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 #include "compat.h"
   9
  10 #define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
  11                                                  parent_objectid) / 4)
  12 #define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
  13                                              parent_root_objectid) / 4)
  14 #define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
  15
  16 static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
  17                            struct inode *parent)
  18 {
  19         struct btrfs_fid *fid = (struct btrfs_fid *)fh;
  20         int len = *max_len;
  21         int type;
  22
  23         if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
  24                 *max_len = BTRFS_FID_SIZE_CONNECTABLE;
  25                 return FILEID_INVALID;
  26         } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
  27                 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
  28                 return FILEID_INVALID;
  29         }
  30
  31         len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
  32         type = FILEID_BTRFS_WITHOUT_PARENT;
  33
  34         fid->objectid = btrfs_ino(inode);
  35         fid->root_objectid = BTRFS_I(inode)->root->objectid;
  36         fid->gen = inode->i_generation;
  37
  38         if (parent) {
  39                 u64 parent_root_id;
  40
  41                 fid->parent_objectid = BTRFS_I(parent)->location.objectid;
  42                 fid->parent_gen = parent->i_generation;
  43                 parent_root_id = BTRFS_I(parent)->root->objectid;
  44
  45                 if (parent_root_id != fid->root_objectid) {
  46                         fid->parent_root_objectid = parent_root_id;
  47                         len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
  48                         type = FILEID_BTRFS_WITH_PARENT_ROOT;
  49                 } else {
  50                         len = BTRFS_FID_SIZE_CONNECTABLE;
  51                         type = FILEID_BTRFS_WITH_PARENT;
  52                 }
  53         }
  54
  55         *max_len = len;
  56         return type;
  57 }
  58
  59 static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
  60                                        u64 root_objectid, u32 generation,
  61                                        int check_generation)
  62 {
  63         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
  64         struct btrfs_root *root;
  65         struct inode *inode;
  66         struct btrfs_key key;
  67         int index;
  68         int err = 0;
  69
  70         if (objectid < BTRFS_FIRST_FREE_OBJECTID)
  71                 return ERR_PTR(-ESTALE);
  72
  73         key.objectid = root_objectid;
  74         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
  75         key.offset = (u64)-1;
  76
  77         index = srcu_read_lock(&fs_info->subvol_srcu);
  78
  79         root = btrfs_read_fs_root_no_name(fs_info, &key);
  80         if (IS_ERR(root)) {
  81                 err = PTR_ERR(root);
  82                 goto fail;
  83         }
  84
  85         if (btrfs_root_refs(&root->root_item) == 0) {
  86                 err = -ENOENT;
  87                 goto fail;
  88         }
  89
  90         key.objectid = objectid;
  91         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
  92         key.offset = 0;
  93
  94         inode = btrfs_iget(sb, &key, root, NULL);
  95         if (IS_ERR(inode)) {
  96                 err = PTR_ERR(inode);
  97                 goto fail;
  98         }
  99
 100         srcu_read_unlock(&fs_info->subvol_srcu, index);
 101
 102         if (check_generation && generation != inode->i_generation) {
 103                 iput(inode);
 104                 return ERR_PTR(-ESTALE);
 105         }
 106
 107         return d_obtain_alias(inode);
 108 fail:
 109         srcu_read_unlock(&fs_info->subvol_srcu, index);
 110         return ERR_PTR(err);
 111 }
 112
 113 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
 114                                          int fh_len, int fh_type)
 115 {
 116         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 117         u64 objectid, root_objectid;
 118         u32 generation;
 119
 120         if (fh_type == FILEID_BTRFS_WITH_PARENT) {
 121                 if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
 122                         return NULL;
 123                 root_objectid = fid->root_objectid;
 124         } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
 125                 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
 126                         return NULL;
 127                 root_objectid = fid->parent_root_objectid;
 128         } else
 129                 return NULL;
 130
 131         objectid = fid->parent_objectid;
 132         generation = fid->parent_gen;
 133
 134         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
 135 }
 136
 137 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
 138                                          int fh_len, int fh_type)
 139 {
 140         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 141         u64 objectid, root_objectid;
 142         u32 generation;
 143
 144         if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
 145              fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
 146             (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
 147              fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
 148             (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
 149              fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
 150                 return NULL;
 151
 152         objectid = fid->objectid;
 153         root_objectid = fid->root_objectid;
