xref: /openbmc/linux/fs/xfs/xfs_fsops.c (revision 4800cd83)
1 /*
2  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
3  * All Rights Reserved.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License as
7  * published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it would be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write the Free Software Foundation,
16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17  */
18 #include "xfs.h"
19 #include "xfs_fs.h"
20 #include "xfs_types.h"
21 #include "xfs_bit.h"
22 #include "xfs_inum.h"
23 #include "xfs_log.h"
24 #include "xfs_trans.h"
25 #include "xfs_sb.h"
26 #include "xfs_ag.h"
27 #include "xfs_mount.h"
28 #include "xfs_bmap_btree.h"
29 #include "xfs_alloc_btree.h"
30 #include "xfs_ialloc_btree.h"
31 #include "xfs_dinode.h"
32 #include "xfs_inode.h"
33 #include "xfs_inode_item.h"
34 #include "xfs_btree.h"
35 #include "xfs_error.h"
36 #include "xfs_alloc.h"
37 #include "xfs_ialloc.h"
38 #include "xfs_fsops.h"
39 #include "xfs_itable.h"
40 #include "xfs_trans_space.h"
41 #include "xfs_rtalloc.h"
42 #include "xfs_rw.h"
43 #include "xfs_filestream.h"
44 #include "xfs_trace.h"
45 
46 /*
47  * File system operations
48  */
49 
50 int
51 xfs_fs_geometry(
52 	xfs_mount_t		*mp,
53 	xfs_fsop_geom_t		*geo,
54 	int			new_version)
55 {
56 
57 	memset(geo, 0, sizeof(*geo));
58 
59 	geo->blocksize = mp->m_sb.sb_blocksize;
60 	geo->rtextsize = mp->m_sb.sb_rextsize;
61 	geo->agblocks = mp->m_sb.sb_agblocks;
62 	geo->agcount = mp->m_sb.sb_agcount;
63 	geo->logblocks = mp->m_sb.sb_logblocks;
64 	geo->sectsize = mp->m_sb.sb_sectsize;
65 	geo->inodesize = mp->m_sb.sb_inodesize;
66 	geo->imaxpct = mp->m_sb.sb_imax_pct;
67 	geo->datablocks = mp->m_sb.sb_dblocks;
68 	geo->rtblocks = mp->m_sb.sb_rblocks;
69 	geo->rtextents = mp->m_sb.sb_rextents;
70 	geo->logstart = mp->m_sb.sb_logstart;
71 	ASSERT(sizeof(geo->uuid)==sizeof(mp->m_sb.sb_uuid));
72 	memcpy(geo->uuid, &mp->m_sb.sb_uuid, sizeof(mp->m_sb.sb_uuid));
73 	if (new_version >= 2) {
74 		geo->sunit = mp->m_sb.sb_unit;
75 		geo->swidth = mp->m_sb.sb_width;
76 	}
77 	if (new_version >= 3) {
78 		geo->version = XFS_FSOP_GEOM_VERSION;
79 		geo->flags =
80 			(xfs_sb_version_hasattr(&mp->m_sb) ?
81 				XFS_FSOP_GEOM_FLAGS_ATTR : 0) |
82 			(xfs_sb_version_hasnlink(&mp->m_sb) ?
83 				XFS_FSOP_GEOM_FLAGS_NLINK : 0) |
84 			(xfs_sb_version_hasquota(&mp->m_sb) ?
85 				XFS_FSOP_GEOM_FLAGS_QUOTA : 0) |
86 			(xfs_sb_version_hasalign(&mp->m_sb) ?
87 				XFS_FSOP_GEOM_FLAGS_IALIGN : 0) |
88 			(xfs_sb_version_hasdalign(&mp->m_sb) ?
89 				XFS_FSOP_GEOM_FLAGS_DALIGN : 0) |
90 			(xfs_sb_version_hasshared(&mp->m_sb) ?
91 				XFS_FSOP_GEOM_FLAGS_SHARED : 0) |
92 			(xfs_sb_version_hasextflgbit(&mp->m_sb) ?
