xref: /linux/fs/xfs/xfs_fsops.c (revision 0dd9ac63ce26ec87b080ca9c3e6efed33c23ace6)
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_dir2.h"
28 #include "xfs_dmapi.h"
29 #include "xfs_mount.h"
30 #include "xfs_bmap_btree.h"
31 #include "xfs_alloc_btree.h"
32 #include "xfs_ialloc_btree.h"
33 #include "xfs_dir2_sf.h"
34 #include "xfs_attr_sf.h"
35 #include "xfs_dinode.h"
36 #include "xfs_inode.h"
37 #include "xfs_inode_item.h"
38 #include "xfs_btree.h"
39 #include "xfs_error.h"
40 #include "xfs_alloc.h"
41 #include "xfs_ialloc.h"
42 #include "xfs_fsops.h"
43 #include "xfs_itable.h"
44 #include "xfs_trans_space.h"
45 #include "xfs_rtalloc.h"
46 #include "xfs_rw.h"
47 #include "xfs_filestream.h"
48 #include "xfs_trace.h"
49 
50 /*
51  * File system operations
52  */
53 
54 int
55 xfs_fs_geometry(
56 	xfs_mount_t		*mp,
57 	xfs_fsop_geom_t		*geo,
58 	int			new_version)
59 {
60 	geo->blocksize = mp->m_sb.sb_blocksize;
61 	geo->rtextsize = mp->m_sb.sb_rextsize;
62 	geo->agblocks = mp->m_sb.sb_agblocks;
63 	geo->agcount = mp->m_sb.sb_agcount;
64 	geo->logblocks = mp->m_sb.sb_logblocks;
65 	geo->sectsize = mp->m_sb.sb_sectsize;
66 	geo->inodesize = mp->m_sb.sb_inodesize;
67 	geo->imaxpct = mp->m_sb.sb_imax_pct;
68 	geo->datablocks = mp->m_sb.sb_dblocks;
69 	geo->rtblocks = mp->m_sb.sb_rblocks;
70 	geo->rtextents = mp->m_sb.sb_rextents;
71 	geo->logstart = mp->m_sb.sb_logstart;
72 	ASSERT(sizeof(geo->uuid)==sizeof(mp->m_sb.sb_uuid));
73 	memcpy(geo->uuid, &mp->m_sb.sb_uuid, sizeof(mp->m_sb.sb_uuid));
74 	if (new_version >= 2) {
75 		geo->sunit = mp->m_sb.sb_unit;
76 		geo->swidth = mp->m_sb.sb_width;
77 	}
78 	if (new_version >= 3) {
79 		geo->version = XFS_FSOP_GEOM_VERSION;
80 		geo->flags =
81 			(xfs_sb_version_hasattr(&mp->m_sb) ?
82 				XFS_FSOP_GEOM_FLAGS_ATTR : 0) |
83 			(xfs_sb_version_hasnlink(&mp->m_sb) ?
84 				XFS_FSOP_GEOM_FLAGS_NLINK : 0) |
85 			(xfs_sb_version_hasquota(&mp->m_sb) ?
86 				XFS_FSOP_GEOM_FLAGS_QUOTA : 0) |
87 			(xfs_sb_version_hasalign(&mp->m_sb) ?
88 				XFS_FSOP_GEOM_FLAGS_IALIGN : 0) |
89 			(xfs_sb_version_hasdalign(&mp->m_sb) ?
90 				XFS_FSOP_GEOM_FLAGS_DALIGN : 0) |
91 			(xfs_sb_version_hasshared(&mp->m_sb) ?
92 				XFS_FSOP_GEOM_FLAGS_SHARED : 0) |
93 			(xfs_sb_version_hasextflgbit(&mp->m_sb) ?
94 				XFS_FSOP_GEOM_FLAGS_EXTFLG : 0) |
95 			(xfs_sb_version_hasdirv2(&mp->m_sb) ?
