xref: /openbmc/linux/fs/xfs/xfs_mount.c (revision c21b37f6)
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_log.h"
23 #include "xfs_inum.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_btree.h"
38 #include "xfs_ialloc.h"
39 #include "xfs_alloc.h"
40 #include "xfs_rtalloc.h"
41 #include "xfs_bmap.h"
42 #include "xfs_error.h"
43 #include "xfs_rw.h"
44 #include "xfs_quota.h"
45 #include "xfs_fsops.h"
46 
47 STATIC void	xfs_mount_log_sbunit(xfs_mount_t *, __int64_t);
48 STATIC int	xfs_uuid_mount(xfs_mount_t *);
49 STATIC void	xfs_uuid_unmount(xfs_mount_t *mp);
50 STATIC void	xfs_unmountfs_wait(xfs_mount_t *);
51 
52 
53 #ifdef HAVE_PERCPU_SB
54 STATIC void	xfs_icsb_destroy_counters(xfs_mount_t *);
55 STATIC void	xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t,
56 						int, int);
57 STATIC void	xfs_icsb_sync_counters(xfs_mount_t *);
58 STATIC int	xfs_icsb_modify_counters(xfs_mount_t *, xfs_sb_field_t,
59 						int64_t, int);
60 STATIC int	xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);
61 
62 #else
63 
64 #define xfs_icsb_destroy_counters(mp)			do { } while (0)
65 #define xfs_icsb_balance_counter(mp, a, b, c)		do { } while (0)
66 #define xfs_icsb_sync_counters(mp)			do { } while (0)
67 #define xfs_icsb_modify_counters(mp, a, b, c)		do { } while (0)
68 
69 #endif
70 
71 static const struct {
72 	short offset;
73 	short type;	/* 0 = integer
74 			 * 1 = binary / string (no translation)
75 			 */
76 } xfs_sb_info[] = {
77     { offsetof(xfs_sb_t, sb_magicnum),   0 },
78     { offsetof(xfs_sb_t, sb_blocksize),  0 },
79     { offsetof(xfs_sb_t, sb_dblocks),    0 },
80     { offsetof(xfs_sb_t, sb_rblocks),    0 },
81     { offsetof(xfs_sb_t, sb_rextents),   0 },
82     { offsetof(xfs_sb_t, sb_uuid),       1 },
83     { offsetof(xfs_sb_t, sb_logstart),   0 },
84     { offsetof(xfs_sb_t, sb_rootino),    0 },
85     { offsetof(xfs_sb_t, sb_rbmino),     0 },
86     { offsetof(xfs_sb_t, sb_rsumino),    0 },
87     { offsetof(xfs_sb_t, sb_rextsize),   0 },
88     { offsetof(xfs_sb_t, sb_agblocks),   0 },
89     { offsetof(xfs_sb_t, sb_agcount),    0 },
90     { offsetof(xfs_sb_t, sb_rbmblocks),  0 },
91     { offsetof(xfs_sb_t, sb_logblocks),  0 },
92     { offsetof(xfs_sb_t, sb_versionnum), 0 },
93     { offsetof(xfs_sb_t, sb_sectsize),   0 },
94     { offsetof(xfs_sb_t, sb_inodesize),  0 },
95     { offsetof(xfs_sb_t, sb_inopblock),  0 },
96     { offsetof(xfs_sb_t, sb_fname[0]),   1 },
97     { offsetof(xfs_sb_t, sb_blocklog),   0 },
98     { offsetof(xfs_sb_t, sb_sectlog),    0 },
99     { offsetof(xfs_sb_t, sb_inodelog),   0 },
100     { offsetof(xfs_sb_t, sb_inopblog),   0 },
101     { offsetof(xfs_sb_t, sb_agblklog),   0 },
102     { offsetof(xfs_sb_t, sb_rextslog),   0 },
103     { offsetof(xfs_sb_t, sb_inprogress), 0 },
104     { offsetof(xfs_sb_t, sb_imax_pct),   0 },
105     { offsetof(xfs_sb_t, sb_icount),     0 },
106     { offsetof(xfs_sb_t, sb_ifree),      0 },
107     { offsetof(xfs_sb_t, sb_fdblocks),   0 },
108     { offsetof(xfs_sb_t, sb_frextents),  0 },
109     { offsetof(xfs_sb_t, sb_uquotino),   0 },
110     { offsetof(xfs_sb_t, sb_gquotino),   0 },
111     { offsetof(xfs_sb_t, sb_qflags),     0 },
112     { offsetof(xfs_sb_t, sb_flags),      0 },
113     { offsetof(xfs_sb_t, sb_shared_vn),  0 },
114     { offsetof(xfs_sb_t, sb_inoalignmt), 0 },
115     { offsetof(xfs_sb_t, sb_unit),	 0 },
116     { offsetof(xfs_sb_t, sb_width),	 0 },
117     { offsetof(xfs_sb_t, sb_dirblklog),	 0 },
118     { offsetof(xfs_sb_t, sb_logsectlog), 0 },
119     { offsetof(xfs_sb_t, sb_logsectsize),0 },
120     { offsetof(xfs_sb_t, sb_logsunit),	 0 },
121     { offsetof(xfs_sb_t, sb_features2),	 0 },
122     { sizeof(xfs_sb_t),			 0 }
123 };
124 
125 /*
126  * Return a pointer to an initialized xfs_mount structure.
127  */
128 xfs_mount_t *
129 xfs_mount_init(void)
130 {
131 	xfs_mount_t *mp;
132 
133 	mp = kmem_zalloc(sizeof(xfs_mount_t), KM_SLEEP);
134 
135 	if (xfs_icsb_init_counters(mp)) {
136 		mp->m_flags |= XFS_MOUNT_NO_PERCPU_SB;
137 	}
138 
139 	AIL_LOCKINIT(&mp->m_ail_lock, "xfs_ail");
140 	spinlock_init(&mp->m_sb_lock, "xfs_sb");
141 	mutex_init(&mp->m_ilock);
142 	initnsema(&mp->m_growlock, 1, "xfs_grow");
143 	/*
144 	 * Initialize the AIL.
