fs/btrfs/export.c

   1 #include <linux/fs.h>
   2 #include <linux/types.h>
   3 #include "ctree.h"
   4 #include "disk-io.h"
   5 #include "btrfs_inode.h"
   6 #include "print-tree.h"
   7 #include "export.h"
   8
   9 #define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
  10                                                  parent_objectid) / 4)
  11 #define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
  12                                              parent_root_objectid) / 4)
  13 #define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
  14
  15 static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
  16                            struct inode *parent)
  17 {
  18         struct btrfs_fid *fid = (struct btrfs_fid *)fh;
  19         int len = *max_len;
  20         int type;
  21
  22         if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
  23                 *max_len = BTRFS_FID_SIZE_CONNECTABLE;
  24                 return FILEID_INVALID;
  25         } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
  26                 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
  27                 return FILEID_INVALID;
  28         }
  29
  30         len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
  31         type = FILEID_BTRFS_WITHOUT_PARENT;
  32
  33         fid->objectid = btrfs_ino(inode);
  34         fid->root_objectid = BTRFS_I(inode)->root->objectid;
  35         fid->gen = inode->i_generation;
  36
  37         if (parent) {
  38                 u64 parent_root_id;
  39
  40                 fid->parent_objectid = BTRFS_I(parent)->location.objectid;
  41                 fid->parent_gen = parent->i_generation;
  42                 parent_root_id = BTRFS_I(parent)->root->objectid;
  43
  44                 if (parent_root_id != fid->root_objectid) {
  45                         fid->parent_root_objectid = parent_root_id;
  46                         len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
  47                         type = FILEID_BTRFS_WITH_PARENT_ROOT;
  48                 } else {
  49                         len = BTRFS_FID_SIZE_CONNECTABLE;
  50                         type = FILEID_BTRFS_WITH_PARENT;
  51                 }
  52         }
  53
  54         *max_len = len;
  55         return type;
  56 }
  57
  58 static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
  59                                        u64 root_objectid, u32 generation,
  60                                        int check_generation)
  61 {
  62         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
  63         struct btrfs_root *root;
  64         struct inode *inode;
  65         struct btrfs_key key;
  66         int index;
  67         int err = 0;
  68
  69         if (objectid < BTRFS_FIRST_FREE_OBJECTID)
  70                 return ERR_PTR(-ESTALE);
  71
  72         key.objectid = root_objectid;
  73         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
  74         key.offset = (u64)-1;
  75
  76         index = srcu_read_lock(&fs_info->subvol_srcu);
  77
  78         root = btrfs_read_fs_root_no_name(fs_info, &key);
  79         if (IS_ERR(root)) {
  80                 err = PTR_ERR(root);
  81                 goto fail;
  82         }
  83
  84         key.objectid = objectid;
  85         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
  86         key.offset = 0;
  87
  88         inode = btrfs_iget(sb, &key, root, NULL);
  89         if (IS_ERR(inode)) {
  90                 err = PTR_ERR(inode);
  91                 goto fail;
  92         }
  93
  94         srcu_read_unlock(&fs_info->subvol_srcu, index);
  95
  96         if (check_generation && generation != inode->i_generation) {
  97                 iput(inode);
  98                 return ERR_PTR(-ESTALE);
  99         }
 100
 101         return d_obtain_alias(inode);
 102 fail:
 103         srcu_read_unlock(&fs_info->subvol_srcu, index);
 104         return ERR_PTR(err);
 105 }
 106
 107 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
 108                                          int fh_len, int fh_type)
 109 {
 110         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 111         u64 objectid, root_objectid;
 112         u32 generation;
 113
 114         if (fh_type == FILEID_BTRFS_WITH_PARENT) {
 115                 if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
 116                         return NULL;
 117                 root_objectid = fid->root_objectid;
 118         } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
 119                 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
 120                         return NULL;
 121                 root_objectid = fid->parent_root_objectid;
 122         } else
 123                 return NULL;
 124
 125         objectid = fid->parent_objectid;
 126         generation = fid->parent_gen;
 127
 128         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
 129 }
 130
 131 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
 132                                          int fh_len, int fh_type)
 133 {
 134         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 135         u64 objectid, root_objectid;
 136         u32 generation;
 137
 138         if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
 139              fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
 140             (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
 141              fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
 142             (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
 143              fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
 144                 return NULL;
 145
 146         objectid = fid->objectid;
 147         root_objectid = fid->root_objectid;
