xref: /openbmc/linux/fs/xfs/xfs_symlink.c (revision 3821a065)
1 /*
2  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
3  * Copyright (c) 2012-2013 Red Hat, Inc.
4  * All rights reserved.
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 as
8  * published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it would be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write the Free Software Foundation,
17  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
18  */
19 #include "xfs.h"
20 #include "xfs_shared.h"
21 #include "xfs_fs.h"
22 #include "xfs_format.h"
23 #include "xfs_log_format.h"
24 #include "xfs_trans_resv.h"
25 #include "xfs_bit.h"
26 #include "xfs_mount.h"
27 #include "xfs_da_format.h"
28 #include "xfs_da_btree.h"
29 #include "xfs_dir2.h"
30 #include "xfs_inode.h"
31 #include "xfs_ialloc.h"
32 #include "xfs_alloc.h"
33 #include "xfs_bmap.h"
34 #include "xfs_bmap_btree.h"
35 #include "xfs_bmap_util.h"
36 #include "xfs_error.h"
37 #include "xfs_quota.h"
38 #include "xfs_trans_space.h"
39 #include "xfs_trace.h"
40 #include "xfs_symlink.h"
41 #include "xfs_trans.h"
42 #include "xfs_log.h"
43 
44 /* ----- Kernel only functions below ----- */
45 STATIC int
46 xfs_readlink_bmap(
47 	struct xfs_inode	*ip,
48 	char			*link)
49 {
50 	struct xfs_mount	*mp = ip->i_mount;
51 	struct xfs_bmbt_irec	mval[XFS_SYMLINK_MAPS];
52 	struct xfs_buf		*bp;
53 	xfs_daddr_t		d;
54 	char			*cur_chunk;
55 	int			pathlen = ip->i_d.di_size;
56 	int			nmaps = XFS_SYMLINK_MAPS;
57 	int			byte_cnt;
58 	int			n;
59 	int			error = 0;
60 	int			fsblocks = 0;
61 	int			offset;
62 
63 	fsblocks = xfs_symlink_blocks(mp, pathlen);
64 	error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
65 	if (error)
66 		goto out;
67 
68 	offset = 0;
69 	for (n = 0; n < nmaps; n++) {
70 		d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
71 		byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
72 
73 		bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
74 				  &xfs_symlink_buf_ops);
75 		if (!bp)
76 			return -ENOMEM;
77 		error = bp->b_error;
78 		if (error) {
79 			xfs_buf_ioerror_alert(bp, __func__);
80 			xfs_buf_relse(bp);
81 
82 			/* bad CRC means corrupted metadata */
83 			if (error == -EFSBADCRC)
84 				error = -EFSCORRUPTED;
85 			goto out;
86 		}
87 		byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
88 		if (pathlen < byte_cnt)
89 			byte_cnt = pathlen;
90 
91 		cur_chunk = bp->b_addr;
92 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
93 			if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
94 							byte_cnt, bp)) {
95 				error = -EFSCORRUPTED;
96 				xfs_alert(mp,
97 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
98 					offset, byte_cnt, ip->i_ino);
99 				xfs_buf_relse(bp);
100 				goto out;
101 
102 			}
103 
104 			cur_chunk += sizeof(struct xfs_dsymlink_hdr);
105 		}
106 
107 		memcpy(link + offset, cur_chunk, byte_cnt);
108 
109 		pathlen -= byte_cnt;
110 		offset += byte_cnt;
111 
112 		xfs_buf_relse(bp);
113 	}
114 	ASSERT(pathlen == 0);
115 
116 	link[ip->i_d.di_size] = '\0';
117 	error = 0;
118 
119  out:
120 	return error;
121 }
122 
123 int
124 xfs_readlink(
125 	struct xfs_inode *ip,
126 	char		*link)
127 {
128 	struct xfs_mount *mp = ip->i_mount;
129 	xfs_fsize_t	pathlen;
130 	int		error = 0;
131 
132 	trace_xfs_readlink(ip);
133 
134 	if (XFS_FORCED_SHUTDOWN(mp))
135 		return -EIO;
136 
137 	xfs_ilock(ip, XFS_ILOCK_SHARED);
138 
139 	pathlen = ip->i_d.di_size;
140 	if (!pathlen)
141 		goto out;
142 
143 	if (pathlen < 0 || pathlen > MAXPATHLEN) {
144 		xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
145 			 __func__, (unsigned long long) ip->i_ino,
146 			 (long long) pathlen);
147 		ASSERT(0);
148 		error = -EFSCORRUPTED;
149 		goto out;
150 	}
151 
152 
153 	if (ip->i_df.if_flags & XFS_IFINLINE) {
154 		memcpy(link, ip->i_df.if_u1.if_data, pathlen);
155 		link[pathlen] = '\0';
156 	} else {
157 		error = xfs_readlink_bmap(ip, link);
158 	}
159 
160  out:
161 	xfs_iunlock(ip, XFS_ILOCK_SHARED);
