xref: /openbmc/linux/fs/xfs/libxfs/xfs_ag.c (revision 08283d30)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
4  * Copyright (c) 2018 Red Hat, Inc.
5  * All rights reserved.
6  */
7 
8 #include "xfs.h"
9 #include "xfs_fs.h"
10 #include "xfs_shared.h"
11 #include "xfs_format.h"
12 #include "xfs_trans_resv.h"
13 #include "xfs_bit.h"
14 #include "xfs_sb.h"
15 #include "xfs_mount.h"
16 #include "xfs_btree.h"
17 #include "xfs_alloc_btree.h"
18 #include "xfs_rmap_btree.h"
19 #include "xfs_alloc.h"
20 #include "xfs_ialloc.h"
21 #include "xfs_rmap.h"
22 #include "xfs_ag.h"
23 #include "xfs_ag_resv.h"
24 #include "xfs_health.h"
25 
26 static struct xfs_buf *
27 xfs_get_aghdr_buf(
28 	struct xfs_mount	*mp,
29 	xfs_daddr_t		blkno,
30 	size_t			numblks,
31 	const struct xfs_buf_ops *ops)
32 {
33 	struct xfs_buf		*bp;
34 
35 	bp = xfs_buf_get_uncached(mp->m_ddev_targp, numblks, 0);
36 	if (!bp)
37 		return NULL;
38 
39 	xfs_buf_zero(bp, 0, BBTOB(bp->b_length));
40 	bp->b_bn = blkno;
41 	bp->b_maps[0].bm_bn = blkno;
42 	bp->b_ops = ops;
43 
44 	return bp;
45 }
46 
47 static inline bool is_log_ag(struct xfs_mount *mp, struct aghdr_init_data *id)
48 {
49 	return mp->m_sb.sb_logstart > 0 &&
50 	       id->agno == XFS_FSB_TO_AGNO(mp, mp->m_sb.sb_logstart);
51 }
52 
53 /*
54  * Generic btree root block init function
55  */
56 static void
57 xfs_btroot_init(
58 	struct xfs_mount	*mp,
59 	struct xfs_buf		*bp,
60 	struct aghdr_init_data	*id)
61 {
62 	xfs_btree_init_block(mp, bp, id->type, 0, 0, id->agno);
63 }
64 
65 /* Finish initializing a free space btree. */
66 static void
67 xfs_freesp_init_recs(
68 	struct xfs_mount	*mp,
69 	struct xfs_buf		*bp,
70 	struct aghdr_init_data	*id)
71 {
72 	struct xfs_alloc_rec	*arec;
73 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
74 
75 	arec = XFS_ALLOC_REC_ADDR(mp, XFS_BUF_TO_BLOCK(bp), 1);
76 	arec->ar_startblock = cpu_to_be32(mp->m_ag_prealloc_blocks);
77 
78 	if (is_log_ag(mp, id)) {
79 		struct xfs_alloc_rec	*nrec;
80 		xfs_agblock_t		start = XFS_FSB_TO_AGBNO(mp,
81 							mp->m_sb.sb_logstart);
82 
83 		ASSERT(start >= mp->m_ag_prealloc_blocks);
84 		if (start != mp->m_ag_prealloc_blocks) {
85 			/*
86 			 * Modify first record to pad stripe align of log
87 			 */
88 			arec->ar_blockcount = cpu_to_be32(start -
89 						mp->m_ag_prealloc_blocks);
90 			nrec = arec + 1;
91 
92 			/*
93 			 * Insert second record at start of internal log
94 			 * which then gets trimmed.
95 			 */
96 			nrec->ar_startblock = cpu_to_be32(
97 					be32_to_cpu(arec->ar_startblock) +
98 					be32_to_cpu(arec->ar_blockcount));
99 			arec = nrec;
100 			be16_add_cpu(&block->bb_numrecs, 1);
101 		}
102 		/*
103 		 * Change record start to after the internal log
104 		 */
105 		be32_add_cpu(&arec->ar_startblock, mp->m_sb.sb_logblocks);
106 	}
107 
108 	/*
109 	 * Calculate the record block count and check for the case where
110 	 * the log might have consumed all available space in the AG. If
111 	 * so, reset the record count to 0 to avoid exposure of an invalid
112 	 * record start block.