93 				XFS_FSOP_GEOM_FLAGS_EXTFLG : 0) |
94 			(xfs_sb_version_hasdirv2(&mp->m_sb) ?
95 				XFS_FSOP_GEOM_FLAGS_DIRV2 : 0) |
96 			(xfs_sb_version_hassector(&mp->m_sb) ?
97 				XFS_FSOP_GEOM_FLAGS_SECTOR : 0) |
98 			(xfs_sb_version_hasasciici(&mp->m_sb) ?
99 				XFS_FSOP_GEOM_FLAGS_DIRV2CI : 0) |
100 			(xfs_sb_version_haslazysbcount(&mp->m_sb) ?
101 				XFS_FSOP_GEOM_FLAGS_LAZYSB : 0) |
102 			(xfs_sb_version_hasattr2(&mp->m_sb) ?
103 				XFS_FSOP_GEOM_FLAGS_ATTR2 : 0);
104 		geo->logsectsize = xfs_sb_version_hassector(&mp->m_sb) ?
105 				mp->m_sb.sb_logsectsize : BBSIZE;
106 		geo->rtsectsize = mp->m_sb.sb_blocksize;
107 		geo->dirblocksize = mp->m_dirblksize;
108 	}
109 	if (new_version >= 4) {
110 		geo->flags |=
111 			(xfs_sb_version_haslogv2(&mp->m_sb) ?
112 				XFS_FSOP_GEOM_FLAGS_LOGV2 : 0);
113 		geo->logsunit = mp->m_sb.sb_logsunit;
114 	}
115 	return 0;
116 }
117 
118 static int
119 xfs_growfs_data_private(
120 	xfs_mount_t		*mp,		/* mount point for filesystem */
121 	xfs_growfs_data_t	*in)		/* growfs data input struct */
122 {
123 	xfs_agf_t		*agf;
124 	xfs_agi_t		*agi;
125 	xfs_agnumber_t		agno;
126 	xfs_extlen_t		agsize;
127 	xfs_extlen_t		tmpsize;
128 	xfs_alloc_rec_t		*arec;
129 	struct xfs_btree_block	*block;
130 	xfs_buf_t		*bp;
131 	int			bucket;
132 	int			dpct;
133 	int			error;
134 	xfs_agnumber_t		nagcount;
135 	xfs_agnumber_t		nagimax = 0;
136 	xfs_rfsblock_t		nb, nb_mod;
137 	xfs_rfsblock_t		new;
138 	xfs_rfsblock_t		nfree;
139 	xfs_agnumber_t		oagcount;
140 	int			pct;
141 	xfs_trans_t		*tp;
142 
143 	nb = in->newblocks;
144 	pct = in->imaxpct;
145 	if (nb < mp->m_sb.sb_dblocks || pct < 0 || pct > 100)
146 		return XFS_ERROR(EINVAL);
147 	if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
148 		return error;
149 	dpct = pct - mp->m_sb.sb_imax_pct;
150 	bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
151 				XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
152 				BBTOB(XFS_FSS_TO_BB(mp, 1)), 0);
153 	if (!bp)
154 		return EIO;
155 	xfs_buf_relse(bp);
156 
157 	new = nb;	/* use new as a temporary here */
158 	nb_mod = do_div(new, mp->m_sb.sb_agblocks);
159 	nagcount = new + (nb_mod != 0);
160 	if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
161 		nagcount--;
162 		nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
163 		if (nb < mp->m_sb.sb_dblocks)
164 			return XFS_ERROR(EINVAL);
165 	}
166 	new = nb - mp->m_sb.sb_dblocks;
167 	oagcount = mp->m_sb.sb_agcount;
168 
169 	/* allocate the new per-ag structures */
170 	if (nagcount > oagcount) {
171 		error = xfs_initialize_perag(mp, nagcount, &nagimax);
172 		if (error)
173 			return error;
174 	}
175 
176 	tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFS);
177 	tp->t_flags |= XFS_TRANS_RESERVE;
178 	if ((error = xfs_trans_reserve(tp, XFS_GROWFS_SPACE_RES(mp),
179 			XFS_GROWDATA_LOG_RES(mp), 0, 0, 0))) {
180 		xfs_trans_cancel(tp, 0);
181 		return error;
182 	}
183 
184 	/*
185 	 * Write new AG headers to disk. Non-transactional, but written
186 	 * synchronously so they are completed prior to the growfs transaction
187 	 * being logged.
