xref: /openbmc/linux/fs/afs/dir.c (revision 87c2ce3b) 
1 /* dir.c: AFS filesystem directory handling
2  *
3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/sched.h>
16 #include <linux/slab.h>
17 #include <linux/fs.h>
18 #include <linux/pagemap.h>
19 #include <linux/smp_lock.h>
20 #include "vnode.h"
21 #include "volume.h"
22 #include <rxrpc/call.h>
23 #include "super.h"
24 #include "internal.h"
25 
26 static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry,
27 				     struct nameidata *nd);
28 static int afs_dir_open(struct inode *inode, struct file *file);
29 static int afs_dir_readdir(struct file *file, void *dirent, filldir_t filldir);
30 static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd);
31 static int afs_d_delete(struct dentry *dentry);
32 static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen,
33 				  loff_t fpos, ino_t ino, unsigned dtype);
34 
35 struct file_operations afs_dir_file_operations = {
36 	.open		= afs_dir_open,
37 	.readdir	= afs_dir_readdir,
38 };
39 
40 struct inode_operations afs_dir_inode_operations = {
41 	.lookup		= afs_dir_lookup,
42 	.getattr	= afs_inode_getattr,
43 #if 0 /* TODO */
44 	.create		= afs_dir_create,
45 	.link		= afs_dir_link,
46 	.unlink		= afs_dir_unlink,
47 	.symlink	= afs_dir_symlink,
48 	.mkdir		= afs_dir_mkdir,
49 	.rmdir		= afs_dir_rmdir,
50 	.mknod		= afs_dir_mknod,
51 	.rename		= afs_dir_rename,
52 #endif
53 };
54 
55 static struct dentry_operations afs_fs_dentry_operations = {
56 	.d_revalidate	= afs_d_revalidate,
57 	.d_delete	= afs_d_delete,
58 };
59 
60 #define AFS_DIR_HASHTBL_SIZE	128
61 #define AFS_DIR_DIRENT_SIZE	32
62 #define AFS_DIRENT_PER_BLOCK	64
63 
64 union afs_dirent {
65 	struct {
66 		uint8_t		valid;
67 		uint8_t		unused[1];
68 		__be16		hash_next;
69 		__be32		vnode;
70 		__be32		unique;
71 		uint8_t		name[16];
72 		uint8_t		overflow[4];	/* if any char of the name (inc
73 						 * NUL) reaches here, consume
74 						 * the next dirent too */
75 	} u;
76 	uint8_t	extended_name[32];
77 };
78 
79 /* AFS directory page header (one at the beginning of every 2048-byte chunk) */
80 struct afs_dir_pagehdr {
81 	__be16		npages;
82 	__be16		magic;
83 #define AFS_DIR_MAGIC htons(1234)
84 	uint8_t		nentries;
85 	uint8_t		bitmap[8];
86 	uint8_t		pad[19];
87 };
88 
89 /* directory block layout */
90 union afs_dir_block {
91 
92 	struct afs_dir_pagehdr pagehdr;
93 
94 	struct {
95 		struct afs_dir_pagehdr	pagehdr;
96 		uint8_t			alloc_ctrs[128];
97 		/* dir hash table */
98 		uint16_t		hashtable[AFS_DIR_HASHTBL_SIZE];
99 	} hdr;
100 
101 	union afs_dirent dirents[AFS_DIRENT_PER_BLOCK];
102 };
103 
104 /* layout on a linux VM page */
105 struct afs_dir_page {
106 	union afs_dir_block blocks[PAGE_SIZE / sizeof(union afs_dir_block)];
107 };
108 
109 struct afs_dir_lookup_cookie {
110 	struct afs_fid	fid;
111 	const char	*name;
112 	size_t		nlen;
113 	int		found;
114 };
115 