 154         generation = fid->gen;
 155
 156         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
 157 }
 158
 159 static struct dentry *btrfs_get_parent(struct dentry *child)
 160 {
 161         struct inode *dir = child->d_inode;
 162         struct btrfs_root *root = BTRFS_I(dir)->root;
 163         struct btrfs_path *path;
 164         struct extent_buffer *leaf;
 165         struct btrfs_root_ref *ref;
 166         struct btrfs_key key;
 167         struct btrfs_key found_key;
 168         int ret;
 169
 170         path = btrfs_alloc_path();
 171         if (!path)
 172                 return ERR_PTR(-ENOMEM);
 173
 174         if (btrfs_ino(dir) == BTRFS_FIRST_FREE_OBJECTID) {
 175                 key.objectid = root->root_key.objectid;
 176                 key.type = BTRFS_ROOT_BACKREF_KEY;
 177                 key.offset = (u64)-1;
 178                 root = root->fs_info->tree_root;
 179         } else {
 180                 key.objectid = btrfs_ino(dir);
 181                 key.type = BTRFS_INODE_REF_KEY;
 182                 key.offset = (u64)-1;
 183         }
 184
 185         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 186         if (ret < 0)
 187                 goto fail;
 188
 189         BUG_ON(ret == 0); /* Key with offset of -1 found */
 190         if (path->slots[0] == 0) {
 191                 ret = -ENOENT;
 192                 goto fail;
 193         }
 194
 195         path->slots[0]--;
 196         leaf = path->nodes[0];
 197
 198         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 199         if (found_key.objectid != key.objectid || found_key.type != key.type) {
 200                 ret = -ENOENT;
 201                 goto fail;
 202         }
 203
 204         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
 205                 ref = btrfs_item_ptr(leaf, path->slots[0],
 206                                      struct btrfs_root_ref);
 207                 key.objectid = btrfs_root_ref_dirid(leaf, ref);
 208         } else {
 209                 key.objectid = found_key.offset;
 210         }
 211         btrfs_free_path(path);
 212
 213         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
 214                 return btrfs_get_dentry(root->fs_info->sb, key.objectid,
 215                                         found_key.offset, 0, 0);
 216         }
 217
 218         key.type = BTRFS_INODE_ITEM_KEY;
 219         key.offset = 0;
 220         return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
 221 fail:
 222         btrfs_free_path(path);
 223         return ERR_PTR(ret);
 224 }
 225
 226 static int btrfs_get_name(struct dentry *parent, char *name,
 227                           struct dentry *child)
 228 {
 229         struct inode *inode = child->d_inode;
 230         struct inode *dir = parent->d_inode;
 231         struct btrfs_path *path;
 232         struct btrfs_root *root = BTRFS_I(dir)->root;
 233         struct btrfs_inode_ref *iref;
 234         struct btrfs_root_ref *rref;
 235         struct extent_buffer *leaf;
 236         unsigned long name_ptr;
 237         struct btrfs_key key;
 238         int name_len;
 239         int ret;
 240         u64 ino;
 241
 242         if (!dir || !inode)
 243                 return -EINVAL;
 244
 245         if (!S_ISDIR(dir->i_mode))
 246                 return -EINVAL;
 247
 248         ino = btrfs_ino(inode);
 249
 250         path = btrfs_alloc_path();
 251         if (!path)
 252                 return -ENOMEM;
 253         path->leave_spinning = 1;
 254
 255         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 256                 key.objectid = BTRFS_I(inode)->root->root_key.objectid;
 257                 key.type = BTRFS_ROOT_BACKREF_KEY;
 258                 key.offset = (u64)-1;
 259                 root = root->fs_info->tree_root;
 260         } else {
 261                 key.objectid = ino;
 262                 key.offset = btrfs_ino(dir);
 263                 key.type = BTRFS_INODE_REF_KEY;
 264         }
 265
 266         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 267         if (ret < 0) {
 268                 btrfs_free_path(path);
 269                 return ret;
 270         } else if (ret > 0) {
 271                 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 272                         path->slots[0]--;
 273                 } else {
 274                         btrfs_free_path(path);
 275                         return -ENOENT;
 276                 }
 277         }
 278         leaf = path->nodes[0];
 279
 280         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 281                 rref = btrfs_item_ptr(leaf, path->slots[0],
 282                                      struct btrfs_root_ref);
 283                 name_ptr = (unsigned long)(rref + 1);
 284                 name_len = btrfs_root_ref_name_len(leaf, rref);
 285         } else {
 286                 iref = btrfs_item_ptr(leaf, path->slots[0],
 287                                       struct btrfs_inode_ref);
 288                 name_ptr = (unsigned long)(iref + 1);
 289                 name_len = btrfs_inode_ref_name_len(leaf, iref);
 290         }
 291
 292         read_extent_buffer(leaf, name, name_ptr, name_len);
 293         btrfs_free_path(path);
 294
 295         /*
 296          * have to add the null termination to make sure that reconnect_path
 297          * gets the right len for strlen
 298          */
 299         name[name_len] = '\0';
 300
 301         return 0;
 302 }
 303
 304 const struct export_operations btrfs_export_ops = {
 305         .encode_fh      = btrfs_encode_fh,
 306         .fh_to_dentry   = btrfs_fh_to_dentry,
 307         .fh_to_parent   = btrfs_fh_to_parent,
 308         .get_parent     = btrfs_get_parent,
 309         .get_name       = btrfs_get_name,
 310 };