188 	 */
189 	nfree = 0;
190 	for (agno = nagcount - 1; agno >= oagcount; agno--, new -= agsize) {
191 		/*
192 		 * AG freelist header block
193 		 */
194 		bp = xfs_buf_get(mp->m_ddev_targp,
195 				 XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
196 				 XFS_FSS_TO_BB(mp, 1), XBF_LOCK | XBF_MAPPED);
197 		agf = XFS_BUF_TO_AGF(bp);
198 		memset(agf, 0, mp->m_sb.sb_sectsize);
199 		agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
200 		agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
201 		agf->agf_seqno = cpu_to_be32(agno);
202 		if (agno == nagcount - 1)
203 			agsize =
204 				nb -
205 				(agno * (xfs_rfsblock_t)mp->m_sb.sb_agblocks);
206 		else
207 			agsize = mp->m_sb.sb_agblocks;
208 		agf->agf_length = cpu_to_be32(agsize);
209 		agf->agf_roots[XFS_BTNUM_BNOi] = cpu_to_be32(XFS_BNO_BLOCK(mp));
210 		agf->agf_roots[XFS_BTNUM_CNTi] = cpu_to_be32(XFS_CNT_BLOCK(mp));
211 		agf->agf_levels[XFS_BTNUM_BNOi] = cpu_to_be32(1);
212 		agf->agf_levels[XFS_BTNUM_CNTi] = cpu_to_be32(1);
213 		agf->agf_flfirst = 0;
214 		agf->agf_fllast = cpu_to_be32(XFS_AGFL_SIZE(mp) - 1);
215 		agf->agf_flcount = 0;
216 		tmpsize = agsize - XFS_PREALLOC_BLOCKS(mp);
217 		agf->agf_freeblks = cpu_to_be32(tmpsize);
218 		agf->agf_longest = cpu_to_be32(tmpsize);
219 		error = xfs_bwrite(mp, bp);
220 		if (error) {
221 			goto error0;
222 		}
223 		/*
224 		 * AG inode header block
225 		 */
226 		bp = xfs_buf_get(mp->m_ddev_targp,
227 				 XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
228 				 XFS_FSS_TO_BB(mp, 1), XBF_LOCK | XBF_MAPPED);
229 		agi = XFS_BUF_TO_AGI(bp);
230 		memset(agi, 0, mp->m_sb.sb_sectsize);
231 		agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
232 		agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
233 		agi->agi_seqno = cpu_to_be32(agno);
234 		agi->agi_length = cpu_to_be32(agsize);
235 		agi->agi_count = 0;
236 		agi->agi_root = cpu_to_be32(XFS_IBT_BLOCK(mp));
237 		agi->agi_level = cpu_to_be32(1);
238 		agi->agi_freecount = 0;
239 		agi->agi_newino = cpu_to_be32(NULLAGINO);
240 		agi->agi_dirino = cpu_to_be32(NULLAGINO);
241 		for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
242 			agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
243 		error = xfs_bwrite(mp, bp);
244 		if (error) {
245 			goto error0;
246 		}
247 		/*
248 		 * BNO btree root block
249 		 */
250 		bp = xfs_buf_get(mp->m_ddev_targp,
251 				 XFS_AGB_TO_DADDR(mp, agno, XFS_BNO_BLOCK(mp)),
252 				 BTOBB(mp->m_sb.sb_blocksize),
253 				 XBF_LOCK | XBF_MAPPED);
254 		block = XFS_BUF_TO_BLOCK(bp);
255 		memset(block, 0, mp->m_sb.sb_blocksize);
256 		block->bb_magic = cpu_to_be32(XFS_ABTB_MAGIC);
257 		block->bb_level = 0;
258 		block->bb_numrecs = cpu_to_be16(1);
259 		block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
