xref: /openbmc/linux/fs/xfs/xfs_mount.c (revision 0edbfea5)
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_shared.h"
21 #include "xfs_format.h"
22 #include "xfs_log_format.h"
23 #include "xfs_trans_resv.h"
24 #include "xfs_bit.h"
25 #include "xfs_sb.h"
26 #include "xfs_mount.h"
27 #include "xfs_da_format.h"
28 #include "xfs_da_btree.h"
29 #include "xfs_inode.h"
30 #include "xfs_dir2.h"
31 #include "xfs_ialloc.h"
32 #include "xfs_alloc.h"
33 #include "xfs_rtalloc.h"
34 #include "xfs_bmap.h"
35 #include "xfs_trans.h"
36 #include "xfs_trans_priv.h"
37 #include "xfs_log.h"
38 #include "xfs_error.h"
39 #include "xfs_quota.h"
40 #include "xfs_fsops.h"
41 #include "xfs_trace.h"
42 #include "xfs_icache.h"
43 #include "xfs_sysfs.h"
44 
45 
46 static DEFINE_MUTEX(xfs_uuid_table_mutex);
47 static int xfs_uuid_table_size;
48 static uuid_t *xfs_uuid_table;
49 
50 void
51 xfs_uuid_table_free(void)
52 {
53 	if (xfs_uuid_table_size == 0)
54 		return;
55 	kmem_free(xfs_uuid_table);
56 	xfs_uuid_table = NULL;
57 	xfs_uuid_table_size = 0;
58 }
59 
60 /*
61  * See if the UUID is unique among mounted XFS filesystems.
62  * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
63  */
64 STATIC int
65 xfs_uuid_mount(
66 	struct xfs_mount	*mp)
67 {
68 	uuid_t			*uuid = &mp->m_sb.sb_uuid;
69 	int			hole, i;
70 
71 	if (mp->m_flags & XFS_MOUNT_NOUUID)
72 		return 0;
73 
74 	if (uuid_is_nil(uuid)) {
75 		xfs_warn(mp, "Filesystem has nil UUID - can't mount");
76 		return -EINVAL;
77 	}
78 
79 	mutex_lock(&xfs_uuid_table_mutex);
80 	for (i = 0, hole = -1; i < xfs_uuid_table_size; i++) {
81 		if (uuid_is_nil(&xfs_uuid_table[i])) {
82 			hole = i;
83 			continue;
84 		}
85 		if (uuid_equal(uuid, &xfs_uuid_table[i]))
86 			goto out_duplicate;
87 	}
88 
89 	if (hole < 0) {
90 		xfs_uuid_table = kmem_realloc(xfs_uuid_table,
91 			(xfs_uuid_table_size + 1) * sizeof(*xfs_uuid_table),
92 			KM_SLEEP);
93 		hole = xfs_uuid_table_size++;
94 	}
95 	xfs_uuid_table[hole] = *uuid;
96 	mutex_unlock(&xfs_uuid_table_mutex);
97 
98 	return 0;
99 
100  out_duplicate:
101 	mutex_unlock(&xfs_uuid_table_mutex);
102 	xfs_warn(mp, "Filesystem has duplicate UUID %pU - can't mount", uuid);
103 	return -EINVAL;
104 }
105 
106 STATIC void
107 xfs_uuid_unmount(
108 	struct xfs_mount	*mp)
109 {
110 	uuid_t			*uuid = &mp->m_sb.sb_uuid;
111 	int			i;
112 
113 	if (mp->m_flags & XFS_MOUNT_NOUUID)
114 		return;
115 
116 	mutex_lock(&xfs_uuid_table_mutex);
117 	for (i = 0; i < xfs_uuid_table_size; i++) {
118 		if (uuid_is_nil(&xfs_uuid_table[i]))
119 			continue;
120 		if (!uuid_equal(uuid, &xfs_uuid_table[i]))
121 			continue;
122 		memset(&xfs_uuid_table[i], 0, sizeof(uuid_t));
123 		break;
124 	}
125 	ASSERT(i < xfs_uuid_table_size);
126 	mutex_unlock(&xfs_uuid_table_mutex);
127 }
128 
129 
130 STATIC void
131 __xfs_free_perag(
132 	struct rcu_head	*head)
133 {
134 	struct xfs_perag *pag = container_of(head, struct xfs_perag, rcu_head);
135 
136 	ASSERT(atomic_read(&pag->pag_ref) == 0);
137 	kmem_free(pag);
138 }
139 
140 /*
141  * Free up the per-ag resources associated with the mount structure.
142  */
143 STATIC void
144 xfs_free_perag(
145 	xfs_mount_t	*mp)
146 {
147 	xfs_agnumber_t	agno;
148 	struct xfs_perag *pag;
149 
150 	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
151 		spin_lock(&mp->m_perag_lock);
152 		pag = radix_tree_delete(&mp->m_perag_tree, agno);
153 		spin_unlock(&mp->m_perag_lock);
154 		ASSERT(pag);
155 		ASSERT(atomic_read(&pag->pag_ref) == 0);
156 		call_rcu(&pag->rcu_head, __xfs_free_perag);
157 	}
158 }
159 
160 /*
161  * Check size of device based on the (data/realtime) block count.
162  * Note: this check is used by the growfs code as well as mount.
163  */
164 int
165 xfs_sb_validate_fsb_count(
166 	xfs_sb_t	*sbp,
167 	__uint64_t	nblocks)
168 {
169 	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
170 	ASSERT(sbp->sb_blocklog >= BBSHIFT);
171 
172 	/* Limited by ULONG_MAX of page cache index */
173 	if (nblocks >> (PAGE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
174 		return -EFBIG;
175 	return 0;
176 }
177 
178 int
179 xfs_initialize_perag(
180 	xfs_mount_t	*mp,
181 	xfs_agnumber_t	agcount,
182 	xfs_agnumber_t	*maxagi)
183 {
184 	xfs_agnumber_t	index;
185 	xfs_agnumber_t	first_initialised = 0;
186 	xfs_perag_t	*pag;
187 	int		error = -ENOMEM;
188 
189 	/*
190 	 * Walk the current per-ag tree so we don't try to initialise AGs
191 	 * that already exist (growfs case). Allocate and insert all the
192 	 * AGs we don't find ready for initialisation.
