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 dentry *dentry, u32 *fh, int *max_len,
  17                            int connectable)
  18 {
  19         struct btrfs_fid *fid = (struct btrfs_fid *)fh;
  20         struct inode *inode = dentry->d_inode;
  21         int len = *max_len;
  22         int type;
  23
  24         if (connectable && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
  25                 *max_len = BTRFS_FID_SIZE_CONNECTABLE;
  26                 return 255;
  27         } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
  28                 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
  29                 return 255;
  30         }
  31
  32         len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
  33         type = FILEID_BTRFS_WITHOUT_PARENT;
  34
  35         fid->objectid = btrfs_ino(inode);
  36         fid->root_objectid = BTRFS_I(inode)->root->objectid;
  37         fid->gen = inode->i_generation;
  38
  39         if (connectable && !S_ISDIR(inode->i_mode)) {
  40                 struct inode *parent;
  41                 u64 parent_root_id;
  42
  43                 spin_lock(&dentry->d_lock);
  44
  45                 parent = dentry->d_parent->d_inode;
  46                 fid->parent_objectid = BTRFS_I(parent)->location.objectid;
  47                 fid->parent_gen = parent->i_generation;
  48                 parent_root_id = BTRFS_I(parent)->root->objectid;
  49
  50                 spin_unlock(&dentry->d_lock);
  51
  52                 if (parent_root_id != fid->root_objectid) {
  53                         fid->parent_root_objectid = parent_root_id;
  54                         len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
  55                         type = FILEID_BTRFS_WITH_PARENT_ROOT;
  56                 } else {
  57                         len = BTRFS_FID_SIZE_CONNECTABLE;
  58                         type = FILEID_BTRFS_WITH_PARENT;
  59                 }
  60         }
  61
  62         *max_len = len;
  63         return type;
  64 }
  65
  66 static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
  67                                        u64 root_objectid, u32 generation,
  68                                        int check_generation)
  69 {
  70         struct btrfs_fs_info *fs_info = btrfs_sb(sb)->fs_info;
  71         struct btrfs_root *root;
  72         struct inode *inode;
  73         struct btrfs_key key;
  74         int index;
  75         int err = 0;
  76
  77         if (objectid < BTRFS_FIRST_FREE_OBJECTID)
  78                 return ERR_PTR(-ESTALE);
  79
  80         key.objectid = root_objectid;
  81         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
  82         key.offset = (u64)-1;
  83
  84         index = srcu_read_lock(&fs_info->subvol_srcu);
  85
  86         root = btrfs_read_fs_root_no_name(fs_info, &key);
  87         if (IS_ERR(root)) {
  88                 err = PTR_ERR(root);
  89                 goto fail;
  90         }
  91
  92         if (btrfs_root_refs(&root->root_item) == 0) {
  93                 err = -ENOENT;
  94                 goto fail;
  95         }
  96
  97         key.objectid = objectid;
  98         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
  99         key.offset = 0;
 100
 101         inode = btrfs_iget(sb, &key, root, NULL);
 102         if (IS_ERR(inode)) {
 103                 err = PTR_ERR(inode);
 104                 goto fail;
 105         }
 106
 107         srcu_read_unlock(&fs_info->subvol_srcu, index);
 108
 109         if (check_generation && generation != inode->i_generation) {
 110                 iput(inode);
 111                 return ERR_PTR(-ESTALE);
 112         }
 113
 114         return d_obtain_alias(inode);
 115 fail:
 116         srcu_read_unlock(&fs_info->subvol_srcu, index);
 117         return ERR_PTR(err);
 118 }
 119
 120 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
 121                                          int fh_len, int fh_type)
 122 {
 123         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 124         u64 objectid, root_objectid;
 125         u32 generation;
 126
 127         if (fh_type == FILEID_BTRFS_WITH_PARENT) {
 128                 if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
 129                         return NULL;
 130                 root_objectid = fid->root_objectid;
 131         } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
 132                 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
 133                         return NULL;
 134                 root_objectid = fid->parent_root_objectid;
 135         } else
 136                 return NULL;
 137
 138         objectid = fid->parent_objectid;
 139         generation = fid->parent_gen;
 140
 141         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
 142 }
 143
 144 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
 145                                          int fh_len, int fh_type)
 146 {
 147         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 148         u64 objectid, root_objectid;
 149         u32 generation;
 150
 151         if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
 152              fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
 153             (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
 154              fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
 155             (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
 156              fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
 157                 return NULL;
 158
 159         objectid = fid->objectid;
 160         root_objectid = fid->root_objectid;
 161         generation = fid->gen;
 162