145 	 */
146 	xfs_trans_ail_init(mp);
147 
148 	atomic_set(&mp->m_active_trans, 0);
149 
150 	return mp;
151 }
152 
153 /*
154  * Free up the resources associated with a mount structure.  Assume that
155  * the structure was initially zeroed, so we can tell which fields got
156  * initialized.
157  */
158 void
159 xfs_mount_free(
160 	xfs_mount_t	*mp,
161 	int		remove_bhv)
162 {
163 	if (mp->m_ihash)
164 		xfs_ihash_free(mp);
165 	if (mp->m_chash)
166 		xfs_chash_free(mp);
167 
168 	if (mp->m_perag) {
169 		int	agno;
170 
171 		for (agno = 0; agno < mp->m_maxagi; agno++)
172 			if (mp->m_perag[agno].pagb_list)
173 				kmem_free(mp->m_perag[agno].pagb_list,
174 						sizeof(xfs_perag_busy_t) *
175 							XFS_PAGB_NUM_SLOTS);
176 		kmem_free(mp->m_perag,
177 			  sizeof(xfs_perag_t) * mp->m_sb.sb_agcount);
178 	}
179 
180 	AIL_LOCK_DESTROY(&mp->m_ail_lock);
181 	spinlock_destroy(&mp->m_sb_lock);
182 	mutex_destroy(&mp->m_ilock);
183 	freesema(&mp->m_growlock);
184 	if (mp->m_quotainfo)
185 		XFS_QM_DONE(mp);
186 
187 	if (mp->m_fsname != NULL)
188 		kmem_free(mp->m_fsname, mp->m_fsname_len);
189 	if (mp->m_rtname != NULL)
190 		kmem_free(mp->m_rtname, strlen(mp->m_rtname) + 1);
191 	if (mp->m_logname != NULL)
192 		kmem_free(mp->m_logname, strlen(mp->m_logname) + 1);
193 
194 	if (remove_bhv) {
195 		struct bhv_vfs	*vfsp = XFS_MTOVFS(mp);
196 
197 		bhv_remove_all_vfsops(vfsp, 0);
198 		VFS_REMOVEBHV(vfsp, &mp->m_bhv);
199 	}
200 
201 	xfs_icsb_destroy_counters(mp);
202 	kmem_free(mp, sizeof(xfs_mount_t));
203 }
204 
205 /*
206  * Check size of device based on the (data/realtime) block count.
207  * Note: this check is used by the growfs code as well as mount.
208  */
209 int
210 xfs_sb_validate_fsb_count(
211 	xfs_sb_t	*sbp,
212 	__uint64_t	nblocks)
213 {
214 	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
215 	ASSERT(sbp->sb_blocklog >= BBSHIFT);
216 
217 #if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
218 	if (nblocks >> (PAGE_CACHE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
219 		return E2BIG;
220 #else                  /* Limited by UINT_MAX of sectors */
221 	if (nblocks << (sbp->sb_blocklog - BBSHIFT) > UINT_MAX)
222 		return E2BIG;
223 #endif
224 	return 0;
225 }
226 
227 /*
228  * Check the validity of the SB found.
229  */
230 STATIC int
231 xfs_mount_validate_sb(
232 	xfs_mount_t	*mp,
233 	xfs_sb_t	*sbp,
234 	int		flags)
235 {
236 	/*
237 	 * If the log device and data device have the
238 	 * same device number, the log is internal.
239 	 * Consequently, the sb_logstart should be non-zero.  If
240 	 * we have a zero sb_logstart in this case, we may be trying to mount
241 	 * a volume filesystem in a non-volume manner.
242 	 */
243 	if (sbp->sb_magicnum != XFS_SB_MAGIC) {
244 		xfs_fs_mount_cmn_err(flags, "bad magic number");
245 		return XFS_ERROR(EWRONGFS);
246 	}
247 
248 	if (!XFS_SB_GOOD_VERSION(sbp)) {
249 		xfs_fs_mount_cmn_err(flags, "bad version");
250 		return XFS_ERROR(EWRONGFS);
251 	}
252 
253 	if (unlikely(
254 	    sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {
255 		xfs_fs_mount_cmn_err(flags,
256 			"filesystem is marked as having an external log; "
257 			"specify logdev on the\nmount command line.");
258 		return XFS_ERROR(EINVAL);
259 	}
260 
261 	if (unlikely(
262 	    sbp->sb_logstart != 0 && mp->m_logdev_targp != mp->m_ddev_targp)) {
263 		xfs_fs_mount_cmn_err(flags,
264 			"filesystem is marked as having an internal log; "
265 			"do not specify logdev on\nthe mount command line.");
266 		return XFS_ERROR(EINVAL);
267 	}
268 
269 	/*
270 	 * More sanity checking. These were stolen directly from
271 	 * xfs_repair.
