xref: /linux/fs/xfs/libxfs/xfs_ag.c (revision e7c22eeaff8565d9a8374f320238c251ca31480b)
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 int
27 xfs_get_aghdr_buf(
28 	struct xfs_mount	*mp,
29 	xfs_daddr_t		blkno,
30 	size_t			numblks,
31 	struct xfs_buf		**bpp,
32 	const struct xfs_buf_ops *ops)
33 {
34 	struct xfs_buf		*bp;
35 	int			error;
36 
37 	error = xfs_buf_get_uncached(mp->m_ddev_targp, numblks, 0, &bp);
38 	if (error)
39 		return error;
40 
41 	xfs_buf_zero(bp, 0, BBTOB(bp->b_length));
42 	bp->b_bn = blkno;
43 	bp->b_maps[0].bm_bn = blkno;
44 	bp->b_ops = ops;
45 
46 	*bpp = bp;
47 	return 0;
48 }
49 
50 static inline bool is_log_ag(struct xfs_mount *mp, struct aghdr_init_data *id)
51 {
52 	return mp->m_sb.sb_logstart > 0 &&
53 	       id->agno == XFS_FSB_TO_AGNO(mp, mp->m_sb.sb_logstart);
54 }
55 
56 /*
57  * Generic btree root block init function
58  */
59 static void
60 xfs_btroot_init(
61 	struct xfs_mount	*mp,
62 	struct xfs_buf		*bp,
63 	struct aghdr_init_data	*id)
64 {
65 	xfs_btree_init_block(mp, bp, id->type, 0, 0, id->agno);
66 }
67 
68 /* Finish initializing a free space btree. */
69 static void
70 xfs_freesp_init_recs(
71 	struct xfs_mount	*mp,
72 	struct xfs_buf		*bp,
73 	struct aghdr_init_data	*id)
74 {
75 	struct xfs_alloc_rec	*arec;
76 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
77 
78 	arec = XFS_ALLOC_REC_ADDR(mp, XFS_BUF_TO_BLOCK(bp), 1);
79 	arec->ar_startblock = cpu_to_be32(mp->m_ag_prealloc_blocks);
80 
81 	if (is_log_ag(mp, id)) {
82 		struct xfs_alloc_rec	*nrec;
83 		xfs_agblock_t		start = XFS_FSB_TO_AGBNO(mp,
84 							mp->m_sb.sb_logstart);
85 
86 		ASSERT(start >= mp->m_ag_prealloc_blocks);
87 		if (start != mp->m_ag_prealloc_blocks) {
88 			/*
89 			 * Modify first record to pad stripe align of log
90 			 */
91 			arec->ar_blockcount = cpu_to_be32(start -
92 						mp->m_ag_prealloc_blocks);
93 			nrec = arec + 1;
94 
95 			/*
96 			 * Insert second record at start of internal log
97 			 * which then gets trimmed.
98 			 */
99 			nrec->ar_startblock = cpu_to_be32(
100 					be32_to_cpu(arec->ar_startblock) +
101 					be32_to_cpu(arec->ar_blockcount));
102 			arec = nrec;
103 			be16_add_cpu(&block->bb_numrecs, 1);
104 		}
105 		/*
106 		 * Change record start to after the internal log
107 		 */
108 		be32_add_cpu(&arec->ar_startblock, mp->m_sb.sb_logblocks);
109 	}
110 
111 	/*
112 	 * Calculate the record block count and check for the case where
113 	 * the log might have consumed all available space in the AG. If
114 	 * so, reset the record count to 0 to avoid exposure of an invalid
115 	 * record start block.