96 				XFS_FSOP_GEOM_FLAGS_DIRV2 : 0) |
97 			(xfs_sb_version_hassector(&mp->m_sb) ?
98 				XFS_FSOP_GEOM_FLAGS_SECTOR : 0) |
99 			(xfs_sb_version_hasasciici(&mp->m_sb) ?
100 				XFS_FSOP_GEOM_FLAGS_DIRV2CI : 0) |
101 			(xfs_sb_version_haslazysbcount(&mp->m_sb) ?
102 				XFS_FSOP_GEOM_FLAGS_LAZYSB : 0) |
103 			(xfs_sb_version_hasattr2(&mp->m_sb) ?
104 				XFS_FSOP_GEOM_FLAGS_ATTR2 : 0);
105 		geo->logsectsize = xfs_sb_version_hassector(&mp->m_sb) ?
106 				mp->m_sb.sb_logsectsize : BBSIZE;
107 		geo->rtsectsize = mp->m_sb.sb_blocksize;
108 		geo->dirblocksize = mp->m_dirblksize;
109 	}
110 	if (new_version >= 4) {
111 		geo->flags |=
112 			(xfs_sb_version_haslogv2(&mp->m_sb) ?
113 				XFS_FSOP_GEOM_FLAGS_LOGV2 : 0);
114 		geo->logsunit = mp->m_sb.sb_logsunit;
115 	}
116 	return 0;
117 }
118 
119 static int
120 xfs_growfs_data_private(
121 	xfs_mount_t		*mp,		/* mount point for filesystem */
122 	xfs_growfs_data_t	*in)		/* growfs data input struct */
123 {
124 	xfs_agf_t		*agf;
125 	xfs_agi_t		*agi;
126 	xfs_agnumber_t		agno;
127 	xfs_extlen_t		agsize;
128 	xfs_extlen_t		tmpsize;
129 	xfs_alloc_rec_t		*arec;
130 	struct xfs_btree_block	*block;
131 	xfs_buf_t		*bp;
132 	int			bucket;
133 	int			dpct;
134 	int			error;
135 	xfs_agnumber_t		nagcount;
136 	xfs_agnumber_t		nagimax = 0;
137 	xfs_rfsblock_t		nb, nb_mod;
138 	xfs_rfsblock_t		new;
139 	xfs_rfsblock_t		nfree;
140 	xfs_agnumber_t		oagcount;
141 	int			pct;
142 	xfs_trans_t		*tp;
143 
144 	nb = in->newblocks;
145 	pct = in->imaxpct;
146 	if (nb < mp->m_sb.sb_dblocks || pct < 0 || pct > 100)
147 		return XFS_ERROR(EINVAL);
148 	if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
149 		return error;
150 	dpct = pct - mp->m_sb.sb_imax_pct;
151 	error = xfs_read_buf(mp, mp->m_ddev_targp,
152 			XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
153 			XFS_FSS_TO_BB(mp, 1), 0, &bp);
154 	if (error)
155 		return error;
156 	ASSERT(bp);
157 	xfs_buf_relse(bp);
158 
159 	new = nb;	/* use new as a temporary here */
160 	nb_mod = do_div(new, mp->m_sb.sb_agblocks);
161 	nagcount = new + (nb_mod != 0);
162 	if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
163 		nagcount--;
164 		nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
165 		if (nb < mp->m_sb.sb_dblocks)
166 			return XFS_ERROR(EINVAL);
167 	}
168 	new = nb - mp->m_sb.sb_dblocks;
169 	oagcount = mp->m_sb.sb_agcount;
170 
171 	/* allocate the new per-ag structures */
172 	if (nagcount > oagcount) {
173 		error = xfs_initialize_perag(mp, nagcount, &nagimax);
174 		if (error)
175 			return error;
176 	}
177 
178 	tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFS);
179 	tp->t_flags |= XFS_TRANS_RESERVE;
180 	if ((error = xfs_trans_reserve(tp, XFS_GROWFS_SPACE_RES(mp),
181 			XFS_GROWDATA_LOG_RES(mp), 0, 0, 0))) {
182 		xfs_trans_cancel(tp, 0);
183 		return error;
184 	}
185 
186 	/*
187 	 * Write new AG headers to disk. Non-transactional, but written
188 	 * synchronously so they are completed prior to the growfs transaction
189 	 * being logged.