113 	 */
114 	arec->ar_blockcount = cpu_to_be32(id->agsize -
115 					  be32_to_cpu(arec->ar_startblock));
116 	if (!arec->ar_blockcount)
117 		block->bb_numrecs = 0;
118 }
119 
120 /*
121  * Alloc btree root block init functions
122  */
123 static void
124 xfs_bnoroot_init(
125 	struct xfs_mount	*mp,
126 	struct xfs_buf		*bp,
127 	struct aghdr_init_data	*id)
128 {
129 	xfs_btree_init_block(mp, bp, XFS_BTNUM_BNO, 0, 1, id->agno);
130 	xfs_freesp_init_recs(mp, bp, id);
131 }
132 
133 static void
134 xfs_cntroot_init(
135 	struct xfs_mount	*mp,
136 	struct xfs_buf		*bp,
137 	struct aghdr_init_data	*id)
138 {
139 	xfs_btree_init_block(mp, bp, XFS_BTNUM_CNT, 0, 1, id->agno);
140 	xfs_freesp_init_recs(mp, bp, id);
141 }
142 
143 /*
144  * Reverse map root block init
145  */
146 static void
147 xfs_rmaproot_init(
148 	struct xfs_mount	*mp,
149 	struct xfs_buf		*bp,
150 	struct aghdr_init_data	*id)
151 {
152 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
153 	struct xfs_rmap_rec	*rrec;
154 
155 	xfs_btree_init_block(mp, bp, XFS_BTNUM_RMAP, 0, 4, id->agno);
156 
157 	/*
158 	 * mark the AG header regions as static metadata The BNO
159 	 * btree block is the first block after the headers, so
160 	 * it's location defines the size of region the static
161 	 * metadata consumes.
162 	 *
163 	 * Note: unlike mkfs, we never have to account for log
164 	 * space when growing the data regions
165 	 */
166 	rrec = XFS_RMAP_REC_ADDR(block, 1);
167 	rrec->rm_startblock = 0;
168 	rrec->rm_blockcount = cpu_to_be32(XFS_BNO_BLOCK(mp));
169 	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_FS);
170 	rrec->rm_offset = 0;
171 
172 	/* account freespace btree root blocks */
173 	rrec = XFS_RMAP_REC_ADDR(block, 2);
174 	rrec->rm_startblock = cpu_to_be32(XFS_BNO_BLOCK(mp));
175 	rrec->rm_blockcount = cpu_to_be32(2);
176 	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_AG);
177 	rrec->rm_offset = 0;
178 
179 	/* account inode btree root blocks */
180 	rrec = XFS_RMAP_REC_ADDR(block, 3);
181 	rrec->rm_startblock = cpu_to_be32(XFS_IBT_BLOCK(mp));
182 	rrec->rm_blockcount = cpu_to_be32(XFS_RMAP_BLOCK(mp) -
183 					  XFS_IBT_BLOCK(mp));
184 	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_INOBT);
185 	rrec->rm_offset = 0;
186 
187 	/* account for rmap btree root */
188 	rrec = XFS_RMAP_REC_ADDR(block, 4);
189 	rrec->rm_startblock = cpu_to_be32(XFS_RMAP_BLOCK(mp));
190 	rrec->rm_blockcount = cpu_to_be32(1);
191 	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_AG);
192 	rrec->rm_offset = 0;
193 
194 	/* account for refc btree root */
195 	if (xfs_sb_version_hasreflink(&mp->m_sb)) {
196 		rrec = XFS_RMAP_REC_ADDR(block, 5);
197 		rrec->rm_startblock = cpu_to_be32(xfs_refc_block(mp));
198 		rrec->rm_blockcount = cpu_to_be32(1);
199 		rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_REFC);
200 		rrec->rm_offset = 0;
201 		be16_add_cpu(&block->bb_numrecs, 1);
202 	}
203 
204 	/* account for the log space */
205 	if (is_log_ag(mp, id)) {
206 		rrec = XFS_RMAP_REC_ADDR(block,
207 				be16_to_cpu(block->bb_numrecs) + 1);
208 		rrec->rm_startblock = cpu_to_be32(
209 				XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart));
210 		rrec->rm_blockcount = cpu_to_be32(mp->m_sb.sb_logblocks);
211 		rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_LOG);
212 		rrec->rm_offset = 0;
213 		be16_add_cpu(&block->bb_numrecs, 1);
214 	}
215 }
216 
217 /*
218  * Initialise new secondary superblocks with the pre-grow geometry, but mark
219  * them as "in progress" so we know they haven't yet been activated. This will
220  * get cleared when the update with the new geometry information is done after
221  * changes to the primary are committed. This isn't strictly necessary, but we
222  * get it for free with the delayed buffer write lists and it means we can tell
223  * if a grow operation didn't complete properly after the fact.