116 	 */
117 	arec->ar_blockcount = cpu_to_be32(id->agsize -
118 					  be32_to_cpu(arec->ar_startblock));
119 	if (!arec->ar_blockcount)
120 		block->bb_numrecs = 0;
121 }
122 
123 /*
124  * Alloc btree root block init functions
125  */
126 static void
127 xfs_bnoroot_init(
128 	struct xfs_mount	*mp,
129 	struct xfs_buf		*bp,
130 	struct aghdr_init_data	*id)
131 {
132 	xfs_btree_init_block(mp, bp, XFS_BTNUM_BNO, 0, 1, id->agno);
133 	xfs_freesp_init_recs(mp, bp, id);
134 }
135 
136 static void
137 xfs_cntroot_init(
138 	struct xfs_mount	*mp,
139 	struct xfs_buf		*bp,
140 	struct aghdr_init_data	*id)
141 {
142 	xfs_btree_init_block(mp, bp, XFS_BTNUM_CNT, 0, 1, id->agno);
143 	xfs_freesp_init_recs(mp, bp, id);
144 }
145 
146 /*
147  * Reverse map root block init
148  */
149 static void
150 xfs_rmaproot_init(
151 	struct xfs_mount	*mp,
152 	struct xfs_buf		*bp,
153 	struct aghdr_init_data	*id)
154 {
155 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
156 	struct xfs_rmap_rec	*rrec;
157 
158 	xfs_btree_init_block(mp, bp, XFS_BTNUM_RMAP, 0, 4, id->agno);
159 
160 	/*
161 	 * mark the AG header regions as static metadata The BNO
162 	 * btree block is the first block after the headers, so
163 	 * it's location defines the size of region the static
164 	 * metadata consumes.
165 	 *
166 	 * Note: unlike mkfs, we never have to account for log
167 	 * space when growing the data regions
168 	 */
169 	rrec = XFS_RMAP_REC_ADDR(block, 1);
170 	rrec->rm_startblock = 0;
171 	rrec->rm_blockcount = cpu_to_be32(XFS_BNO_BLOCK(mp));
172 	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_FS);
173 	rrec->rm_offset = 0;
174 
175 	/* account freespace btree root blocks */
176 	rrec = XFS_RMAP_REC_ADDR(block, 2);
177 	rrec->rm_startblock = cpu_to_be32(XFS_BNO_BLOCK(mp));
178 	rrec->rm_blockcount = cpu_to_be32(2);
179 	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_AG);
180 	rrec->rm_offset = 0;
181 
182 	/* account inode btree root blocks */
183 	rrec = XFS_RMAP_REC_ADDR(block, 3);
184 	rrec->rm_startblock = cpu_to_be32(XFS_IBT_BLOCK(mp));
185 	rrec->rm_blockcount = cpu_to_be32(XFS_RMAP_BLOCK(mp) -
186 					  XFS_IBT_BLOCK(mp));
187 	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_INOBT);
188 	rrec->rm_offset = 0;
189 
190 	/* account for rmap btree root */
191 	rrec = XFS_RMAP_REC_ADDR(block, 4);
192 	rrec->rm_startblock = cpu_to_be32(XFS_RMAP_BLOCK(mp));
193 	rrec->rm_blockcount = cpu_to_be32(1);
194 	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_AG);
195 	rrec->rm_offset = 0;
196 
197 	/* account for refc btree root */
198 	if (xfs_sb_version_hasreflink(&mp->m_sb)) {
199 		rrec = XFS_RMAP_REC_ADDR(block, 5);
200 		rrec->rm_startblock = cpu_to_be32(xfs_refc_block(mp));
201 		rrec->rm_blockcount = cpu_to_be32(1);
202 		rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_REFC);
203 		rrec->rm_offset = 0;
204 		be16_add_cpu(&block->bb_numrecs, 1);
205 	}
206 
207 	/* account for the log space */
208 	if (is_log_ag(mp, id)) {
209 		rrec = XFS_RMAP_REC_ADDR(block,
210 				be16_to_cpu(block->bb_numrecs) + 1);
211 		rrec->rm_startblock = cpu_to_be32(
212 				XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart));
213 		rrec->rm_blockcount = cpu_to_be32(mp->m_sb.sb_logblocks);
214 		rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_LOG);
215 		rrec->rm_offset = 0;
216 		be16_add_cpu(&block->bb_numrecs, 1);
217 	}
218 }
219 
220 /*
221  * Initialise new secondary superblocks with the pre-grow geometry, but mark
222  * them as "in progress" so we know they haven't yet been activated. This will
223  * get cleared when the update with the new geometry information is done after
224  * changes to the primary are committed. This isn't strictly necessary, but we
225  * get it for free with the delayed buffer write lists and it means we can tell
226  * if a grow operation didn't complete properly after the fact.