272 	 */
273 	if (unlikely(
274 	    sbp->sb_agcount <= 0					||
275 	    sbp->sb_sectsize < XFS_MIN_SECTORSIZE			||
276 	    sbp->sb_sectsize > XFS_MAX_SECTORSIZE			||
277 	    sbp->sb_sectlog < XFS_MIN_SECTORSIZE_LOG			||
278 	    sbp->sb_sectlog > XFS_MAX_SECTORSIZE_LOG			||
279 	    sbp->sb_blocksize < XFS_MIN_BLOCKSIZE			||
280 	    sbp->sb_blocksize > XFS_MAX_BLOCKSIZE			||
281 	    sbp->sb_blocklog < XFS_MIN_BLOCKSIZE_LOG			||
282 	    sbp->sb_blocklog > XFS_MAX_BLOCKSIZE_LOG			||
283 	    sbp->sb_inodesize < XFS_DINODE_MIN_SIZE			||
284 	    sbp->sb_inodesize > XFS_DINODE_MAX_SIZE			||
285 	    sbp->sb_inodelog < XFS_DINODE_MIN_LOG			||
286 	    sbp->sb_inodelog > XFS_DINODE_MAX_LOG			||
287 	    (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog)	||
288 	    (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE)	||
289 	    (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE)	||
290 	    (sbp->sb_imax_pct > 100 /* zero sb_imax_pct is valid */))) {
291 		xfs_fs_mount_cmn_err(flags, "SB sanity check 1 failed");
292 		return XFS_ERROR(EFSCORRUPTED);
293 	}
294 
295 	/*
296 	 * Sanity check AG count, size fields against data size field
297 	 */
298 	if (unlikely(
299 	    sbp->sb_dblocks == 0 ||
300 	    sbp->sb_dblocks >
301 	     (xfs_drfsbno_t)sbp->sb_agcount * sbp->sb_agblocks ||
302 	    sbp->sb_dblocks < (xfs_drfsbno_t)(sbp->sb_agcount - 1) *
303 			      sbp->sb_agblocks + XFS_MIN_AG_BLOCKS)) {
304 		xfs_fs_mount_cmn_err(flags, "SB sanity check 2 failed");
305 		return XFS_ERROR(EFSCORRUPTED);
306 	}
307 
308 	if (xfs_sb_validate_fsb_count(sbp, sbp->sb_dblocks) ||
309 	    xfs_sb_validate_fsb_count(sbp, sbp->sb_rblocks)) {
310 		xfs_fs_mount_cmn_err(flags,
311 			"file system too large to be mounted on this system.");
312 		return XFS_ERROR(E2BIG);
313 	}
314 
315 	if (unlikely(sbp->sb_inprogress)) {
316 		xfs_fs_mount_cmn_err(flags, "file system busy");
317 		return XFS_ERROR(EFSCORRUPTED);
318 	}
319 
320 	/*
321 	 * Version 1 directory format has never worked on Linux.
322 	 */
323 	if (unlikely(!XFS_SB_VERSION_HASDIRV2(sbp))) {
324 		xfs_fs_mount_cmn_err(flags,
325 			"file system using version 1 directory format");
326 		return XFS_ERROR(ENOSYS);
327 	}
328 
329 	/*
330 	 * Until this is fixed only page-sized or smaller data blocks work.
331 	 */
332 	if (unlikely(sbp->sb_blocksize > PAGE_SIZE)) {
333 		xfs_fs_mount_cmn_err(flags,
334 			"file system with blocksize %d bytes",
335 			sbp->sb_blocksize);
336 		xfs_fs_mount_cmn_err(flags,
337 			"only pagesize (%ld) or less will currently work.",
338 			PAGE_SIZE);
339 		return XFS_ERROR(ENOSYS);
340 	}
341 
342 	return 0;
343 }
344 
345 xfs_agnumber_t
346 xfs_initialize_perag(
347 	bhv_vfs_t	*vfs,
348 	xfs_mount_t	*mp,
349 	xfs_agnumber_t	agcount)
350 {
351 	xfs_agnumber_t	index, max_metadata;
352 	xfs_perag_t	*pag;
353 	xfs_agino_t	agino;
354 	xfs_ino_t	ino;
355 	xfs_sb_t	*sbp = &mp->m_sb;
356 	xfs_ino_t	max_inum = XFS_MAXINUMBER_32;
357 
358 	/* Check to see if the filesystem can overflow 32 bit inodes */
359 	agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
360 	ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
361 
362 	/* Clear the mount flag if no inode can overflow 32 bits
363 	 * on this filesystem, or if specifically requested..
364 	 */
365 	if ((vfs->vfs_flag & VFS_32BITINODES) && ino > max_inum) {
366 		mp->m_flags |= XFS_MOUNT_32BITINODES;
367 	} else {
368 		mp->m_flags &= ~XFS_MOUNT_32BITINODES;
369 	}
370 
371 	/* If we can overflow then setup the ag headers accordingly */
372 	if (mp->m_flags & XFS_MOUNT_32BITINODES) {
373 		/* Calculate how much should be reserved for inodes to
374 		 * meet the max inode percentage.
375 		 */
376 		if (mp->m_maxicount) {
377 			__uint64_t	icount;
378 
379 			icount = sbp->sb_dblocks * sbp->sb_imax_pct;
380 			do_div(icount, 100);
381 			icount += sbp->sb_agblocks - 1;
382 			do_div(icount, sbp->sb_agblocks);
383 			max_metadata = icount;
384 		} else {
385 			max_metadata = agcount;
386 		}
387 		for (index = 0; index < agcount; index++) {
388 			ino = XFS_AGINO_TO_INO(mp, index, agino);
389 			if (ino > max_inum) {
390 				index++;
391 				break;
392 			}
393 
394 			/* This ag is preferred for inodes */
395 			pag = &mp->m_perag[index];
396 			pag->pagi_inodeok = 1;
397 			if (index < max_metadata)
398 				pag->pagf_metadata = 1;
399 		}
400 	} else {
401 		/* Setup default behavior for smaller filesystems */
402 		for (index = 0; index < agcount; index++) {
403 			pag = &mp->m_perag[index];
404 			pag->pagi_inodeok = 1;
405 		}
406 	}
407 	return index;
408 }
409 
410 /*
411  * xfs_xlatesb
412  *
413  *     data       - on disk version of sb
414  *     sb         - a superblock
415  *     dir        - conversion direction: <0 - convert sb to buf
416  *                                        >0 - convert buf to sb
417  *     fields     - which fields to copy (bitmask)
418  */
419 void
420 xfs_xlatesb(
421 	void		*data,
422 	xfs_sb_t	*sb,
423 	int		dir,
424 	__int64_t	fields)
425 {
426 	xfs_caddr_t	buf_ptr;
427 	xfs_caddr_t	mem_ptr;
428 	xfs_sb_field_t	f;
429 	int		first;
430 	int		size;
431 
432 	ASSERT(dir);
433 	ASSERT(fields);
434 
435 	if (!fields)
436 		return;
437 
438 	buf_ptr = (xfs_caddr_t)data;
439 	mem_ptr = (xfs_caddr_t)sb;
440 
441 	while (fields) {
442 		f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
443 		first = xfs_sb_info[f].offset;
444 		size = xfs_sb_info[f + 1].offset - first;
445 
446 		ASSERT(xfs_sb_info[f].type == 0 || xfs_sb_info[f].type == 1);
447 
448 		if (size == 1 || xfs_sb_info[f].type == 1) {
449 			if (dir > 0) {
450 				memcpy(mem_ptr + first, buf_ptr + first, size);
451 			} else {
452 				memcpy(buf_ptr + first, mem_ptr + first, size);
453 			}
454 		} else {
455 			switch (size) {
456 			case 2:
457 				INT_XLATE(*(__uint16_t*)(buf_ptr+first),
458 					  *(__uint16_t*)(mem_ptr+first),
459 					  dir, ARCH_CONVERT);
460 				break;
461 			case 4:
462 				INT_XLATE(*(__uint32_t*)(buf_ptr+first),
463 					  *(__uint32_t*)(mem_ptr+first),
464 					  dir, ARCH_CONVERT);
465 				break;
466 			case 8:
467 				INT_XLATE(*(__uint64_t*)(buf_ptr+first),
468 					  *(__uint64_t*)(mem_ptr+first), dir, ARCH_CONVERT);
469 				break;
470 			default:
471 				ASSERT(0);
472 			}
473 		}
474 
475 		fields &= ~(1LL << f);
476 	}
477 }
478 
479 /*
480  * xfs_readsb
481  *
482  * Does the initial read of the superblock.
