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 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)
  11 #define FILEID_BTRFS_WITHOUT_PARENT             0x4d
  12 #define FILEID_BTRFS_WITH_PARENT                0x4e
  13 #define FILEID_BTRFS_WITH_PARENT_ROOT           0x4f
  14 #endif
  15
  16 #define BTRFS_FID_SIZE_NON_CONNECTABLE          (offsetof(struct btrfs_fid, parent_objectid)/4)
  17 #define BTRFS_FID_SIZE_CONNECTABLE              (offsetof(struct btrfs_fid, parent_root_objectid)/4)
  18 #define BTRFS_FID_SIZE_CONNECTABLE_ROOT         (sizeof(struct btrfs_fid)/4)
  19
  20 static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
  21                            int connectable)
  22 {
  23         struct btrfs_fid *fid = (struct btrfs_fid *)fh;
  24         struct inode *inode = dentry->d_inode;
  25         int len = *max_len;
  26         int type;
  27
  28         if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) ||
  29             (connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
  30                 return 255;
  31
  32         len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
  33         type = FILEID_BTRFS_WITHOUT_PARENT;
  34
  35         fid->objectid = BTRFS_I(inode)->location.objectid;
  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 {
  69         struct btrfs_root *root;
  70         struct inode *inode;
  71         struct dentry *result;
  72         struct btrfs_key key;
  73
  74         key.objectid = objectid;
  75         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
  76         key.offset = 0;
  77
  78         root = btrfs_lookup_fs_root(btrfs_sb(sb)->fs_info, root_objectid);
  79         inode = btrfs_iget(sb, &key, root, NULL);
  80         if (IS_ERR(inode))
  81                 return (void *)inode;
  82
  83         if (generation != inode->i_generation) {
  84                 iput(inode);
  85                 return ERR_PTR(-ESTALE);
  86         }
  87
  88         result = d_obtain_alias(inode);
  89         if (!result)
  90                 return ERR_PTR(-ENOMEM);
  91
  92         return result;
  93 }
  94
  95 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
  96                                          int fh_len, int fh_type)
  97 {
  98         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
  99         u64 objectid, root_objectid;
 100         u32 generation;
 101
 102         if (fh_type == FILEID_BTRFS_WITH_PARENT) {
 103                 if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
 104                         return NULL;
 105                 root_objectid = fid->root_objectid;
 106         } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
 107                 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
 108                         return NULL;
 109                 root_objectid = fid->parent_root_objectid;
 110         } else
 111                 return NULL;
 112
 113         objectid = fid->parent_objectid;
 114         generation = fid->parent_gen;
 115
 116         return btrfs_get_dentry(sb, objectid, root_objectid, generation);
 117 }
 118
 119 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
 120                                          int fh_len, int fh_type)
 121 {
 122         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
 123         u64 objectid, root_objectid;
 124         u32 generation;
 125
 126         if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
 127              fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
 128             (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
 129              fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
 130             (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
 131              fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
 132                 return NULL;
 133
 134         objectid = fid->objectid;
 135         root_objectid = fid->root_objectid;
 136         generation = fid->gen;
 137
 138         return btrfs_get_dentry(sb, objectid, root_objectid, generation);
 139 }
 140
 141 static struct dentry *btrfs_get_parent(struct dentry *child)
 142 {
 143         struct inode *dir = child->d_inode;
 144         struct inode *inode;
 145         struct dentry *parent;
 146         struct btrfs_root *root = BTRFS_I(dir)->root;
 147         struct btrfs_key key;
 148         struct btrfs_path *path;
 149         struct extent_buffer *leaf;
 150         int slot;
 151         u64 objectid;
 152         int ret;
 153
 154         path = btrfs_alloc_path();
 155
 156         key.objectid = dir->i_ino;
 157         btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
 158         key.offset = (u64)-1;
 159
 160         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 161         leaf = path->nodes[0];
 162         slot = path->slots[0];
 163         if (ret < 0 || slot == 0) {
 164                 btrfs_free_path(path);
 165                 goto out;
 166         }
 167         /* btrfs_search_slot() returns the slot where we'd want to insert
 168            an INODE_REF_KEY for parent inode #0xFFFFFFFFFFFFFFFF. The _real_
 169            one, telling us what the parent inode _actually_ is, will be in
 170            the slot _before_ the one that btrfs_search_slot() returns. */
 171         slot--;
 172
 173         btrfs_item_key_to_cpu(leaf, &key, slot);
 174         btrfs_free_path(path);
 175
 176         if (key.objectid != dir->i_ino || key.type != BTRFS_INODE_REF_KEY)
 177                 goto out;
 178
 179         objectid = key.offset;
 180
 181         /* Build a new key for the inode item */
 182         key.objectid = objectid;
 183         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 184         key.offset = 0;
 185
 186         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
 187
 188         parent = d_obtain_alias(inode);
 189         if (!parent)
 190                 parent = ERR_PTR(-ENOMEM);
 191
 192         return parent;
 193
 194 out:
 195         btrfs_free_path(path);
 196         return ERR_PTR(-EINVAL);
 197 }
 198
 199 const struct export_operations btrfs_export_ops = {
 200         .encode_fh      = btrfs_encode_fh,
 201         .fh_to_dentry   = btrfs_fh_to_dentry,
 202         .fh_to_parent   = btrfs_fh_to_parent,
 203         .get_parent     = btrfs_get_parent,
 204 };