116 /*****************************************************************************/
117 /*
118  * check that a directory page is valid
119  */
120 static inline void afs_dir_check_page(struct inode *dir, struct page *page)
121 {
122 	struct afs_dir_page *dbuf;
123 	loff_t latter;
124 	int tmp, qty;
125 
126 #if 0
127 	/* check the page count */
128 	qty = desc.size / sizeof(dbuf->blocks[0]);
129 	if (qty == 0)
130 		goto error;
131 
132 	if (page->index==0 && qty!=ntohs(dbuf->blocks[0].pagehdr.npages)) {
133 		printk("kAFS: %s(%lu): wrong number of dir blocks %d!=%hu\n",
134 		       __FUNCTION__,dir->i_ino,qty,ntohs(dbuf->blocks[0].pagehdr.npages));
135 		goto error;
136 	}
137 #endif
138 
139 	/* determine how many magic numbers there should be in this page */
140 	latter = dir->i_size - page_offset(page);
141 	if (latter >= PAGE_SIZE)
142 		qty = PAGE_SIZE;
143 	else
144 		qty = latter;
145 	qty /= sizeof(union afs_dir_block);
146 
147 	/* check them */
148 	dbuf = page_address(page);
149 	for (tmp = 0; tmp < qty; tmp++) {
150 		if (dbuf->blocks[tmp].pagehdr.magic != AFS_DIR_MAGIC) {
151 			printk("kAFS: %s(%lu): bad magic %d/%d is %04hx\n",
152 			       __FUNCTION__, dir->i_ino, tmp, qty,
153 			       ntohs(dbuf->blocks[tmp].pagehdr.magic));
154 			goto error;
155 		}
156 	}
157 
158 	SetPageChecked(page);
159 	return;
160 
161  error:
162 	SetPageChecked(page);
163 	SetPageError(page);
164 
165 } /* end afs_dir_check_page() */
166 
167 /*****************************************************************************/
168 /*
169  * discard a page cached in the pagecache
170  */
171 static inline void afs_dir_put_page(struct page *page)
172 {
173 	kunmap(page);
174 	page_cache_release(page);
175 
176 } /* end afs_dir_put_page() */
177 
178 /*****************************************************************************/
179 /*
180  * get a page into the pagecache
181  */
182 static struct page *afs_dir_get_page(struct inode *dir, unsigned long index)
183 {
184 	struct page *page;
185 
186 	_enter("{%lu},%lu", dir->i_ino, index);
187 
188 	page = read_cache_page(dir->i_mapping,index,
189 			       (filler_t *) dir->i_mapping->a_ops->readpage,
190 			       NULL);
191 	if (!IS_ERR(page)) {
192 		wait_on_page_locked(page);
193 		kmap(page);
194 		if (!PageUptodate(page))
195 			goto fail;
196 		if (!PageChecked(page))
197 			afs_dir_check_page(dir, page);
198 		if (PageError(page))
199 			goto fail;
200 	}
201 	return page;
202 
203  fail:
204 	afs_dir_put_page(page);
205 	return ERR_PTR(-EIO);
206 } /* end afs_dir_get_page() */
207 
208 /*****************************************************************************/
209 /*
210  * open an AFS directory file
211  */
212 static int afs_dir_open(struct inode *inode, struct file *file)
213 {
214 	_enter("{%lu}", inode->i_ino);
215 
216 	BUG_ON(sizeof(union afs_dir_block) != 2048);
217 	BUG_ON(sizeof(union afs_dirent) != 32);