260 		block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
261 		arec = XFS_ALLOC_REC_ADDR(mp, block, 1);
262 		arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
263 		arec->ar_blockcount = cpu_to_be32(
264 			agsize - be32_to_cpu(arec->ar_startblock));
265 		error = xfs_bwrite(mp, bp);
266 		if (error) {
267 			goto error0;
268 		}
269 		/*
270 		 * CNT btree root block
271 		 */
272 		bp = xfs_buf_get(mp->m_ddev_targp,
273 				 XFS_AGB_TO_DADDR(mp, agno, XFS_CNT_BLOCK(mp)),
274 				 BTOBB(mp->m_sb.sb_blocksize),
275 				 XBF_LOCK | XBF_MAPPED);
276 		block = XFS_BUF_TO_BLOCK(bp);
277 		memset(block, 0, mp->m_sb.sb_blocksize);
278 		block->bb_magic = cpu_to_be32(XFS_ABTC_MAGIC);
279 		block->bb_level = 0;
280 		block->bb_numrecs = cpu_to_be16(1);
281 		block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
282 		block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
283 		arec = XFS_ALLOC_REC_ADDR(mp, block, 1);
284 		arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
285 		arec->ar_blockcount = cpu_to_be32(
286 			agsize - be32_to_cpu(arec->ar_startblock));
287 		nfree += be32_to_cpu(arec->ar_blockcount);
288 		error = xfs_bwrite(mp, bp);
289 		if (error) {
290 			goto error0;
291 		}
292 		/*
293 		 * INO btree root block
294 		 */
295 		bp = xfs_buf_get(mp->m_ddev_targp,
296 				 XFS_AGB_TO_DADDR(mp, agno, XFS_IBT_BLOCK(mp)),
297 				 BTOBB(mp->m_sb.sb_blocksize),
298 				 XBF_LOCK | XBF_MAPPED);
299 		block = XFS_BUF_TO_BLOCK(bp);
300 		memset(block, 0, mp->m_sb.sb_blocksize);
301 		block->bb_magic = cpu_to_be32(XFS_IBT_MAGIC);
302 		block->bb_level = 0;
303 		block->bb_numrecs = 0;
304 		block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
305 		block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
306 		error = xfs_bwrite(mp, bp);
307 		if (error) {
308 			goto error0;
309 		}
310 	}
311 	xfs_trans_agblocks_delta(tp, nfree);
312 	/*
313 	 * There are new blocks in the old last a.g.
314 	 */
315 	if (new) {
316 		/*
317 		 * Change the agi length.
318 		 */
319 		error = xfs_ialloc_read_agi(mp, tp, agno, &bp);
320 		if (error) {
321 			goto error0;
322 		}
323 		ASSERT(bp);
324 		agi = XFS_BUF_TO_AGI(bp);
325 		be32_add_cpu(&agi->agi_length, new);
326 		ASSERT(nagcount == oagcount ||
327 		       be32_to_cpu(agi->agi_length) == mp->m_sb.sb_agblocks);
328 		xfs_ialloc_log_agi(tp, bp, XFS_AGI_LENGTH);
329 		/*
330 		 * Change agf length.
331 		 */
332 		error = xfs_alloc_read_agf(mp, tp, agno, 0, &bp);
333 		if (error) {
334 			goto error0;
335 		}
336 		ASSERT(bp);
337 		agf = XFS_BUF_TO_AGF(bp);
338 		be32_add_cpu(&agf->agf_length, new);
339 		ASSERT(be32_to_cpu(agf->agf_length) ==
340 		       be32_to_cpu(agi->agi_length));
341 
342 		xfs_alloc_log_agf(tp, bp, XFS_AGF_LENGTH);
343 		/*
344 		 * Free the new space.
