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 ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) ||
  25             (connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
  26                 return 255;
  27
  28         len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
  29         type = FILEID_BTRFS_WITHOUT_PARENT;
  30
  31         fid->objectid = inode->i_ino;
  32         fid->root_objectid = BTRFS_I(inode)->root->objectid;
  33         fid->gen = inode->i_generation;
  34
  35         if (connectable && !S_ISDIR(inode->i_mode)) {
  36                 struct inode *parent;
  37                 u64 parent_root_id;
  38
  39                 spin_lock(&dentry->d_lock);
  40
  41                 parent = dentry->d_parent->d_inode;
  42                 fid->parent_objectid = BTRFS_I(parent)->location.objectid;
  43                 fid->parent_gen = parent->i_generation;
  44                 parent_root_id = BTRFS_I(parent)->root->objectid;
  45
  46                 spin_unlock(&dentry->d_lock);
  47
  48                 if (parent_root_id != fid->root_objectid) {
  49                         fid->parent_root_objectid = parent_root_id;
  50                         len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
  51                         type = FILEID_BTRFS_WITH_PARENT_ROOT;
  52                 } else {
  53                         len = BTRFS_FID_SIZE_CONNECTABLE;
  54                         type = FILEID_BTRFS_WITH_PARENT;
  55                 }
  56         }
  57
  58         *max_len = len;
  59         return type;
  60 }
  61
  62 static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
  63                                        u64 root_objectid, u32 generation,
  64                                        int check_generation)
  65 {
  66         struct btrfs_fs_info *fs_info = btrfs_sb(sb)->fs_info;
  67         struct btrfs_root *root;
  68         struct inode *inode;
  69         struct btrfs_key key;
  70         int index;
  71         int err = 0;
  72
  73         if (objectid < BTRFS_FIRST_FREE_OBJECTID)
  74                 return ERR_PTR(-ESTALE);
  75
  76         key.objectid = root_objectid;
  77         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
  78         key.offset = (u64)-1;
  79
  80         index = srcu_read_lock(&fs_info->subvol_srcu);
  81
  82         root = btrfs_read_fs_root_no_name(fs_info, &key);
  83         if (IS_ERR(root)) {
  84                 err = PTR_ERR(root);
  85                 goto fail;
  86         }
  87
  88         if (btrfs_root_refs(&root->root_item) == 0) {
  89                 err = -ENOENT;
  90                 goto fail;
  91         }
  92
  93         key.objectid = objectid;
  94         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
  95         key.offset = 0;
  96
  97         inode = btrfs_iget(sb, &key, root, NULL);
  98         if (IS_ERR(inode)) {
  99                 err = PTR_ERR(inode);
 100                 goto fail;
 101         }
 102
 103         srcu_read_unlock(&fs_info->subvol_srcu, index);
 104
 105         if (check_generation && generation != inode->i_generation) {
 106                 iput(inode);
 107                 return ERR_PTR(-ESTALE);
 108         }
 109
 110         return d_obtain_alias(inode);
 111 fail:
 112         srcu_read_unlock(&fs_info->subvol_srcu, index);
 113         return ERR_PTR(err);
 114 }
 115
 116 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
 117                                          int fh_len, int fh_type)
 118 {
 119         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 120         u64 objectid, root_objectid;
 121         u32 generation;
 122
 123         if (fh_type == FILEID_BTRFS_WITH_PARENT) {
 124                 if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
 125                         return NULL;
 126                 root_objectid = fid->root_objectid;
 127         } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
 128                 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
 129                         return NULL;
 130                 root_objectid = fid->parent_root_objectid;
 131         } else
 132                 return NULL;
 133
 134         objectid = fid->parent_objectid;
 135         generation = fid->parent_gen;
 136
 137         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
 138 }
 139
 140 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
 141                                          int fh_len, int fh_type)
 142 {
 143         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 144         u64 objectid, root_objectid;
 145         u32 generation;
 146
 147         if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
 148              fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
 149             (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
 150              fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
 151             (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
 152              fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
 153                 return NULL;
 154
 155         objectid = fid->objectid;
 156         root_objectid = fid->root_objectid;
 157         generation = fid->gen;
 158
 159         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
 160 }
 161
 162 static struct dentry *btrfs_get_parent(struct dentry *child)
 163 {
 164         struct inode *dir = child->d_inode;
 165         struct btrfs_root *root = BTRFS_I(dir)->root;
 166         struct btrfs_path *path;
 167         struct extent_buffer *leaf;
 168         struct btrfs_root_ref *ref;
 169         struct btrfs_key key;
 170         struct btrfs_key found_key;
 171         int ret;
 172
 173         path = btrfs_alloc_path();
 174         if (!path)
 175                 return ERR_PTR(-ENOMEM);
 176
 177         if (dir->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
 178                 key.objectid = root->root_key.objectid;
 179                 key.type = BTRFS_ROOT_BACKREF_KEY;
 180                 key.offset = (u64)-1;
 181                 root = root->fs_info->tree_root;
 182         } else {
 183                 key.objectid = dir->i_ino;
 184                 key.type = BTRFS_INODE_REF_KEY;
 185                 key.offset = (u64)-1;
 186         }
 187
 188         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 189         if (ret < 0)
 190                 goto fail;
 191
 192         BUG_ON(ret == 0);
 193         if (path->slots[0] == 0) {
 194                 ret = -ENOENT;
 195                 goto fail;
 196         }
 197
 198         path->slots[0]--;
 199         leaf = path->nodes[0];
 200
 201         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 202         if (found_key.objectid != key.objectid || found_key.type != key.type) {
 203                 ret = -ENOENT;
 204                 goto fail;
 205         }
 206
 207         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
 208                 ref = btrfs_item_ptr(leaf, path->slots[0],
 209                                      struct btrfs_root_ref);
 210                 key.objectid = btrfs_root_ref_dirid(leaf, ref);
 211         } else {
 212                 key.objectid = found_key.offset;
 213         }
 214         btrfs_free_path(path);
 215
 216         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
 217                 return btrfs_get_dentry(root->fs_info->sb, key.objectid,
 218                                         found_key.offset, 0, 0);
 219         }
 220
 221         key.type = BTRFS_INODE_ITEM_KEY;
 222         key.offset = 0;
 223         return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
 224 fail:
 225         btrfs_free_path(path);
 226         return ERR_PTR(ret);
 227 }
 228
 229 static int btrfs_get_name(struct dentry *parent, char *name,
 230                           struct dentry *child)
 231 {
 232         struct inode *inode = child->d_inode;
 233         struct inode *dir = parent->d_inode;
 234         struct btrfs_path *path;
 235         struct btrfs_root *root = BTRFS_I(dir)->root;
 236         struct btrfs_inode_ref *iref;
 237         struct btrfs_root_ref *rref;
 238         struct extent_buffer *leaf;
 239         unsigned long name_ptr;
 240         struct btrfs_key key;
 241         int name_len;
 242         int ret;
 243
 244         if (!dir || !inode)
 245                 return -EINVAL;
 246
 247         if (!S_ISDIR(dir->i_mode))
 248                 return -EINVAL;
 249
 250         path = btrfs_alloc_path();
 251         if (!path)
 252                 return -ENOMEM;
 253         path->leave_spinning = 1;
 254
 255         if (inode->i_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 = inode->i_ino;
 262                 key.offset = dir->i_ino;
 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 (inode->i_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 (inode->i_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 };