227  */
228 static void
229 xfs_sbblock_init(
230 	struct xfs_mount	*mp,
231 	struct xfs_buf		*bp,
232 	struct aghdr_init_data	*id)
233 {
234 	struct xfs_dsb		*dsb = bp->b_addr;
235 
236 	xfs_sb_to_disk(dsb, &mp->m_sb);
237 	dsb->sb_inprogress = 1;
238 }
239 
240 static void
241 xfs_agfblock_init(
242 	struct xfs_mount	*mp,
243 	struct xfs_buf		*bp,
244 	struct aghdr_init_data	*id)
245 {
246 	struct xfs_agf		*agf = bp->b_addr;
247 	xfs_extlen_t		tmpsize;
248 
249 	agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
250 	agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
251 	agf->agf_seqno = cpu_to_be32(id->agno);
252 	agf->agf_length = cpu_to_be32(id->agsize);
253 	agf->agf_roots[XFS_BTNUM_BNOi] = cpu_to_be32(XFS_BNO_BLOCK(mp));
254 	agf->agf_roots[XFS_BTNUM_CNTi] = cpu_to_be32(XFS_CNT_BLOCK(mp));
255 	agf->agf_levels[XFS_BTNUM_BNOi] = cpu_to_be32(1);
256 	agf->agf_levels[XFS_BTNUM_CNTi] = cpu_to_be32(1);
257 	if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
258 		agf->agf_roots[XFS_BTNUM_RMAPi] =
259 					cpu_to_be32(XFS_RMAP_BLOCK(mp));
260 		agf->agf_levels[XFS_BTNUM_RMAPi] = cpu_to_be32(1);
261 		agf->agf_rmap_blocks = cpu_to_be32(1);
262 	}
263 
264 	agf->agf_flfirst = cpu_to_be32(1);
265 	agf->agf_fllast = 0;
266 	agf->agf_flcount = 0;
267 	tmpsize = id->agsize - mp->m_ag_prealloc_blocks;
268 	agf->agf_freeblks = cpu_to_be32(tmpsize);
269 	agf->agf_longest = cpu_to_be32(tmpsize);
270 	if (xfs_sb_version_hascrc(&mp->m_sb))
271 		uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid);
272 	if (xfs_sb_version_hasreflink(&mp->m_sb)) {
273 		agf->agf_refcount_root = cpu_to_be32(
274 				xfs_refc_block(mp));
275 		agf->agf_refcount_level = cpu_to_be32(1);
276 		agf->agf_refcount_blocks = cpu_to_be32(1);
277 	}
278 
279 	if (is_log_ag(mp, id)) {
280 		int64_t	logblocks = mp->m_sb.sb_logblocks;
281 
282 		be32_add_cpu(&agf->agf_freeblks, -logblocks);
283 		agf->agf_longest = cpu_to_be32(id->agsize -
284 			XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart) - logblocks);
285 	}
286 }
287 
288 static void
289 xfs_agflblock_init(
290 	struct xfs_mount	*mp,
291 	struct xfs_buf		*bp,
292 	struct aghdr_init_data	*id)
293 {
294 	struct xfs_agfl		*agfl = XFS_BUF_TO_AGFL(bp);
295 	__be32			*agfl_bno;
296 	int			bucket;
297 
298 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
299 		agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
300 		agfl->agfl_seqno = cpu_to_be32(id->agno);
301 		uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid);
302 	}
303 
304 	agfl_bno = xfs_buf_to_agfl_bno(bp);
305 	for (bucket = 0; bucket < xfs_agfl_size(mp); bucket++)