483  */
484 int
485 xfs_readsb(xfs_mount_t *mp, int flags)
486 {
487 	unsigned int	sector_size;
488 	unsigned int	extra_flags;
489 	xfs_buf_t	*bp;
490 	xfs_sb_t	*sbp;
491 	int		error;
492 
493 	ASSERT(mp->m_sb_bp == NULL);
494 	ASSERT(mp->m_ddev_targp != NULL);
495 
496 	/*
497 	 * Allocate a (locked) buffer to hold the superblock.
498 	 * This will be kept around at all times to optimize
499 	 * access to the superblock.
500 	 */
501 	sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
502 	extra_flags = XFS_BUF_LOCK | XFS_BUF_MANAGE | XFS_BUF_MAPPED;
503 
504 	bp = xfs_buf_read_flags(mp->m_ddev_targp, XFS_SB_DADDR,
505 				BTOBB(sector_size), extra_flags);
506 	if (!bp || XFS_BUF_ISERROR(bp)) {
507 		xfs_fs_mount_cmn_err(flags, "SB read failed");
508 		error = bp ? XFS_BUF_GETERROR(bp) : ENOMEM;
509 		goto fail;
510 	}
511 	ASSERT(XFS_BUF_ISBUSY(bp));
512 	ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
513 
514 	/*
515 	 * Initialize the mount structure from the superblock.
516 	 * But first do some basic consistency checking.
517 	 */
518 	sbp = XFS_BUF_TO_SBP(bp);
519 	xfs_xlatesb(XFS_BUF_PTR(bp), &(mp->m_sb), 1, XFS_SB_ALL_BITS);
520 
521 	error = xfs_mount_validate_sb(mp, &(mp->m_sb), flags);
522 	if (error) {
523 		xfs_fs_mount_cmn_err(flags, "SB validate failed");
524 		goto fail;
525 	}
526 
527 	/*
528 	 * We must be able to do sector-sized and sector-aligned IO.
529 	 */
530 	if (sector_size > mp->m_sb.sb_sectsize) {
531 		xfs_fs_mount_cmn_err(flags,
532 			"device supports only %u byte sectors (not %u)",
533 			sector_size, mp->m_sb.sb_sectsize);
534 		error = ENOSYS;
535 		goto fail;
536 	}
537 
538 	/*
539 	 * If device sector size is smaller than the superblock size,
540 	 * re-read the superblock so the buffer is correctly sized.
541 	 */
542 	if (sector_size < mp->m_sb.sb_sectsize) {
543 		XFS_BUF_UNMANAGE(bp);
544 		xfs_buf_relse(bp);
545 		sector_size = mp->m_sb.sb_sectsize;
546 		bp = xfs_buf_read_flags(mp->m_ddev_targp, XFS_SB_DADDR,
547 					BTOBB(sector_size), extra_flags);
548 		if (!bp || XFS_BUF_ISERROR(bp)) {
549 			xfs_fs_mount_cmn_err(flags, "SB re-read failed");
550 			error = bp ? XFS_BUF_GETERROR(bp) : ENOMEM;
551 			goto fail;
552 		}
553 		ASSERT(XFS_BUF_ISBUSY(bp));
554 		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
555 	}
556 
557 	/* Initialize per-cpu counters */
558 	xfs_icsb_reinit_counters(mp);
559 
560 	mp->m_sb_bp = bp;
561 	xfs_buf_relse(bp);
562 	ASSERT(XFS_BUF_VALUSEMA(bp) > 0);
563 	return 0;
564 
565  fail:
566 	if (bp) {
567 		XFS_BUF_UNMANAGE(bp);
568 		xfs_buf_relse(bp);
569 	}
570 	return error;
571 }
572 
573 
574 /*
575  * xfs_mount_common
576  *
577  * Mount initialization code establishing various mount
578  * fields from the superblock associated with the given
579  * mount structure
580  */
581 STATIC void
582 xfs_mount_common(xfs_mount_t *mp, xfs_sb_t *sbp)
583 {
584 	int	i;
585 
586 	mp->m_agfrotor = mp->m_agirotor = 0;
587 	spinlock_init(&mp->m_agirotor_lock, "m_agirotor_lock");
588 	mp->m_maxagi = mp->m_sb.sb_agcount;
589 	mp->m_blkbit_log = sbp->sb_blocklog + XFS_NBBYLOG;
590 	mp->m_blkbb_log = sbp->sb_blocklog - BBSHIFT;
591 	mp->m_sectbb_log = sbp->sb_sectlog - BBSHIFT;
592 	mp->m_agno_log = xfs_highbit32(sbp->sb_agcount - 1) + 1;
593 	mp->m_agino_log = sbp->sb_inopblog + sbp->sb_agblklog;
594 	mp->m_litino = sbp->sb_inodesize -
595 		((uint)sizeof(xfs_dinode_core_t) + (uint)sizeof(xfs_agino_t));
596 	mp->m_blockmask = sbp->sb_blocksize - 1;
597 	mp->m_blockwsize = sbp->sb_blocksize >> XFS_WORDLOG;
598 	mp->m_blockwmask = mp->m_blockwsize - 1;
599 	INIT_LIST_HEAD(&mp->m_del_inodes);
600 
601 	/*
602 	 * Setup for attributes, in case they get created.