 148         generation = fid->gen;
 149
 150         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
 151 }
 152
 153 static struct dentry *btrfs_get_parent(struct dentry *child)
 154 {
 155         struct inode *dir = child->d_inode;
 156         struct btrfs_root *root = BTRFS_I(dir)->root;
 157         struct btrfs_path *path;
 158         struct extent_buffer *leaf;
 159         struct btrfs_root_ref *ref;
 160         struct btrfs_key key;
 161         struct btrfs_key found_key;
 162         int ret;
 163
 164         path = btrfs_alloc_path();
 165         if (!path)
 166                 return ERR_PTR(-ENOMEM);
 167
 168         if (btrfs_ino(dir) == BTRFS_FIRST_FREE_OBJECTID) {
 169                 key.objectid = root->root_key.objectid;
 170                 key.type = BTRFS_ROOT_BACKREF_KEY;
 171                 key.offset = (u64)-1;
 172                 root = root->fs_info->tree_root;
 173         } else {
 174                 key.objectid = btrfs_ino(dir);
 175                 key.type = BTRFS_INODE_REF_KEY;
 176                 key.offset = (u64)-1;
 177         }
 178
 179         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 180         if (ret < 0)
 181                 goto fail;
 182
 183         BUG_ON(ret == 0); /* Key with offset of -1 found */
 184         if (path->slots[0] == 0) {
 185                 ret = -ENOENT;
 186                 goto fail;
 187         }
 188
 189         path->slots[0]--;
 190         leaf = path->nodes[0];
 191
 192         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 193         if (found_key.objectid != key.objectid || found_key.type != key.type) {
 194                 ret = -ENOENT;
 195                 goto fail;
 196         }
 197
 198         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
 199                 ref = btrfs_item_ptr(leaf, path->slots[0],
 200                                      struct btrfs_root_ref);
 201                 key.objectid = btrfs_root_ref_dirid(leaf, ref);
 202         } else {
 203                 key.objectid = found_key.offset;
 204         }
 205         btrfs_free_path(path);
 206
 207         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
 208                 return btrfs_get_dentry(root->fs_info->sb, key.objectid,
 209                                         found_key.offset, 0, 0);
 210         }
 211
 212         key.type = BTRFS_INODE_ITEM_KEY;
 213         key.offset = 0;
 214         return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
 215 fail:
 216         btrfs_free_path(path);
 217         return ERR_PTR(ret);
 218 }
 219
 220 static int btrfs_get_name(struct dentry *parent, char *name,
 221                           struct dentry *child)
 222 {
 223         struct inode *inode = child->d_inode;
 224         struct inode *dir = parent->d_inode;
 225         struct btrfs_path *path;
 226         struct btrfs_root *root = BTRFS_I(dir)->root;
 227         struct btrfs_inode_ref *iref;
 228         struct btrfs_root_ref *rref;
 229         struct extent_buffer *leaf;
 230         unsigned long name_ptr;
 231         struct btrfs_key key;
 232         int name_len;
 233         int ret;
 234         u64 ino;
 235
 236         if (!dir || !inode)
 237                 return -EINVAL;
 238
 239         if (!S_ISDIR(dir->i_mode))
 240                 return -EINVAL;
 241
 242         ino = btrfs_ino(inode);
 243
 244         path = btrfs_alloc_path();
 245         if (!path)
 246                 return -ENOMEM;
 247         path->leave_spinning = 1;
 248
 249         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 250                 key.objectid = BTRFS_I(inode)->root->root_key.objectid;
 251                 key.type = BTRFS_ROOT_BACKREF_KEY;
 252                 key.offset = (u64)-1;
 253                 root = root->fs_info->tree_root;
 254         } else {
 255                 key.objectid = ino;
 256                 key.offset = btrfs_ino(dir);
 257                 key.type = BTRFS_INODE_REF_KEY;
 258         }
 259
 260         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 261         if (ret < 0) {
 262                 btrfs_free_path(path);
 263                 return ret;
 264         } else if (ret > 0) {
 265                 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 266                         path->slots[0]--;
 267                 } else {
 268                         btrfs_free_path(path);
 269                         return -ENOENT;
 270                 }
 271         }
 272         leaf = path->nodes[0];
 273
 274         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 275                 rref = btrfs_item_ptr(leaf, path->slots[0],
 276                                      struct btrfs_root_ref);
 277                 name_ptr = (unsigned long)(rref + 1);
 278                 name_len = btrfs_root_ref_name_len(leaf, rref);
 279         } else {
 280                 iref = btrfs_item_ptr(leaf, path->slots[0],
 281                                       struct btrfs_inode_ref);
 282                 name_ptr = (unsigned long)(iref + 1);
 283                 name_len = btrfs_inode_ref_name_len(leaf, iref);
 284         }
 285
 286         read_extent_buffer(leaf, name, name_ptr, name_len);
 287         btrfs_free_path(path);
 288
 289         /*
 290          * have to add the null termination to make sure that reconnect_path
 291          * gets the right len for strlen
 292          */
 293         name[name_len] = '\0';
 294
 295         return 0;
 296 }
 297
 298 const struct export_operations btrfs_export_ops = {
 299         .encode_fh      = btrfs_encode_fh,
 300         .fh_to_dentry   = btrfs_fh_to_dentry,
 301         .fh_to_parent   = btrfs_fh_to_parent,
 302         .get_parent     = btrfs_get_parent,
 303         .get_name       = btrfs_get_name,
 304 };