306 		agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);
307 }
308 
309 static void
310 xfs_agiblock_init(
311 	struct xfs_mount	*mp,
312 	struct xfs_buf		*bp,
313 	struct aghdr_init_data	*id)
314 {
315 	struct xfs_agi		*agi = bp->b_addr;
316 	int			bucket;
317 
318 	agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
319 	agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
320 	agi->agi_seqno = cpu_to_be32(id->agno);
321 	agi->agi_length = cpu_to_be32(id->agsize);
322 	agi->agi_count = 0;
323 	agi->agi_root = cpu_to_be32(XFS_IBT_BLOCK(mp));
324 	agi->agi_level = cpu_to_be32(1);
325 	agi->agi_freecount = 0;
326 	agi->agi_newino = cpu_to_be32(NULLAGINO);
327 	agi->agi_dirino = cpu_to_be32(NULLAGINO);
328 	if (xfs_sb_version_hascrc(&mp->m_sb))
329 		uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid);
330 	if (xfs_sb_version_hasfinobt(&mp->m_sb)) {
331 		agi->agi_free_root = cpu_to_be32(XFS_FIBT_BLOCK(mp));
332 		agi->agi_free_level = cpu_to_be32(1);
333 	}
334 	for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
335 		agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
336 	if (xfs_sb_version_hasinobtcounts(&mp->m_sb)) {
337 		agi->agi_iblocks = cpu_to_be32(1);
338 		if (xfs_sb_version_hasfinobt(&mp->m_sb))
339 			agi->agi_fblocks = cpu_to_be32(1);
340 	}
341 }
342 
343 typedef void (*aghdr_init_work_f)(struct xfs_mount *mp, struct xfs_buf *bp,
344 				  struct aghdr_init_data *id);
345 static int
346 xfs_ag_init_hdr(
347 	struct xfs_mount	*mp,
348 	struct aghdr_init_data	*id,
349 	aghdr_init_work_f	work,
350 	const struct xfs_buf_ops *ops)
351 {
352 	struct xfs_buf		*bp;
353 	int			error;
354 
355 	error = xfs_get_aghdr_buf(mp, id->daddr, id->numblks, &bp, ops);
356 	if (error)
357 		return error;
358 
359 	(*work)(mp, bp, id);
360 
361 	xfs_buf_delwri_queue(bp, &id->buffer_list);
362 	xfs_buf_relse(bp);
363 	return 0;
364 }
365 
366 struct xfs_aghdr_grow_data {
367 	xfs_daddr_t		daddr;
368 	size_t			numblks;
369 	const struct xfs_buf_ops *ops;
370 	aghdr_init_work_f	work;
371 	xfs_btnum_t		type;
372 	bool			need_init;
373 };
374 
375 /*
376  * Prepare new AG headers to be written to disk. We use uncached buffers here,
377  * as it is assumed these new AG headers are currently beyond the currently
378  * valid filesystem address space. Using cached buffers would trip over EOFS
379  * corruption detection alogrithms in the buffer cache lookup routines.
380  *
381  * This is a non-transactional function, but the prepared buffers are added to a
382  * delayed write buffer list supplied by the caller so they can submit them to
383  * disk and wait on them as required.