224  */
225 static void
226 xfs_sbblock_init(
227 	struct xfs_mount	*mp,
228 	struct xfs_buf		*bp,
229 	struct aghdr_init_data	*id)
230 {
231 	struct xfs_dsb		*dsb = XFS_BUF_TO_SBP(bp);
232 
233 	xfs_sb_to_disk(dsb, &mp->m_sb);
234 	dsb->sb_inprogress = 1;
235 }
236 
237 static void
238 xfs_agfblock_init(
239 	struct xfs_mount	*mp,
240 	struct xfs_buf		*bp,
241 	struct aghdr_init_data	*id)
242 {
243 	struct xfs_agf		*agf = XFS_BUF_TO_AGF(bp);
244 	xfs_extlen_t		tmpsize;
245 
246 	agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
247 	agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
248 	agf->agf_seqno = cpu_to_be32(id->agno);
249 	agf->agf_length = cpu_to_be32(id->agsize);
250 	agf->agf_roots[XFS_BTNUM_BNOi] = cpu_to_be32(XFS_BNO_BLOCK(mp));
251 	agf->agf_roots[XFS_BTNUM_CNTi] = cpu_to_be32(XFS_CNT_BLOCK(mp));
252 	agf->agf_levels[XFS_BTNUM_BNOi] = cpu_to_be32(1);
253 	agf->agf_levels[XFS_BTNUM_CNTi] = cpu_to_be32(1);
254 	if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
255 		agf->agf_roots[XFS_BTNUM_RMAPi] =
256 					cpu_to_be32(XFS_RMAP_BLOCK(mp));
257 		agf->agf_levels[XFS_BTNUM_RMAPi] = cpu_to_be32(1);
258 		agf->agf_rmap_blocks = cpu_to_be32(1);
259 	}
260 
261 	agf->agf_flfirst = cpu_to_be32(1);
262 	agf->agf_fllast = 0;
263 	agf->agf_flcount = 0;
264 	tmpsize = id->agsize - mp->m_ag_prealloc_blocks;
265 	agf->agf_freeblks = cpu_to_be32(tmpsize);
266 	agf->agf_longest = cpu_to_be32(tmpsize);
267 	if (xfs_sb_version_hascrc(&mp->m_sb))
268 		uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid);
269 	if (xfs_sb_version_hasreflink(&mp->m_sb)) {
270 		agf->agf_refcount_root = cpu_to_be32(
271 				xfs_refc_block(mp));
272 		agf->agf_refcount_level = cpu_to_be32(1);
273 		agf->agf_refcount_blocks = cpu_to_be32(1);
274 	}
275 
276 	if (is_log_ag(mp, id)) {
277 		int64_t	logblocks = mp->m_sb.sb_logblocks;
278 
279 		be32_add_cpu(&agf->agf_freeblks, -logblocks);
280 		agf->agf_longest = cpu_to_be32(id->agsize -
281 			XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart) - logblocks);
282 	}
283 }
284 
285 static void
286 xfs_agflblock_init(
287 	struct xfs_mount	*mp,
288 	struct xfs_buf		*bp,
289 	struct aghdr_init_data	*id)
290 {
291 	struct xfs_agfl		*agfl = XFS_BUF_TO_AGFL(bp);
292 	__be32			*agfl_bno;
293 	int			bucket;
294 
295 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
296 		agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
297 		agfl->agfl_seqno = cpu_to_be32(id->agno);
298 		uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid);
299 	}
300 