162 	return error;
163 }
164 
165 int
166 xfs_symlink(
167 	struct xfs_inode	*dp,
168 	struct xfs_name		*link_name,
169 	const char		*target_path,
170 	umode_t			mode,
171 	struct xfs_inode	**ipp)
172 {
173 	struct xfs_mount	*mp = dp->i_mount;
174 	struct xfs_trans	*tp = NULL;
175 	struct xfs_inode	*ip = NULL;
176 	int			error = 0;
177 	int			pathlen;
178 	struct xfs_bmap_free	free_list;
179 	xfs_fsblock_t		first_block;
180 	bool                    unlock_dp_on_error = false;
181 	int			committed;
182 	xfs_fileoff_t		first_fsb;
183 	xfs_filblks_t		fs_blocks;
184 	int			nmaps;
185 	struct xfs_bmbt_irec	mval[XFS_SYMLINK_MAPS];
186 	xfs_daddr_t		d;
187 	const char		*cur_chunk;
188 	int			byte_cnt;
189 	int			n;
190 	xfs_buf_t		*bp;
191 	prid_t			prid;
192 	struct xfs_dquot	*udqp = NULL;
193 	struct xfs_dquot	*gdqp = NULL;
194 	struct xfs_dquot	*pdqp = NULL;
195 	uint			resblks;
196 
197 	*ipp = NULL;
198 
199 	trace_xfs_symlink(dp, link_name);
200 
201 	if (XFS_FORCED_SHUTDOWN(mp))
202 		return -EIO;
203 
204 	/*
205 	 * Check component lengths of the target path name.
206 	 */
207 	pathlen = strlen(target_path);
208 	if (pathlen >= MAXPATHLEN)      /* total string too long */
209 		return -ENAMETOOLONG;
210 
211 	udqp = gdqp = NULL;
212 	prid = xfs_get_initial_prid(dp);
213 
214 	/*
215 	 * Make sure that we have allocated dquot(s) on disk.
216 	 */
217 	error = xfs_qm_vop_dqalloc(dp,
218 			xfs_kuid_to_uid(current_fsuid()),
219 			xfs_kgid_to_gid(current_fsgid()), prid,
220 			XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
221 			&udqp, &gdqp, &pdqp);
222 	if (error)
223 		return error;
224 
225 	tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
226 	/*
227 	 * The symlink will fit into the inode data fork?
228 	 * There can't be any attributes so we get the whole variable part.
229 	 */
230 	if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
231 		fs_blocks = 0;
232 	else
233 		fs_blocks = xfs_symlink_blocks(mp, pathlen);
234 	resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
235 	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
236 	if (error == -ENOSPC && fs_blocks == 0) {
237 		resblks = 0;
238 		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
239 	}
240 	if (error)
241 		goto out_trans_cancel;
242 
243 	xfs_ilock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL |
244 		      XFS_IOLOCK_PARENT | XFS_ILOCK_PARENT);
245 	unlock_dp_on_error = true;
246 
247 	/*
248 	 * Check whether the directory allows new symlinks or not.
249 	 */
250 	if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
251 		error = -EPERM;
252 		goto out_trans_cancel;
253 	}
254 
255 	/*
256 	 * Reserve disk quota : blocks and inode.
257 	 */
258 	error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
259 						pdqp, resblks, 1, 0);
260 	if (error)
261 		goto out_trans_cancel;
262 
263 	/*
264 	 * Check for ability to enter directory entry, if no space reserved.
265 	 */
266 	if (!resblks) {
267 		error = xfs_dir_canenter(tp, dp, link_name);
268 		if (error)
269 			goto out_trans_cancel;
270 	}
271 	/*
272 	 * Initialize the bmap freelist prior to calling either
273 	 * bmapi or the directory create code.
274 	 */
275 	xfs_bmap_init(&free_list, &first_block);
276 
277 	/*
278 	 * Allocate an inode for the symlink.
279 	 */
280 	error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
281 			       prid, resblks > 0, &ip, NULL);
282 	if (error)
283 		goto out_trans_cancel;
284 
285 	/*
286 	 * Now we join the directory inode to the transaction.  We do not do it
287 	 * earlier because xfs_dir_ialloc might commit the previous transaction
288 	 * (and release all the locks).  An error from here on will result in
289 	 * the transaction cancel unlocking dp so don't do it explicitly in the
290 	 * error path.
291 	 */
292 	xfs_trans_ijoin(tp, dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
293 	unlock_dp_on_error = false;
294 
295 	/*
296 	 * Also attach the dquot(s) to it, if applicable.