193 	 */
194 	for (index = 0; index < agcount; index++) {
195 		pag = xfs_perag_get(mp, index);
196 		if (pag) {
197 			xfs_perag_put(pag);
198 			continue;
199 		}
200 		if (!first_initialised)
201 			first_initialised = index;
202 
203 		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
204 		if (!pag)
205 			goto out_unwind;
206 		pag->pag_agno = index;
207 		pag->pag_mount = mp;
208 		spin_lock_init(&pag->pag_ici_lock);
209 		mutex_init(&pag->pag_ici_reclaim_lock);
210 		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
211 		spin_lock_init(&pag->pag_buf_lock);
212 		pag->pag_buf_tree = RB_ROOT;
213 
214 		if (radix_tree_preload(GFP_NOFS))
215 			goto out_unwind;
216 
217 		spin_lock(&mp->m_perag_lock);
218 		if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
219 			BUG();
220 			spin_unlock(&mp->m_perag_lock);
221 			radix_tree_preload_end();
222 			error = -EEXIST;
223 			goto out_unwind;
224 		}
225 		spin_unlock(&mp->m_perag_lock);
226 		radix_tree_preload_end();
227 	}
228 
229 	index = xfs_set_inode_alloc(mp, agcount);
230 
231 	if (maxagi)
232 		*maxagi = index;
233 	return 0;
234 
235 out_unwind:
236 	kmem_free(pag);
237 	for (; index > first_initialised; index--) {
238 		pag = radix_tree_delete(&mp->m_perag_tree, index);
239 		kmem_free(pag);
240 	}
241 	return error;
242 }
243 
244 /*
245  * xfs_readsb
246  *
247  * Does the initial read of the superblock.
248  */
249 int
250 xfs_readsb(
251 	struct xfs_mount *mp,
252 	int		flags)
253 {
254 	unsigned int	sector_size;
255 	struct xfs_buf	*bp;
256 	struct xfs_sb	*sbp = &mp->m_sb;
257 	int		error;
258 	int		loud = !(flags & XFS_MFSI_QUIET);
259 	const struct xfs_buf_ops *buf_ops;
260 
261 	ASSERT(mp->m_sb_bp == NULL);
262 	ASSERT(mp->m_ddev_targp != NULL);
263 
264 	/*
265 	 * For the initial read, we must guess at the sector
266 	 * size based on the block device.  It's enough to
267 	 * get the sb_sectsize out of the superblock and
268 	 * then reread with the proper length.
269 	 * We don't verify it yet, because it may not be complete.
270 	 */
271 	sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
272 	buf_ops = NULL;
273 
274 	/*
275 	 * Allocate a (locked) buffer to hold the superblock.
276 	 * This will be kept around at all times to optimize
277 	 * access to the superblock.
278 	 */
279 reread:
280 	error = xfs_buf_read_uncached(mp->m_ddev_targp, XFS_SB_DADDR,
281 				   BTOBB(sector_size), 0, &bp, buf_ops);
282 	if (error) {
283 		if (loud)
284 			xfs_warn(mp, "SB validate failed with error %d.", error);
285 		/* bad CRC means corrupted metadata */
286 		if (error == -EFSBADCRC)
287 			error = -EFSCORRUPTED;
288 		return error;
289 	}
290 
291 	/*
292 	 * Initialize the mount structure from the superblock.
293 	 */
294 	xfs_sb_from_disk(sbp, XFS_BUF_TO_SBP(bp));
295 
296 	/*
297 	 * If we haven't validated the superblock, do so now before we try
298 	 * to check the sector size and reread the superblock appropriately.
299 	 */
300 	if (sbp->sb_magicnum != XFS_SB_MAGIC) {
301 		if (loud)
302 			xfs_warn(mp, "Invalid superblock magic number");
303 		error = -EINVAL;
304 		goto release_buf;
305 	}
306 
307 	/*
308 	 * We must be able to do sector-sized and sector-aligned IO.
309 	 */
310 	if (sector_size > sbp->sb_sectsize) {
311 		if (loud)
312 			xfs_warn(mp, "device supports %u byte sectors (not %u)",
313 				sector_size, sbp->sb_sectsize);
314 		error = -ENOSYS;
315 		goto release_buf;
316 	}
317 
318 	if (buf_ops == NULL) {
319 		/*
320 		 * Re-read the superblock so the buffer is correctly sized,
321 		 * and properly verified.
322 		 */
323 		xfs_buf_relse(bp);
324 		sector_size = sbp->sb_sectsize;
325 		buf_ops = loud ? &xfs_sb_buf_ops : &xfs_sb_quiet_buf_ops;
326 		goto reread;
327 	}
328 
329 	xfs_reinit_percpu_counters(mp);
330 
331 	/* no need to be quiet anymore, so reset the buf ops */
332 	bp->b_ops = &xfs_sb_buf_ops;
333 
334 	mp->m_sb_bp = bp;
335 	xfs_buf_unlock(bp);
336 	return 0;
337 
338 release_buf:
339 	xfs_buf_relse(bp);
340 	return error;
341 }
342 
343 /*
344  * Update alignment values based on mount options and sb values
345  */
346 STATIC int
347 xfs_update_alignment(xfs_mount_t *mp)
348 {
349 	xfs_sb_t	*sbp = &(mp->m_sb);
350 
351 	if (mp->m_dalign) {
352 		/*
353 		 * If stripe unit and stripe width are not multiples
354 		 * of the fs blocksize turn off alignment.
355 		 */
356 		if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
357 		    (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
358 			xfs_warn(mp,
359 		"alignment check failed: sunit/swidth vs. blocksize(%d)",
360 				sbp->sb_blocksize);
361 			return -EINVAL;
362 		} else {
363 			/*
364 			 * Convert the stripe unit and width to FSBs.