301 	agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, bp);
302 	for (bucket = 0; bucket < xfs_agfl_size(mp); bucket++)
303 		agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);
304 }
305 
306 static void
307 xfs_agiblock_init(
308 	struct xfs_mount	*mp,
309 	struct xfs_buf		*bp,
310 	struct aghdr_init_data	*id)
311 {
312 	struct xfs_agi		*agi = XFS_BUF_TO_AGI(bp);
313 	int			bucket;
314 
315 	agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
316 	agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
317 	agi->agi_seqno = cpu_to_be32(id->agno);
318 	agi->agi_length = cpu_to_be32(id->agsize);
319 	agi->agi_count = 0;
320 	agi->agi_root = cpu_to_be32(XFS_IBT_BLOCK(mp));
321 	agi->agi_level = cpu_to_be32(1);
322 	agi->agi_freecount = 0;
323 	agi->agi_newino = cpu_to_be32(NULLAGINO);
324 	agi->agi_dirino = cpu_to_be32(NULLAGINO);
325 	if (xfs_sb_version_hascrc(&mp->m_sb))
326 		uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid);
327 	if (xfs_sb_version_hasfinobt(&mp->m_sb)) {
328 		agi->agi_free_root = cpu_to_be32(XFS_FIBT_BLOCK(mp));
329 		agi->agi_free_level = cpu_to_be32(1);
330 	}
331 	for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
332 		agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
333 }
334 
335 typedef void (*aghdr_init_work_f)(struct xfs_mount *mp, struct xfs_buf *bp,
336 				  struct aghdr_init_data *id);
337 static int
338 xfs_ag_init_hdr(
339 	struct xfs_mount	*mp,
340 	struct aghdr_init_data	*id,
341 	aghdr_init_work_f	work,
342 	const struct xfs_buf_ops *ops)
343 
344 {
345 	struct xfs_buf		*bp;
346 
347 	bp = xfs_get_aghdr_buf(mp, id->daddr, id->numblks, ops);
348 	if (!bp)
349 		return -ENOMEM;
350 
351 	(*work)(mp, bp, id);
352 
353 	xfs_buf_delwri_queue(bp, &id->buffer_list);
354 	xfs_buf_relse(bp);
355 	return 0;
356 }
357 
358 struct xfs_aghdr_grow_data {
359 	xfs_daddr_t		daddr;
360 	size_t			numblks;
361 	const struct xfs_buf_ops *ops;
362 	aghdr_init_work_f	work;
363 	xfs_btnum_t		type;
364 	bool			need_init;
365 };
366 
367 /*
368  * Prepare new AG headers to be written to disk. We use uncached buffers here,
369  * as it is assumed these new AG headers are currently beyond the currently
370  * valid filesystem address space. Using cached buffers would trip over EOFS
371  * corruption detection alogrithms in the buffer cache lookup routines.
372  *
373  * This is a non-transactional function, but the prepared buffers are added to a
374  * delayed write buffer list supplied by the caller so they can submit them to
375  * disk and wait on them as required.