218 
219 	if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED)
220 		return -ENOENT;
221 
222 	_leave(" = 0");
223 	return 0;
224 
225 } /* end afs_dir_open() */
226 
227 /*****************************************************************************/
228 /*
229  * deal with one block in an AFS directory
230  */
231 static int afs_dir_iterate_block(unsigned *fpos,
232 				 union afs_dir_block *block,
233 				 unsigned blkoff,
234 				 void *cookie,
235 				 filldir_t filldir)
236 {
237 	union afs_dirent *dire;
238 	unsigned offset, next, curr;
239 	size_t nlen;
240 	int tmp, ret;
241 
242 	_enter("%u,%x,%p,,",*fpos,blkoff,block);
243 
244 	curr = (*fpos - blkoff) / sizeof(union afs_dirent);
245 
246 	/* walk through the block, an entry at a time */
247 	for (offset = AFS_DIRENT_PER_BLOCK - block->pagehdr.nentries;
248 	     offset < AFS_DIRENT_PER_BLOCK;
249 	     offset = next
250 	     ) {
251 		next = offset + 1;
252 
253 		/* skip entries marked unused in the bitmap */
254 		if (!(block->pagehdr.bitmap[offset / 8] &
255 		      (1 << (offset % 8)))) {
256 			_debug("ENT[%Zu.%u]: unused\n",
257 			       blkoff / sizeof(union afs_dir_block), offset);
258 			if (offset >= curr)
259 				*fpos = blkoff +
260 					next * sizeof(union afs_dirent);
261 			continue;
262 		}
263 
264 		/* got a valid entry */
265 		dire = &block->dirents[offset];
266 		nlen = strnlen(dire->u.name,
267 			       sizeof(*block) -
268 			       offset * sizeof(union afs_dirent));
269 
270 		_debug("ENT[%Zu.%u]: %s %Zu \"%s\"\n",
271 		       blkoff / sizeof(union afs_dir_block), offset,
272 		       (offset < curr ? "skip" : "fill"),
273 		       nlen, dire->u.name);
274 
275 		/* work out where the next possible entry is */
276 		for (tmp = nlen; tmp > 15; tmp -= sizeof(union afs_dirent)) {
277 			if (next >= AFS_DIRENT_PER_BLOCK) {
278 				_debug("ENT[%Zu.%u]:"
279 				       " %u travelled beyond end dir block"
280 				       " (len %u/%Zu)\n",
281 				       blkoff / sizeof(union afs_dir_block),
282 				       offset, next, tmp, nlen);
283 				return -EIO;
284 			}
285 			if (!(block->pagehdr.bitmap[next / 8] &
286 			      (1 << (next % 8)))) {
287 				_debug("ENT[%Zu.%u]:"
288 				       " %u unmarked extension (len %u/%Zu)\n",
289 				       blkoff / sizeof(union afs_dir_block),
290 				       offset, next, tmp, nlen);
291 				return -EIO;
292 			}
293 
294 			_debug("ENT[%Zu.%u]: ext %u/%Zu\n",
295 			       blkoff / sizeof(union afs_dir_block),
296 			       next, tmp, nlen);
297 			next++;
298 		}
299 
300 		/* skip if starts before the current position */
301 		if (offset < curr)
302 			continue;
303 
304 		/* found the next entry */
305 		ret = filldir(cookie,
306 			      dire->u.name,
307 			      nlen,
308 			      blkoff + offset * sizeof(union afs_dirent),
309 			      ntohl(dire->u.vnode),
310 			      filldir == afs_dir_lookup_filldir ?