603 	 * This value is for inodes getting attributes for the first time,
604 	 * the per-inode value is for old attribute values.
605 	 */
606 	ASSERT(sbp->sb_inodesize >= 256 && sbp->sb_inodesize <= 2048);
607 	switch (sbp->sb_inodesize) {
608 	case 256:
609 		mp->m_attroffset = XFS_LITINO(mp) -
610 				   XFS_BMDR_SPACE_CALC(MINABTPTRS);
611 		break;
612 	case 512:
613 	case 1024:
614 	case 2048:
615 		mp->m_attroffset = XFS_BMDR_SPACE_CALC(6 * MINABTPTRS);
616 		break;
617 	default:
618 		ASSERT(0);
619 	}
620 	ASSERT(mp->m_attroffset < XFS_LITINO(mp));
621 
622 	for (i = 0; i < 2; i++) {
623 		mp->m_alloc_mxr[i] = XFS_BTREE_BLOCK_MAXRECS(sbp->sb_blocksize,
624 			xfs_alloc, i == 0);
625 		mp->m_alloc_mnr[i] = XFS_BTREE_BLOCK_MINRECS(sbp->sb_blocksize,
626 			xfs_alloc, i == 0);
627 	}
628 	for (i = 0; i < 2; i++) {
629 		mp->m_bmap_dmxr[i] = XFS_BTREE_BLOCK_MAXRECS(sbp->sb_blocksize,
630 			xfs_bmbt, i == 0);
631 		mp->m_bmap_dmnr[i] = XFS_BTREE_BLOCK_MINRECS(sbp->sb_blocksize,
632 			xfs_bmbt, i == 0);
633 	}
634 	for (i = 0; i < 2; i++) {
635 		mp->m_inobt_mxr[i] = XFS_BTREE_BLOCK_MAXRECS(sbp->sb_blocksize,
636 			xfs_inobt, i == 0);
637 		mp->m_inobt_mnr[i] = XFS_BTREE_BLOCK_MINRECS(sbp->sb_blocksize,
638 			xfs_inobt, i == 0);
639 	}
640 
641 	mp->m_bsize = XFS_FSB_TO_BB(mp, 1);
642 	mp->m_ialloc_inos = (int)MAX((__uint16_t)XFS_INODES_PER_CHUNK,
643 					sbp->sb_inopblock);
644 	mp->m_ialloc_blks = mp->m_ialloc_inos >> sbp->sb_inopblog;
645 }
646 
647 /*
648  * xfs_initialize_perag_data
649  *
650  * Read in each per-ag structure so we can count up the number of
651  * allocated inodes, free inodes and used filesystem blocks as this
652  * information is no longer persistent in the superblock. Once we have
653  * this information, write it into the in-core superblock structure.
654  */
655 STATIC int
656 xfs_initialize_perag_data(xfs_mount_t *mp, xfs_agnumber_t agcount)
657 {
658 	xfs_agnumber_t	index;
659 	xfs_perag_t	*pag;
660 	xfs_sb_t	*sbp = &mp->m_sb;
661 	uint64_t	ifree = 0;
662 	uint64_t	ialloc = 0;
663 	uint64_t	bfree = 0;
664 	uint64_t	bfreelst = 0;
665 	uint64_t	btree = 0;
666 	int		error;
667 	int		s;
668 
669 	for (index = 0; index < agcount; index++) {
670 		/*
671 		 * read the agf, then the agi. This gets us
672 		 * all the inforamtion we need and populates the
673 		 * per-ag structures for us.
674 		 */
675 		error = xfs_alloc_pagf_init(mp, NULL, index, 0);
676 		if (error)
677 			return error;
678 
679 		error = xfs_ialloc_pagi_init(mp, NULL, index);
680 		if (error)
681 			return error;
682 		pag = &mp->m_perag[index];
683 		ifree += pag->pagi_freecount;
684 		ialloc += pag->pagi_count;
685 		bfree += pag->pagf_freeblks;
686 		bfreelst += pag->pagf_flcount;
687 		btree += pag->pagf_btreeblks;
688 	}
689 	/*
690 	 * Overwrite incore superblock counters with just-read data
691 	 */
692 	s = XFS_SB_LOCK(mp);
693 	sbp->sb_ifree = ifree;
694 	sbp->sb_icount = ialloc;
695 	sbp->sb_fdblocks = bfree + bfreelst + btree;
696 	XFS_SB_UNLOCK(mp, s);
697 
698 	/* Fixup the per-cpu counters as well. */
699 	xfs_icsb_reinit_counters(mp);
700 
701 	return 0;
702 }
703 
704 /*
705  * xfs_mountfs
706  *
707  * This function does the following on an initial mount of a file system:
708  *	- reads the superblock from disk and init the mount struct
709  *	- if we're a 32-bit kernel, do a size check on the superblock
710  *		so we don't mount terabyte filesystems
711  *	- init mount struct realtime fields
712  *	- allocate inode hash table for fs
713  *	- init directory manager
714  *	- perform recovery and init the log manager
715  */
716 int
717 xfs_mountfs(
718 	bhv_vfs_t	*vfsp,
719 	xfs_mount_t	*mp,
720 	int		mfsi_flags)
721 {
722 	xfs_buf_t	*bp;
723 	xfs_sb_t	*sbp = &(mp->m_sb);
724 	xfs_inode_t	*rip;
725 	bhv_vnode_t	*rvp = NULL;
726 	int		readio_log, writeio_log;
727 	xfs_daddr_t	d;
728 	__uint64_t	resblks;
729 	__int64_t	update_flags;
730 	uint		quotamount, quotaflags;
731 	int		agno;
732 	int		uuid_mounted = 0;
733 	int		error = 0;
734 
735 	if (mp->m_sb_bp == NULL) {
736 		if ((error = xfs_readsb(mp, mfsi_flags))) {
737 			return error;
738 		}
739 	}
740 	xfs_mount_common(mp, sbp);
741 
742 	/*
743 	 * Check if sb_agblocks is aligned at stripe boundary
744 	 * If sb_agblocks is NOT aligned turn off m_dalign since
745 	 * allocator alignment is within an ag, therefore ag has
746 	 * to be aligned at stripe boundary.