376  */
377 int
378 xfs_ag_init_headers(
379 	struct xfs_mount	*mp,
380 	struct aghdr_init_data	*id)
381 
382 {
383 	struct xfs_aghdr_grow_data aghdr_data[] = {
384 	{ /* SB */
385 		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_SB_DADDR),
386 		.numblks = XFS_FSS_TO_BB(mp, 1),
387 		.ops = &xfs_sb_buf_ops,
388 		.work = &xfs_sbblock_init,
389 		.need_init = true
390 	},
391 	{ /* AGF */
392 		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGF_DADDR(mp)),
393 		.numblks = XFS_FSS_TO_BB(mp, 1),
394 		.ops = &xfs_agf_buf_ops,
395 		.work = &xfs_agfblock_init,
396 		.need_init = true
397 	},
398 	{ /* AGFL */
399 		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGFL_DADDR(mp)),
400 		.numblks = XFS_FSS_TO_BB(mp, 1),
401 		.ops = &xfs_agfl_buf_ops,
402 		.work = &xfs_agflblock_init,
403 		.need_init = true
404 	},
405 	{ /* AGI */
406 		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGI_DADDR(mp)),
407 		.numblks = XFS_FSS_TO_BB(mp, 1),
408 		.ops = &xfs_agi_buf_ops,
409 		.work = &xfs_agiblock_init,
410 		.need_init = true
411 	},
412 	{ /* BNO root block */
413 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_BNO_BLOCK(mp)),
414 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
415 		.ops = &xfs_bnobt_buf_ops,
416 		.work = &xfs_bnoroot_init,
417 		.need_init = true
418 	},
419 	{ /* CNT root block */
420 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_CNT_BLOCK(mp)),
421 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
422 		.ops = &xfs_cntbt_buf_ops,
423 		.work = &xfs_cntroot_init,
424 		.need_init = true
425 	},
426 	{ /* INO root block */
427 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_IBT_BLOCK(mp)),
428 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
429 		.ops = &xfs_inobt_buf_ops,
430 		.work = &xfs_btroot_init,
431 		.type = XFS_BTNUM_INO,
432 		.need_init = true
433 	},
434 	{ /* FINO root block */
435 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_FIBT_BLOCK(mp)),
436 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
437 		.ops = &xfs_finobt_buf_ops,
438 		.work = &xfs_btroot_init,
439 		.type = XFS_BTNUM_FINO,
440 		.need_init =  xfs_sb_version_hasfinobt(&mp->m_sb)
441 	},
442 	{ /* RMAP root block */
443 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_RMAP_BLOCK(mp)),
444 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
445 		.ops = &xfs_rmapbt_buf_ops,
446 		.work = &xfs_rmaproot_init,
447 		.need_init = xfs_sb_version_hasrmapbt(&mp->m_sb)
448 	},
449 	{ /* REFC root block */
450 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, xfs_refc_block(mp)),
451 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
452 		.ops = &xfs_refcountbt_buf_ops,
453 		.work = &xfs_btroot_init,
454 		.type = XFS_BTNUM_REFC,
455 		.need_init = xfs_sb_version_hasreflink(&mp->m_sb)
456 	},
457 	{ /* NULL terminating block */
458 		.daddr = XFS_BUF_DADDR_NULL,
459 	}
460 	};
461 	struct  xfs_aghdr_grow_data *dp;
462 	int			error = 0;
463 
464 	/* Account for AG free space in new AG */
465 	id->nfree += id->agsize - mp->m_ag_prealloc_blocks;
466 	for (dp = &aghdr_data[0]; dp->daddr != XFS_BUF_DADDR_NULL; dp++) {
467 		if (!dp->need_init)
468 			continue;
469 
470 		id->daddr = dp->daddr;
471 		id->numblks = dp->numblks;
472 		id->type = dp->type;
473 		error = xfs_ag_init_hdr(mp, id, dp->work, dp->ops);
474 		if (error)
475 			break;
476 	}
477 	return error;
478 }
479 
480 /*
481  * Extent the AG indicated by the @id by the length passed in
482  */
483 int
484 xfs_ag_extend_space(
485 	struct xfs_mount	*mp,
486 	struct xfs_trans	*tp,
487 	struct aghdr_init_data	*id,
488 	xfs_extlen_t		len)
489 {
490 	struct xfs_buf		*bp;
491 	struct xfs_agi		*agi;
492 	struct xfs_agf		*agf;
493 	int			error;
494 
495 	/*
496 	 * Change the agi length.