190 	 */
191 	nfree = 0;
192 	for (agno = nagcount - 1; agno >= oagcount; agno--, new -= agsize) {
193 		/*
194 		 * AG freelist header block
195 		 */
196 		bp = xfs_buf_get(mp->m_ddev_targp,
197 				 XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
198 				 XFS_FSS_TO_BB(mp, 1), XBF_LOCK | XBF_MAPPED);
199 		agf = XFS_BUF_TO_AGF(bp);
200 		memset(agf, 0, mp->m_sb.sb_sectsize);
201 		agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
202 		agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
203 		agf->agf_seqno = cpu_to_be32(agno);
204 		if (agno == nagcount - 1)
205 			agsize =
206 				nb -
207 				(agno * (xfs_rfsblock_t)mp->m_sb.sb_agblocks);
208 		else
209 			agsize = mp->m_sb.sb_agblocks;
210 		agf->agf_length = cpu_to_be32(agsize);
211 		agf->agf_roots[XFS_BTNUM_BNOi] = cpu_to_be32(XFS_BNO_BLOCK(mp));
212 		agf->agf_roots[XFS_BTNUM_CNTi] = cpu_to_be32(XFS_CNT_BLOCK(mp));
213 		agf->agf_levels[XFS_BTNUM_BNOi] = cpu_to_be32(1);
214 		agf->agf_levels[XFS_BTNUM_CNTi] = cpu_to_be32(1);
215 		agf->agf_flfirst = 0;
216 		agf->agf_fllast = cpu_to_be32(XFS_AGFL_SIZE(mp) - 1);
217 		agf->agf_flcount = 0;
218 		tmpsize = agsize - XFS_PREALLOC_BLOCKS(mp);
219 		agf->agf_freeblks = cpu_to_be32(tmpsize);
220 		agf->agf_longest = cpu_to_be32(tmpsize);
221 		error = xfs_bwrite(mp, bp);
222 		if (error) {
223 			goto error0;
224 		}
225 		/*
226 		 * AG inode header block
227 		 */
228 		bp = xfs_buf_get(mp->m_ddev_targp,
229 				 XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
230 				 XFS_FSS_TO_BB(mp, 1), XBF_LOCK | XBF_MAPPED);
231 		agi = XFS_BUF_TO_AGI(bp);
232 		memset(agi, 0, mp->m_sb.sb_sectsize);
233 		agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
234 		agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
235 		agi->agi_seqno = cpu_to_be32(agno);
236 		agi->agi_length = cpu_to_be32(agsize);
237 		agi->agi_count = 0;
238 		agi->agi_root = cpu_to_be32(XFS_IBT_BLOCK(mp));
239 		agi->agi_level = cpu_to_be32(1);
240 		agi->agi_freecount = 0;
241 		agi->agi_newino = cpu_to_be32(NULLAGINO);
242 		agi->agi_dirino = cpu_to_be32(NULLAGINO);
243 		for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
244 			agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
245 		error = xfs_bwrite(mp, bp);
246 		if (error) {
247 			goto error0;
248 		}
249 		/*
250 		 * BNO btree root block
251 		 */
252 		bp = xfs_buf_get(mp->m_ddev_targp,
253 				 XFS_AGB_TO_DADDR(mp, agno, XFS_BNO_BLOCK(mp)),
254 				 BTOBB(mp->m_sb.sb_blocksize),
255 				 XBF_LOCK | XBF_MAPPED);
256 		block = XFS_BUF_TO_BLOCK(bp);
257 		memset(block, 0, mp->m_sb.sb_blocksize);
258 		block->bb_magic = cpu_to_be32(XFS_ABTB_MAGIC);
259 		block->bb_level = 0;
260 		block->bb_numrecs = cpu_to_be16(1);
261 		block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
