1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS filesystem directory editing
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/fs.h>
10 #include <linux/namei.h>
11 #include <linux/pagemap.h>
12 #include <linux/iversion.h>
13 #include "internal.h"
14 #include "xdr_fs.h"
15
16 /*
17 * Find a number of contiguous clear bits in a directory block bitmask.
18 *
19 * There are 64 slots, which means we can load the entire bitmap into a
20 * variable. The first bit doesn't count as it corresponds to the block header
21 * slot. nr_slots is between 1 and 9.
22 */
afs_find_contig_bits(union afs_xdr_dir_block * block,unsigned int nr_slots)23 static int afs_find_contig_bits(union afs_xdr_dir_block *block, unsigned int nr_slots)
24 {
25 u64 bitmap;
26 u32 mask;
27 int bit, n;
28
29 bitmap = (u64)block->hdr.bitmap[0] << 0 * 8;
30 bitmap |= (u64)block->hdr.bitmap[1] << 1 * 8;
31 bitmap |= (u64)block->hdr.bitmap[2] << 2 * 8;
32 bitmap |= (u64)block->hdr.bitmap[3] << 3 * 8;
33 bitmap |= (u64)block->hdr.bitmap[4] << 4 * 8;
34 bitmap |= (u64)block->hdr.bitmap[5] << 5 * 8;
35 bitmap |= (u64)block->hdr.bitmap[6] << 6 * 8;
36 bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8;
37 bitmap >>= 1; /* The first entry is metadata */
38 bit = 1;
39 mask = (1 << nr_slots) - 1;
40
41 do {
42 if (sizeof(unsigned long) == 8)
43 n = ffz(bitmap);
44 else
45 n = ((u32)bitmap) != 0 ?
46 ffz((u32)bitmap) :
47 ffz((u32)(bitmap >> 32)) + 32;
48 bitmap >>= n;
49 bit += n;
50
51 if ((bitmap & mask) == 0) {
52 if (bit > 64 - nr_slots)
53 return -1;
54 return bit;
55 }
56
57 n = __ffs(bitmap);
58 bitmap >>= n;
59 bit += n;
60 } while (bitmap);
61
62 return -1;
63 }
64
65 /*
66 * Set a number of contiguous bits in the directory block bitmap.
67 */
afs_set_contig_bits(union afs_xdr_dir_block * block,int bit,unsigned int nr_slots)68 static void afs_set_contig_bits(union afs_xdr_dir_block *block,
69 int bit, unsigned int nr_slots)
70 {
71 u64 mask;
72
73 mask = (1 << nr_slots) - 1;
74 mask <<= bit;
75
76 block->hdr.bitmap[0] |= (u8)(mask >> 0 * 8);
77 block->hdr.bitmap[1] |= (u8)(mask >> 1 * 8);
78 block->hdr.bitmap[2] |= (u8)(mask >> 2 * 8);
79 block->hdr.bitmap[3] |= (u8)(mask >> 3 * 8);
80 block->hdr.bitmap[4] |= (u8)(mask >> 4 * 8);
81 block->hdr.bitmap[5] |= (u8)(mask >> 5 * 8);
82 block->hdr.bitmap[6] |= (u8)(mask >> 6 * 8);
83 block->hdr.bitmap[7] |= (u8)(mask >> 7 * 8);
84 }
85
86 /*
87 * Clear a number of contiguous bits in the directory block bitmap.