497 	 */
498 	error = xfs_ialloc_read_agi(mp, tp, id->agno, &bp);
499 	if (error)
500 		return error;
501 
502 	agi = XFS_BUF_TO_AGI(bp);
503 	be32_add_cpu(&agi->agi_length, len);
504 	ASSERT(id->agno == mp->m_sb.sb_agcount - 1 ||
505 	       be32_to_cpu(agi->agi_length) == mp->m_sb.sb_agblocks);
506 	xfs_ialloc_log_agi(tp, bp, XFS_AGI_LENGTH);
507 
508 	/*
509 	 * Change agf length.
510 	 */
511 	error = xfs_alloc_read_agf(mp, tp, id->agno, 0, &bp);
512 	if (error)
513 		return error;
514 
515 	agf = XFS_BUF_TO_AGF(bp);
516 	be32_add_cpu(&agf->agf_length, len);
517 	ASSERT(agf->agf_length == agi->agi_length);
518 	xfs_alloc_log_agf(tp, bp, XFS_AGF_LENGTH);
519 
520 	/*
521 	 * Free the new space.
522 	 *
523 	 * XFS_RMAP_OINFO_SKIP_UPDATE is used here to tell the rmap btree that
524 	 * this doesn't actually exist in the rmap btree.
525 	 */
526 	error = xfs_rmap_free(tp, bp, id->agno,
527 				be32_to_cpu(agf->agf_length) - len,
528 				len, &XFS_RMAP_OINFO_SKIP_UPDATE);
529 	if (error)
530 		return error;
531 
532 	return  xfs_free_extent(tp, XFS_AGB_TO_FSB(mp, id->agno,
533 					be32_to_cpu(agf->agf_length) - len),
534 				len, &XFS_RMAP_OINFO_SKIP_UPDATE,
535 				XFS_AG_RESV_NONE);
536 }
537 
538 /* Retrieve AG geometry. */
539 int
540 xfs_ag_get_geometry(
541 	struct xfs_mount	*mp,
542 	xfs_agnumber_t		agno,
543 	struct xfs_ag_geometry	*ageo)
544 {
545 	struct xfs_buf		*agi_bp;
546 	struct xfs_buf		*agf_bp;
547 	struct xfs_agi		*agi;
548 	struct xfs_agf		*agf;
549 	struct xfs_perag	*pag;
550 	unsigned int		freeblks;
551 	int			error;
552 
553 	if (agno >= mp->m_sb.sb_agcount)
554 		return -EINVAL;
555 
556 	/* Lock the AG headers. */
557 	error = xfs_ialloc_read_agi(mp, NULL, agno, &agi_bp);
558 	if (error)
559 		return error;
560 	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agf_bp);
561 	if (error)
562 		goto out_agi;
563 	pag = xfs_perag_get(mp, agno);
564 
565 	/* Fill out form. */
566 	memset(ageo, 0, sizeof(*ageo));
567 	ageo->ag_number = agno;
568 
569 	agi = XFS_BUF_TO_AGI(agi_bp);
570 	ageo->ag_icount = be32_to_cpu(agi->agi_count);
571 	ageo->ag_ifree = be32_to_cpu(agi->agi_freecount);
572 
573 	agf = XFS_BUF_TO_AGF(agf_bp);
574 	ageo->ag_length = be32_to_cpu(agf->agf_length);
575 	freeblks = pag->pagf_freeblks +
576 		   pag->pagf_flcount +
577 		   pag->pagf_btreeblks -
578 		   xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE);
579 	ageo->ag_freeblks = freeblks;
580 	xfs_ag_geom_health(pag, ageo);
581 
582 	/* Release resources. */
583 	xfs_perag_put(pag);
584 	xfs_buf_relse(agf_bp);
585 out_agi:
586 	xfs_buf_relse(agi_bp);
587 	return error;
588 }
589