From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Michael Chang <mchang@suse.com>

Date: Tue, 9 Jul 2019 13:56:16 +0200

Subject: [PATCH] grub2-btrfs-06-subvol-mount

---

 grub-core/fs/btrfs.c            | 195 +++++++++++++++++++++++++++++++++++++++-

 grub-core/osdep/linux/getroot.c | 148 +++++++++++++++++++++++++++++-

 util/grub-install.c             |  49 ++++++++++

 include/grub/emu/getroot.h      |   5 ++

 4 files changed, 392 insertions(+), 5 deletions(-)

diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c

index 113c1f746c9..d323746ecfa 100644

--- a/grub-core/fs/btrfs.c

+++ b/grub-core/fs/btrfs.c

@@ -41,6 +41,7 @@

 #include <grub/command.h>

 #include <grub/env.h>

 #include <grub/extcmd.h>

+#include <grub/list.h>

 #include <grub/crypto.h>

 #include <grub/diskfilter.h>

 #include <grub/safemath.h>

@@ -266,6 +267,12 @@ static grub_err_t

 grub_btrfs_read_logical (struct grub_btrfs_data *data,

 			 grub_disk_addr_t addr, void *buf, grub_size_t size,

 			 int recursion_depth);

+static grub_err_t

+get_root (struct grub_btrfs_data *data, struct grub_btrfs_key *key,

+	  grub_uint64_t *tree, grub_uint8_t *type);

+

+grub_uint64_t

+find_mtab_subvol_tree (const char *path, char **path_in_subvol);

 static grub_err_t

 read_sblock (grub_disk_t disk, struct grub_btrfs_superblock *sb)

@@ -1223,9 +1230,26 @@ lookup_root_by_name(struct grub_btrfs_data *data, const char *path)

   grub_err_t err;

   grub_uint64_t tree = 0;

   grub_uint8_t type;

+  grub_uint64_t saved_tree;

   struct grub_btrfs_key key;

+  if (path[0] == '\0')

+    {

+      data->fs_tree = 0;

+      return GRUB_ERR_NONE;

+    }

+

+  err = get_root (data, &key, &tree, &type);

+  if (err)

+    return err;

+

+  saved_tree = data->fs_tree;

+  data->fs_tree = tree;

+

   err = find_path (data, path, &key, &tree, &type);

+

+  data->fs_tree = saved_tree;

+

   if (err)

       return grub_error(GRUB_ERR_FILE_NOT_FOUND, "couldn't locate %s\n", path);

@@ -2199,11 +2223,20 @@ grub_btrfs_dir (grub_device_t device, const char *path,

   int r = 0;

   grub_uint64_t tree;

   grub_uint8_t type;

+  char *new_path = NULL;

   if (!data)

     return grub_errno;

-  err = find_path (data, path, &key_in, &tree, &type);

+  tree = find_mtab_subvol_tree (path, &new_path);

+

+  if (tree)

+    data->fs_tree = tree;

+

+  err = find_path (data, new_path ? new_path : path, &key_in, &tree, &type);

+  if (new_path)

+    grub_free (new_path);

+

   if (err)

     {

       grub_btrfs_unmount (data);

@@ -2305,11 +2338,21 @@ grub_btrfs_open (struct grub_file *file, const char *name)

   struct grub_btrfs_inode inode;

   grub_uint8_t type;

   struct grub_btrfs_key key_in;

+  grub_uint64_t tree;

+  char *new_path = NULL;

   if (!data)

     return grub_errno;

-  err = find_path (data, name, &key_in, &data->tree, &type);

+  tree = find_mtab_subvol_tree (name, &new_path);

+

+  if (tree)

+    data->fs_tree = tree;

+

+  err = find_path (data, new_path ? new_path : name, &key_in, &data->tree, &type);

+  if (new_path)

+    grub_free (new_path);

+

   if (err)

     {

       grub_btrfs_unmount (data);

@@ -2480,6 +2523,150 @@ grub_cmd_btrfs_info (grub_command_t cmd __attribute__ ((unused)), int argc,

   return 0;

 }

+struct grub_btrfs_mtab

+{

+  struct grub_btrfs_mtab *next;

+  struct grub_btrfs_mtab **prev;

+  char *path;

+  char *subvol;

+  grub_uint64_t tree;

+};

+

+typedef struct grub_btrfs_mtab* grub_btrfs_mtab_t;

+

+static struct grub_btrfs_mtab *btrfs_mtab;

+

+#define FOR_GRUB_MTAB(var) FOR_LIST_ELEMENTS (var, btrfs_mtab)

+#define FOR_GRUB_MTAB_SAFE(var, next) FOR_LIST_ELEMENTS_SAFE((var), (next), btrfs_mtab)