88 */
afs_clear_contig_bits(union afs_xdr_dir_block * block,int bit,unsigned int nr_slots)89 static void afs_clear_contig_bits(union afs_xdr_dir_block *block,
90 int bit, unsigned int nr_slots)
91 {
92 u64 mask;
93
94 mask = (1 << nr_slots) - 1;
95 mask <<= bit;
96
97 block->hdr.bitmap[0] &= ~(u8)(mask >> 0 * 8);
98 block->hdr.bitmap[1] &= ~(u8)(mask >> 1 * 8);
99 block->hdr.bitmap[2] &= ~(u8)(mask >> 2 * 8);
100 block->hdr.bitmap[3] &= ~(u8)(mask >> 3 * 8);
101 block->hdr.bitmap[4] &= ~(u8)(mask >> 4 * 8);
102 block->hdr.bitmap[5] &= ~(u8)(mask >> 5 * 8);
103 block->hdr.bitmap[6] &= ~(u8)(mask >> 6 * 8);
104 block->hdr.bitmap[7] &= ~(u8)(mask >> 7 * 8);
105 }
106
107 /*
108 * Get a new directory folio.
109 */
afs_dir_get_folio(struct afs_vnode * vnode,pgoff_t index)110 static struct folio *afs_dir_get_folio(struct afs_vnode *vnode, pgoff_t index)
111 {
112 struct address_space *mapping = vnode->netfs.inode.i_mapping;
113 struct folio *folio;
114
115 folio = __filemap_get_folio(mapping, index,
116 FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
117 mapping->gfp_mask);
118 if (!folio)
119 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
120 else if (folio && !folio_test_private(folio))
121 folio_attach_private(folio, (void *)1);
122
123 return folio;
124 }
125
126 /*
127 * Scan a directory block looking for a dirent of the right name.
128 */
afs_dir_scan_block(union afs_xdr_dir_block * block,struct qstr * name,unsigned int blocknum)129 static int afs_dir_scan_block(union afs_xdr_dir_block *block, struct qstr *name,
130 unsigned int blocknum)
131 {
132 union afs_xdr_dirent *de;
133 u64 bitmap;
134 int d, len, n;
135
136 _enter("");
137
138 bitmap = (u64)block->hdr.bitmap[0] << 0 * 8;
139 bitmap |= (u64)block->hdr.bitmap[1] << 1 * 8;
140 bitmap |= (u64)block->hdr.bitmap[2] << 2 * 8;
141 bitmap |= (u64)block->hdr.bitmap[3] << 3 * 8;
142 bitmap |= (u64)block->hdr.bitmap[4] << 4 * 8;
143 bitmap |= (u64)block->hdr.bitmap[5] << 5 * 8;
144 bitmap |= (u64)block->hdr.bitmap[6] << 6 * 8;
145 bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8;
146
147 for (d = (blocknum == 0 ? AFS_DIR_RESV_BLOCKS0 : AFS_DIR_RESV_BLOCKS);
148 d < AFS_DIR_SLOTS_PER_BLOCK;
149 d++) {
150 if (!((bitmap >> d) & 1))
151 continue;
152 de = &block->dirents[d];
153 if (de->u.valid != 1)
154 continue;
155
156 /* The block was NUL-terminated by afs_dir_check_page(). */
157 len = strlen(de->u.name);
158 if (len == name->len &&
159 memcmp(de->u.name, name->name, name->len) == 0)
160 return d;
161
162 n = round_up(12 + len + 1 + 4, AFS_DIR_DIRENT_SIZE);
163 n /= AFS_DIR_DIRENT_SIZE;
164 d += n - 1;
165 }
166
167 return -1;
168 }
169
170 /*
171 * Initialise a new directory block. Note that block 0 is special and contains
172 * some extra metadata.
