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Linux/fs/btrfs/uuid-tree.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Copyright (C) STRATO AG 2013.  All rights reserved.
  4  */
  5 
  6 #include <linux/uuid.h>
  7 #include <asm/unaligned.h>
  8 #include "ctree.h"
  9 #include "transaction.h"
 10 #include "disk-io.h"
 11 #include "print-tree.h"
 12 
 13 
 14 static void btrfs_uuid_to_key(u8 *uuid, u8 type, struct btrfs_key *key)
 15 {
 16         key->type = type;
 17         key->objectid = get_unaligned_le64(uuid);
 18         key->offset = get_unaligned_le64(uuid + sizeof(u64));
 19 }
 20 
 21 /* return -ENOENT for !found, < 0 for errors, or 0 if an item was found */
 22 static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, u8 *uuid,
 23                                   u8 type, u64 subid)
 24 {
 25         int ret;
 26         struct btrfs_path *path = NULL;
 27         struct extent_buffer *eb;
 28         int slot;
 29         u32 item_size;
 30         unsigned long offset;
 31         struct btrfs_key key;
 32 
 33         if (WARN_ON_ONCE(!uuid_root)) {
 34                 ret = -ENOENT;
 35                 goto out;
 36         }
 37 
 38         path = btrfs_alloc_path();
 39         if (!path) {
 40                 ret = -ENOMEM;
 41                 goto out;
 42         }
 43 
 44         btrfs_uuid_to_key(uuid, type, &key);
 45         ret = btrfs_search_slot(NULL, uuid_root, &key, path, 0, 0);
 46         if (ret < 0) {
 47                 goto out;
 48         } else if (ret > 0) {
 49                 ret = -ENOENT;
 50                 goto out;
 51         }
 52 
 53         eb = path->nodes[0];
 54         slot = path->slots[0];
 55         item_size = btrfs_item_size_nr(eb, slot);
 56         offset = btrfs_item_ptr_offset(eb, slot);
 57         ret = -ENOENT;
 58 
 59         if (!IS_ALIGNED(item_size, sizeof(u64))) {
 60                 btrfs_warn(uuid_root->fs_info,
 61                            "uuid item with illegal size %lu!",
 62                            (unsigned long)item_size);
 63                 goto out;
 64         }
 65         while (item_size) {
 66                 __le64 data;
 67 
 68                 read_extent_buffer(eb, &data, offset, sizeof(data));
 69                 if (le64_to_cpu(data) == subid) {
 70                         ret = 0;
 71                         break;
 72                 }
 73                 offset += sizeof(data);
 74                 item_size -= sizeof(data);
 75         }
 76 
 77 out:
 78         btrfs_free_path(path);
 79         return ret;
 80 }
 81 
 82 int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
 83                         u64 subid_cpu)
 84 {
 85         struct btrfs_fs_info *fs_info = trans->fs_info;
 86         struct btrfs_root *uuid_root = fs_info->uuid_root;
 87         int ret;
 88         struct btrfs_path *path = NULL;
 89         struct btrfs_key key;
 90         struct extent_buffer *eb;
 91         int slot;
 92         unsigned long offset;
 93         __le64 subid_le;
 94 
 95         ret = btrfs_uuid_tree_lookup(uuid_root, uuid, type, subid_cpu);
 96         if (ret != -ENOENT)
 97                 return ret;
 98 
 99         if (WARN_ON_ONCE(!uuid_root)) {
100                 ret = -EINVAL;
101                 goto out;
102         }
103 
104         btrfs_uuid_to_key(uuid, type, &key);
105 
106         path = btrfs_alloc_path();
107         if (!path) {
108                 ret = -ENOMEM;
109                 goto out;
110         }
111 
112         ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
113                                       sizeof(subid_le));
114         if (ret >= 0) {
115                 /* Add an item for the type for the first time */
116                 eb = path->nodes[0];
117                 slot = path->slots[0];
118                 offset = btrfs_item_ptr_offset(eb, slot);
119         } else if (ret == -EEXIST) {
120                 /*
121                  * An item with that type already exists.
122                  * Extend the item and store the new subid at the end.