+

+static void

+add_mountpoint (const char *path, const char *subvol, grub_uint64_t tree)

+{

+  grub_btrfs_mtab_t m = grub_malloc (sizeof (*m));

+

+  m->path = grub_strdup (path);

+  m->subvol = grub_strdup (subvol);

+  m->tree = tree;

+  grub_list_push (GRUB_AS_LIST_P (&btrfs_mtab), GRUB_AS_LIST (m));

+}

+

+static grub_err_t

+grub_cmd_btrfs_mount_subvol (grub_command_t cmd __attribute__ ((unused)), int argc,

+		     char **argv)

+{

+  char *devname, *dirname, *subvol;

+  struct grub_btrfs_key key_in;

+  grub_uint8_t type;

+  grub_uint64_t tree;

+  grub_uint64_t saved_tree;

+  grub_err_t err;

+  struct grub_btrfs_data *data = NULL;

+  grub_device_t dev = NULL;

+

+  if (argc < 3)

+    return grub_error (GRUB_ERR_BAD_ARGUMENT, "required <dev> <dir> and <subvol>");

+

+  devname = grub_file_get_device_name(argv[0]);

+  dev = grub_device_open (devname);

+  grub_free (devname);

+

+  if (!dev)

+    {

+      err = grub_errno;

+      goto err_out;

+    }

+

+  dirname = argv[1];

+  subvol = argv[2];

+

+  data = grub_btrfs_mount (dev);

+  if (!data)

+    {

+      err = grub_errno;

+      goto err_out;

+    }

+

+  err = find_path (data, dirname, &key_in, &tree, &type);

+  if (err)

+    goto err_out;

+

+  if (type !=  GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY)

+    {

+      err = grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a directory"));

+      goto err_out;

+    }

+

+  err = get_root (data, &key_in, &tree, &type);

+

+  if (err)

+    goto err_out;

+

+  saved_tree = data->fs_tree;

+  data->fs_tree = tree;

+  err = find_path (data, subvol, &key_in, &tree, &type);

+  data->fs_tree = saved_tree;

+

+  if (err)

+    goto err_out;

+

+  if (key_in.object_id != grub_cpu_to_le64_compile_time (GRUB_BTRFS_OBJECT_ID_CHUNK) || tree == 0)

+    {

+      err = grub_error (GRUB_ERR_BAD_FILE_TYPE, "%s: not a subvolume\n", subvol);

+      goto err_out;

+    }

+

+  grub_btrfs_unmount (data);

+  grub_device_close (dev);

+  add_mountpoint (dirname, subvol, tree);

+

+  return GRUB_ERR_NONE;

+

+err_out:

+

+  if (data)

+    grub_btrfs_unmount (data);

+

+  if (dev)

+    grub_device_close (dev);

+

+  return err;

+}

+

+grub_uint64_t

+find_mtab_subvol_tree (const char *path, char **path_in_subvol)

+{

+  grub_btrfs_mtab_t m, cm;

+  grub_uint64_t tree;

+

+  if (!path || !path_in_subvol)

+    return 0;

+

+  *path_in_subvol = NULL;

+  tree = 0;

+  cm = NULL;

+

+  FOR_GRUB_MTAB (m)

+    {

+      if (grub_strncmp (path, m->path, grub_strlen (m->path)) == 0)

+	{

+	  if (!cm)

+	    cm = m;

+	  else

+	    if (grub_strcmp (m->path, cm->path) > 0)

+	      cm = m;

+	}

+    }

+

+  if (cm)

+    {

+      const char *s = path + grub_strlen (cm->path);

+      *path_in_subvol = (s[0] == '\0') ? grub_strdup ("/") : grub_strdup (s);

+      tree = cm->tree;

+    }

+

+  return tree;

+}

+

 static grub_err_t

 get_fs_root(struct grub_btrfs_data *data, grub_uint64_t tree,

             grub_uint64_t objectid, grub_uint64_t offset,

@@ -2686,6 +2873,7 @@ static struct grub_fs grub_btrfs_fs = {

 };

 static grub_command_t cmd_info;

+static grub_command_t cmd_mount_subvol;

 static grub_extcmd_t cmd_list_subvols;

 static char *

@@ -2749,6 +2937,9 @@ GRUB_MOD_INIT (btrfs)

   cmd_info = grub_register_command("btrfs-info", grub_cmd_btrfs_info,

 				   "DEVICE",

 				   "Print BtrFS info about DEVICE.");

+  cmd_mount_subvol = grub_register_command("btrfs-mount-subvol", grub_cmd_btrfs_mount_subvol,

