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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 #include "compression.h"
 26 
 27 #define BTRFS_PROP_HANDLERS_HT_BITS 8
 28 static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
 29 
 30 struct prop_handler {
 31         struct hlist_node node;
 32         const char *xattr_name;
 33         int (*validate)(const char *value, size_t len);
 34         int (*apply)(struct inode *inode, const char *value, size_t len);
 35         const char *(*extract)(struct inode *inode);
 36         int inheritable;
 37 };
 38 
 39 static int prop_compression_validate(const char *value, size_t len);
 40 static int prop_compression_apply(struct inode *inode,
 41                                   const char *value,
 42                                   size_t len);
 43 static const char *prop_compression_extract(struct inode *inode);
 44 
 45 static struct prop_handler prop_handlers[] = {
 46         {
 47                 .xattr_name = XATTR_BTRFS_PREFIX "compression",
 48                 .validate = prop_compression_validate,
 49                 .apply = prop_compression_apply,
 50                 .extract = prop_compression_extract,
 51                 .inheritable = 1
 52         },
 53 };
 54 
 55 void __init btrfs_props_init(void)
 56 {
 57         int i;
 58 
 59         hash_init(prop_handlers_ht);
 60 
 61         for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
 62                 struct prop_handler *p = &prop_handlers[i];
 63                 u64 h = btrfs_name_hash(p->xattr_name, strlen(p->xattr_name));
 64 
 65                 hash_add(prop_handlers_ht, &p->node, h);
 66         }
 67 }
 68 
 69 static const struct hlist_head *find_prop_handlers_by_hash(const u64 hash)
 70 {
 71         struct hlist_head *h;
 72 
 73         h = &prop_handlers_ht[hash_min(hash, BTRFS_PROP_HANDLERS_HT_BITS)];
 74         if (hlist_empty(h))
 75                 return NULL;
 76 
 77         return h;
 78 }
 79 
 80 static const struct prop_handler *
 81 find_prop_handler(const char *name,
 82                   const struct hlist_head *handlers)
 83 {
 84         struct prop_handler *h;
 85 
 86         if (!handlers) {
 87                 u64 hash = btrfs_name_hash(name, strlen(name));
 88 
 89                 handlers = find_prop_handlers_by_hash(hash);
 90                 if (!handlers)
 91                         return NULL;
 92         }
 93 
 94         hlist_for_each_entry(h, handlers, node)
 95                 if (!strcmp(h->xattr_name, name))
 96                         return h;
 97 
 98         return NULL;
 99 }
100 
101 static int __btrfs_set_prop(struct btrfs_trans_handle *trans,
102                             struct inode *inode,
103                             const char *name,
104                             const char *value,
105                             size_t value_len,
106                             int flags)
107 {
108         const struct prop_handler *handler;
109         int ret;
110 
111         if (strlen(name) <= XATTR_BTRFS_PREFIX_LEN)
112                 return -EINVAL;
113 
114         handler = find_prop_handler(name, NULL);
115         if (!handler)
116                 return -EINVAL;
117 
118         if (value_len == 0) {
119                 ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
120                                        NULL, 0, flags);
121                 if (ret)
122                         return ret;
123 
124                 ret = handler->apply(inode, NULL, 0);
125                 ASSERT(ret == 0);
126 
127                 return ret;
128         }
129 
130         ret = handler->validate(value, value_len);
131         if (ret)
132                 return ret;
133         ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
134                                value, value_len, flags);
135         if (ret)
136                 return ret;
137         ret = handler->apply(inode, value, value_len);
138         if (ret) {
139                 __btrfs_setxattr(trans, inode, handler->xattr_name,
140                                  NULL, 0, flags);
141                 return ret;
142         }
143 
144         set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
145 
146         return 0;
147 }
148 
149 int btrfs_set_prop(struct inode *inode,
150                    const char *name,
151                    const char *value,
152                    size_t value_len,
153                    int flags)
154 {
155         return __btrfs_set_prop(NULL, inode, name, value, value_len, flags);
156 }
157 
158 static int iterate_object_props(struct btrfs_root *root,
159                                 struct btrfs_path *path,
160                                 u64 objectid,
161                                 void (*iterator)(void *,
162                                                  const struct prop_handler *,
163                                                  const char *,
164                                                  size_t),
165                                 void *ctx)
166 {
167         int ret;
168         char *name_buf = NULL;
169         char *value_buf = NULL;
170         int name_buf_len = 0;