747 	 */
748 	update_flags = 0LL;
749 	if (mp->m_dalign && !(mfsi_flags & XFS_MFSI_SECOND)) {
750 		/*
751 		 * If stripe unit and stripe width are not multiples
752 		 * of the fs blocksize turn off alignment.
753 		 */
754 		if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
755 		    (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
756 			if (mp->m_flags & XFS_MOUNT_RETERR) {
757 				cmn_err(CE_WARN,
758 					"XFS: alignment check 1 failed");
759 				error = XFS_ERROR(EINVAL);
760 				goto error1;
761 			}
762 			mp->m_dalign = mp->m_swidth = 0;
763 		} else {
764 			/*
765 			 * Convert the stripe unit and width to FSBs.
766 			 */
767 			mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
768 			if (mp->m_dalign && (sbp->sb_agblocks % mp->m_dalign)) {
769 				if (mp->m_flags & XFS_MOUNT_RETERR) {
770 					error = XFS_ERROR(EINVAL);
771 					goto error1;
772 				}
773 				xfs_fs_cmn_err(CE_WARN, mp,
774 "stripe alignment turned off: sunit(%d)/swidth(%d) incompatible with agsize(%d)",
775 					mp->m_dalign, mp->m_swidth,
776 					sbp->sb_agblocks);
777 
778 				mp->m_dalign = 0;
779 				mp->m_swidth = 0;
780 			} else if (mp->m_dalign) {
781 				mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
782 			} else {
783 				if (mp->m_flags & XFS_MOUNT_RETERR) {
784 					xfs_fs_cmn_err(CE_WARN, mp,
785 "stripe alignment turned off: sunit(%d) less than bsize(%d)",
786                                         	mp->m_dalign,
787 						mp->m_blockmask +1);
788 					error = XFS_ERROR(EINVAL);
789 					goto error1;
790 				}
791 				mp->m_swidth = 0;
792 			}
793 		}
794 
795 		/*
796 		 * Update superblock with new values
797 		 * and log changes
798 		 */
799 		if (XFS_SB_VERSION_HASDALIGN(sbp)) {
800 			if (sbp->sb_unit != mp->m_dalign) {
801 				sbp->sb_unit = mp->m_dalign;
802 				update_flags |= XFS_SB_UNIT;
803 			}
804 			if (sbp->sb_width != mp->m_swidth) {
805 				sbp->sb_width = mp->m_swidth;
806 				update_flags |= XFS_SB_WIDTH;
807 			}
808 		}
809 	} else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
810 		    XFS_SB_VERSION_HASDALIGN(&mp->m_sb)) {
811 			mp->m_dalign = sbp->sb_unit;
812 			mp->m_swidth = sbp->sb_width;
813 	}
814 
815 	xfs_alloc_compute_maxlevels(mp);
816 	xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
817 	xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
818 	xfs_ialloc_compute_maxlevels(mp);
819 
820 	if (sbp->sb_imax_pct) {
821 		__uint64_t	icount;
822 
823 		/* Make sure the maximum inode count is a multiple of the
824 		 * units we allocate inodes in.
825 		 */
826 
827 		icount = sbp->sb_dblocks * sbp->sb_imax_pct;
828 		do_div(icount, 100);
829 		do_div(icount, mp->m_ialloc_blks);
830 		mp->m_maxicount = (icount * mp->m_ialloc_blks)  <<
831 				   sbp->sb_inopblog;
832 	} else
833 		mp->m_maxicount = 0;
834 
835 	mp->m_maxioffset = xfs_max_file_offset(sbp->sb_blocklog);
836 
837 	/*
838 	 * XFS uses the uuid from the superblock as the unique
839 	 * identifier for fsid.  We can not use the uuid from the volume
840 	 * since a single partition filesystem is identical to a single
841 	 * partition volume/filesystem.
842 	 */
843 	if ((mfsi_flags & XFS_MFSI_SECOND) == 0 &&
844 	    (mp->m_flags & XFS_MOUNT_NOUUID) == 0) {
845 		__uint64_t	ret64;
846 		if (xfs_uuid_mount(mp)) {
847 			error = XFS_ERROR(EINVAL);
848 			goto error1;
849 		}
850 		uuid_mounted=1;
851 		ret64 = uuid_hash64(&sbp->sb_uuid);
852 		memcpy(&vfsp->vfs_fsid, &ret64, sizeof(ret64));
853 	}
854 
855 	/*
856 	 * Set the default minimum read and write sizes unless
857 	 * already specified in a mount option.
858 	 * We use smaller I/O sizes when the file system
859 	 * is being used for NFS service (wsync mount option).
860 	 */
861 	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
862 		if (mp->m_flags & XFS_MOUNT_WSYNC) {
863 			readio_log = XFS_WSYNC_READIO_LOG;
864 			writeio_log = XFS_WSYNC_WRITEIO_LOG;
865 		} else {
866 			readio_log = XFS_READIO_LOG_LARGE;
867 			writeio_log = XFS_WRITEIO_LOG_LARGE;
868 		}
869 	} else {
870 		readio_log = mp->m_readio_log;
871 		writeio_log = mp->m_writeio_log;
872 	}
873 
874 	/*
875 	 * Set the number of readahead buffers to use based on
876 	 * physical memory size.