297 	 */
298 	xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
299 
300 	if (resblks)
301 		resblks -= XFS_IALLOC_SPACE_RES(mp);
302 	/*
303 	 * If the symlink will fit into the inode, write it inline.
304 	 */
305 	if (pathlen <= XFS_IFORK_DSIZE(ip)) {
306 		xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
307 		memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
308 		ip->i_d.di_size = pathlen;
309 
310 		/*
311 		 * The inode was initially created in extent format.
312 		 */
313 		ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
314 		ip->i_df.if_flags |= XFS_IFINLINE;
315 
316 		ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
317 		xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
318 
319 	} else {
320 		int	offset;
321 
322 		first_fsb = 0;
323 		nmaps = XFS_SYMLINK_MAPS;
324 
325 		error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
326 				  XFS_BMAPI_METADATA, &first_block, resblks,
327 				  mval, &nmaps, &free_list);
328 		if (error)
329 			goto out_bmap_cancel;
330 
331 		if (resblks)
332 			resblks -= fs_blocks;
333 		ip->i_d.di_size = pathlen;
334 		xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
335 
336 		cur_chunk = target_path;
337 		offset = 0;
338 		for (n = 0; n < nmaps; n++) {
339 			char	*buf;
340 
341 			d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
342 			byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
343 			bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
344 					       BTOBB(byte_cnt), 0);
345 			if (!bp) {
346 				error = -ENOMEM;
347 				goto out_bmap_cancel;
348 			}
349 			bp->b_ops = &xfs_symlink_buf_ops;
350 
351 			byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
352 			byte_cnt = min(byte_cnt, pathlen);
353 
354 			buf = bp->b_addr;
355 			buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
356 						   byte_cnt, bp);
357 
358 			memcpy(buf, cur_chunk, byte_cnt);
359 
360 			cur_chunk += byte_cnt;
361 			pathlen -= byte_cnt;
362 			offset += byte_cnt;
363 
364 			xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
365 			xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
366 							(char *)bp->b_addr);
367 		}
368 		ASSERT(pathlen == 0);
369 	}
370 
371 	/*
372 	 * Create the directory entry for the symlink.
373 	 */
374 	error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
375 					&first_block, &free_list, resblks);
376 	if (error)
377 		goto out_bmap_cancel;
378 	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
379 	xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
380 
381 	/*
382 	 * If this is a synchronous mount, make sure that the
383 	 * symlink transaction goes to disk before returning to
384 	 * the user.
385 	 */
386 	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
387 		xfs_trans_set_sync(tp);
388 	}
389 
390 	error = xfs_bmap_finish(&tp, &free_list, &committed);
391 	if (error)
392 		goto out_bmap_cancel;
393 
394 	error = xfs_trans_commit(tp);
395 	if (error)
396 		goto out_release_inode;
397 
398 	xfs_qm_dqrele(udqp);
399 	xfs_qm_dqrele(gdqp);
400 	xfs_qm_dqrele(pdqp);
401 
402 	*ipp = ip;
403 	return 0;
404 
405 out_bmap_cancel:
406 	xfs_bmap_cancel(&free_list);
407 out_trans_cancel:
408 	xfs_trans_cancel(tp);
409 out_release_inode:
410 	/*
411 	 * Wait until after the current transaction is aborted to finish the
412 	 * setup of the inode and release the inode.  This prevents recursive
413 	 * transactions and deadlocks from xfs_inactive.
414 	 */
415 	if (ip) {
416 		xfs_finish_inode_setup(ip);
417 		IRELE(ip);
418 	}
419 
420 	xfs_qm_dqrele(udqp);
421 	xfs_qm_dqrele(gdqp);
422 	xfs_qm_dqrele(pdqp);
423 
424 	if (unlock_dp_on_error)
425 		xfs_iunlock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
426 	return error;
427 }
428 
429 /*
430  * Free a symlink that has blocks associated with it.
431  */
432 STATIC int
433 xfs_inactive_symlink_rmt(
434 	struct xfs_inode *ip)
435 {
436 	xfs_buf_t	*bp;
437 	int		committed;
438 	int		done;
439 	int		error;
440 	xfs_fsblock_t	first_block;
441 	xfs_bmap_free_t	free_list;
442 	int		i;
443 	xfs_mount_t	*mp;
444 	xfs_bmbt_irec_t	mval[XFS_SYMLINK_MAPS];
445 	int		nmaps;
446 	int		size;
447 	xfs_trans_t	*tp;
448 
449 	mp = ip->i_mount;
450 	ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
451 	/*
452 	 * We're freeing a symlink that has some
453 	 * blocks allocated to it.  Free the
454 	 * blocks here.  We know that we've got
455 	 * either 1 or 2 extents and that we can
456 	 * free them all in one bunmapi call.