345 		 */
346 		error = xfs_free_extent(tp, XFS_AGB_TO_FSB(mp, agno,
347 			be32_to_cpu(agf->agf_length) - new), new);
348 		if (error) {
349 			goto error0;
350 		}
351 	}
352 
353 	/*
354 	 * Update changed superblock fields transactionally. These are not
355 	 * seen by the rest of the world until the transaction commit applies
356 	 * them atomically to the superblock.
357 	 */
358 	if (nagcount > oagcount)
359 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
360 	if (nb > mp->m_sb.sb_dblocks)
361 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS,
362 				 nb - mp->m_sb.sb_dblocks);
363 	if (nfree)
364 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, nfree);
365 	if (dpct)
366 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
367 	error = xfs_trans_commit(tp, 0);
368 	if (error)
369 		return error;
370 
371 	/* New allocation groups fully initialized, so update mount struct */
372 	if (nagimax)
373 		mp->m_maxagi = nagimax;
374 	if (mp->m_sb.sb_imax_pct) {
375 		__uint64_t icount = mp->m_sb.sb_dblocks * mp->m_sb.sb_imax_pct;
376 		do_div(icount, 100);
377 		mp->m_maxicount = icount << mp->m_sb.sb_inopblog;
378 	} else
379 		mp->m_maxicount = 0;
380 	xfs_set_low_space_thresholds(mp);
381 
382 	/* update secondary superblocks. */
383 	for (agno = 1; agno < nagcount; agno++) {
384 		error = xfs_read_buf(mp, mp->m_ddev_targp,
385 				  XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
386 				  XFS_FSS_TO_BB(mp, 1), 0, &bp);
387 		if (error) {
388 			xfs_fs_cmn_err(CE_WARN, mp,
389 			"error %d reading secondary superblock for ag %d",
390 				error, agno);
391 			break;
392 		}
393 		xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, XFS_SB_ALL_BITS);
394 		/*
395 		 * If we get an error writing out the alternate superblocks,
396 		 * just issue a warning and continue.  The real work is
397 		 * already done and committed.
398 		 */
399 		if (!(error = xfs_bwrite(mp, bp))) {
400 			continue;
401 		} else {
402 			xfs_fs_cmn_err(CE_WARN, mp,
403 		"write error %d updating secondary superblock for ag %d",
404 				error, agno);
405 			break; /* no point in continuing */
406 		}
407 	}
408 	return 0;
409 
410  error0:
411 	xfs_trans_cancel(tp, XFS_TRANS_ABORT);
412 	return error;
413 }
414 
415 static int
416 xfs_growfs_log_private(
417 	xfs_mount_t		*mp,	/* mount point for filesystem */
418 	xfs_growfs_log_t	*in)	/* growfs log input struct */
419 {
420 	xfs_extlen_t		nb;
421 
422 	nb = in->newblocks;
423 	if (nb < XFS_MIN_LOG_BLOCKS || nb < XFS_B_TO_FSB(mp, XFS_MIN_LOG_BYTES))
424 		return XFS_ERROR(EINVAL);
425 	if (nb == mp->m_sb.sb_logblocks &&
426 	    in->isint == (mp->m_sb.sb_logstart != 0))
427 		return XFS_ERROR(EINVAL);
428 	/*
429 	 * Moving the log is hard, need new interfaces to sync
430 	 * the log first, hold off all activity while moving it.
431 	 * Can have shorter or longer log in the same space,
432 	 * or transform internal to external log or vice versa.
