ovl: make use of ->layers safe in rcu pathwalk

[linux-2.6-microblaze.git] / fs / overlayfs / super.c

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 905d3aa..3fa2416 100644 (file)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -572,11 +572,6 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
        upper_layer->idx = 0;
        upper_layer->fsid = 0;
 
-       err = -ENOMEM;
-       upper_layer->name = kstrdup(ofs->config.upperdir, GFP_KERNEL);
-       if (!upper_layer->name)
-               goto out;
-
        /*
         * Inherit SB_NOSEC flag from upperdir.
         *
@@ -1125,7 +1120,8 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
                layers[ofs->numlayer].idx = ofs->numlayer;
                layers[ofs->numlayer].fsid = fsid;
                layers[ofs->numlayer].fs = &ofs->fs[fsid];
-               layers[ofs->numlayer].name = l->name;
+               /* Store for printing lowerdir=... in ovl_show_options() */
+               ofs->config.lowerdirs[ofs->numlayer] = l->name;
                l->name = NULL;
                ofs->numlayer++;
                ofs->fs[fsid].is_lower = true;
@@ -1370,8 +1366,16 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
        if (!layers)
                goto out_err;
 
+       ofs->config.lowerdirs = kcalloc(ctx->nr + 1, sizeof(char *), GFP_KERNEL);
+       if (!ofs->config.lowerdirs) {
+               kfree(layers);
+               goto out_err;
+       }
        ofs->layers = layers;
-       /* Layer 0 is reserved for upper even if there's no upper */
+       /*
+        * Layer 0 is reserved for upper even if there's no upper.
+        * For consistency, config.lowerdirs[0] is NULL.
+        */
        ofs->numlayer = 1;
 
        sb->s_stack_depth = 0;