linux/fs/btrfs/export.c
<<
>>
Prefs
   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
  16static 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 255;
  26        } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
  27                *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
  28                return 255;
  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
  59static 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);
 108fail:
 109        srcu_read_unlock(&fs_info->subvol_srcu, index);
 110        return ERR_PTR(err);
 111}
 112
 113static 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
 137static 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
 159static 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));
 221fail:
 222        btrfs_free_path(path);
 223        return ERR_PTR(ret);
 224}
 225
 226static 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
 304const 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};
 311
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.