365 			 */
366 			mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
367 			if (mp->m_dalign && (sbp->sb_agblocks % mp->m_dalign)) {
368 				xfs_warn(mp,
369 			"alignment check failed: sunit/swidth vs. agsize(%d)",
370 					 sbp->sb_agblocks);
371 				return -EINVAL;
372 			} else if (mp->m_dalign) {
373 				mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
374 			} else {
375 				xfs_warn(mp,
376 			"alignment check failed: sunit(%d) less than bsize(%d)",
377 					 mp->m_dalign, sbp->sb_blocksize);
378 				return -EINVAL;
379 			}
380 		}
381 
382 		/*
383 		 * Update superblock with new values
384 		 * and log changes
385 		 */
386 		if (xfs_sb_version_hasdalign(sbp)) {
387 			if (sbp->sb_unit != mp->m_dalign) {
388 				sbp->sb_unit = mp->m_dalign;
389 				mp->m_update_sb = true;
390 			}
391 			if (sbp->sb_width != mp->m_swidth) {
392 				sbp->sb_width = mp->m_swidth;
393 				mp->m_update_sb = true;
394 			}
395 		} else {
396 			xfs_warn(mp,
397 	"cannot change alignment: superblock does not support data alignment");
398 			return -EINVAL;
399 		}
400 	} else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
401 		    xfs_sb_version_hasdalign(&mp->m_sb)) {
402 			mp->m_dalign = sbp->sb_unit;
403 			mp->m_swidth = sbp->sb_width;
404 	}
405 
406 	return 0;
407 }
408 
409 /*
410  * Set the maximum inode count for this filesystem
411  */
412 STATIC void
413 xfs_set_maxicount(xfs_mount_t *mp)
414 {
415 	xfs_sb_t	*sbp = &(mp->m_sb);
416 	__uint64_t	icount;
417 
418 	if (sbp->sb_imax_pct) {
419 		/*
420 		 * Make sure the maximum inode count is a multiple
421 		 * of the units we allocate inodes in.
422 		 */
423 		icount = sbp->sb_dblocks * sbp->sb_imax_pct;
424 		do_div(icount, 100);
425 		do_div(icount, mp->m_ialloc_blks);
426 		mp->m_maxicount = (icount * mp->m_ialloc_blks)  <<
427 				   sbp->sb_inopblog;
428 	} else {
429 		mp->m_maxicount = 0;
430 	}
431 }
432 
433 /*
434  * Set the default minimum read and write sizes unless
435  * already specified in a mount option.
436  * We use smaller I/O sizes when the file system
437  * is being used for NFS service (wsync mount option).
438  */
439 STATIC void
440 xfs_set_rw_sizes(xfs_mount_t *mp)
441 {
442 	xfs_sb_t	*sbp = &(mp->m_sb);
443 	int		readio_log, writeio_log;
444 
445 	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
446 		if (mp->m_flags & XFS_MOUNT_WSYNC) {
447 			readio_log = XFS_WSYNC_READIO_LOG;
448 			writeio_log = XFS_WSYNC_WRITEIO_LOG;
449 		} else {
450 			readio_log = XFS_READIO_LOG_LARGE;
451 			writeio_log = XFS_WRITEIO_LOG_LARGE;
452 		}
453 	} else {
454 		readio_log = mp->m_readio_log;
455 		writeio_log = mp->m_writeio_log;
456 	}
457 
458 	if (sbp->sb_blocklog > readio_log) {
459 		mp->m_readio_log = sbp->sb_blocklog;
460 	} else {
461 		mp->m_readio_log = readio_log;
462 	}
463 	mp->m_readio_blocks = 1 << (mp->m_readio_log - sbp->sb_blocklog);
464 	if (sbp->sb_blocklog > writeio_log) {
465 		mp->m_writeio_log = sbp->sb_blocklog;
466 	} else {
467 		mp->m_writeio_log = writeio_log;
468 	}
469 	mp->m_writeio_blocks = 1 << (mp->m_writeio_log - sbp->sb_blocklog);
470 }
471 
472 /*
473  * precalculate the low space thresholds for dynamic speculative preallocation.
474  */
475 void
476 xfs_set_low_space_thresholds(
477 	struct xfs_mount	*mp)
478 {
479 	int i;
480 
481 	for (i = 0; i < XFS_LOWSP_MAX; i++) {
482 		__uint64_t space = mp->m_sb.sb_dblocks;
483 
484 		do_div(space, 100);
485 		mp->m_low_space[i] = space * (i + 1);
486 	}
487 }
488 
489 
490 /*
491  * Set whether we're using inode alignment.
492  */
493 STATIC void
494 xfs_set_inoalignment(xfs_mount_t *mp)
495 {
496 	if (xfs_sb_version_hasalign(&mp->m_sb) &&
497 	    mp->m_sb.sb_inoalignmt >=
498 	    XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size))
499 		mp->m_inoalign_mask = mp->m_sb.sb_inoalignmt - 1;
500 	else
501 		mp->m_inoalign_mask = 0;
502 	/*
503 	 * If we are using stripe alignment, check whether
504 	 * the stripe unit is a multiple of the inode alignment
505 	 */
506 	if (mp->m_dalign && mp->m_inoalign_mask &&
507 	    !(mp->m_dalign & mp->m_inoalign_mask))
508 		mp->m_sinoalign = mp->m_dalign;
509 	else
510 		mp->m_sinoalign = 0;
511 }
512 
513 /*
514  * Check that the data (and log if separate) is an ok size.
515  */
516 STATIC int
517 xfs_check_sizes(
518 	struct xfs_mount *mp)
519 {
520 	struct xfs_buf	*bp;
521 	xfs_daddr_t	d;
522 	int		error;
523 
524 	d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
525 	if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {
526 		xfs_warn(mp, "filesystem size mismatch detected");
527 		return -EFBIG;
528 	}
529 	error = xfs_buf_read_uncached(mp->m_ddev_targp,
530 					d - XFS_FSS_TO_BB(mp, 1),
531 					XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
532 	if (error) {
533 		xfs_warn(mp, "last sector read failed");
534 		return error;
535 	}
536 	xfs_buf_relse(bp);
537 
538 	if (mp->m_logdev_targp == mp->m_ddev_targp)
539 		return 0;
540 
541 	d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
542 	if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {
543 		xfs_warn(mp, "log size mismatch detected");
544 		return -EFBIG;
545 	}
546 	error = xfs_buf_read_uncached(mp->m_logdev_targp,
547 					d - XFS_FSB_TO_BB(mp, 1),
548 					XFS_FSB_TO_BB(mp, 1), 0, &bp, NULL);
549 	if (error) {
550 		xfs_warn(mp, "log device read failed");
551 		return error;
552 	}
553 	xfs_buf_relse(bp);
554 	return 0;
555 }
556 
557 /*
558  * Clear the quotaflags in memory and in the superblock.