877 	 */
878 	if (xfs_physmem <= 4096)		/* <= 16MB */
879 		mp->m_nreadaheads = XFS_RW_NREADAHEAD_16MB;
880 	else if (xfs_physmem <= 8192)	/* <= 32MB */
881 		mp->m_nreadaheads = XFS_RW_NREADAHEAD_32MB;
882 	else
883 		mp->m_nreadaheads = XFS_RW_NREADAHEAD_K32;
884 	if (sbp->sb_blocklog > readio_log) {
885 		mp->m_readio_log = sbp->sb_blocklog;
886 	} else {
887 		mp->m_readio_log = readio_log;
888 	}
889 	mp->m_readio_blocks = 1 << (mp->m_readio_log - sbp->sb_blocklog);
890 	if (sbp->sb_blocklog > writeio_log) {
891 		mp->m_writeio_log = sbp->sb_blocklog;
892 	} else {
893 		mp->m_writeio_log = writeio_log;
894 	}
895 	mp->m_writeio_blocks = 1 << (mp->m_writeio_log - sbp->sb_blocklog);
896 
897 	/*
898 	 * Set the inode cluster size based on the physical memory
899 	 * size.  This may still be overridden by the file system
900 	 * block size if it is larger than the chosen cluster size.
901 	 */
902 	if (xfs_physmem <= btoc(32 * 1024 * 1024)) { /* <= 32 MB */
903 		mp->m_inode_cluster_size = XFS_INODE_SMALL_CLUSTER_SIZE;
904 	} else {
905 		mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
906 	}
907 	/*
908 	 * Set whether we're using inode alignment.
909 	 */
910 	if (XFS_SB_VERSION_HASALIGN(&mp->m_sb) &&
911 	    mp->m_sb.sb_inoalignmt >=
912 	    XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size))
913 		mp->m_inoalign_mask = mp->m_sb.sb_inoalignmt - 1;
914 	else
915 		mp->m_inoalign_mask = 0;
916 	/*
917 	 * If we are using stripe alignment, check whether
918 	 * the stripe unit is a multiple of the inode alignment
919 	 */
920 	if (mp->m_dalign && mp->m_inoalign_mask &&
921 	    !(mp->m_dalign & mp->m_inoalign_mask))
922 		mp->m_sinoalign = mp->m_dalign;
923 	else
924 		mp->m_sinoalign = 0;
925 	/*
926 	 * Check that the data (and log if separate) are an ok size.
927 	 */
928 	d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
929 	if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {
930 		cmn_err(CE_WARN, "XFS: size check 1 failed");
931 		error = XFS_ERROR(E2BIG);
932 		goto error1;
933 	}
934 	error = xfs_read_buf(mp, mp->m_ddev_targp,
935 			     d - XFS_FSS_TO_BB(mp, 1),
936 			     XFS_FSS_TO_BB(mp, 1), 0, &bp);
937 	if (!error) {
938 		xfs_buf_relse(bp);
939 	} else {
940 		cmn_err(CE_WARN, "XFS: size check 2 failed");
941 		if (error == ENOSPC) {
942 			error = XFS_ERROR(E2BIG);
943 		}
944 		goto error1;
945 	}
946 
947 	if (((mfsi_flags & XFS_MFSI_CLIENT) == 0) &&
948 	    mp->m_logdev_targp != mp->m_ddev_targp) {
949 		d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
950 		if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {
951 			cmn_err(CE_WARN, "XFS: size check 3 failed");
952 			error = XFS_ERROR(E2BIG);
953 			goto error1;
954 		}
955 		error = xfs_read_buf(mp, mp->m_logdev_targp,
956 				     d - XFS_FSB_TO_BB(mp, 1),
957 				     XFS_FSB_TO_BB(mp, 1), 0, &bp);
958 		if (!error) {
959 			xfs_buf_relse(bp);
960 		} else {
961 			cmn_err(CE_WARN, "XFS: size check 3 failed");
962 			if (error == ENOSPC) {
963 				error = XFS_ERROR(E2BIG);
964 			}
965 			goto error1;
966 		}
967 	}
968 
969 	/*
970 	 * Initialize realtime fields in the mount structure
971 	 */
972 	if ((error = xfs_rtmount_init(mp))) {
973 		cmn_err(CE_WARN, "XFS: RT mount failed");
974 		goto error1;
975 	}
976 
977 	/*
978 	 * For client case we are done now
979 	 */
980 	if (mfsi_flags & XFS_MFSI_CLIENT) {
981 		return 0;
982 	}
983 
984 	/*
985 	 *  Copies the low order bits of the timestamp and the randomly
986 	 *  set "sequence" number out of a UUID.
987 	 */
988 	uuid_getnodeuniq(&sbp->sb_uuid, mp->m_fixedfsid);
989 
990 	/*
991 	 *  The vfs structure needs to have a file system independent
992 	 *  way of checking for the invariant file system ID.  Since it
993 	 *  can't look at mount structures it has a pointer to the data
994 	 *  in the mount structure.
995 	 *
996 	 *  File systems that don't support user level file handles (i.e.
997 	 *  all of them except for XFS) will leave vfs_altfsid as NULL.
998 	 */
999 	vfsp->vfs_altfsid = (xfs_fsid_t *)mp->m_fixedfsid;
1000 	mp->m_dmevmask = 0;	/* not persistent; set after each mount */
1001 
1002 	xfs_dir_mount(mp);
1003 
1004 	/*
1005 	 * Initialize the attribute manager's entries.
1006 	 */
1007 	mp->m_attr_magicpct = (mp->m_sb.sb_blocksize * 37) / 100;
1008 
1009 	/*
1010 	 * Initialize the precomputed transaction reservations values.
1011 	 */
1012 	xfs_trans_init(mp);
1013 
1014 	/*
1015 	 * Allocate and initialize the inode hash table for this
1016 	 * file system.
1017 	 */
1018 	xfs_ihash_init(mp);
1019 	xfs_chash_init(mp);
1020 
1021 	/*
1022 	 * Allocate and initialize the per-ag data.