173 */
afs_edit_init_block(union afs_xdr_dir_block * meta,union afs_xdr_dir_block * block,int block_num)174 static void afs_edit_init_block(union afs_xdr_dir_block *meta,
175 union afs_xdr_dir_block *block, int block_num)
176 {
177 memset(block, 0, sizeof(*block));
178 block->hdr.npages = htons(1);
179 block->hdr.magic = AFS_DIR_MAGIC;
180 block->hdr.bitmap[0] = 1;
181
182 if (block_num == 0) {
183 block->hdr.bitmap[0] = 0xff;
184 block->hdr.bitmap[1] = 0x1f;
185 memset(block->meta.alloc_ctrs,
186 AFS_DIR_SLOTS_PER_BLOCK,
187 sizeof(block->meta.alloc_ctrs));
188 meta->meta.alloc_ctrs[0] =
189 AFS_DIR_SLOTS_PER_BLOCK - AFS_DIR_RESV_BLOCKS0;
190 }
191
192 if (block_num < AFS_DIR_BLOCKS_WITH_CTR)
193 meta->meta.alloc_ctrs[block_num] =
194 AFS_DIR_SLOTS_PER_BLOCK - AFS_DIR_RESV_BLOCKS;
195 }
196
197 /*
198 * Edit a directory's file data to add a new directory entry. Doing this after
199 * create, mkdir, symlink, link or rename if the data version number is
200 * incremented by exactly one avoids the need to re-download the entire
201 * directory contents.
202 *
203 * The caller must hold the inode locked.
204 */
afs_edit_dir_add(struct afs_vnode * vnode,struct qstr * name,struct afs_fid * new_fid,enum afs_edit_dir_reason why)205 void afs_edit_dir_add(struct afs_vnode *vnode,
206 struct qstr *name, struct afs_fid *new_fid,
207 enum afs_edit_dir_reason why)
208 {
209 union afs_xdr_dir_block *meta, *block;
210 union afs_xdr_dirent *de;
211 struct folio *folio0, *folio;
212 unsigned int need_slots, nr_blocks, b;
213 pgoff_t index;
214 loff_t i_size;
215 int slot;
216
217 _enter(",,{%d,%s},", name->len, name->name);
218
219 i_size = i_size_read(&vnode->netfs.inode);
220 if (i_size > AFS_DIR_BLOCK_SIZE * AFS_DIR_MAX_BLOCKS ||
221 (i_size & (AFS_DIR_BLOCK_SIZE - 1))) {
222 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
223 return;
224 }
225
226 folio0 = afs_dir_get_folio(vnode, 0);
227 if (!folio0) {
228 _leave(" [fgp]");
229 return;
230 }
231
232 /* Work out how many slots we're going to need. */
233 need_slots = afs_dir_calc_slots(name->len);
234
235 meta = kmap_local_folio(folio0, 0);
236 if (i_size == 0)
237 goto new_directory;
238 nr_blocks = i_size / AFS_DIR_BLOCK_SIZE;
239
240 /* Find a block that has sufficient slots available. Each folio
241 * contains two or more directory blocks.
242 */
243 for (b = 0; b < nr_blocks + 1; b++) {
244 /* If the directory extended into a new folio, then we need to
245 * tack a new folio on the end.
246 */
247 index = b / AFS_DIR_BLOCKS_PER_PAGE;
248 if (nr_blocks >= AFS_DIR_MAX_BLOCKS)
249 goto error;
250 if (index >= folio_nr_pages(folio0)) {
251 folio = afs_dir_get_folio(vnode, index);
252 if (!folio)
253 goto error;
254 } else {
255 folio = folio0;
256 }
257
258 block = kmap_local_folio(folio, b * AFS_DIR_BLOCK_SIZE - folio_file_pos(folio));
259
260 /* Abandon the edit if we got a callback break. */
261 if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
262 goto invalidated;
263
264 _debug("block %u: %2u %3u %u",
265 b,
266 (b < AFS_DIR_BLOCKS_WITH_CTR) ? meta->meta.alloc_ctrs[b] : 99,
267 ntohs(block->hdr.npages),
268 ntohs(block->hdr.magic));
269
270 /* Initialise the block if necessary. */
271 if (b == nr_blocks) {
272 _debug("init %u", b);
273 afs_edit_init_block(meta, block, b);
274 afs_set_i_size(vnode, (b + 1) * AFS_DIR_BLOCK_SIZE);
275 }
276
277 /* Only lower dir blocks have a counter in the header. */
278 if (b >= AFS_DIR_BLOCKS_WITH_CTR ||
279 meta->meta.alloc_ctrs[b] >= need_slots) {
280 /* We need to try and find one or more consecutive
281 * slots to hold the entry.