 163         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
 164 }
 165
 166 static struct dentry *btrfs_get_parent(struct dentry *child)
 167 {
 168         struct inode *dir = child->d_inode;
 169         struct btrfs_root *root = BTRFS_I(dir)->root;
 170         struct btrfs_path *path;
 171         struct extent_buffer *leaf;
 172         struct btrfs_root_ref *ref;
 173         struct btrfs_key key;
 174         struct btrfs_key found_key;
 175         int ret;
 176
 177         path = btrfs_alloc_path();
 178         if (!path)
 179                 return ERR_PTR(-ENOMEM);
 180
 181         if (btrfs_ino(dir) == BTRFS_FIRST_FREE_OBJECTID) {
 182                 key.objectid = root->root_key.objectid;
 183                 key.type = BTRFS_ROOT_BACKREF_KEY;
 184                 key.offset = (u64)-1;
 185                 root = root->fs_info->tree_root;
 186         } else {
 187                 key.objectid = btrfs_ino(dir);
 188                 key.type = BTRFS_INODE_REF_KEY;
 189                 key.offset = (u64)-1;
 190         }
 191
 192         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 193         if (ret < 0)
 194                 goto fail;
 195
 196         BUG_ON(ret == 0);
 197         if (path->slots[0] == 0) {
 198                 ret = -ENOENT;
 199                 goto fail;
 200         }
 201
 202         path->slots[0]--;
 203         leaf = path->nodes[0];
 204
 205         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 206         if (found_key.objectid != key.objectid || found_key.type != key.type) {
 207                 ret = -ENOENT;
 208                 goto fail;
 209         }
 210
 211         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
 212                 ref = btrfs_item_ptr(leaf, path->slots[0],
 213                                      struct btrfs_root_ref);
 214                 key.objectid = btrfs_root_ref_dirid(leaf, ref);
 215         } else {
 216                 key.objectid = found_key.offset;
 217         }
 218         btrfs_free_path(path);
 219
 220         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
 221                 return btrfs_get_dentry(root->fs_info->sb, key.objectid,
 222                                         found_key.offset, 0, 0);
 223         }
 224
 225         key.type = BTRFS_INODE_ITEM_KEY;
 226         key.offset = 0;
 227         return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
 228 fail:
 229         btrfs_free_path(path);
 230         return ERR_PTR(ret);
 231 }
 232
 233 static int btrfs_get_name(struct dentry *parent, char *name,
 234                           struct dentry *child)
 235 {
 236         struct inode *inode = child->d_inode;
 237         struct inode *dir = parent->d_inode;
 238         struct btrfs_path *path;
 239         struct btrfs_root *root = BTRFS_I(dir)->root;
 240         struct btrfs_inode_ref *iref;
 241         struct btrfs_root_ref *rref;
 242         struct extent_buffer *leaf;
 243         unsigned long name_ptr;
 244         struct btrfs_key key;
 245         int name_len;
 246         int ret;
 247         u64 ino;
 248
 249         if (!dir || !inode)
 250                 return -EINVAL;
 251
 252         if (!S_ISDIR(dir->i_mode))
 253                 return -EINVAL;
 254
 255         ino = btrfs_ino(inode);
 256
 257         path = btrfs_alloc_path();
 258         if (!path)
 259                 return -ENOMEM;
 260         path->leave_spinning = 1;
 261
 262         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 263                 key.objectid = BTRFS_I(inode)->root->root_key.objectid;
 264                 key.type = BTRFS_ROOT_BACKREF_KEY;
 265                 key.offset = (u64)-1;
 266                 root = root->fs_info->tree_root;
 267         } else {
 268                 key.objectid = ino;
 269                 key.offset = btrfs_ino(dir);
 270                 key.type = BTRFS_INODE_REF_KEY;
 271         }
 272
 273         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 274         if (ret < 0) {
 275                 btrfs_free_path(path);
 276                 return ret;
 277         } else if (ret > 0) {
 278                 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 279                         path->slots[0]--;
 280                 } else {
 281                         btrfs_free_path(path);
 282                         return -ENOENT;
 283                 }
 284         }
 285         leaf = path->nodes[0];
 286
 287         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
 288                 rref = btrfs_item_ptr(leaf, path->slots[0],
 289                                      struct btrfs_root_ref);
 290                 name_ptr = (unsigned long)(rref + 1);
 291                 name_len = btrfs_root_ref_name_len(leaf, rref);
 292         } else {
 293                 iref = btrfs_item_ptr(leaf, path->slots[0],
 294                                       struct btrfs_inode_ref);
 295                 name_ptr = (unsigned long)(iref + 1);
 296                 name_len = btrfs_inode_ref_name_len(leaf, iref);
 297         }
 298
 299         read_extent_buffer(leaf, name, name_ptr, name_len);
 300         btrfs_free_path(path);
 301
 302         /*
 303          * have to add the null termination to make sure that reconnect_path
 304          * gets the right len for strlen
 305          */
 306         name[name_len] = '\0';
 307
 308         return 0;
 309 }
 310
 311 const struct export_operations btrfs_export_ops = {
 312         .encode_fh      = btrfs_encode_fh,
 313         .fh_to_dentry   = btrfs_fh_to_dentry,
 314         .fh_to_parent   = btrfs_fh_to_parent,
 315         .get_parent     = btrfs_get_parent,
 316         .get_name       = btrfs_get_name,
 317 };