559  */
560 int
561 xfs_mount_reset_sbqflags(
562 	struct xfs_mount	*mp)
563 {
564 	mp->m_qflags = 0;
565 
566 	/* It is OK to look at sb_qflags in the mount path without m_sb_lock. */
567 	if (mp->m_sb.sb_qflags == 0)
568 		return 0;
569 	spin_lock(&mp->m_sb_lock);
570 	mp->m_sb.sb_qflags = 0;
571 	spin_unlock(&mp->m_sb_lock);
572 
573 	if (!xfs_fs_writable(mp, SB_FREEZE_WRITE))
574 		return 0;
575 
576 	return xfs_sync_sb(mp, false);
577 }
578 
579 __uint64_t
580 xfs_default_resblks(xfs_mount_t *mp)
581 {
582 	__uint64_t resblks;
583 
584 	/*
585 	 * We default to 5% or 8192 fsbs of space reserved, whichever is
586 	 * smaller.  This is intended to cover concurrent allocation
587 	 * transactions when we initially hit enospc. These each require a 4
588 	 * block reservation. Hence by default we cover roughly 2000 concurrent
589 	 * allocation reservations.
590 	 */
591 	resblks = mp->m_sb.sb_dblocks;
592 	do_div(resblks, 20);
593 	resblks = min_t(__uint64_t, resblks, 8192);
594 	return resblks;
595 }
596 
597 /*
598  * This function does the following on an initial mount of a file system:
599  *	- reads the superblock from disk and init the mount struct
600  *	- if we're a 32-bit kernel, do a size check on the superblock
601  *		so we don't mount terabyte filesystems
602  *	- init mount struct realtime fields
603  *	- allocate inode hash table for fs
604  *	- init directory manager
605  *	- perform recovery and init the log manager
606  */
607 int
608 xfs_mountfs(
609 	struct xfs_mount	*mp)
610 {
611 	struct xfs_sb		*sbp = &(mp->m_sb);
612 	struct xfs_inode	*rip;
613 	__uint64_t		resblks;
614 	uint			quotamount = 0;
615 	uint			quotaflags = 0;
616 	int			error = 0;
617 
618 	xfs_sb_mount_common(mp, sbp);
619 
620 	/*
621 	 * Check for a mismatched features2 values.  Older kernels read & wrote
622 	 * into the wrong sb offset for sb_features2 on some platforms due to
623 	 * xfs_sb_t not being 64bit size aligned when sb_features2 was added,
624 	 * which made older superblock reading/writing routines swap it as a
625 	 * 64-bit value.
626 	 *
627 	 * For backwards compatibility, we make both slots equal.
628 	 *
629 	 * If we detect a mismatched field, we OR the set bits into the existing
630 	 * features2 field in case it has already been modified; we don't want
631 	 * to lose any features.  We then update the bad location with the ORed
632 	 * value so that older kernels will see any features2 flags. The
633 	 * superblock writeback code ensures the new sb_features2 is copied to
634 	 * sb_bad_features2 before it is logged or written to disk.
635 	 */
636 	if (xfs_sb_has_mismatched_features2(sbp)) {
637 		xfs_warn(mp, "correcting sb_features alignment problem");
638 		sbp->sb_features2 |= sbp->sb_bad_features2;
639 		mp->m_update_sb = true;
640 
641 		/*
642 		 * Re-check for ATTR2 in case it was found in bad_features2
643 		 * slot.
644 		 */
645 		if (xfs_sb_version_hasattr2(&mp->m_sb) &&
646 		   !(mp->m_flags & XFS_MOUNT_NOATTR2))
647 			mp->m_flags |= XFS_MOUNT_ATTR2;
648 	}
649 
650 	if (xfs_sb_version_hasattr2(&mp->m_sb) &&
651 	   (mp->m_flags & XFS_MOUNT_NOATTR2)) {
652 		xfs_sb_version_removeattr2(&mp->m_sb);
653 		mp->m_update_sb = true;
654 
655 		/* update sb_versionnum for the clearing of the morebits */
656 		if (!sbp->sb_features2)
657 			mp->m_update_sb = true;
658 	}
659 
660 	/* always use v2 inodes by default now */
661 	if (!(mp->m_sb.sb_versionnum & XFS_SB_VERSION_NLINKBIT)) {
662 		mp->m_sb.sb_versionnum |= XFS_SB_VERSION_NLINKBIT;
663 		mp->m_update_sb = true;
664 	}
665 
666 	/*
667 	 * Check if sb_agblocks is aligned at stripe boundary
668 	 * If sb_agblocks is NOT aligned turn off m_dalign since
669 	 * allocator alignment is within an ag, therefore ag has
670 	 * to be aligned at stripe boundary.
671 	 */
672 	error = xfs_update_alignment(mp);
673 	if (error)
674 		goto out;
675 
676 	xfs_alloc_compute_maxlevels(mp);
677 	xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
678 	xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
679 	xfs_ialloc_compute_maxlevels(mp);
680 
681 	xfs_set_maxicount(mp);
682 
683 	/* enable fail_at_unmount as default */
684 	mp->m_fail_unmount = 1;
685 
686 	error = xfs_sysfs_init(&mp->m_kobj, &xfs_mp_ktype, NULL, mp->m_fsname);
687 	if (error)
688 		goto out;
689 
690 	error = xfs_sysfs_init(&mp->m_stats.xs_kobj, &xfs_stats_ktype,
691 			       &mp->m_kobj, "stats");
692 	if (error)
693 		goto out_remove_sysfs;
694 
695 	error = xfs_error_sysfs_init(mp);
696 	if (error)
697 		goto out_del_stats;
698 
699 
700 	error = xfs_uuid_mount(mp);
701 	if (error)
702 		goto out_remove_error_sysfs;
703 
704 	/*
705 	 * Set the minimum read and write sizes
706 	 */
707 	xfs_set_rw_sizes(mp);
708 
709 	/* set the low space thresholds for dynamic preallocation */
710 	xfs_set_low_space_thresholds(mp);
711 
712 	/*
713 	 * Set the inode cluster size.
