ovl: remove unused code in lowerdir param parsing

Commit beae836e9c61 ("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: Amir Goldstein <amir73il@gmail.com>

diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index f6ff23fd101c8f3cda5f485c657a51b24fd565d1..0059cc405159ec2bc5bd252bf2de629af9c799e2 100644 (file)
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -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);
+       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);