171         int value_buf_len = 0;
172 
173         while (1) {
174                 struct btrfs_key key;
175                 struct btrfs_dir_item *di;
176                 struct extent_buffer *leaf;
177                 u32 total_len, cur, this_len;
178                 int slot;
179                 const struct hlist_head *handlers;
180 
181                 slot = path->slots[0];
182                 leaf = path->nodes[0];
183 
184                 if (slot >= btrfs_header_nritems(leaf)) {
185                         ret = btrfs_next_leaf(root, path);
186                         if (ret < 0)
187                                 goto out;
188                         else if (ret > 0)
189                                 break;
190                         continue;
191                 }
192 
193                 btrfs_item_key_to_cpu(leaf, &key, slot);
194                 if (key.objectid != objectid)
195                         break;
196                 if (key.type != BTRFS_XATTR_ITEM_KEY)
197                         break;
198 
199                 handlers = find_prop_handlers_by_hash(key.offset);
200                 if (!handlers)
201                         goto next_slot;
202 
203                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
204                 cur = 0;
205                 total_len = btrfs_item_size_nr(leaf, slot);
206 
207                 while (cur < total_len) {
208                         u32 name_len = btrfs_dir_name_len(leaf, di);
209                         u32 data_len = btrfs_dir_data_len(leaf, di);
210                         unsigned long name_ptr, data_ptr;
211                         const struct prop_handler *handler;
212 
213                         this_len = sizeof(*di) + name_len + data_len;
214                         name_ptr = (unsigned long)(di + 1);
215                         data_ptr = name_ptr + name_len;
216 
217                         if (name_len <= XATTR_BTRFS_PREFIX_LEN ||
218                             memcmp_extent_buffer(leaf, XATTR_BTRFS_PREFIX,
219                                                  name_ptr,
220                                                  XATTR_BTRFS_PREFIX_LEN))
221                                 goto next_dir_item;
222 
223                         if (name_len >= name_buf_len) {
224                                 kfree(name_buf);
225                                 name_buf_len = name_len + 1;
226                                 name_buf = kmalloc(name_buf_len, GFP_NOFS);
227                                 if (!name_buf) {
228                                         ret = -ENOMEM;
229                                         goto out;
230                                 }
231                         }
232                         read_extent_buffer(leaf, name_buf, name_ptr, name_len);
233                         name_buf[name_len] = '\0';
234 
235                         handler = find_prop_handler(name_buf, handlers);
236                         if (!handler)
237                                 goto next_dir_item;
238 
239                         if (data_len > value_buf_len) {
240                                 kfree(value_buf);
241                                 value_buf_len = data_len;
242                                 value_buf = kmalloc(data_len, GFP_NOFS);
243                                 if (!value_buf) {
244                                         ret = -ENOMEM;
245                                         goto out;
246                                 }
247                         }
248                         read_extent_buffer(leaf, value_buf, data_ptr, data_len);
249 
250                         iterator(ctx, handler, value_buf, data_len);
251 next_dir_item:
252                         cur += this_len;
253                         di = (struct btrfs_dir_item *)((char *) di + this_len);
254                 }
255 
256 next_slot:
257                 path->slots[0]++;
258         }
259 
260         ret = 0;
261 out:
262         btrfs_release_path(path);
263         kfree(name_buf);
264         kfree(value_buf);
265 
266         return ret;
267 }
268 
269 static void inode_prop_iterator(void *ctx,
270                                 const struct prop_handler *handler,
271                                 const char *value,
272                                 size_t len)
273 {
274         struct inode *inode = ctx;
275         struct btrfs_root *root = BTRFS_I(inode)->root;
276         int ret;
277 
278         ret = handler->apply(inode, value, len);
279         if (unlikely(ret))
280                 btrfs_warn(root->fs_info,
281                            "error applying prop %s to ino %llu (root %llu): %d",
282                            handler->xattr_name, btrfs_ino(BTRFS_I(inode)),
283                            root->root_key.objectid, ret);
284         else
285                 set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
286 }
287 
288 int btrfs_load_inode_props(struct inode *inode, struct btrfs_path *path)
289 {
290         struct btrfs_root *root = BTRFS_I(inode)->root;
291         u64 ino = btrfs_ino(BTRFS_I(inode));
292         int ret;
293 