262 		block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
263 		arec = XFS_ALLOC_REC_ADDR(mp, block, 1);
264 		arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
265 		arec->ar_blockcount = cpu_to_be32(
266 			agsize - be32_to_cpu(arec->ar_startblock));
267 		error = xfs_bwrite(mp, bp);
268 		if (error) {
269 			goto error0;
270 		}
271 		/*
272 		 * CNT btree root block
273 		 */
274 		bp = xfs_buf_get(mp->m_ddev_targp,
275 				 XFS_AGB_TO_DADDR(mp, agno, XFS_CNT_BLOCK(mp)),
276 				 BTOBB(mp->m_sb.sb_blocksize),
277 				 XBF_LOCK | XBF_MAPPED);
278 		block = XFS_BUF_TO_BLOCK(bp);
279 		memset(block, 0, mp->m_sb.sb_blocksize);
280 		block->bb_magic = cpu_to_be32(XFS_ABTC_MAGIC);
281 		block->bb_level = 0;
282 		block->bb_numrecs = cpu_to_be16(1);
283 		block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
284 		block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
285 		arec = XFS_ALLOC_REC_ADDR(mp, block, 1);
286 		arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
287 		arec->ar_blockcount = cpu_to_be32(
288 			agsize - be32_to_cpu(arec->ar_startblock));
289 		nfree += be32_to_cpu(arec->ar_blockcount);
290 		error = xfs_bwrite(mp, bp);
291 		if (error) {
292 			goto error0;
293 		}
294 		/*
295 		 * INO btree root block
296 		 */
297 		bp = xfs_buf_get(mp->m_ddev_targp,
298 				 XFS_AGB_TO_DADDR(mp, agno, XFS_IBT_BLOCK(mp)),
299 				 BTOBB(mp->m_sb.sb_blocksize),
300 				 XBF_LOCK | XBF_MAPPED);
301 		block = XFS_BUF_TO_BLOCK(bp);
302 		memset(block, 0, mp->m_sb.sb_blocksize);
303 		block->bb_magic = cpu_to_be32(XFS_IBT_MAGIC);
304 		block->bb_level = 0;
305 		block->bb_numrecs = 0;
306 		block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
307 		block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
308 		error = xfs_bwrite(mp, bp);
309 		if (error) {
310 			goto error0;
311 		}
312 	}
313 	xfs_trans_agblocks_delta(tp, nfree);
314 	/*
315 	 * There are new blocks in the old last a.g.
316 	 */
317 	if (new) {
318 		/*
319 		 * Change the agi length.
320 		 */
321 		error = xfs_ialloc_read_agi(mp, tp, agno, &bp);
322 		if (error) {
323 			goto error0;
324 		}
325 		ASSERT(bp);
326 		agi = XFS_BUF_TO_AGI(bp);
327 		be32_add_cpu(&agi->agi_length, new);
328 		ASSERT(nagcount == oagcount ||
329 		       be32_to_cpu(agi->agi_length) == mp->m_sb.sb_agblocks);
330 		xfs_ialloc_log_agi(tp, bp, XFS_AGI_LENGTH);
331 		/*
332 		 * Change agf length.
333 		 */
334 		error = xfs_alloc_read_agf(mp, tp, agno, 0, &bp);
335 		if (error) {
336 			goto error0;
337 		}
338 		ASSERT(bp);
339 		agf = XFS_BUF_TO_AGF(bp);
340 		be32_add_cpu(&agf->agf_length, new);
341 		ASSERT(be32_to_cpu(agf->agf_length) ==
342 		       be32_to_cpu(agi->agi_length));
343 
344 		xfs_alloc_log_agf(tp, bp, XFS_AGF_LENGTH);
345 		/*
346 		 * Free the new space.