714 	 * This may still be overridden by the file system
715 	 * block size if it is larger than the chosen cluster size.
716 	 *
717 	 * For v5 filesystems, scale the cluster size with the inode size to
718 	 * keep a constant ratio of inode per cluster buffer, but only if mkfs
719 	 * has set the inode alignment value appropriately for larger cluster
720 	 * sizes.
721 	 */
722 	mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
723 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
724 		int	new_size = mp->m_inode_cluster_size;
725 
726 		new_size *= mp->m_sb.sb_inodesize / XFS_DINODE_MIN_SIZE;
727 		if (mp->m_sb.sb_inoalignmt >= XFS_B_TO_FSBT(mp, new_size))
728 			mp->m_inode_cluster_size = new_size;
729 	}
730 
731 	/*
732 	 * If enabled, sparse inode chunk alignment is expected to match the
733 	 * cluster size. Full inode chunk alignment must match the chunk size,
734 	 * but that is checked on sb read verification...
735 	 */
736 	if (xfs_sb_version_hassparseinodes(&mp->m_sb) &&
737 	    mp->m_sb.sb_spino_align !=
738 			XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size)) {
739 		xfs_warn(mp,
740 	"Sparse inode block alignment (%u) must match cluster size (%llu).",
741 			 mp->m_sb.sb_spino_align,
742 			 XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size));
743 		error = -EINVAL;
744 		goto out_remove_uuid;
745 	}
746 
747 	/*
748 	 * Set inode alignment fields
749 	 */
750 	xfs_set_inoalignment(mp);
751 
752 	/*
753 	 * Check that the data (and log if separate) is an ok size.
754 	 */
755 	error = xfs_check_sizes(mp);
756 	if (error)
757 		goto out_remove_uuid;
758 
759 	/*
760 	 * Initialize realtime fields in the mount structure
761 	 */
762 	error = xfs_rtmount_init(mp);
763 	if (error) {
764 		xfs_warn(mp, "RT mount failed");
765 		goto out_remove_uuid;
766 	}
767 
768 	/*
769 	 *  Copies the low order bits of the timestamp and the randomly
770 	 *  set "sequence" number out of a UUID.
771 	 */
772 	uuid_getnodeuniq(&sbp->sb_uuid, mp->m_fixedfsid);
773 
774 	mp->m_dmevmask = 0;	/* not persistent; set after each mount */
775 
776 	error = xfs_da_mount(mp);
777 	if (error) {
778 		xfs_warn(mp, "Failed dir/attr init: %d", error);
779 		goto out_remove_uuid;
780 	}
781 
782 	/*
783 	 * Initialize the precomputed transaction reservations values.
784 	 */
785 	xfs_trans_init(mp);
786 
787 	/*
788 	 * Allocate and initialize the per-ag data.
789 	 */
790 	spin_lock_init(&mp->m_perag_lock);
791 	INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
792 	error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
793 	if (error) {
794 		xfs_warn(mp, "Failed per-ag init: %d", error);
795 		goto out_free_dir;
796 	}
797 
798 	if (!sbp->sb_logblocks) {
799 		xfs_warn(mp, "no log defined");
800 		XFS_ERROR_REPORT("xfs_mountfs", XFS_ERRLEVEL_LOW, mp);
801 		error = -EFSCORRUPTED;
802 		goto out_free_perag;
803 	}
804 
805 	/*
806 	 * Log's mount-time initialization. The first part of recovery can place
807 	 * some items on the AIL, to be handled when recovery is finished or
808 	 * cancelled.
809 	 */
810 	error = xfs_log_mount(mp, mp->m_logdev_targp,
811 			      XFS_FSB_TO_DADDR(mp, sbp->sb_logstart),
812 			      XFS_FSB_TO_BB(mp, sbp->sb_logblocks));
813 	if (error) {
814 		xfs_warn(mp, "log mount failed");
815 		goto out_fail_wait;
816 	}
817 
818 	/*
819 	 * Now the log is mounted, we know if it was an unclean shutdown or
820 	 * not. If it was, with the first phase of recovery has completed, we
821 	 * have consistent AG blocks on disk. We have not recovered EFIs yet,
822 	 * but they are recovered transactionally in the second recovery phase
823 	 * later.
824 	 *
825 	 * Hence we can safely re-initialise incore superblock counters from
826 	 * the per-ag data. These may not be correct if the filesystem was not
827 	 * cleanly unmounted, so we need to wait for recovery to finish before
828 	 * doing this.
829 	 *
830 	 * If the filesystem was cleanly unmounted, then we can trust the
831 	 * values in the superblock to be correct and we don't need to do
832 	 * anything here.
833 	 *
834 	 * If we are currently making the filesystem, the initialisation will
835 	 * fail as the perag data is in an undefined state.
836 	 */
837 	if (xfs_sb_version_haslazysbcount(&mp->m_sb) &&
838 	    !XFS_LAST_UNMOUNT_WAS_CLEAN(mp) &&
839 	     !mp->m_sb.sb_inprogress) {
840 		error = xfs_initialize_perag_data(mp, sbp->sb_agcount);
841 		if (error)
842 			goto out_log_dealloc;
843 	}
844 
845 	/*
846 	 * Get and sanity-check the root inode.
847 	 * Save the pointer to it in the mount structure.