294         ret = iterate_object_props(root, path, ino, inode_prop_iterator, inode);
295 
296         return ret;
297 }
298 
299 static int inherit_props(struct btrfs_trans_handle *trans,
300                          struct inode *inode,
301                          struct inode *parent)
302 {
303         struct btrfs_root *root = BTRFS_I(inode)->root;
304         struct btrfs_fs_info *fs_info = root->fs_info;
305         int ret;
306         int i;
307 
308         if (!test_bit(BTRFS_INODE_HAS_PROPS,
309                       &BTRFS_I(parent)->runtime_flags))
310                 return 0;
311 
312         for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
313                 const struct prop_handler *h = &prop_handlers[i];
314                 const char *value;
315                 u64 num_bytes;
316 
317                 if (!h->inheritable)
318                         continue;
319 
320                 value = h->extract(parent);
321                 if (!value)
322                         continue;
323 
324                 num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
325                 ret = btrfs_block_rsv_add(root, trans->block_rsv,
326                                           num_bytes, BTRFS_RESERVE_NO_FLUSH);
327                 if (ret)
328                         goto out;
329                 ret = __btrfs_set_prop(trans, inode, h->xattr_name,
330                                        value, strlen(value), 0);
331                 btrfs_block_rsv_release(fs_info, trans->block_rsv, num_bytes);
332                 if (ret)
333                         goto out;
334         }
335         ret = 0;
336 out:
337         return ret;
338 }
339 
340 int btrfs_inode_inherit_props(struct btrfs_trans_handle *trans,
341                               struct inode *inode,
342                               struct inode *dir)
343 {
344         if (!dir)
345                 return 0;
346 
347         return inherit_props(trans, inode, dir);
348 }
349 
350 int btrfs_subvol_inherit_props(struct btrfs_trans_handle *trans,
351                                struct btrfs_root *root,
352                                struct btrfs_root *parent_root)
353 {
354         struct super_block *sb = root->fs_info->sb;
355         struct btrfs_key key;
356         struct inode *parent_inode, *child_inode;
357         int ret;
358 
359         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
360         key.type = BTRFS_INODE_ITEM_KEY;
361         key.offset = 0;
362 
363         parent_inode = btrfs_iget(sb, &key, parent_root, NULL);
364         if (IS_ERR(parent_inode))
365                 return PTR_ERR(parent_inode);
366 
367         child_inode = btrfs_iget(sb, &key, root, NULL);
368         if (IS_ERR(child_inode)) {
369                 iput(parent_inode);
370                 return PTR_ERR(child_inode);
371         }
372 
373         ret = inherit_props(trans, child_inode, parent_inode);
374         iput(child_inode);
375         iput(parent_inode);
376 
377         return ret;
378 }
379 
380 static int prop_compression_validate(const char *value, size_t len)
381 {
382         if (!strncmp("lzo", value, len))
383                 return 0;
384         else if (!strncmp("zlib", value, len))
385                 return 0;
386         else if (!strncmp("zstd", value, len))
387                 return 0;
388 
389         return -EINVAL;
390 }
391 
392 static int prop_compression_apply(struct inode *inode,
393                                   const char *value,
394                                   size_t len)
395 {
396         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
397         int type;
398 
399         if (len == 0) {
400                 BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
401                 BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
402                 BTRFS_I(inode)->prop_compress = BTRFS_COMPRESS_NONE;
403 
404                 return 0;
405         }
406 
407         if (!strncmp("lzo", value, 3)) {
408                 type = BTRFS_COMPRESS_LZO;
409                 btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
410         } else if (!strncmp("zlib", value, 4)) {
411                 type = BTRFS_COMPRESS_ZLIB;
412         } else if (!strncmp("zstd", value, len)) {
413                 type = BTRFS_COMPRESS_ZSTD;
414                 btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
415         } else {
416                 return -EINVAL;
417         }
418 
419         BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
420         BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
421         BTRFS_I(inode)->prop_compress = type;
422 
423         return 0;
424 }
425 
426 static const char *prop_compression_extract(struct inode *inode)
427 {
428         switch (BTRFS_I(inode)->prop_compress) {
429         case BTRFS_COMPRESS_ZLIB:
430         case BTRFS_COMPRESS_LZO:
431         case BTRFS_COMPRESS_ZSTD:
432                 return btrfs_compress_type2str(BTRFS_I(inode)->prop_compress);
433         default:
434                 break;
435         }
436 
437         return NULL;
438 }
439 
440 
441 

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