl: temporarily disable appending lowedirs")
removed the ability to append lowerdirs with syntax lowerdir=":<path>".
Remove leftover code and comments that are irrelevant with lowerdir
append mode disabled.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
parent bb7055a7

fs/overlayfs/params.c

+16 −79
Original line number Diff line number Diff line
@@ -346,7 +346,7 @@ static void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx) 
/*

 * Parse lowerdir= mount option:

 *

 * (1) lowerdir=/lower1:/lower2:/lower3::/data1::/data2

 * e.g.: lowerdir=/lower1:/lower2:/lower3::/data1::/data2

 *     Set "/lower1", "/lower2", and "/lower3" as lower layers and

 *     "/data1" and "/data2" as data lower layers. Any existing lower

 *     layers are replaced.
@@ -356,9 +356,9 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
	int err;

	struct ovl_fs_context *ctx = fc->fs_private;

	struct ovl_fs_context_layer *l;

	char *dup = NULL, *dup_iter;

	char *dup = NULL, *iter;

	ssize_t nr_lower = 0, nr = 0, nr_data = 0;

	bool append = false, data_layer = false;

	bool data_layer = false;



	/*

	 * Ensure we're backwards compatible with mount(2)
@@ -366,10 +366,10 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
	 */



	/* drop all existing lower layers */

	if (!*name) {

	ovl_parse_param_drop_lowerdir(ctx);



	if (!*name)

		return 0;

	}



	if (*name == ':') {

		pr_err("cannot append lower layer");
@@ -385,36 +385,11 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
	if (nr_lower < 0)

		goto out_err;



	if ((nr_lower > OVL_MAX_STACK) ||

	    (append && (size_add(ctx->nr, nr_lower) > OVL_MAX_STACK))) {

	if (nr_lower > OVL_MAX_STACK) {

		pr_err("too many lower directories, limit is %d\n", OVL_MAX_STACK);

		goto out_err;

	}



	if (!append)

		ovl_parse_param_drop_lowerdir(ctx);



	/*

	 * (1) append

	 *

	 * We want nr <= nr_lower <= capacity We know nr > 0 and nr <=

	 * capacity. If nr == 0 this wouldn't be append. If nr +

	 * nr_lower is <= capacity then nr <= nr_lower <= capacity

	 * already holds. If nr + nr_lower exceeds capacity, we realloc.

	 *

	 * (2) replace

	 *

	 * Ensure we're backwards compatible with mount(2) which allows

	 * "lowerdir=/a:/b:/c,lowerdir=/d:/e:/f" causing the last

	 * specified lowerdir mount option to win.

	 *

	 * We want nr <= nr_lower <= capacity We know either (i) nr == 0

	 * or (ii) nr > 0. We also know nr_lower > 0. The capacity

	 * could've been changed multiple times already so we only know

	 * nr <= capacity. If nr + nr_lower > capacity we realloc,

	 * otherwise nr <= nr_lower <= capacity holds already.

	 */

	nr_lower += ctx->nr;

	if (nr_lower > ctx->capacity) {

		err = -ENOMEM;

		l = krealloc_array(ctx->lower, nr_lower, sizeof(*ctx->lower),
@@ -426,41 +401,17 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
		ctx->capacity = nr_lower;

	}



	/*

	 *   (3) By (1) and (2) we know nr <= nr_lower <= capacity.

	 *   (4) If ctx->nr == 0 => replace

	 *       We have verified above that the lowerdir mount option

	 *       isn't an append, i.e., the lowerdir mount option

	 *       doesn't start with ":" or "::".

	 * (4.1) The lowerdir mount options only contains regular lower

	 *       layers ":".

	 *       => Nothing to verify.

	 * (4.2) The lowerdir mount options contains regular ":" and

	 *       data "::" layers.

	 *       => We need to verify that data lower layers "::" aren't

	 *          followed by regular ":" lower layers

	 *   (5) If ctx->nr > 0 => append

	 *       We know that there's at least one regular layer

	 *       otherwise we would've failed when parsing the previous

	 *       lowerdir mount option.

	 * (5.1) The lowerdir mount option is a regular layer ":" append

	 *       => We need to verify that no data layers have been

	 *          specified before.

	 * (5.2) The lowerdir mount option is a data layer "::" append

	 *       We know that there's at least one regular layer or

	 *       other data layers. => There's nothing to verify.

	 */

	dup_iter = dup;

	for (nr = ctx->nr; nr < nr_lower; nr++) {

		l = &ctx->lower[nr];

	iter = dup;

	l = ctx->lower;

	for (nr = 0; nr < nr_lower; nr++, l++) {

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



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

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

		if (err)

			goto out_put;



		err = -ENOMEM;

		l->name = kstrdup(dup_iter, GFP_KERNEL_ACCOUNT);

		l->name = kstrdup(iter, GFP_KERNEL_ACCOUNT);

		if (!l->name)

			goto out_put;
@@ -472,8 +423,8 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
			break;



		err = -EINVAL;

		dup_iter = strchr(dup_iter, '\0') + 1;

		if (*dup_iter) {

		iter = strchr(iter, '\0') + 1;

		if (*iter) {

			/*

			 * This is a regular layer so we require that

			 * there are no data layers.
@@ -489,7 +440,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 


		/* This is a data lower layer. */

		data_layer = true;

		dup_iter++;

		iter++;

	}

	ctx->nr = nr_lower;

	ctx->nr_data += nr_data;
@@ -497,21 +448,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
	return 0;



out_put:

	/*

	 * We know nr >= ctx->nr < nr_lower. If we failed somewhere

	 * we want to undo until nr == ctx->nr. This is correct for

	 * both ctx->nr == 0 and ctx->nr > 0.

	 */

	for (; nr >= ctx->nr; nr--) {

		l = &ctx->lower[nr];

		kfree(l->name);

		l->name = NULL;

		path_put(&l->path);



		/* don't overflow */

		if (nr == 0)

			break;

	}

	ovl_parse_param_drop_lowerdir(ctx);



out_err:

	kfree(dup);