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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Michael Chang <mchang@suse.com>
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Date: Thu, 21 Aug 2014 03:39:11 +0000
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Subject: [PATCH] grub2-btrfs-03-follow_default
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---
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 grub-core/fs/btrfs.c | 107 ++++++++++++++++++++++++++++++++++++---------------
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 1 file changed, 76 insertions(+), 31 deletions(-)
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diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
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index 88d727d161f..a47d297567f 100644
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--- a/grub-core/fs/btrfs.c
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+++ b/grub-core/fs/btrfs.c
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@@ -920,6 +920,7 @@ grub_btrfs_mount (grub_device_t dev)
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 {
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   struct grub_btrfs_data *data;
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   grub_err_t err;
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+  const char *relpath = grub_env_get ("btrfs_relative_path");
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   if (!dev->disk)
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     {
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@@ -950,11 +951,14 @@ grub_btrfs_mount (grub_device_t dev)
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   data->devices_attached[0].dev = dev;
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   data->devices_attached[0].id = data->sblock.this_device.device_id;
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-  err = btrfs_handle_subvol (data);
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-  if (err)
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+  if (relpath && (relpath[0] == '1' || relpath[0] == 'y'))
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     {
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-      grub_free (data);
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-      return NULL;
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+      err = btrfs_handle_subvol (data);
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+      if (err)
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+      {
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+        grub_free (data);
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+        return NULL;
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+      }
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     }
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   return data;
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@@ -1414,24 +1418,39 @@ find_path (struct grub_btrfs_data *data,
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   grub_size_t allocated = 0;
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   struct grub_btrfs_dir_item *direl = NULL;
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   struct grub_btrfs_key key_out;
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+  int follow_default;
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   const char *ctoken;
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   grub_size_t ctokenlen;
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   char *path_alloc = NULL;
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   char *origpath = NULL;
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   unsigned symlinks_max = 32;
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+  const char *relpath = grub_env_get ("btrfs_relative_path");
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+  follow_default = 0;
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   origpath = grub_strdup (path);
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   if (!origpath)
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     return grub_errno;
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-  if (data->fs_tree)
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+  if (relpath && (relpath[0] == '1' || relpath[0] == 'y'))
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     {
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-      *type = GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY;
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-      *tree = data->fs_tree;
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-      /* This is a tree root, so everything starts at objectid 256 */
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-      key->object_id = grub_cpu_to_le64_compile_time (GRUB_BTRFS_OBJECT_ID_CHUNK);
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-      key->type = GRUB_BTRFS_ITEM_TYPE_DIR_ITEM;
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-      key->offset = 0;
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+      if (data->fs_tree)
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+        {
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+          *type = GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY;
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+          *tree = data->fs_tree;
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+          /* This is a tree root, so everything starts at objectid 256 */
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+          key->object_id = grub_cpu_to_le64_compile_time (GRUB_BTRFS_OBJECT_ID_CHUNK);
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+          key->type = GRUB_BTRFS_ITEM_TYPE_DIR_ITEM;
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+          key->offset = 0;
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+        }
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+      else
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+        {
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+          *type = GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY;
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+          *tree = data->sblock.root_tree;
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+          key->object_id = data->sblock.root_dir_objectid;
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+          key->type = GRUB_BTRFS_ITEM_TYPE_DIR_ITEM;
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+          key->offset = 0;
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+          follow_default = 1;
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+        }
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     }
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   else
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     {
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@@ -1442,15 +1461,23 @@ find_path (struct grub_btrfs_data *data,
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   while (1)
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     {
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-      while (path[0] == '/')
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-	path++;
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-      if (!path[0])
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-	break;
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-      slash = grub_strchr (path, '/');
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-      if (!slash)
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-	slash = path + grub_strlen (path);
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-      ctoken = path;
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-      ctokenlen = slash - path;
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+      if (!follow_default)
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+	{
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+	  while (path[0] == '/')
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+	    path++;
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+	  if (!path[0])
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+	    break;
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+	  slash = grub_strchr (path, '/');
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+	  if (!slash)
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+	    slash = path + grub_strlen (path);
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+	  ctoken = path;
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+	  ctokenlen = slash - path;
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+	}
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+      else
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+	{
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+	  ctoken = "default";
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+	  ctokenlen = sizeof ("default") - 1;
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+	}
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       if (*type != GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY)
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 	{
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@@ -1461,7 +1488,9 @@ find_path (struct grub_btrfs_data *data,
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       if (ctokenlen == 1 && ctoken[0] == '.')
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 	{
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-	  path = slash;
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+	  if (!follow_default)
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+	    path = slash;
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+	  follow_default = 0;
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 	  continue;
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 	}
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       if (ctokenlen == 2 && ctoken[0] == '.' && ctoken[1] == '.')
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@@ -1492,8 +1521,9 @@ find_path (struct grub_btrfs_data *data,
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 	  *type = GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY;
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 	  key->object_id = key_out.offset;
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-	  path = slash;
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-
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+	  if (!follow_default)
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+	    path = slash;
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+	  follow_default = 0;
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 	  continue;
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 	}
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@@ -1562,7 +1592,9 @@ find_path (struct grub_btrfs_data *data,
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 	  return err;
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 	}
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-      path = slash;
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+      if (!follow_default)
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+	path = slash;
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+      follow_default = 0;
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       if (cdirel->type == GRUB_BTRFS_DIR_ITEM_TYPE_SYMLINK)
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 	{
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 	  struct grub_btrfs_inode inode;
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@@ -1612,14 +1644,26 @@ find_path (struct grub_btrfs_data *data,
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 	  path = path_alloc = tmp;
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 	  if (path[0] == '/')
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 	    {
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-	      if (data->fs_tree)
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+              if (relpath && (relpath[0] == '1' || relpath[0] == 'y'))
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 		{
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-		  *type = GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY;
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-		  *tree = data->fs_tree;
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-		  /* This is a tree root, so everything starts at objectid 256 */
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-		  key->object_id = grub_cpu_to_le64_compile_time (GRUB_BTRFS_OBJECT_ID_CHUNK);
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-		  key->type = GRUB_BTRFS_ITEM_TYPE_DIR_ITEM;
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-		  key->offset = 0;
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+	          if (data->fs_tree)
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+		    {
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+		      *type = GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY;
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+		      *tree = data->fs_tree;
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+		      /* This is a tree root, so everything starts at objectid 256 */
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+		      key->object_id = grub_cpu_to_le64_compile_time (GRUB_BTRFS_OBJECT_ID_CHUNK);
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+		      key->type = GRUB_BTRFS_ITEM_TYPE_DIR_ITEM;
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+		      key->offset = 0;
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+		    }
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+		  else
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+		    {
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+	              *type = GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY;
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+	              *tree = data->sblock.root_tree;
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+	              key->object_id = data->sblock.root_dir_objectid;
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+	              key->type = GRUB_BTRFS_ITEM_TYPE_DIR_ITEM;
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+	              key->offset = 0;
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+	              follow_default = 1;
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+		    }
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 		}
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 	      else
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 		{
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@@ -2275,6 +2319,7 @@ GRUB_MOD_INIT (btrfs)
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                                subvolid_set_env);
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   grub_env_export ("btrfs_subvol");
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   grub_env_export ("btrfs_subvolid");
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+  grub_env_export ("btrfs_relative_path");
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 }
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 GRUB_MOD_FINI (btrfs)