282 */
283 slot = afs_find_contig_bits(block, need_slots);
284 if (slot >= 0) {
285 _debug("slot %u", slot);
286 goto found_space;
287 }
288 }
289
290 kunmap_local(block);
291 if (folio != folio0) {
292 folio_unlock(folio);
293 folio_put(folio);
294 }
295 }
296
297 /* There are no spare slots of sufficient size, yet the operation
298 * succeeded. Download the directory again.
299 */
300 trace_afs_edit_dir(vnode, why, afs_edit_dir_create_nospc, 0, 0, 0, 0, name->name);
301 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
302 goto out_unmap;
303
304 new_directory:
305 afs_edit_init_block(meta, meta, 0);
306 i_size = AFS_DIR_BLOCK_SIZE;
307 afs_set_i_size(vnode, i_size);
308 slot = AFS_DIR_RESV_BLOCKS0;
309 folio = folio0;
310 block = kmap_local_folio(folio, 0);
311 nr_blocks = 1;
312 b = 0;
313
314 found_space:
315 /* Set the dirent slot. */
316 trace_afs_edit_dir(vnode, why, afs_edit_dir_create, b, slot,
317 new_fid->vnode, new_fid->unique, name->name);
318 de = &block->dirents[slot];
319 de->u.valid = 1;
320 de->u.unused[0] = 0;
321 de->u.hash_next = 0; // TODO: Really need to maintain this
322 de->u.vnode = htonl(new_fid->vnode);
323 de->u.unique = htonl(new_fid->unique);
324 memcpy(de->u.name, name->name, name->len + 1);
325 de->u.name[name->len] = 0;
326
327 /* Adjust the bitmap. */
328 afs_set_contig_bits(block, slot, need_slots);
329 kunmap_local(block);
330 if (folio != folio0) {
331 folio_unlock(folio);
332 folio_put(folio);
333 }
334
335 /* Adjust the allocation counter. */
336 if (b < AFS_DIR_BLOCKS_WITH_CTR)
337 meta->meta.alloc_ctrs[b] -= need_slots;
338
339 inode_inc_iversion_raw(&vnode->netfs.inode);
340 afs_stat_v(vnode, n_dir_cr);
341 _debug("Insert %s in %u[%u]", name->name, b, slot);
342
343 out_unmap:
344 kunmap_local(meta);
345 folio_unlock(folio0);
346 folio_put(folio0);
347 _leave("");
348 return;
349
350 invalidated:
351 trace_afs_edit_dir(vnode, why, afs_edit_dir_create_inval, 0, 0, 0, 0, name->name);
352 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
353 kunmap_local(block);
354 if (folio != folio0) {
355 folio_unlock(folio);
356 folio_put(folio);
357 }
358 goto out_unmap;
359
360 error:
361 trace_afs_edit_dir(vnode, why, afs_edit_dir_create_error, 0, 0, 0, 0, name->name);
362 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
363 goto out_unmap;
364 }
365
366 /*
367 * Edit a directory's file data to remove a new directory entry. Doing this
368 * after unlink, rmdir or rename if the data version number is incremented by
369 * exactly one avoids the need to re-download the entire directory contents.
370 *
371 * The caller must hold the inode locked.