123                  */
124                 btrfs_extend_item(fs_info, path, sizeof(subid_le));
125                 eb = path->nodes[0];
126                 slot = path->slots[0];
127                 offset = btrfs_item_ptr_offset(eb, slot);
128                 offset += btrfs_item_size_nr(eb, slot) - sizeof(subid_le);
129         } else if (ret < 0) {
130                 btrfs_warn(fs_info,
131                            "insert uuid item failed %d (0x%016llx, 0x%016llx) type %u!",
132                            ret, (unsigned long long)key.objectid,
133                            (unsigned long long)key.offset, type);
134                 goto out;
135         }
136 
137         ret = 0;
138         subid_le = cpu_to_le64(subid_cpu);
139         write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
140         btrfs_mark_buffer_dirty(eb);
141 
142 out:
143         btrfs_free_path(path);
144         return ret;
145 }
146 
147 int btrfs_uuid_tree_remove(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
148                         u64 subid)
149 {
150         struct btrfs_fs_info *fs_info = trans->fs_info;
151         struct btrfs_root *uuid_root = fs_info->uuid_root;
152         int ret;
153         struct btrfs_path *path = NULL;
154         struct btrfs_key key;
155         struct extent_buffer *eb;
156         int slot;
157         unsigned long offset;
158         u32 item_size;
159         unsigned long move_dst;
160         unsigned long move_src;
161         unsigned long move_len;
162 
163         if (WARN_ON_ONCE(!uuid_root)) {
164                 ret = -EINVAL;
165                 goto out;
166         }
167 
168         btrfs_uuid_to_key(uuid, type, &key);
169 
170         path = btrfs_alloc_path();
171         if (!path) {
172                 ret = -ENOMEM;
173                 goto out;
174         }
175 
176         ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
177         if (ret < 0) {
178                 btrfs_warn(fs_info, "error %d while searching for uuid item!",
179                            ret);
180                 goto out;
181         }
182         if (ret > 0) {
183                 ret = -ENOENT;
184                 goto out;
185         }
186 
187         eb = path->nodes[0];
188         slot = path->slots[0];
189         offset = btrfs_item_ptr_offset(eb, slot);
190         item_size = btrfs_item_size_nr(eb, slot);
191         if (!IS_ALIGNED(item_size, sizeof(u64))) {
192                 btrfs_warn(fs_info, "uuid item with illegal size %lu!",
193                            (unsigned long)item_size);
194                 ret = -ENOENT;
195                 goto out;
196         }
197         while (item_size) {
198                 __le64 read_subid;
199 
200                 read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
201                 if (le64_to_cpu(read_subid) == subid)
202                         break;
203                 offset += sizeof(read_subid);
204                 item_size -= sizeof(read_subid);
205         }
206 
207         if (!item_size) {
208                 ret = -ENOENT;
209                 goto out;
210         }
211 
212         item_size = btrfs_item_size_nr(eb, slot);
213         if (item_size == sizeof(subid)) {
214                 ret = btrfs_del_item(trans, uuid_root, path);
215                 goto out;
216         }
217 
218         move_dst = offset;
219         move_src = offset + sizeof(subid);
220         move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
221         memmove_extent_buffer(eb, move_dst, move_src, move_len);
222         btrfs_truncate_item(fs_info, path, item_size - sizeof(subid), 1);
223 
224 out:
225         btrfs_free_path(path);
226         return ret;
227 }
228 
229 static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
230                                u64 subid)
231 {
232         struct btrfs_trans_handle *trans;
233         int ret;
234 
235         /* 1 - for the uuid item */
236         trans = btrfs_start_transaction(uuid_root, 1);
237         if (IS_ERR(trans)) {
238                 ret = PTR_ERR(trans);
239                 goto out;
240         }
241 
242         ret = btrfs_uuid_tree_remove(trans, uuid, type, subid);
243         btrfs_end_transaction(trans);
244 
245 out:
246         return ret;
247 }
248 
249 int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info,
250                             int (*check_func)(struct btrfs_fs_info *, u8 *, u8,
251                                               u64))
252 {
253         struct btrfs_root *root = fs_info->uuid_root;
254         struct btrfs_key key;
255         struct btrfs_path *path;
256         int ret = 0;
257         struct extent_buffer *leaf;
258         int slot;
259         u32 item_size;
260         unsigned long offset;
261 
262         path = btrfs_alloc_path();
263         if (!path) {
264                 ret = -ENOMEM;
265                 goto out;
266         }
267 
268         key.objectid = 0;
269         key.type = 0;
270         key.offset = 0;
271 
272 again_search_slot:
273         ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION);
274         if (ret) {
275                 if (ret > 0)
276                         ret = 0;
277                 goto out;
278         }
279 
280         while (1) {
281                 cond_resched();
282                 leaf = path->nodes[0];
283                 slot = path->slots[0];
284                 btrfs_item_key_to_cpu(leaf, &key, slot);
285 
286                 if (key.type != BTRFS_UUID_KEY_SUBVOL &&
287                     key.type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
288                         goto skip;
289 
290                 offset = btrfs_item_ptr_offset(leaf, slot);
291                 item_size = btrfs_item_size_nr(leaf, slot);
292                 if (!IS_ALIGNED(item_size, sizeof(u64))) {
293                         btrfs_warn(fs_info,
294                                    "uuid item with illegal size %lu!",
295                                    (unsigned long)item_size);
296                         goto skip;
297                 }
298                 while (item_size) {
299                         u8 uuid[BTRFS_UUID_SIZE];
300                         __le64 subid_le;
301                         u64 subid_cpu;
302 
303                         put_unaligned_le64(key.objectid, uuid);
304                         put_unaligned_le64(key.offset, uuid + sizeof(u64));
305                         read_extent_buffer(leaf, &subid_le, offset,
306                                            sizeof(subid_le));
307                         subid_cpu = le64_to_cpu(subid_le);
308                         ret = check_func(fs_info, uuid, key.type, subid_cpu);
309                         if (ret < 0)
310                                 goto out;
311                         if (ret > 0) {
312                                 btrfs_release_path(path);
313                                 ret = btrfs_uuid_iter_rem(root, uuid, key.type,
314                                                           subid_cpu);
315                                 if (ret == 0) {
316                                         /*
317                                          * this might look inefficient, but the
318                                          * justification is that it is an
319                                          * exception that check_func returns 1,
320                                          * and that in the regular case only one
321                                          * entry per UUID exists.
322                                          */
323                                         goto again_search_slot;
324                                 }
325                                 if (ret < 0 && ret != -ENOENT)
326                                         goto out;
327                         }
328                         item_size -= sizeof(subid_le);
329                         offset += sizeof(subid_le);
330                 }
331 
332 skip:
333                 ret = btrfs_next_item(root, path);
334                 if (ret == 0)
335                         continue;
336                 else if (ret > 0)
337                         ret = 0;
338                 break;
339         }
340 
341 out:
342         btrfs_free_path(path);
343         return ret;
344 }
345 

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