384  */
385 int
386 xfs_ag_init_headers(
387 	struct xfs_mount	*mp,
388 	struct aghdr_init_data	*id)
389 
390 {
391 	struct xfs_aghdr_grow_data aghdr_data[] = {
392 	{ /* SB */
393 		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_SB_DADDR),
394 		.numblks = XFS_FSS_TO_BB(mp, 1),
395 		.ops = &xfs_sb_buf_ops,
396 		.work = &xfs_sbblock_init,
397 		.need_init = true
398 	},
399 	{ /* AGF */
400 		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGF_DADDR(mp)),
401 		.numblks = XFS_FSS_TO_BB(mp, 1),
402 		.ops = &xfs_agf_buf_ops,
403 		.work = &xfs_agfblock_init,
404 		.need_init = true
405 	},
406 	{ /* AGFL */
407 		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGFL_DADDR(mp)),
408 		.numblks = XFS_FSS_TO_BB(mp, 1),
409 		.ops = &xfs_agfl_buf_ops,
410 		.work = &xfs_agflblock_init,
411 		.need_init = true
412 	},
413 	{ /* AGI */
414 		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGI_DADDR(mp)),
415 		.numblks = XFS_FSS_TO_BB(mp, 1),
416 		.ops = &xfs_agi_buf_ops,
417 		.work = &xfs_agiblock_init,
418 		.need_init = true
419 	},
420 	{ /* BNO root block */
421 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_BNO_BLOCK(mp)),
422 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
423 		.ops = &xfs_bnobt_buf_ops,
424 		.work = &xfs_bnoroot_init,
425 		.need_init = true
426 	},
427 	{ /* CNT root block */
428 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_CNT_BLOCK(mp)),
429 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
430 		.ops = &xfs_cntbt_buf_ops,
431 		.work = &xfs_cntroot_init,
432 		.need_init = true
433 	},
434 	{ /* INO root block */
435 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_IBT_BLOCK(mp)),
436 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
437 		.ops = &xfs_inobt_buf_ops,
438 		.work = &xfs_btroot_init,
439 		.type = XFS_BTNUM_INO,
440 		.need_init = true
441 	},
442 	{ /* FINO root block */
443 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_FIBT_BLOCK(mp)),
444 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
445 		.ops = &xfs_finobt_buf_ops,
446 		.work = &xfs_btroot_init,
447 		.type = XFS_BTNUM_FINO,
448 		.need_init =  xfs_sb_version_hasfinobt(&mp->m_sb)
449 	},
450 	{ /* RMAP root block */
451 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_RMAP_BLOCK(mp)),
452 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
453 		.ops = &xfs_rmapbt_buf_ops,
454 		.work = &xfs_rmaproot_init,
455 		.need_init = xfs_sb_version_hasrmapbt(&mp->m_sb)
456 	},
457 	{ /* REFC root block */
458 		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, xfs_refc_block(mp)),
459 		.numblks = BTOBB(mp->m_sb.sb_blocksize),
460 		.ops = &xfs_refcountbt_buf_ops,
461 		.work = &xfs_btroot_init,
462 		.type = XFS_BTNUM_REFC,
463 		.need_init = xfs_sb_version_hasreflink(&mp->m_sb)
464 	},
465 	{ /* NULL terminating block */
466 		.daddr = XFS_BUF_DADDR_NULL,
467 	}
468 	};
469 	struct  xfs_aghdr_grow_data *dp;
470 	int			error = 0;
471 
472 	/* Account for AG free space in new AG */
473 	id->nfree += id->agsize - mp->m_ag_prealloc_blocks;
474 	for (dp = &aghdr_data[0]; dp->daddr != XFS_BUF_DADDR_NULL; dp++) {
475 		if (!dp->need_init)
476 			continue;
477 
478 		id->daddr = dp->daddr;
479 		id->numblks = dp->numblks;
480 		id->type = dp->type;
481 		error = xfs_ag_init_hdr(mp, id, dp->work, dp->ops);
482 		if (error)
483 			break;
484 	}
485 	return error;
486 }
487 
488 /*
489  * Extent the AG indicated by the @id by the length passed in
490  */
491 int
492 xfs_ag_extend_space(
493 	struct xfs_mount	*mp,
494 	struct xfs_trans	*tp,
495 	struct aghdr_init_data	*id,
496 	xfs_extlen_t		len)
497 {
498 	struct xfs_buf		*bp;
499 	struct xfs_agi		*agi;
500 	struct xfs_agf		*agf;
501 	int			error;
502 
503 	/*
504 	 * Change the agi length.