457 	 */
458 	ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
459 
460 	tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
461 	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
462 	if (error) {
463 		xfs_trans_cancel(tp);
464 		return error;
465 	}
466 
467 	xfs_ilock(ip, XFS_ILOCK_EXCL);
468 	xfs_trans_ijoin(tp, ip, 0);
469 
470 	/*
471 	 * Lock the inode, fix the size, and join it to the transaction.
472 	 * Hold it so in the normal path, we still have it locked for
473 	 * the second transaction.  In the error paths we need it
474 	 * held so the cancel won't rele it, see below.
475 	 */
476 	size = (int)ip->i_d.di_size;
477 	ip->i_d.di_size = 0;
478 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
479 	/*
480 	 * Find the block(s) so we can inval and unmap them.
481 	 */
482 	done = 0;
483 	xfs_bmap_init(&free_list, &first_block);
484 	nmaps = ARRAY_SIZE(mval);
485 	error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
486 				mval, &nmaps, 0);
487 	if (error)
488 		goto error_trans_cancel;
489 	/*
490 	 * Invalidate the block(s). No validation is done.
491 	 */
492 	for (i = 0; i < nmaps; i++) {
493 		bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
494 			XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
495 			XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
496 		if (!bp) {
497 			error = -ENOMEM;
498 			goto error_bmap_cancel;
499 		}
500 		xfs_trans_binval(tp, bp);
501 	}
502 	/*
503 	 * Unmap the dead block(s) to the free_list.
504 	 */
505 	error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps,
506 			    &first_block, &free_list, &done);
507 	if (error)
508 		goto error_bmap_cancel;
509 	ASSERT(done);
510 	/*
511 	 * Commit the first transaction.  This logs the EFI and the inode.
512 	 */
513 	error = xfs_bmap_finish(&tp, &free_list, &committed);
514 	if (error)
515 		goto error_bmap_cancel;
516 	/*
517 	 * The transaction must have been committed, since there were
518 	 * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
519 	 * The new tp has the extent freeing and EFDs.
520 	 */
521 	ASSERT(committed);
522 	/*
523 	 * The first xact was committed, so add the inode to the new one.
524 	 * Mark it dirty so it will be logged and moved forward in the log as
525 	 * part of every commit.
526 	 */
527 	xfs_trans_ijoin(tp, ip, 0);
528 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
529 	/*
530 	 * Commit the transaction containing extent freeing and EFDs.
531 	 */
532 	error = xfs_trans_commit(tp);
533 	if (error) {
534 		ASSERT(XFS_FORCED_SHUTDOWN(mp));
535 		goto error_unlock;
536 	}
537 
538 	/*
539 	 * Remove the memory for extent descriptions (just bookkeeping).
540 	 */
541 	if (ip->i_df.if_bytes)
542 		xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
543 	ASSERT(ip->i_df.if_bytes == 0);
544 
545 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
546 	return 0;
547 
548 error_bmap_cancel:
549 	xfs_bmap_cancel(&free_list);
550 error_trans_cancel:
551 	xfs_trans_cancel(tp);
552 error_unlock:
553 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
554 	return error;
555 }
556 
557 /*
558  * xfs_inactive_symlink - free a symlink
559  */
560 int
561 xfs_inactive_symlink(
562 	struct xfs_inode	*ip)
563 {
564 	struct xfs_mount	*mp = ip->i_mount;
565 	int			pathlen;
566 
567 	trace_xfs_inactive_symlink(ip);
568 
569 	if (XFS_FORCED_SHUTDOWN(mp))
570 		return -EIO;
571 
572 	xfs_ilock(ip, XFS_ILOCK_EXCL);
573 
574 	/*
575 	 * Zero length symlinks _can_ exist.
576 	 */
577 	pathlen = (int)ip->i_d.di_size;
578 	if (!pathlen) {
579 		xfs_iunlock(ip, XFS_ILOCK_EXCL);
580 		return 0;
581 	}
582 
583 	if (pathlen < 0 || pathlen > MAXPATHLEN) {
584 		xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
585 			 __func__, (unsigned long long)ip->i_ino, pathlen);
586 		xfs_iunlock(ip, XFS_ILOCK_EXCL);
587 		ASSERT(0);
588 		return -EFSCORRUPTED;
589 	}
590 
591 	if (ip->i_df.if_flags & XFS_IFINLINE) {
592 		if (ip->i_df.if_bytes > 0)
593 			xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
594 					  XFS_DATA_FORK);
595 		xfs_iunlock(ip, XFS_ILOCK_EXCL);
596 		ASSERT(ip->i_df.if_bytes == 0);
597 		return 0;
598 	}
599 
600 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
601 
602 	/* remove the remote symlink */
603 	return xfs_inactive_symlink_rmt(ip);
604 }
605