311 			      ntohl(dire->u.unique) : DT_UNKNOWN);
312 		if (ret < 0) {
313 			_leave(" = 0 [full]");
314 			return 0;
315 		}
316 
317 		*fpos = blkoff + next * sizeof(union afs_dirent);
318 	}
319 
320 	_leave(" = 1 [more]");
321 	return 1;
322 } /* end afs_dir_iterate_block() */
323 
324 /*****************************************************************************/
325 /*
326  * read an AFS directory
327  */
328 static int afs_dir_iterate(struct inode *dir, unsigned *fpos, void *cookie,
329 			   filldir_t filldir)
330 {
331 	union afs_dir_block	*dblock;
332 	struct afs_dir_page *dbuf;
333 	struct page *page;
334 	unsigned blkoff, limit;
335 	int ret;
336 
337 	_enter("{%lu},%u,,", dir->i_ino, *fpos);
338 
339 	if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
340 		_leave(" = -ESTALE");
341 		return -ESTALE;
342 	}
343 
344 	/* round the file position up to the next entry boundary */
345 	*fpos += sizeof(union afs_dirent) - 1;
346 	*fpos &= ~(sizeof(union afs_dirent) - 1);
347 
348 	/* walk through the blocks in sequence */
349 	ret = 0;
350 	while (*fpos < dir->i_size) {
351 		blkoff = *fpos & ~(sizeof(union afs_dir_block) - 1);
352 
353 		/* fetch the appropriate page from the directory */
354 		page = afs_dir_get_page(dir, blkoff / PAGE_SIZE);
355 		if (IS_ERR(page)) {
356 			ret = PTR_ERR(page);
357 			break;
358 		}
359 
360 		limit = blkoff & ~(PAGE_SIZE - 1);
361 
362 		dbuf = page_address(page);
363 
364 		/* deal with the individual blocks stashed on this page */
365 		do {
366 			dblock = &dbuf->blocks[(blkoff % PAGE_SIZE) /
367 					       sizeof(union afs_dir_block)];
368 			ret = afs_dir_iterate_block(fpos, dblock, blkoff,
369 						    cookie, filldir);
370 			if (ret != 1) {
371 				afs_dir_put_page(page);
372 				goto out;
373 			}
374 
375 			blkoff += sizeof(union afs_dir_block);
376 
377 		} while (*fpos < dir->i_size && blkoff < limit);
378 
379 		afs_dir_put_page(page);
380 		ret = 0;
381 	}
382 
383  out:
384 	_leave(" = %d", ret);
385 	return ret;
386 } /* end afs_dir_iterate() */
387 
388 /*****************************************************************************/
389 /*
390  * read an AFS directory
391  */
392 static int afs_dir_readdir(struct file *file, void *cookie, filldir_t filldir)
393 {
394 	unsigned fpos;
395 	int ret;
396 
397 	_enter("{%Ld,{%lu}}", file->f_pos, file->f_dentry->d_inode->i_ino);
398 
399 	fpos = file->f_pos;
400 	ret = afs_dir_iterate(file->f_dentry->d_inode, &fpos, cookie, filldir);
401 	file->f_pos = fpos;
402 
403 	_leave(" = %d", ret);
404 	return ret;
405 } /* end afs_dir_readdir() */
406 
407 /*****************************************************************************/
408 /*
409  * search the directory for a name
410  * - if afs_dir_iterate_block() spots this function, it'll pass the FID
411  *   uniquifier through dtype
412  */
413 static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen,
414 				  loff_t fpos, ino_t ino, unsigned dtype)
415 {
416 	struct afs_dir_lookup_cookie *cookie = _cookie;
417 
418 	_enter("{%s,%Zu},%s,%u,,%lu,%u",
419 	       cookie->name, cookie->nlen, name, nlen, ino, dtype);
420 
421 	if (cookie->nlen != nlen || memcmp(cookie->name, name, nlen) != 0) {
422 		_leave(" = 0 [no]");
423 		return 0;
424 	}
425 
426 	cookie->fid.vnode = ino;
427 	cookie->fid.unique = dtype;
428 	cookie->found = 1;
429 
430 	_leave(" = -1 [found]");
431 	return -1;
432 } /* end afs_dir_lookup_filldir() */