+				   "DEVICE DIRECTORY SUBVOL",

+				   "Set btrfs DEVICE the DIRECTORY a mountpoint of SUBVOL.");

   cmd_list_subvols = grub_register_extcmd("btrfs-list-subvols",

 					 grub_cmd_btrfs_list_subvols, 0,

 					 "[-p|-n] [-o var] DEVICE",

diff --git a/grub-core/osdep/linux/getroot.c b/grub-core/osdep/linux/getroot.c

index caf9b1ccd3f..28790307e00 100644

--- a/grub-core/osdep/linux/getroot.c

+++ b/grub-core/osdep/linux/getroot.c

@@ -107,6 +107,14 @@ struct btrfs_ioctl_search_key

   grub_uint32_t unused[9];

 };

+struct btrfs_ioctl_search_header {

+  grub_uint64_t transid;

+  grub_uint64_t objectid;

+  grub_uint64_t offset;

+  grub_uint32_t type;

+  grub_uint32_t len;

+};

+

 struct btrfs_ioctl_search_args {

   struct btrfs_ioctl_search_key key;

   grub_uint64_t buf[(4096 - sizeof(struct btrfs_ioctl_search_key))

@@ -378,6 +386,109 @@ get_btrfs_fs_prefix (const char *mount_path)

 int use_relative_path_on_btrfs = 0;

+static char *

+get_btrfs_subvol (const char *path)

+{

+  struct btrfs_ioctl_ino_lookup_args args;

+  grub_uint64_t tree_id;

+  int fd = -1;

+  char *ret = NULL;

+

+  fd = open (path, O_RDONLY);

+

+  if (fd < 0)

+    return NULL;

+

+  memset (&args, 0, sizeof(args));

+  args.objectid = GRUB_BTRFS_TREE_ROOT_OBJECTID;

+

+  if (ioctl (fd, BTRFS_IOC_INO_LOOKUP, &args) < 0)

+    goto error;

+

+  tree_id = args.treeid;

+

+  while (tree_id != GRUB_BTRFS_ROOT_VOL_OBJECTID)

+    {

+      struct btrfs_ioctl_search_args sargs;

+      struct grub_btrfs_root_backref *br;

+      struct btrfs_ioctl_search_header *search_header;

+      char *old;

+      grub_uint16_t len;

+      grub_uint64_t inode_id;

+

+      memset (&sargs, 0, sizeof(sargs));

+

+      sargs.key.tree_id = 1;

+      sargs.key.min_objectid = tree_id;

+      sargs.key.max_objectid = tree_id;

+

+      sargs.key.min_offset = 0;

+      sargs.key.max_offset = ~0ULL;

+      sargs.key.min_transid = 0;

+      sargs.key.max_transid = ~0ULL;

+      sargs.key.min_type = GRUB_BTRFS_ITEM_TYPE_ROOT_BACKREF;

+      sargs.key.max_type = GRUB_BTRFS_ITEM_TYPE_ROOT_BACKREF;

+

+      sargs.key.nr_items = 1;

+

+      if (ioctl (fd, BTRFS_IOC_TREE_SEARCH, &sargs) < 0)

+	goto error;

+

+      if (sargs.key.nr_items == 0)

+	goto error;

+

+      search_header = (struct btrfs_ioctl_search_header *)sargs.buf;

+      br = (struct grub_btrfs_root_backref *) (search_header + 1);

+

+      len = grub_le_to_cpu16 (br->n);

+      inode_id = grub_le_to_cpu64 (br->inode_id);

+      tree_id = search_header->offset;

+

+      old = ret;

+      ret = malloc (len + 1);

+      memcpy (ret, br->name, len);

+      ret[len] = '\0';

+

+      if (inode_id != GRUB_BTRFS_TREE_ROOT_OBJECTID)

+	{

+	  char *s;

+

+	  memset(&args, 0, sizeof(args));

+	  args.treeid = search_header->offset;

+	  args.objectid = inode_id;

+

+	  if (ioctl (fd, BTRFS_IOC_INO_LOOKUP, &args) < 0)

+	    goto error;

+

+	  s = xasprintf ("%s%s", args.name, ret);

+	  free (ret);

+	  ret = s;

+	}

+

+      if (old)

+	{

+	  char *s = xasprintf ("%s/%s", ret, old);

+	  free (ret);

+	  free (old);

+	  ret = s;

+	}

+    }

+

+  close (fd);

+  return ret;

+

+error:

+

+  if (fd >= 0)

+    close (fd);

+  if (ret)

+    free (ret);

+

+  return NULL;

+}

+

+void (*grub_find_root_btrfs_mount_path_hook)(const char *mount_path);