372 */
afs_edit_dir_remove(struct afs_vnode * vnode,struct qstr * name,enum afs_edit_dir_reason why)373 void afs_edit_dir_remove(struct afs_vnode *vnode,
374 struct qstr *name, enum afs_edit_dir_reason why)
375 {
376 union afs_xdr_dir_block *meta, *block;
377 union afs_xdr_dirent *de;
378 struct folio *folio0, *folio;
379 unsigned int need_slots, nr_blocks, b;
380 pgoff_t index;
381 loff_t i_size;
382 int slot;
383
384 _enter(",,{%d,%s},", name->len, name->name);
385
386 i_size = i_size_read(&vnode->netfs.inode);
387 if (i_size < AFS_DIR_BLOCK_SIZE ||
388 i_size > AFS_DIR_BLOCK_SIZE * AFS_DIR_MAX_BLOCKS ||
389 (i_size & (AFS_DIR_BLOCK_SIZE - 1))) {
390 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
391 return;
392 }
393 nr_blocks = i_size / AFS_DIR_BLOCK_SIZE;
394
395 folio0 = afs_dir_get_folio(vnode, 0);
396 if (!folio0) {
397 _leave(" [fgp]");
398 return;
399 }
400
401 /* Work out how many slots we're going to discard. */
402 need_slots = afs_dir_calc_slots(name->len);
403
404 meta = kmap_local_folio(folio0, 0);
405
406 /* Find a block that has sufficient slots available. Each folio
407 * contains two or more directory blocks.
408 */
409 for (b = 0; b < nr_blocks; b++) {
410 index = b / AFS_DIR_BLOCKS_PER_PAGE;
411 if (index >= folio_nr_pages(folio0)) {
412 folio = afs_dir_get_folio(vnode, index);
413 if (!folio)
414 goto error;
415 } else {
416 folio = folio0;
417 }
418
419 block = kmap_local_folio(folio, b * AFS_DIR_BLOCK_SIZE - folio_file_pos(folio));
420
421 /* Abandon the edit if we got a callback break. */
422 if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
423 goto invalidated;
424
425 if (b > AFS_DIR_BLOCKS_WITH_CTR ||
426 meta->meta.alloc_ctrs[b] <= AFS_DIR_SLOTS_PER_BLOCK - 1 - need_slots) {
427 slot = afs_dir_scan_block(block, name, b);
428 if (slot >= 0)
429 goto found_dirent;
430 }
431
432 kunmap_local(block);
433 if (folio != folio0) {
434 folio_unlock(folio);
435 folio_put(folio);
436 }
437 }
438
439 /* Didn't find the dirent to clobber. Download the directory again. */
440 trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_noent,
441 0, 0, 0, 0, name->name);
442 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
443 goto out_unmap;
444
445 found_dirent:
446 de = &block->dirents[slot];
447
448 trace_afs_edit_dir(vnode, why, afs_edit_dir_delete, b, slot,
449 ntohl(de->u.vnode), ntohl(de->u.unique),
450 name->name);
451
452 memset(de, 0, sizeof(*de) * need_slots);
453
454 /* Adjust the bitmap. */
455 afs_clear_contig_bits(block, slot, need_slots);
456 kunmap_local(block);
457 if (folio != folio0) {
458 folio_unlock(folio);
459 folio_put(folio);
460 }
461
462 /* Adjust the allocation counter. */
463 if (b < AFS_DIR_BLOCKS_WITH_CTR)
464 meta->meta.alloc_ctrs[b] += need_slots;
465
466 inode_set_iversion_raw(&vnode->netfs.inode, vnode->status.data_version);
467 afs_stat_v(vnode, n_dir_rm);
468 _debug("Remove %s from %u[%u]", name->name, b, slot);
469
470 out_unmap:
471 kunmap_local(meta);
472 folio_unlock(folio0);
473 folio_put(folio0);
474 _leave("");
475 return;
476
477 invalidated:
478 trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_inval,
479 0, 0, 0, 0, name->name);
480 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
481 kunmap_local(block);
482 if (folio != folio0) {
483 folio_unlock(folio);
484 folio_put(folio);
485 }
486 goto out_unmap;
487
488 error:
489 trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_error,
490 0, 0, 0, 0, name->name);
491 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
492 goto out_unmap;
493 }
494