347 		 */
348 		error = xfs_free_extent(tp, XFS_AGB_TO_FSB(mp, agno,
349 			be32_to_cpu(agf->agf_length) - new), new);
350 		if (error) {
351 			goto error0;
352 		}
353 	}
354 
355 	/*
356 	 * Update changed superblock fields transactionally. These are not
357 	 * seen by the rest of the world until the transaction commit applies
358 	 * them atomically to the superblock.
359 	 */
360 	if (nagcount > oagcount)
361 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
362 	if (nb > mp->m_sb.sb_dblocks)
363 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS,
364 				 nb - mp->m_sb.sb_dblocks);
365 	if (nfree)
366 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, nfree);
367 	if (dpct)
368 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
369 	error = xfs_trans_commit(tp, 0);
370 	if (error)
371 		return error;
372 
373 	/* New allocation groups fully initialized, so update mount struct */
374 	if (nagimax)
375 		mp->m_maxagi = nagimax;
376 	if (mp->m_sb.sb_imax_pct) {
377 		__uint64_t icount = mp->m_sb.sb_dblocks * mp->m_sb.sb_imax_pct;
378 		do_div(icount, 100);
379 		mp->m_maxicount = icount << mp->m_sb.sb_inopblog;
380 	} else
381 		mp->m_maxicount = 0;
382 
383 	/* update secondary superblocks. */
384 	for (agno = 1; agno < nagcount; agno++) {
385 		error = xfs_read_buf(mp, mp->m_ddev_targp,
386 				  XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
387 				  XFS_FSS_TO_BB(mp, 1), 0, &bp);
388 		if (error) {
389 			xfs_fs_cmn_err(CE_WARN, mp,
390 			"error %d reading secondary superblock for ag %d",
391 				error, agno);
392 			break;
393 		}
394 		xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, XFS_SB_ALL_BITS);
395 		/*
396 		 * If we get an error writing out the alternate superblocks,
397 		 * just issue a warning and continue.  The real work is
398 		 * already done and committed.
399 		 */
400 		if (!(error = xfs_bwrite(mp, bp))) {
401 			continue;
402 		} else {
403 			xfs_fs_cmn_err(CE_WARN, mp,
404 		"write error %d updating secondary superblock for ag %d",
405 				error, agno);
406 			break; /* no point in continuing */
407 		}
408 	}
409 	return 0;
410 
411  error0:
412 	xfs_trans_cancel(tp, XFS_TRANS_ABORT);
413 	return error;
414 }
415 
416 static int
417 xfs_growfs_log_private(
418 	xfs_mount_t		*mp,	/* mount point for filesystem */
419 	xfs_growfs_log_t	*in)	/* growfs log input struct */
420 {
421 	xfs_extlen_t		nb;
422 
423 	nb = in->newblocks;
424 	if (nb < XFS_MIN_LOG_BLOCKS || nb < XFS_B_TO_FSB(mp, XFS_MIN_LOG_BYTES))
425 		return XFS_ERROR(EINVAL);
426 	if (nb == mp->m_sb.sb_logblocks &&
427 	    in->isint == (mp->m_sb.sb_logstart != 0))
428 		return XFS_ERROR(EINVAL);
429 	/*
430 	 * Moving the log is hard, need new interfaces to sync
431 	 * the log first, hold off all activity while moving it.
432 	 * Can have shorter or longer log in the same space,
433 	 * or transform internal to external log or vice versa.