848 	 */
849 	error = xfs_iget(mp, NULL, sbp->sb_rootino, 0, XFS_ILOCK_EXCL, &rip);
850 	if (error) {
851 		xfs_warn(mp, "failed to read root inode");
852 		goto out_log_dealloc;
853 	}
854 
855 	ASSERT(rip != NULL);
856 
857 	if (unlikely(!S_ISDIR(VFS_I(rip)->i_mode))) {
858 		xfs_warn(mp, "corrupted root inode %llu: not a directory",
859 			(unsigned long long)rip->i_ino);
860 		xfs_iunlock(rip, XFS_ILOCK_EXCL);
861 		XFS_ERROR_REPORT("xfs_mountfs_int(2)", XFS_ERRLEVEL_LOW,
862 				 mp);
863 		error = -EFSCORRUPTED;
864 		goto out_rele_rip;
865 	}
866 	mp->m_rootip = rip;	/* save it */
867 
868 	xfs_iunlock(rip, XFS_ILOCK_EXCL);
869 
870 	/*
871 	 * Initialize realtime inode pointers in the mount structure
872 	 */
873 	error = xfs_rtmount_inodes(mp);
874 	if (error) {
875 		/*
876 		 * Free up the root inode.
877 		 */
878 		xfs_warn(mp, "failed to read RT inodes");
879 		goto out_rele_rip;
880 	}
881 
882 	/*
883 	 * If this is a read-only mount defer the superblock updates until
884 	 * the next remount into writeable mode.  Otherwise we would never
885 	 * perform the update e.g. for the root filesystem.
886 	 */
887 	if (mp->m_update_sb && !(mp->m_flags & XFS_MOUNT_RDONLY)) {
888 		error = xfs_sync_sb(mp, false);
889 		if (error) {
890 			xfs_warn(mp, "failed to write sb changes");
891 			goto out_rtunmount;
892 		}
893 	}
894 
895 	/*
896 	 * Initialise the XFS quota management subsystem for this mount
897 	 */
898 	if (XFS_IS_QUOTA_RUNNING(mp)) {
899 		error = xfs_qm_newmount(mp, &quotamount, &quotaflags);
900 		if (error)
901 			goto out_rtunmount;
902 	} else {
903 		ASSERT(!XFS_IS_QUOTA_ON(mp));
904 
905 		/*
906 		 * If a file system had quotas running earlier, but decided to
907 		 * mount without -o uquota/pquota/gquota options, revoke the
908 		 * quotachecked license.
909 		 */
910 		if (mp->m_sb.sb_qflags & XFS_ALL_QUOTA_ACCT) {
911 			xfs_notice(mp, "resetting quota flags");
912 			error = xfs_mount_reset_sbqflags(mp);
913 			if (error)
914 				goto out_rtunmount;
915 		}
916 	}
917 
918 	/*
919 	 * Finish recovering the file system.  This part needed to be delayed
920 	 * until after the root and real-time bitmap inodes were consistently
921 	 * read in.
922 	 */
923 	error = xfs_log_mount_finish(mp);
924 	if (error) {
925 		xfs_warn(mp, "log mount finish failed");
926 		goto out_rtunmount;
927 	}
928 
929 	/*
930 	 * Complete the quota initialisation, post-log-replay component.
931 	 */
932 	if (quotamount) {
933 		ASSERT(mp->m_qflags == 0);
934 		mp->m_qflags = quotaflags;
935 
936 		xfs_qm_mount_quotas(mp);
937 	}
938 
939 	/*
940 	 * Now we are mounted, reserve a small amount of unused space for
941 	 * privileged transactions. This is needed so that transaction
942 	 * space required for critical operations can dip into this pool
943 	 * when at ENOSPC. This is needed for operations like create with
944 	 * attr, unwritten extent conversion at ENOSPC, etc. Data allocations
945 	 * are not allowed to use this reserved space.
946 	 *
947 	 * This may drive us straight to ENOSPC on mount, but that implies
948 	 * we were already there on the last unmount. Warn if this occurs.
949 	 */
950 	if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
951 		resblks = xfs_default_resblks(mp);
952 		error = xfs_reserve_blocks(mp, &resblks, NULL);
953 		if (error)
954 			xfs_warn(mp,
955 	"Unable to allocate reserve blocks. Continuing without reserve pool.");
956 	}
957 
958 	return 0;
959 
960  out_rtunmount:
961 	xfs_rtunmount_inodes(mp);
962  out_rele_rip:
963 	IRELE(rip);
964 	cancel_delayed_work_sync(&mp->m_reclaim_work);
965 	xfs_reclaim_inodes(mp, SYNC_WAIT);
966  out_log_dealloc:
967 	mp->m_flags |= XFS_MOUNT_UNMOUNTING;
968 	xfs_log_mount_cancel(mp);
969  out_fail_wait:
970 	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
971 		xfs_wait_buftarg(mp->m_logdev_targp);
972 	xfs_wait_buftarg(mp->m_ddev_targp);
973  out_free_perag:
974 	xfs_free_perag(mp);
975  out_free_dir:
976 	xfs_da_unmount(mp);
977  out_remove_uuid:
978 	xfs_uuid_unmount(mp);
979  out_remove_error_sysfs:
980 	xfs_error_sysfs_del(mp);
981  out_del_stats:
982 	xfs_sysfs_del(&mp->m_stats.xs_kobj);
983  out_remove_sysfs:
984 	xfs_sysfs_del(&mp->m_kobj);
985  out:
986 	return error;
987 }
988 
989 /*
990  * This flushes out the inodes,dquots and the superblock, unmounts the
991  * log and makes sure that incore structures are freed.
992  */
993 void
994 xfs_unmountfs(
995 	struct xfs_mount	*mp)
996 {
997 	__uint64_t		resblks;
998 	int			error;
999 
1000 	cancel_delayed_work_sync(&mp->m_eofblocks_work);
1001 
1002 	xfs_qm_unmount_quotas(mp);
1003 	xfs_rtunmount_inodes(mp);
1004 	IRELE(mp->m_rootip);
1005 
1006 	/*
1007 	 * We can potentially deadlock here if we have an inode cluster
1008 	 * that has been freed has its buffer still pinned in memory because
1009 	 * the transaction is still sitting in a iclog. The stale inodes
1010 	 * on that buffer will have their flush locks held until the
1011 	 * transaction hits the disk and the callbacks run. the inode
1012 	 * flush takes the flush lock unconditionally and with nothing to
1013 	 * push out the iclog we will never get that unlocked. hence we
1014 	 * need to force the log first.