433 
434 /*****************************************************************************/
435 /*
436  * look up an entry in a directory
437  */
438 static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry,
439 				     struct nameidata *nd)
440 {
441 	struct afs_dir_lookup_cookie cookie;
442 	struct afs_super_info *as;
443 	struct afs_vnode *vnode;
444 	struct inode *inode;
445 	unsigned fpos;
446 	int ret;
447 
448 	_enter("{%lu},%p{%s}", dir->i_ino, dentry, dentry->d_name.name);
449 
450 	/* insanity checks first */
451 	BUG_ON(sizeof(union afs_dir_block) != 2048);
452 	BUG_ON(sizeof(union afs_dirent) != 32);
453 
454 	if (dentry->d_name.len > 255) {
455 		_leave(" = -ENAMETOOLONG");
456 		return ERR_PTR(-ENAMETOOLONG);
457 	}
458 
459 	vnode = AFS_FS_I(dir);
460 	if (vnode->flags & AFS_VNODE_DELETED) {
461 		_leave(" = -ESTALE");
462 		return ERR_PTR(-ESTALE);
463 	}
464 
465 	as = dir->i_sb->s_fs_info;
466 
467 	/* search the directory */
468 	cookie.name	= dentry->d_name.name;
469 	cookie.nlen	= dentry->d_name.len;
470 	cookie.fid.vid	= as->volume->vid;
471 	cookie.found	= 0;
472 
473 	fpos = 0;
474 	ret = afs_dir_iterate(dir, &fpos, &cookie, afs_dir_lookup_filldir);
475 	if (ret < 0) {
476 		_leave(" = %d", ret);
477 		return ERR_PTR(ret);
478 	}
479 
480 	ret = -ENOENT;
481 	if (!cookie.found) {
482 		_leave(" = %d", ret);
483 		return ERR_PTR(ret);
484 	}
485 
486 	/* instantiate the dentry */
487 	ret = afs_iget(dir->i_sb, &cookie.fid, &inode);
488 	if (ret < 0) {
489 		_leave(" = %d", ret);
490 		return ERR_PTR(ret);
491 	}
492 
493 	dentry->d_op = &afs_fs_dentry_operations;
494 	dentry->d_fsdata = (void *) (unsigned long) vnode->status.version;
495 
496 	d_add(dentry, inode);
497 	_leave(" = 0 { vn=%u u=%u } -> { ino=%lu v=%lu }",
498 	       cookie.fid.vnode,
499 	       cookie.fid.unique,
500 	       dentry->d_inode->i_ino,
501 	       dentry->d_inode->i_version);
502 
503 	return NULL;
504 } /* end afs_dir_lookup() */
505 
506 /*****************************************************************************/
507 /*
508  * check that a dentry lookup hit has found a valid entry
509  * - NOTE! the hit can be a negative hit too, so we can't assume we have an
510  *   inode
511  * (derived from nfs_lookup_revalidate)
512  */
513 static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
514 {
515 	struct afs_dir_lookup_cookie cookie;
516 	struct dentry *parent;
517 	struct inode *inode, *dir;
518 	unsigned fpos;
519 	int ret;
520 
521 	_enter("{sb=%p n=%s},", dentry->d_sb, dentry->d_name.name);
522 
523 	/* lock down the parent dentry so we can peer at it */
524 	parent = dget_parent(dentry->d_parent);
525 
526 	dir = parent->d_inode;
527 	inode = dentry->d_inode;
528 
529 	/* handle a negative dentry */
530 	if (!inode)
531 		goto out_bad;
532 
533 	/* handle a bad inode */
534 	if (is_bad_inode(inode)) {
535 		printk("kAFS: afs_d_revalidate: %s/%s has bad inode\n",
536 		       dentry->d_parent->d_name.name, dentry->d_name.name);
537 		goto out_bad;
538 	}
539 
540 	/* force a full look up if the parent directory changed since last the
541 	 * server was consulted
542 	 * - otherwise this inode must still exist, even if the inode details
543 	 *   themselves have changed
544 	 */
545 	if (AFS_FS_I(dir)->flags & AFS_VNODE_CHANGED)
546 		afs_vnode_fetch_status(AFS_FS_I(dir));
547 
548 	if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