433 	 */
434 	return XFS_ERROR(ENOSYS);
435 }
436 
437 /*
438  * protected versions of growfs function acquire and release locks on the mount
439  * point - exported through ioctls: XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG,
440  * XFS_IOC_FSGROWFSRT
441  */
442 
443 
444 int
445 xfs_growfs_data(
446 	xfs_mount_t		*mp,
447 	xfs_growfs_data_t	*in)
448 {
449 	int error;
450 
451 	if (!capable(CAP_SYS_ADMIN))
452 		return XFS_ERROR(EPERM);
453 	if (!mutex_trylock(&mp->m_growlock))
454 		return XFS_ERROR(EWOULDBLOCK);
455 	error = xfs_growfs_data_private(mp, in);
456 	mutex_unlock(&mp->m_growlock);
457 	return error;
458 }
459 
460 int
461 xfs_growfs_log(
462 	xfs_mount_t		*mp,
463 	xfs_growfs_log_t	*in)
464 {
465 	int error;
466 
467 	if (!capable(CAP_SYS_ADMIN))
468 		return XFS_ERROR(EPERM);
469 	if (!mutex_trylock(&mp->m_growlock))
470 		return XFS_ERROR(EWOULDBLOCK);
471 	error = xfs_growfs_log_private(mp, in);
472 	mutex_unlock(&mp->m_growlock);
473 	return error;
474 }
475 
476 /*
477  * exported through ioctl XFS_IOC_FSCOUNTS
478  */
479 
480 int
481 xfs_fs_counts(
482 	xfs_mount_t		*mp,
483 	xfs_fsop_counts_t	*cnt)
484 {
485 	xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
486 	spin_lock(&mp->m_sb_lock);
487 	cnt->freedata = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
488 	cnt->freertx = mp->m_sb.sb_frextents;
489 	cnt->freeino = mp->m_sb.sb_ifree;
490 	cnt->allocino = mp->m_sb.sb_icount;
491 	spin_unlock(&mp->m_sb_lock);
492 	return 0;
493 }
494 
495 /*
496  * exported through ioctl XFS_IOC_SET_RESBLKS & XFS_IOC_GET_RESBLKS
497  *
498  * xfs_reserve_blocks is called to set m_resblks
499  * in the in-core mount table. The number of unused reserved blocks
500  * is kept in m_resblks_avail.
501  *
502  * Reserve the requested number of blocks if available. Otherwise return
503  * as many as possible to satisfy the request. The actual number
504  * reserved are returned in outval
505  *
506  * A null inval pointer indicates that only the current reserved blocks
507  * available  should  be returned no settings are changed.
508  */
509 
510 int
511 xfs_reserve_blocks(
512 	xfs_mount_t             *mp,
513 	__uint64_t              *inval,
514 	xfs_fsop_resblks_t      *outval)
515 {
516 	__int64_t		lcounter, delta, fdblks_delta;
517 	__uint64_t		request;
518 
519 	/* If inval is null, report current values and return */
520 	if (inval == (__uint64_t *)NULL) {
521 		if (!outval)
522 			return EINVAL;
523 		outval->resblks = mp->m_resblks;
524 		outval->resblks_avail = mp->m_resblks_avail;
525 		return 0;
526 	}
527 
528 	request = *inval;
529 
530 	/*
531 	 * With per-cpu counters, this becomes an interesting
532 	 * problem. we needto work out if we are freeing or allocation
533 	 * blocks first, then we can do the modification as necessary.
534 	 *
535 	 * We do this under the m_sb_lock so that if we are near
536 	 * ENOSPC, we will hold out any changes while we work out
537 	 * what to do. This means that the amount of free space can
538 	 * change while we do this, so we need to retry if we end up
539 	 * trying to reserve more space than is available.
540 	 *
541 	 * We also use the xfs_mod_incore_sb() interface so that we
542 	 * don't have to care about whether per cpu counter are
543 	 * enabled, disabled or even compiled in....
544 	 */
545 retry:
546 	spin_lock(&mp->m_sb_lock);
547 	xfs_icsb_sync_counters_locked(mp, 0);
548 
549 	/*
550 	 * If our previous reservation was larger than the current value,
551 	 * then move any unused blocks back to the free pool.
