blob: 85315d2c90de0677e593ce21ea11174d5bce9031 [file] [log] [blame]
Balaji Raobe6e8dc2008-07-21 02:01:56 +05301#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
Chris Masond3977122009-01-05 21:25:51 -050010#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)
Balaji Raobe6e8dc2008-07-21 02:01:56 +053015
16static 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 = BTRFS_I(inode)->location.objectid;
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
62static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
63 u64 root_objectid, u32 generation)
64{
65 struct btrfs_root *root;
66 struct inode *inode;
Balaji Raobe6e8dc2008-07-21 02:01:56 +053067 struct btrfs_key key;
68
David Woodhouse2d4d9fbd2008-08-19 22:20:17 +010069 key.objectid = root_objectid;
70 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
71 key.offset = (u64)-1;
72
73 root = btrfs_read_fs_root_no_name(btrfs_sb(sb)->fs_info, &key);
74 if (IS_ERR(root))
75 return ERR_CAST(root);
76
Balaji Raobe6e8dc2008-07-21 02:01:56 +053077 key.objectid = objectid;
78 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
79 key.offset = 0;
80
Balaji Raobe6e8dc2008-07-21 02:01:56 +053081 inode = btrfs_iget(sb, &key, root, NULL);
82 if (IS_ERR(inode))
83 return (void *)inode;
84
85 if (generation != inode->i_generation) {
86 iput(inode);
87 return ERR_PTR(-ESTALE);
88 }
89
Christoph Hellwig50ec8912008-09-05 16:43:20 -040090 return d_obtain_alias(inode);
Balaji Raobe6e8dc2008-07-21 02:01:56 +053091}
92
93static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
94 int fh_len, int fh_type)
95{
96 struct btrfs_fid *fid = (struct btrfs_fid *) fh;
97 u64 objectid, root_objectid;
98 u32 generation;
99
100 if (fh_type == FILEID_BTRFS_WITH_PARENT) {
101 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE)
102 return NULL;
103 root_objectid = fid->root_objectid;
104 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
105 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
106 return NULL;
107 root_objectid = fid->parent_root_objectid;
108 } else
109 return NULL;
110
111 objectid = fid->parent_objectid;
112 generation = fid->parent_gen;
113
114 return btrfs_get_dentry(sb, objectid, root_objectid, generation);
115}
116
117static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
118 int fh_len, int fh_type)
119{
120 struct btrfs_fid *fid = (struct btrfs_fid *) fh;
121 u64 objectid, root_objectid;
122 u32 generation;
123
124 if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
125 fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
126 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
127 fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
128 (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
129 fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
130 return NULL;
131
132 objectid = fid->objectid;
133 root_objectid = fid->root_objectid;
134 generation = fid->gen;
135
136 return btrfs_get_dentry(sb, objectid, root_objectid, generation);
137}
138
139static struct dentry *btrfs_get_parent(struct dentry *child)
140{
141 struct inode *dir = child->d_inode;
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530142 struct btrfs_root *root = BTRFS_I(dir)->root;
143 struct btrfs_key key;
144 struct btrfs_path *path;
145 struct extent_buffer *leaf;
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530146 int slot;
147 u64 objectid;
148 int ret;
149
150 path = btrfs_alloc_path();
151
152 key.objectid = dir->i_ino;
153 btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
David Woodhouse87acb4e2008-08-18 22:50:22 +0100154 key.offset = (u64)-1;
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530155
David Woodhouse87acb4e2008-08-18 22:50:22 +0100156 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
David Woodhoused54a8392008-08-19 22:33:04 +0100157 if (ret < 0) {
158 /* Error */
159 btrfs_free_path(path);
160 return ERR_PTR(ret);
161 }
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530162 leaf = path->nodes[0];
163 slot = path->slots[0];
David Woodhoused54a8392008-08-19 22:33:04 +0100164 if (ret) {
165 /* btrfs_search_slot() returns the slot where we'd want to
166 insert a backref for parent inode #0xFFFFFFFFFFFFFFFF.
167 The _real_ backref, telling us what the parent inode
168 _actually_ is, will be in the slot _before_ the one
169 that btrfs_search_slot() returns. */
170 if (!slot) {
171 /* Unless there is _no_ key in the tree before... */
172 btrfs_free_path(path);
173 return ERR_PTR(-EIO);
174 }
175 slot--;
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530176 }
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530177
178 btrfs_item_key_to_cpu(leaf, &key, slot);
David Woodhouse87acb4e2008-08-18 22:50:22 +0100179 btrfs_free_path(path);
180
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530181 if (key.objectid != dir->i_ino || key.type != BTRFS_INODE_REF_KEY)
David Woodhoused54a8392008-08-19 22:33:04 +0100182 return ERR_PTR(-EINVAL);
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530183
184 objectid = key.offset;
185
David Woodhouse2d4d9fbd2008-08-19 22:20:17 +0100186 /* If we are already at the root of a subvol, return the real root */
187 if (objectid == dir->i_ino)
188 return dget(dir->i_sb->s_root);
189
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530190 /* Build a new key for the inode item */
191 key.objectid = objectid;
192 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
193 key.offset = 0;
194
Christoph Hellwig50ec8912008-09-05 16:43:20 -0400195 return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
Balaji Raobe6e8dc2008-07-21 02:01:56 +0530196}
197
198const struct export_operations btrfs_export_ops = {
199 .encode_fh = btrfs_encode_fh,
200 .fh_to_dentry = btrfs_fh_to_dentry,
201 .fh_to_parent = btrfs_fh_to_parent,
202 .get_parent = btrfs_get_parent,
203};