434 	 */
435 	return XFS_ERROR(ENOSYS);
436 }
437 
438 /*
439  * protected versions of growfs function acquire and release locks on the mount
440  * point - exported through ioctls: XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG,
441  * XFS_IOC_FSGROWFSRT
442  */
443 
444 
445 int
446 xfs_growfs_data(
447 	xfs_mount_t		*mp,
448 	xfs_growfs_data_t	*in)
449 {
450 	int error;
451 
452 	if (!capable(CAP_SYS_ADMIN))
453 		return XFS_ERROR(EPERM);
454 	if (!mutex_trylock(&mp->m_growlock))
455 		return XFS_ERROR(EWOULDBLOCK);
456 	error = xfs_growfs_data_private(mp, in);
457 	mutex_unlock(&mp->m_growlock);
458 	return error;
459 }
460 
461 int
462 xfs_growfs_log(
463 	xfs_mount_t		*mp,
464 	xfs_growfs_log_t	*in)
465 {
466 	int error;
467 
468 	if (!capable(CAP_SYS_ADMIN))
469 		return XFS_ERROR(EPERM);
470 	if (!mutex_trylock(&mp->m_growlock))
471 		return XFS_ERROR(EWOULDBLOCK);
472 	error = xfs_growfs_log_private(mp, in);
473 	mutex_unlock(&mp->m_growlock);
474 	return error;
475 }
476 
477 /*
478  * exported through ioctl XFS_IOC_FSCOUNTS
479  */
480 
481 int
482 xfs_fs_counts(
483 	xfs_mount_t		*mp,
484 	xfs_fsop_counts_t	*cnt)
485 {
486 	xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
487 	spin_lock(&mp->m_sb_lock);
488 	cnt->freedata = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
489 	cnt->freertx = mp->m_sb.sb_frextents;
490 	cnt->freeino = mp->m_sb.sb_ifree;
491 	cnt->allocino = mp->m_sb.sb_icount;
492 	spin_unlock(&mp->m_sb_lock);
493 	return 0;
494 }
495 
496 /*
497  * exported through ioctl XFS_IOC_SET_RESBLKS & XFS_IOC_GET_RESBLKS
498  *
499  * xfs_reserve_blocks is called to set m_resblks
500  * in the in-core mount table. The number of unused reserved blocks
501  * is kept in m_resblks_avail.
502  *
503  * Reserve the requested number of blocks if available. Otherwise return
504  * as many as possible to satisfy the request. The actual number
505  * reserved are returned in outval
506  *
507  * A null inval pointer indicates that only the current reserved blocks
508  * available  should  be returned no settings are changed.
509  */
510 
511 int
512 xfs_reserve_blocks(
513 	xfs_mount_t             *mp,
514 	__uint64_t              *inval,
515 	xfs_fsop_resblks_t      *outval)
516 {
517 	__int64_t		lcounter, delta, fdblks_delta;
518 	__uint64_t		request;
519 
520 	/* If inval is null, report current values and return */
521 	if (inval == (__uint64_t *)NULL) {
522 		if (!outval)
523 			return EINVAL;
524 		outval->resblks = mp->m_resblks;
525 		outval->resblks_avail = mp->m_resblks_avail;
526 		return 0;
527 	}
528 
529 	request = *inval;
530 
531 	/*
532 	 * With per-cpu counters, this becomes an interesting
533 	 * problem. we needto work out if we are freeing or allocation
534 	 * blocks first, then we can do the modification as necessary.
535 	 *
536 	 * We do this under the m_sb_lock so that if we are near
537 	 * ENOSPC, we will hold out any changes while we work out
538 	 * what to do. This means that the amount of free space can
539 	 * change while we do this, so we need to retry if we end up
540 	 * trying to reserve more space than is available.
541 	 *
542 	 * We also use the xfs_mod_incore_sb() interface so that we
543 	 * don't have to care about whether per cpu counter are
544 	 * enabled, disabled or even compiled in....
545 	 */
546 retry:
547 	spin_lock(&mp->m_sb_lock);
548 	xfs_icsb_sync_counters_locked(mp, 0);
549 
550 	/*
551 	 * If our previous reservation was larger than the current value,
552 	 * then move any unused blocks back to the free pool.