505 	 */
506 	error = xfs_ialloc_read_agi(mp, tp, id->agno, &bp);
507 	if (error)
508 		return error;
509 
510 	agi = bp->b_addr;
511 	be32_add_cpu(&agi->agi_length, len);
512 	ASSERT(id->agno == mp->m_sb.sb_agcount - 1 ||
513 	       be32_to_cpu(agi->agi_length) == mp->m_sb.sb_agblocks);
514 	xfs_ialloc_log_agi(tp, bp, XFS_AGI_LENGTH);
515 
516 	/*
517 	 * Change agf length.
518 	 */
519 	error = xfs_alloc_read_agf(mp, tp, id->agno, 0, &bp);
520 	if (error)
521 		return error;
522 
523 	agf = bp->b_addr;
524 	be32_add_cpu(&agf->agf_length, len);
525 	ASSERT(agf->agf_length == agi->agi_length);
526 	xfs_alloc_log_agf(tp, bp, XFS_AGF_LENGTH);
527 
528 	/*
529 	 * Free the new space.
530 	 *
531 	 * XFS_RMAP_OINFO_SKIP_UPDATE is used here to tell the rmap btree that
532 	 * this doesn't actually exist in the rmap btree.
533 	 */
534 	error = xfs_rmap_free(tp, bp, id->agno,
535 				be32_to_cpu(agf->agf_length) - len,
536 				len, &XFS_RMAP_OINFO_SKIP_UPDATE);
537 	if (error)
538 		return error;
539 
540 	return  xfs_free_extent(tp, XFS_AGB_TO_FSB(mp, id->agno,
541 					be32_to_cpu(agf->agf_length) - len),
542 				len, &XFS_RMAP_OINFO_SKIP_UPDATE,
543 				XFS_AG_RESV_NONE);
544 }
545 
546 /* Retrieve AG geometry. */
547 int
548 xfs_ag_get_geometry(
549 	struct xfs_mount	*mp,
550 	xfs_agnumber_t		agno,
551 	struct xfs_ag_geometry	*ageo)
552 {
553 	struct xfs_buf		*agi_bp;
554 	struct xfs_buf		*agf_bp;
555 	struct xfs_agi		*agi;
556 	struct xfs_agf		*agf;
557 	struct xfs_perag	*pag;
558 	unsigned int		freeblks;
559 	int			error;
560 
561 	if (agno >= mp->m_sb.sb_agcount)
562 		return -EINVAL;
563 
564 	/* Lock the AG headers. */
565 	error = xfs_ialloc_read_agi(mp, NULL, agno, &agi_bp);
566 	if (error)
567 		return error;
568 	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agf_bp);
569 	if (error)
570 		goto out_agi;
571 
572 	pag = agi_bp->b_pag;
573 
574 	/* Fill out form. */
575 	memset(ageo, 0, sizeof(*ageo));
576 	ageo->ag_number = agno;
577 
578 	agi = agi_bp->b_addr;
579 	ageo->ag_icount = be32_to_cpu(agi->agi_count);
580 	ageo->ag_ifree = be32_to_cpu(agi->agi_freecount);
581 
582 	agf = agf_bp->b_addr;
583 	ageo->ag_length = be32_to_cpu(agf->agf_length);
584 	freeblks = pag->pagf_freeblks +
585 		   pag->pagf_flcount +
586 		   pag->pagf_btreeblks -
587 		   xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE);
588 	ageo->ag_freeblks = freeblks;
589 	xfs_ag_geom_health(pag, ageo);
590 
591 	/* Release resources. */
592 	xfs_buf_relse(agf_bp);
593 out_agi:
594 	xfs_buf_relse(agi_bp);
595 	return error;
596 }
597