549 		_debug("%s: parent dir deleted", dentry->d_name.name);
550 		goto out_bad;
551 	}
552 
553 	if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED) {
554 		_debug("%s: file already deleted", dentry->d_name.name);
555 		goto out_bad;
556 	}
557 
558 	if ((unsigned long) dentry->d_fsdata !=
559 	    (unsigned long) AFS_FS_I(dir)->status.version) {
560 		_debug("%s: parent changed %lu -> %u",
561 		       dentry->d_name.name,
562 		       (unsigned long) dentry->d_fsdata,
563 		       (unsigned) AFS_FS_I(dir)->status.version);
564 
565 		/* search the directory for this vnode */
566 		cookie.name	= dentry->d_name.name;
567 		cookie.nlen	= dentry->d_name.len;
568 		cookie.fid.vid	= AFS_FS_I(inode)->volume->vid;
569 		cookie.found	= 0;
570 
571 		fpos = 0;
572 		ret = afs_dir_iterate(dir, &fpos, &cookie,
573 				      afs_dir_lookup_filldir);
574 		if (ret < 0) {
575 			_debug("failed to iterate dir %s: %d",
576 			       parent->d_name.name, ret);
577 			goto out_bad;
578 		}
579 
580 		if (!cookie.found) {
581 			_debug("%s: dirent not found", dentry->d_name.name);
582 			goto not_found;
583 		}
584 
585 		/* if the vnode ID has changed, then the dirent points to a
586 		 * different file */
587 		if (cookie.fid.vnode != AFS_FS_I(inode)->fid.vnode) {
588 			_debug("%s: dirent changed", dentry->d_name.name);
589 			goto not_found;
590 		}
591 
592 		/* if the vnode ID uniqifier has changed, then the file has
593 		 * been deleted */
594 		if (cookie.fid.unique != AFS_FS_I(inode)->fid.unique) {
595 			_debug("%s: file deleted (uq %u -> %u I:%lu)",
596 			       dentry->d_name.name,
597 			       cookie.fid.unique,
598 			       AFS_FS_I(inode)->fid.unique,
599 			       inode->i_version);
600 			spin_lock(&AFS_FS_I(inode)->lock);
601 			AFS_FS_I(inode)->flags |= AFS_VNODE_DELETED;
602 			spin_unlock(&AFS_FS_I(inode)->lock);
603 			invalidate_remote_inode(inode);
604 			goto out_bad;
605 		}
606 
607 		dentry->d_fsdata =
608 			(void *) (unsigned long) AFS_FS_I(dir)->status.version;
609 	}
610 
611  out_valid:
612 	dput(parent);
613 	_leave(" = 1 [valid]");
614 	return 1;
615 
616 	/* the dirent, if it exists, now points to a different vnode */
617  not_found:
618 	spin_lock(&dentry->d_lock);
619 	dentry->d_flags |= DCACHE_NFSFS_RENAMED;
620 	spin_unlock(&dentry->d_lock);
621 
622  out_bad:
623 	if (inode) {
624 		/* don't unhash if we have submounts */
625 		if (have_submounts(dentry))
626 			goto out_valid;
627 	}
628 
629 	shrink_dcache_parent(dentry);
630 
631 	_debug("dropping dentry %s/%s",
632 	       dentry->d_parent->d_name.name, dentry->d_name.name);
633 	d_drop(dentry);
634 
635 	dput(parent);
636 
637 	_leave(" = 0 [bad]");
638 	return 0;
639 } /* end afs_d_revalidate() */
640 
641 /*****************************************************************************/
642 /*
643  * allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
644  * sleep)
645  * - called from dput() when d_count is going to 0.
646  * - return 1 to request dentry be unhashed, 0 otherwise
647  */
648 static int afs_d_delete(struct dentry *dentry)
649 {
650 	_enter("%s", dentry->d_name.name);
651 
652 	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
653 		goto zap;
654 
655 	if (dentry->d_inode) {
656 		if (AFS_FS_I(dentry->d_inode)->flags & AFS_VNODE_DELETED)
657 			goto zap;
658 	}
659 
660 	_leave(" = 0 [keep]");
661 	return 0;
662 
663  zap:
664 	_leave(" = 1 [zap]");
665 	return 1;
666 } /* end afs_d_delete() */
667