553 	 */
554 	fdblks_delta = 0;
555 	if (mp->m_resblks > request) {
556 		lcounter = mp->m_resblks_avail - request;
557 		if (lcounter  > 0) {		/* release unused blocks */
558 			fdblks_delta = lcounter;
559 			mp->m_resblks_avail -= lcounter;
560 		}
561 		mp->m_resblks = request;
562 	} else {
563 		__int64_t	free;
564 
565 		free =  mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
566 		if (!free)
567 			goto out; /* ENOSPC and fdblks_delta = 0 */
568 
569 		delta = request - mp->m_resblks;
570 		lcounter = free - delta;
571 		if (lcounter < 0) {
572 			/* We can't satisfy the request, just get what we can */
573 			mp->m_resblks += free;
574 			mp->m_resblks_avail += free;
575 			fdblks_delta = -free;
576 		} else {
577 			fdblks_delta = -delta;
578 			mp->m_resblks = request;
579 			mp->m_resblks_avail += delta;
580 		}
581 	}
582 out:
583 	if (outval) {
584 		outval->resblks = mp->m_resblks;
585 		outval->resblks_avail = mp->m_resblks_avail;
586 	}
587 	spin_unlock(&mp->m_sb_lock);
588 
589 	if (fdblks_delta) {
590 		/*
591 		 * If we are putting blocks back here, m_resblks_avail is
592 		 * already at its max so this will put it in the free pool.
593 		 *
594 		 * If we need space, we'll either succeed in getting it
595 		 * from the free block count or we'll get an enospc. If
596 		 * we get a ENOSPC, it means things changed while we were
597 		 * calculating fdblks_delta and so we should try again to
598 		 * see if there is anything left to reserve.
599 		 *
600 		 * Don't set the reserved flag here - we don't want to reserve
601 		 * the extra reserve blocks from the reserve.....
602 		 */
603 		int error;
604 		error = xfs_mod_incore_sb(mp, XFS_SBS_FDBLOCKS, fdblks_delta, 0);
605 		if (error == ENOSPC)
606 			goto retry;
607 	}
608 	return 0;
609 }
610 
611 int
612 xfs_fs_log_dummy(
613 	xfs_mount_t	*mp)
614 {
615 	xfs_trans_t	*tp;
616 	xfs_inode_t	*ip;
617 	int		error;
618 
619 	tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
620 	error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0);
621 	if (error) {
622 		xfs_trans_cancel(tp, 0);
623 		return error;
624 	}
625 
626 	ip = mp->m_rootip;
627 	xfs_ilock(ip, XFS_ILOCK_EXCL);
628 
629 	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
630 	xfs_trans_ihold(tp, ip);
631 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
632 	xfs_trans_set_sync(tp);
633 	error = xfs_trans_commit(tp, 0);
634 
635 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
636 	return error;
637 }
638 
639 int
640 xfs_fs_goingdown(
641 	xfs_mount_t	*mp,
642 	__uint32_t	inflags)
643 {
644 	switch (inflags) {
645 	case XFS_FSOP_GOING_FLAGS_DEFAULT: {
646 		struct super_block *sb = freeze_bdev(mp->m_super->s_bdev);
647 
648 		if (sb && !IS_ERR(sb)) {
649 			xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
650 			thaw_bdev(sb->s_bdev, sb);
651 		}
652 
653 		break;
654 	}
655 	case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
656 		xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
657 		break;
658 	case XFS_FSOP_GOING_FLAGS_NOLOGFLUSH:
659 		xfs_force_shutdown(mp,
660 				SHUTDOWN_FORCE_UMOUNT | SHUTDOWN_LOG_IO_ERROR);
661 		break;
662 	default:
663 		return XFS_ERROR(EINVAL);
664 	}
665 
666 	return 0;
667 }
668