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TOMOYO Linux Cross Reference
Linux/fs/btrfs/props.c

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  1 /*
  2  * Copyright (C) 2014 Filipe David Borba Manana <fdmanana@gmail.com>
  3  *
  4  * This program is free software; you can redistribute it and/or
  5  * modify it under the terms of the GNU General Public
  6  * License v2 as published by the Free Software Foundation.
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 11  * General Public License for more details.
 12  *
 13  * You should have received a copy of the GNU General Public
 14  * License along with this program; if not, write to the
 15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 16  * Boston, MA 021110-1307, USA.
 17  */
 18 
 19 #include <linux/hashtable.h>
 20 #include "props.h"
 21 #include "btrfs_inode.h"
 22 #include "hash.h"
 23 #include "transaction.h"
 24 #include "xattr.h"
 25 
 26 #define BTRFS_PROP_HANDLERS_HT_BITS 8
 27 static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
 28 
 29 struct prop_handler {
 30         struct hlist_node node;
 31         const char *xattr_name;
 32         int (*validate)(const char *value, size_t len);
 33         int (*apply)(struct inode *inode, const char *value, size_t len);
 34         const char *(*extract)(struct inode *inode);
 35         int inheritable;
 36 };
 37 
 38 static int prop_compression_validate(const char *value, size_t len);
 39 static int prop_compression_apply(struct inode *inode,
 40                                   const char *value,
 41                                   size_t len);
 42 static const char *prop_compression_extract(struct inode *inode);
 43 
 44 static struct prop_handler prop_handlers[] = {
 45         {
 46                 .xattr_name = XATTR_BTRFS_PREFIX "compression",
 47                 .validate = prop_compression_validate,
 48                 .apply = prop_compression_apply,
 49                 .extract = prop_compression_extract,
 50                 .inheritable = 1
 51         },
 52         {
 53                 .xattr_name = NULL
 54         }
 55 };
 56 
 57 void __init btrfs_props_init(void)
 58 {
 59         struct prop_handler *p;
 60 
 61         hash_init(prop_handlers_ht);
 62 
 63         for (p = &prop_handlers[0]; p->xattr_name; p++) {
 64                 u64 h = btrfs_name_hash(p->xattr_name, strlen(p->xattr_name));
 65 
 66                 hash_add(prop_handlers_ht, &p->node, h);
 67         }
 68 }
 69 
 70 static const struct hlist_head *find_prop_handlers_by_hash(const u64 hash)
 71 {
 72         struct hlist_head *h;
 73 
 74         h = &prop_handlers_ht[hash_min(hash, BTRFS_PROP_HANDLERS_HT_BITS)];
 75         if (hlist_empty(h))
 76                 return NULL;
 77 
 78         return h;
 79 }
 80 
 81 static const struct prop_handler *
 82 find_prop_handler(const char *name,
 83                   const struct hlist_head *handlers)
 84 {
 85         struct prop_handler *h;
 86 
 87         if (!handlers) {
 88                 u64 hash = btrfs_name_hash(name, strlen(name));
 89 
 90                 handlers = find_prop_handlers_by_hash(hash);
 91                 if (!handlers)
 92                         return NULL;
 93         }
 94 
 95         hlist_for_each_entry(h, handlers, node)
 96                 if (!strcmp(h->xattr_name, name))
 97                         return h;
 98 
 99         return NULL;
100 }
101 
102 static int __btrfs_set_prop(struct btrfs_trans_handle *trans,
103                             struct inode *inode,
104                             const char *name,
105                             const char *value,
106                             size_t value_len,
107                             int flags)
108 {
109         const struct prop_handler *handler;
110         int ret;
111 
112         if (strlen(name) <= XATTR_BTRFS_PREFIX_LEN)
113                 return -EINVAL;
114 
115         handler = find_prop_handler(name, NULL);
116         if (!handler)
117                 return -EINVAL;
118 
119         if (value_len == 0) {
120                 ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
121                                        NULL, 0, flags);
122                 if (ret)
123                         return ret;
124 
125                 ret = handler->apply(inode, NULL, 0);
126                 ASSERT(ret == 0);
127 
128                 return ret;
129         }
130 
131         ret = handler->validate(value, value_len);
132         if (ret)
133                 return ret;
134         ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
135                                value, value_len, flags);
136         if (ret)
137                 return ret;
138         ret = handler->apply(inode, value, value_len);
139         if (ret) {
140                 __btrfs_setxattr(trans, inode, handler->xattr_name,
141                                  NULL, 0, flags);
142                 return ret;
143         }
144 
145         set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
146 
147         return 0;
148 }
149 
150 int btrfs_set_prop(struct inode *inode,
151                    const char *name,
152                    const char *value,
153                    size_t value_len,