1015 	 */
1016 	xfs_log_force(mp, XFS_LOG_SYNC);
1017 
1018 	/*
1019 	 * We now need to tell the world we are unmounting. This will allow
1020 	 * us to detect that the filesystem is going away and we should error
1021 	 * out anything that we have been retrying in the background. This will
1022 	 * prevent neverending retries in AIL pushing from hanging the unmount.
1023 	 */
1024 	mp->m_flags |= XFS_MOUNT_UNMOUNTING;
1025 
1026 	/*
1027 	 * Flush all pending changes from the AIL.
1028 	 */
1029 	xfs_ail_push_all_sync(mp->m_ail);
1030 
1031 	/*
1032 	 * And reclaim all inodes.  At this point there should be no dirty
1033 	 * inodes and none should be pinned or locked, but use synchronous
1034 	 * reclaim just to be sure. We can stop background inode reclaim
1035 	 * here as well if it is still running.
1036 	 */
1037 	cancel_delayed_work_sync(&mp->m_reclaim_work);
1038 	xfs_reclaim_inodes(mp, SYNC_WAIT);
1039 
1040 	xfs_qm_unmount(mp);
1041 
1042 	/*
1043 	 * Unreserve any blocks we have so that when we unmount we don't account
1044 	 * the reserved free space as used. This is really only necessary for
1045 	 * lazy superblock counting because it trusts the incore superblock
1046 	 * counters to be absolutely correct on clean unmount.
1047 	 *
1048 	 * We don't bother correcting this elsewhere for lazy superblock
1049 	 * counting because on mount of an unclean filesystem we reconstruct the
1050 	 * correct counter value and this is irrelevant.
1051 	 *
1052 	 * For non-lazy counter filesystems, this doesn't matter at all because
1053 	 * we only every apply deltas to the superblock and hence the incore
1054 	 * value does not matter....
1055 	 */
1056 	resblks = 0;
1057 	error = xfs_reserve_blocks(mp, &resblks, NULL);
1058 	if (error)
1059 		xfs_warn(mp, "Unable to free reserved block pool. "
1060 				"Freespace may not be correct on next mount.");
1061 
1062 	error = xfs_log_sbcount(mp);
1063 	if (error)
1064 		xfs_warn(mp, "Unable to update superblock counters. "
1065 				"Freespace may not be correct on next mount.");
1066 
1067 
1068 	xfs_log_unmount(mp);
1069 	xfs_da_unmount(mp);
1070 	xfs_uuid_unmount(mp);
1071 
1072 #if defined(DEBUG)
1073 	xfs_errortag_clearall(mp, 0);
1074 #endif
1075 	xfs_free_perag(mp);
1076 
1077 	xfs_error_sysfs_del(mp);
1078 	xfs_sysfs_del(&mp->m_stats.xs_kobj);
1079 	xfs_sysfs_del(&mp->m_kobj);
1080 }
1081 
1082 /*
1083  * Determine whether modifications can proceed. The caller specifies the minimum
1084  * freeze level for which modifications should not be allowed. This allows
1085  * certain operations to proceed while the freeze sequence is in progress, if
1086  * necessary.
1087  */
1088 bool
1089 xfs_fs_writable(
1090 	struct xfs_mount	*mp,
1091 	int			level)
1092 {
1093 	ASSERT(level > SB_UNFROZEN);
1094 	if ((mp->m_super->s_writers.frozen >= level) ||
1095 	    XFS_FORCED_SHUTDOWN(mp) || (mp->m_flags & XFS_MOUNT_RDONLY))
1096 		return false;
1097 
1098 	return true;
1099 }
1100 
1101 /*
1102  * xfs_log_sbcount
1103  *
1104  * Sync the superblock counters to disk.
1105  *
1106  * Note this code can be called during the process of freezing, so we use the
1107  * transaction allocator that does not block when the transaction subsystem is
1108  * in its frozen state.
1109  */
1110 int
1111 xfs_log_sbcount(xfs_mount_t *mp)
1112 {
1113 	/* allow this to proceed during the freeze sequence... */
1114 	if (!xfs_fs_writable(mp, SB_FREEZE_COMPLETE))
1115 		return 0;
1116 
1117 	/*
1118 	 * we don't need to do this if we are updating the superblock
1119 	 * counters on every modification.
1120 	 */
1121 	if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
1122 		return 0;
1123 
1124 	return xfs_sync_sb(mp, true);
1125 }
1126 
1127 /*
1128  * Deltas for the inode count are +/-64, hence we use a large batch size
1129  * of 128 so we don't need to take the counter lock on every update.
1130  */
1131 #define XFS_ICOUNT_BATCH	128
1132 int
1133 xfs_mod_icount(
1134 	struct xfs_mount	*mp,
1135 	int64_t			delta)
1136 {
1137 	__percpu_counter_add(&mp->m_icount, delta, XFS_ICOUNT_BATCH);
1138 	if (__percpu_counter_compare(&mp->m_icount, 0, XFS_ICOUNT_BATCH) < 0) {
1139 		ASSERT(0);
1140 		percpu_counter_add(&mp->m_icount, -delta);
1141 		return -EINVAL;
1142 	}
1143 	return 0;
1144 }
1145 
1146 int
1147 xfs_mod_ifree(
1148 	struct xfs_mount	*mp,
1149 	int64_t			delta)
1150 {
1151 	percpu_counter_add(&mp->m_ifree, delta);
1152 	if (percpu_counter_compare(&mp->m_ifree, 0) < 0) {
1153 		ASSERT(0);
1154 		percpu_counter_add(&mp->m_ifree, -delta);
1155 		return -EINVAL;
1156 	}
1157 	return 0;
1158 }
1159 
1160 /*
1161  * Deltas for the block count can vary from 1 to very large, but lock contention
1162  * only occurs on frequent small block count updates such as in the delayed
1163  * allocation path for buffered writes (page a time updates). Hence we set
1164  * a large batch count (1024) to minimise global counter updates except when
1165  * we get near to ENOSPC and we have to be very accurate with our updates.