552 	 */
553 	fdblks_delta = 0;
554 	if (mp->m_resblks > request) {
555 		lcounter = mp->m_resblks_avail - request;
556 		if (lcounter  > 0) {		/* release unused blocks */
557 			fdblks_delta = lcounter;
558 			mp->m_resblks_avail -= lcounter;
559 		}
560 		mp->m_resblks = request;
561 	} else {
562 		__int64_t	free;
563 
564 		free =  mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
565 		if (!free)
566 			goto out; /* ENOSPC and fdblks_delta = 0 */
567 
568 		delta = request - mp->m_resblks;
569 		lcounter = free - delta;
570 		if (lcounter < 0) {
571 			/* We can't satisfy the request, just get what we can */
572 			mp->m_resblks += free;
573 			mp->m_resblks_avail += free;
574 			fdblks_delta = -free;
575 		} else {
576 			fdblks_delta = -delta;
577 			mp->m_resblks = request;
578 			mp->m_resblks_avail += delta;
579 		}
580 	}
581 out:
582 	if (outval) {
583 		outval->resblks = mp->m_resblks;
584 		outval->resblks_avail = mp->m_resblks_avail;
585 	}
586 	spin_unlock(&mp->m_sb_lock);
587 
588 	if (fdblks_delta) {
589 		/*
590 		 * If we are putting blocks back here, m_resblks_avail is
591 		 * already at its max so this will put it in the free pool.
592 		 *
593 		 * If we need space, we'll either succeed in getting it
594 		 * from the free block count or we'll get an enospc. If
595 		 * we get a ENOSPC, it means things changed while we were
596 		 * calculating fdblks_delta and so we should try again to
597 		 * see if there is anything left to reserve.
598 		 *
599 		 * Don't set the reserved flag here - we don't want to reserve
600 		 * the extra reserve blocks from the reserve.....
601 		 */
602 		int error;
603 		error = xfs_icsb_modify_counters(mp, XFS_SBS_FDBLOCKS,
604 						 fdblks_delta, 0);
605 		if (error == ENOSPC)
606 			goto retry;
607 	}
608 	return 0;
609 }
610 
611 /*
612  * Dump a transaction into the log that contains no real change. This is needed
613  * to be able to make the log dirty or stamp the current tail LSN into the log
614  * during the covering operation.
615  *
616  * We cannot use an inode here for this - that will push dirty state back up
617  * into the VFS and then periodic inode flushing will prevent log covering from
618  * making progress. Hence we log a field in the superblock instead and use a
619  * synchronous transaction to ensure the superblock is immediately unpinned
620  * and can be written back.
621  */
622 int
623 xfs_fs_log_dummy(
624 	xfs_mount_t	*mp)
625 {
626 	xfs_trans_t	*tp;
627 	int		error;
628 
629 	tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
630 	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
631 					XFS_DEFAULT_LOG_COUNT);
632 	if (error) {
633 		xfs_trans_cancel(tp, 0);
634 		return error;
635 	}
636 
637 	/* log the UUID because it is an unchanging field */
638 	xfs_mod_sb(tp, XFS_SB_UUID);
639 	xfs_trans_set_sync(tp);
640 	return xfs_trans_commit(tp, 0);
641 }
642 
643 int
644 xfs_fs_goingdown(
645 	xfs_mount_t	*mp,
646 	__uint32_t	inflags)
647 {
648 	switch (inflags) {
649 	case XFS_FSOP_GOING_FLAGS_DEFAULT: {
650 		struct super_block *sb = freeze_bdev(mp->m_super->s_bdev);
651 
652 		if (sb && !IS_ERR(sb)) {
653 			xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
654 			thaw_bdev(sb->s_bdev, sb);
655 		}
656 
657 		break;
658 	}
659 	case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
660 		xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
661 		break;
662 	case XFS_FSOP_GOING_FLAGS_NOLOGFLUSH:
663 		xfs_force_shutdown(mp,
664 				SHUTDOWN_FORCE_UMOUNT | SHUTDOWN_LOG_IO_ERROR);
665 		break;
666 	default:
667 		return XFS_ERROR(EINVAL);
668 	}
669 
670 	return 0;
671 }
672