154                    int flags)
155 {
156         return __btrfs_set_prop(NULL, inode, name, value, value_len, flags);
157 }
158 
159 static int iterate_object_props(struct btrfs_root *root,
160                                 struct btrfs_path *path,
161                                 u64 objectid,
162                                 void (*iterator)(void *,
163                                                  const struct prop_handler *,
164                                                  const char *,
165                                                  size_t),
166                                 void *ctx)
167 {
168         int ret;
169         char *name_buf = NULL;
170         char *value_buf = NULL;
171         int name_buf_len = 0;
172         int value_buf_len = 0;
173 
174         while (1) {
175                 struct btrfs_key key;
176                 struct btrfs_dir_item *di;
177                 struct extent_buffer *leaf;
178                 u32 total_len, cur, this_len;
179                 int slot;
180                 const struct hlist_head *handlers;
181 
182                 slot = path->slots[0];
183                 leaf = path->nodes[0];
184 
185                 if (slot >= btrfs_header_nritems(leaf)) {
186                         ret = btrfs_next_leaf(root, path);
187                         if (ret < 0)
188                                 goto out;
189                         else if (ret > 0)
190                                 break;
191                         continue;
192                 }
193 
194                 btrfs_item_key_to_cpu(leaf, &key, slot);
195                 if (key.objectid != objectid)
196                         break;
197                 if (key.type != BTRFS_XATTR_ITEM_KEY)
198                         break;
199 
200                 handlers = find_prop_handlers_by_hash(key.offset);
201                 if (!handlers)
202                         goto next_slot;
203 
204                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
205                 cur = 0;
206                 total_len = btrfs_item_size_nr(leaf, slot);
207 
208                 while (cur < total_len) {
209                         u32 name_len = btrfs_dir_name_len(leaf, di);
210                         u32 data_len = btrfs_dir_data_len(leaf, di);
211                         unsigned long name_ptr, data_ptr;
212                         const struct prop_handler *handler;
213 
214                         this_len = sizeof(*di) + name_len + data_len;
215                         name_ptr = (unsigned long)(di + 1);
216                         data_ptr = name_ptr + name_len;
217 
218                         if (name_len <= XATTR_BTRFS_PREFIX_LEN ||
219                             memcmp_extent_buffer(leaf, XATTR_BTRFS_PREFIX,
220                                                  name_ptr,
221                                                  XATTR_BTRFS_PREFIX_LEN))
222                                 goto next_dir_item;
223 
224                         if (name_len >= name_buf_len) {
225                                 kfree(name_buf);
226                                 name_buf_len = name_len + 1;
227                                 name_buf = kmalloc(name_buf_len, GFP_NOFS);
228                                 if (!name_buf) {
229                                         ret = -ENOMEM;
230                                         goto out;
231                                 }
232                         }
233                         read_extent_buffer(leaf, name_buf, name_ptr, name_len);
234                         name_buf[name_len] = '\0';
235 
236                         handler = find_prop_handler(name_buf, handlers);
237                         if (!handler)
238                                 goto next_dir_item;
239 
240                         if (data_len > value_buf_len) {
241                                 kfree(value_buf);
242                                 value_buf_len = data_len;
243                                 value_buf = kmalloc(data_len, GFP_NOFS);
244                                 if (!value_buf) {
245                                         ret = -ENOMEM;
246                                         goto out;
247                                 }
248                         }
249                         read_extent_buffer(leaf, value_buf, data_ptr, data_len);
250 
251                         iterator(ctx, handler, value_buf, data_len);
252 next_dir_item:
253                         cur += this_len;
254                         di = (struct btrfs_dir_item *)((char *) di + this_len);
255                 }
256 
257 next_slot:
258                 path->slots[0]++;
259         }
260 
261         ret = 0;
262 out:
263         btrfs_release_path(path);
264         kfree(name_buf);
265         kfree(value_buf);
266 
267         return ret;
268 }
269 
270 static void inode_prop_iterator(void *ctx,
271                                 const struct prop_handler *handler,
272                                 const char *value,
273                                 size_t len)
274 {
275         struct inode *inode = ctx;
276         struct btrfs_root *root = BTRFS_I(inode)->root;
277         int ret;
278 