1166  */
1167 #define XFS_FDBLOCKS_BATCH	1024
1168 int
1169 xfs_mod_fdblocks(
1170 	struct xfs_mount	*mp,
1171 	int64_t			delta,
1172 	bool			rsvd)
1173 {
1174 	int64_t			lcounter;
1175 	long long		res_used;
1176 	s32			batch;
1177 
1178 	if (delta > 0) {
1179 		/*
1180 		 * If the reserve pool is depleted, put blocks back into it
1181 		 * first. Most of the time the pool is full.
1182 		 */
1183 		if (likely(mp->m_resblks == mp->m_resblks_avail)) {
1184 			percpu_counter_add(&mp->m_fdblocks, delta);
1185 			return 0;
1186 		}
1187 
1188 		spin_lock(&mp->m_sb_lock);
1189 		res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
1190 
1191 		if (res_used > delta) {
1192 			mp->m_resblks_avail += delta;
1193 		} else {
1194 			delta -= res_used;
1195 			mp->m_resblks_avail = mp->m_resblks;
1196 			percpu_counter_add(&mp->m_fdblocks, delta);
1197 		}
1198 		spin_unlock(&mp->m_sb_lock);
1199 		return 0;
1200 	}
1201 
1202 	/*
1203 	 * Taking blocks away, need to be more accurate the closer we
1204 	 * are to zero.
1205 	 *
1206 	 * If the counter has a value of less than 2 * max batch size,
1207 	 * then make everything serialise as we are real close to
1208 	 * ENOSPC.
1209 	 */
1210 	if (__percpu_counter_compare(&mp->m_fdblocks, 2 * XFS_FDBLOCKS_BATCH,
1211 				     XFS_FDBLOCKS_BATCH) < 0)
1212 		batch = 1;
1213 	else
1214 		batch = XFS_FDBLOCKS_BATCH;
1215 
1216 	__percpu_counter_add(&mp->m_fdblocks, delta, batch);
1217 	if (__percpu_counter_compare(&mp->m_fdblocks, XFS_ALLOC_SET_ASIDE(mp),
1218 				     XFS_FDBLOCKS_BATCH) >= 0) {
1219 		/* we had space! */
1220 		return 0;
1221 	}
1222 
1223 	/*
1224 	 * lock up the sb for dipping into reserves before releasing the space
1225 	 * that took us to ENOSPC.
1226 	 */
1227 	spin_lock(&mp->m_sb_lock);
1228 	percpu_counter_add(&mp->m_fdblocks, -delta);
1229 	if (!rsvd)
1230 		goto fdblocks_enospc;
1231 
1232 	lcounter = (long long)mp->m_resblks_avail + delta;
1233 	if (lcounter >= 0) {
1234 		mp->m_resblks_avail = lcounter;
1235 		spin_unlock(&mp->m_sb_lock);
1236 		return 0;
1237 	}
1238 	printk_once(KERN_WARNING
1239 		"Filesystem \"%s\": reserve blocks depleted! "
1240 		"Consider increasing reserve pool size.",
1241 		mp->m_fsname);
1242 fdblocks_enospc:
1243 	spin_unlock(&mp->m_sb_lock);
1244 	return -ENOSPC;
1245 }
1246 
1247 int
1248 xfs_mod_frextents(
1249 	struct xfs_mount	*mp,
1250 	int64_t			delta)
1251 {
1252 	int64_t			lcounter;
1253 	int			ret = 0;
1254 
1255 	spin_lock(&mp->m_sb_lock);
1256 	lcounter = mp->m_sb.sb_frextents + delta;
1257 	if (lcounter < 0)
1258 		ret = -ENOSPC;
1259 	else
1260 		mp->m_sb.sb_frextents = lcounter;
1261 	spin_unlock(&mp->m_sb_lock);
1262 	return ret;
1263 }
1264 
1265 /*
1266  * xfs_getsb() is called to obtain the buffer for the superblock.
1267  * The buffer is returned locked and read in from disk.
1268  * The buffer should be released with a call to xfs_brelse().
1269  *
1270  * If the flags parameter is BUF_TRYLOCK, then we'll only return
1271  * the superblock buffer if it can be locked without sleeping.
1272  * If it can't then we'll return NULL.
1273  */
1274 struct xfs_buf *
1275 xfs_getsb(
1276 	struct xfs_mount	*mp,
1277 	int			flags)
1278 {
1279 	struct xfs_buf		*bp = mp->m_sb_bp;
1280 
1281 	if (!xfs_buf_trylock(bp)) {
1282 		if (flags & XBF_TRYLOCK)
1283 			return NULL;
1284 		xfs_buf_lock(bp);
1285 	}
1286 
1287 	xfs_buf_hold(bp);
1288 	ASSERT(bp->b_flags & XBF_DONE);
1289 	return bp;
1290 }
1291 
1292 /*
1293  * Used to free the superblock along various error paths.
1294  */
1295 void
1296 xfs_freesb(
1297 	struct xfs_mount	*mp)
1298 {
1299 	struct xfs_buf		*bp = mp->m_sb_bp;
1300 
1301 	xfs_buf_lock(bp);
1302 	mp->m_sb_bp = NULL;
1303 	xfs_buf_relse(bp);
1304 }
1305 
1306 /*
1307  * If the underlying (data/log/rt) device is readonly, there are some
1308  * operations that cannot proceed.
1309  */
1310 int
1311 xfs_dev_is_read_only(
1312 	struct xfs_mount	*mp,
1313 	char			*message)
1314 {
1315 	if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
1316 	    xfs_readonly_buftarg(mp->m_logdev_targp) ||
1317 	    (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
1318 		xfs_notice(mp, "%s required on read-only device.", message);
1319 		xfs_notice(mp, "write access unavailable, cannot proceed.");
1320 		return -EROFS;
1321 	}
1322 	return 0;
1323 }
1324