+

 char **

 grub_find_root_devices_from_mountinfo (const char *dir, char **relroot)

 {

@@ -519,12 +630,15 @@ again:

       else if (grub_strcmp (entries[i].fstype, "btrfs") == 0)

 	{

 	  ret = grub_find_root_devices_from_btrfs (dir);

-	  fs_prefix = get_btrfs_fs_prefix (entries[i].enc_path);

 	  if (use_relative_path_on_btrfs)

 	    {

-	      if (fs_prefix)

-	        free (fs_prefix);

 	      fs_prefix = xstrdup ("/");

+	      if (grub_find_root_btrfs_mount_path_hook)

+		grub_find_root_btrfs_mount_path_hook (entries[i].enc_path);

+	    }

+	  else

+	    {

+	      fs_prefix = get_btrfs_fs_prefix (entries[i].enc_path);

 	    }

 	}

       else if (!retry && grub_strcmp (entries[i].fstype, "autofs") == 0)

@@ -1150,6 +1264,34 @@ grub_util_get_grub_dev_os (const char *os_dev)

   return grub_dev;

 }

+

+char *

+grub_util_get_btrfs_subvol (const char *path, char **mount_path)

+{

+  char *mp = NULL;

+

+  if (mount_path)

+    *mount_path = NULL;

+

+  auto void

+  mount_path_hook (const char *m)

+  {

+    mp = strdup (m);

+  }

+

+  grub_find_root_btrfs_mount_path_hook = mount_path_hook;

+  grub_free (grub_find_root_devices_from_mountinfo (path, NULL));

+  grub_find_root_btrfs_mount_path_hook = NULL;

+

+  if (!mp)

+    return NULL;

+

+  if (mount_path)

+    *mount_path = mp;

+

+  return get_btrfs_subvol (mp);

+}

+

 char *

 grub_make_system_path_relative_to_its_root_os (const char *path)

 {

diff --git a/util/grub-install.c b/util/grub-install.c

index 0f66f36d23a..84ed6e88ecb 100644

--- a/util/grub-install.c

+++ b/util/grub-install.c

@@ -1569,6 +1569,55 @@ main (int argc, char *argv[])

       prefix_drive = xasprintf ("(%s)", grub_drives[0]);

     }

+#ifdef __linux__

+

+  if (config.is_suse_btrfs_snapshot_enabled

+      && grub_strncmp(grub_fs->name, "btrfs", sizeof ("btrfs") - 1) == 0)

+    {

+      char *subvol = NULL;

+      char *mount_path = NULL;

+      char **rootdir_devices = NULL;

+      char *rootdir_path = grub_util_path_concat (2, "/", rootdir);

+

+      if (grub_util_is_directory (rootdir_path))

+	rootdir_devices = grub_guess_root_devices (rootdir_path);

+

+      free (rootdir_path);

+

+      if (rootdir_devices && rootdir_devices[0])

+	if (grub_strcmp (rootdir_devices[0], grub_devices[0]) == 0)

+	  subvol = grub_util_get_btrfs_subvol (platdir, &mount_path);

+

+      if (subvol && mount_path)

+	{

+	  char *def_subvol;

+

+	  def_subvol = grub_util_get_btrfs_subvol ("/", NULL);

+

+	  if (def_subvol)

+	    {

+	      if (!load_cfg_f)

+		load_cfg_f = grub_util_fopen (load_cfg, "wb");

+	      have_load_cfg = 1;

+

+	      if (grub_strcmp (subvol, def_subvol) != 0)

+		fprintf (load_cfg_f, "btrfs-mount-subvol ($root) %s %s\n", mount_path, subvol);

+	      free (def_subvol);

+	    }

+	}

+

+      for (curdev = rootdir_devices; *curdev; curdev++)

+	free (*curdev);

+      if (rootdir_devices)

+	free (rootdir_devices);

+      if (subvol)

+	free (subvol);

+      if (mount_path)

+	free (mount_path);

+    }

+

+#endif

+

   char mkimage_target[200];

   const char *core_name = NULL;

diff --git a/include/grub/emu/getroot.h b/include/grub/emu/getroot.h

index 73fa2d34abb..9c642ae3fe3 100644

--- a/include/grub/emu/getroot.h

+++ b/include/grub/emu/getroot.h

@@ -53,6 +53,11 @@ char **

 grub_find_root_devices_from_mountinfo (const char *dir, char **relroot);

 #endif

+#ifdef __linux__

+char *

+grub_util_get_btrfs_subvol (const char *path, char **mount_path);

+#endif

+

 /* Devmapper functions provided by getroot_devmapper.c.  */

 void

 grub_util_pull_devmapper (const char *os_dev);