279         ret = handler->apply(inode, value, len);
280         if (unlikely(ret))
281                 btrfs_warn(root->fs_info,
282                            "error applying prop %s to ino %llu (root %llu): %d",
283                            handler->xattr_name, btrfs_ino(inode),
284                            root->root_key.objectid, ret);
285         else
286                 set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
287 }
288 
289 int btrfs_load_inode_props(struct inode *inode, struct btrfs_path *path)
290 {
291         struct btrfs_root *root = BTRFS_I(inode)->root;
292         u64 ino = btrfs_ino(inode);
293         int ret;
294 
295         ret = iterate_object_props(root, path, ino, inode_prop_iterator, inode);
296 
297         return ret;
298 }
299 
300 static int inherit_props(struct btrfs_trans_handle *trans,
301                          struct inode *inode,
302                          struct inode *parent)
303 {
304         const struct prop_handler *h;
305         struct btrfs_root *root = BTRFS_I(inode)->root;
306         int ret;
307 
308         if (!test_bit(BTRFS_INODE_HAS_PROPS,
309                       &BTRFS_I(parent)->runtime_flags))
310                 return 0;
311 
312         for (h = &prop_handlers[0]; h->xattr_name; h++) {
313                 const char *value;
314                 u64 num_bytes;
315 
316                 if (!h->inheritable)
317                         continue;
318 
319                 value = h->extract(parent);
320                 if (!value)
321                         continue;
322 
323                 num_bytes = btrfs_calc_trans_metadata_size(root, 1);
324                 ret = btrfs_block_rsv_add(root, trans->block_rsv,
325                                           num_bytes, BTRFS_RESERVE_NO_FLUSH);
326                 if (ret)
327                         goto out;
328                 ret = __btrfs_set_prop(trans, inode, h->xattr_name,
329                                        value, strlen(value), 0);
330                 btrfs_block_rsv_release(root, trans->block_rsv, num_bytes);
331                 if (ret)
332                         goto out;
333         }
334         ret = 0;
335 out:
336         return ret;
337 }
338 
339 int btrfs_inode_inherit_props(struct btrfs_trans_handle *trans,
340                               struct inode *inode,
341                               struct inode *dir)
342 {
343         if (!dir)
344                 return 0;
345 
346         return inherit_props(trans, inode, dir);
347 }
348 
349 int btrfs_subvol_inherit_props(struct btrfs_trans_handle *trans,
350                                struct btrfs_root *root,
351                                struct btrfs_root *parent_root)
352 {
353         struct btrfs_key key;
354         struct inode *parent_inode, *child_inode;
355         int ret;
356 
357         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
358         key.type = BTRFS_INODE_ITEM_KEY;
359         key.offset = 0;
360 
361         parent_inode = btrfs_iget(parent_root->fs_info->sb, &key,
362                                   parent_root, NULL);
363         if (IS_ERR(parent_inode))
364                 return PTR_ERR(parent_inode);
365 
366         child_inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
367         if (IS_ERR(child_inode)) {
368                 iput(parent_inode);
369                 return PTR_ERR(child_inode);
370         }
371 
372         ret = inherit_props(trans, child_inode, parent_inode);
373         iput(child_inode);
374         iput(parent_inode);
375 
376         return ret;
377 }
378 
379 static int prop_compression_validate(const char *value, size_t len)
380 {
381         if (!strncmp("lzo", value, len))
382                 return 0;
383         else if (!strncmp("zlib", value, len))
384                 return 0;
385 
386         return -EINVAL;
387 }
388 
389 static int prop_compression_apply(struct inode *inode,
390                                   const char *value,
391                                   size_t len)
392 {
393         int type;
394 
395         if (len == 0) {
396                 BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
397                 BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
398                 BTRFS_I(inode)->force_compress = BTRFS_COMPRESS_NONE;
399 
400                 return 0;
401         }
402 
403         if (!strncmp("lzo", value, len))
404                 type = BTRFS_COMPRESS_LZO;
405         else if (!strncmp("zlib", value, len))
406                 type = BTRFS_COMPRESS_ZLIB;
407         else
408                 return -EINVAL;
409 
410         BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
411         BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
412         BTRFS_I(inode)->force_compress = type;
413 
414         return 0;
415 }
416 
417 static const char *prop_compression_extract(struct inode *inode)
418 {
419         switch (BTRFS_I(inode)->force_compress) {
420         case BTRFS_COMPRESS_ZLIB:
421                 return "zlib";
422         case BTRFS_COMPRESS_LZO:
423                 return "lzo";
424         }
425 
426         return NULL;
427 }
428 
429 
430 

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