1023 	 */
1024 	init_rwsem(&mp->m_peraglock);
1025 	mp->m_perag =
1026 		kmem_zalloc(sbp->sb_agcount * sizeof(xfs_perag_t), KM_SLEEP);
1027 
1028 	mp->m_maxagi = xfs_initialize_perag(vfsp, mp, sbp->sb_agcount);
1029 
1030 	/*
1031 	 * log's mount-time initialization. Perform 1st part recovery if needed
1032 	 */
1033 	if (likely(sbp->sb_logblocks > 0)) {	/* check for volume case */
1034 		error = xfs_log_mount(mp, mp->m_logdev_targp,
1035 				      XFS_FSB_TO_DADDR(mp, sbp->sb_logstart),
1036 				      XFS_FSB_TO_BB(mp, sbp->sb_logblocks));
1037 		if (error) {
1038 			cmn_err(CE_WARN, "XFS: log mount failed");
1039 			goto error2;
1040 		}
1041 	} else {	/* No log has been defined */
1042 		cmn_err(CE_WARN, "XFS: no log defined");
1043 		XFS_ERROR_REPORT("xfs_mountfs_int(1)", XFS_ERRLEVEL_LOW, mp);
1044 		error = XFS_ERROR(EFSCORRUPTED);
1045 		goto error2;
1046 	}
1047 
1048 	/*
1049 	 * Now the log is mounted, we know if it was an unclean shutdown or
1050 	 * not. If it was, with the first phase of recovery has completed, we
1051 	 * have consistent AG blocks on disk. We have not recovered EFIs yet,
1052 	 * but they are recovered transactionally in the second recovery phase
1053 	 * later.
1054 	 *
1055 	 * Hence we can safely re-initialise incore superblock counters from
1056 	 * the per-ag data. These may not be correct if the filesystem was not
1057 	 * cleanly unmounted, so we need to wait for recovery to finish before
1058 	 * doing this.
1059 	 *
1060 	 * If the filesystem was cleanly unmounted, then we can trust the
1061 	 * values in the superblock to be correct and we don't need to do
1062 	 * anything here.
1063 	 *
1064 	 * If we are currently making the filesystem, the initialisation will
1065 	 * fail as the perag data is in an undefined state.
1066 	 */
1067 
1068 	if (xfs_sb_version_haslazysbcount(&mp->m_sb) &&
1069 	    !XFS_LAST_UNMOUNT_WAS_CLEAN(mp) &&
1070 	     !mp->m_sb.sb_inprogress) {
1071 		error = xfs_initialize_perag_data(mp, sbp->sb_agcount);
1072 		if (error) {
1073 			goto error2;
1074 		}
1075 	}
1076 	/*
1077 	 * Get and sanity-check the root inode.
1078 	 * Save the pointer to it in the mount structure.
1079 	 */
1080 	error = xfs_iget(mp, NULL, sbp->sb_rootino, 0, XFS_ILOCK_EXCL, &rip, 0);
1081 	if (error) {
1082 		cmn_err(CE_WARN, "XFS: failed to read root inode");
1083 		goto error3;
1084 	}
1085 
1086 	ASSERT(rip != NULL);
1087 	rvp = XFS_ITOV(rip);
1088 
1089 	if (unlikely((rip->i_d.di_mode & S_IFMT) != S_IFDIR)) {
1090 		cmn_err(CE_WARN, "XFS: corrupted root inode");
1091 		cmn_err(CE_WARN, "Device %s - root %llu is not a directory",
1092 			XFS_BUFTARG_NAME(mp->m_ddev_targp),
1093 			(unsigned long long)rip->i_ino);
1094 		xfs_iunlock(rip, XFS_ILOCK_EXCL);
1095 		XFS_ERROR_REPORT("xfs_mountfs_int(2)", XFS_ERRLEVEL_LOW,
1096 				 mp);
1097 		error = XFS_ERROR(EFSCORRUPTED);
1098 		goto error4;
1099 	}
1100 	mp->m_rootip = rip;	/* save it */
1101 
1102 	xfs_iunlock(rip, XFS_ILOCK_EXCL);
1103 
1104 	/*
1105 	 * Initialize realtime inode pointers in the mount structure
1106 	 */
1107 	if ((error = xfs_rtmount_inodes(mp))) {
1108 		/*
1109 		 * Free up the root inode.
1110 		 */
1111 		cmn_err(CE_WARN, "XFS: failed to read RT inodes");
1112 		goto error4;
1113 	}
1114 
1115 	/*
1116 	 * If fs is not mounted readonly, then update the superblock
1117 	 * unit and width changes.
1118 	 */
1119 	if (update_flags && !(vfsp->vfs_flag & VFS_RDONLY))
1120 		xfs_mount_log_sbunit(mp, update_flags);
1121 
1122 	/*
1123 	 * Initialise the XFS quota management subsystem for this mount
1124 	 */
1125 	if ((error = XFS_QM_INIT(mp, &quotamount, &quotaflags)))
1126 		goto error4;
1127 
1128 	/*
1129 	 * Finish recovering the file system.  This part needed to be
1130 	 * delayed until after the root and real-time bitmap inodes
1131 	 * were consistently read in.
1132 	 */
1133 	error = xfs_log_mount_finish(mp, mfsi_flags);
1134 	if (error) {
1135 		cmn_err(CE_WARN, "XFS: log mount finish failed");
1136 		goto error4;
1137 	}
1138 
1139 	/*
1140 	 * Complete the quota initialisation, post-log-replay component.
1141 	 */
1142 	if ((error = XFS_QM_MOUNT(mp, quotamount, quotaflags, mfsi_flags)))
1143 		goto error4;
1144 
1145 	/*
1146 	 * Now we are mounted, reserve a small amount of unused space for
1147 	 * privileged transactions. This is needed so that transaction
1148 	 * space required for critical operations can dip into this pool
1149 	 * when at ENOSPC. This is needed for operations like create with
1150 	 * attr, unwritten extent conversion at ENOSPC, etc. Data allocations
1151 	 * are not allowed to use this reserved space.
1152 	 *
1153 	 * We default to 5% or 1024 fsbs of space reserved, whichever is smaller.
1154 	 * This may drive us straight to ENOSPC on mount, but that implies
1155 	 * we were already there on the last unmount.
1156 	 */
1157 	resblks = mp->m_sb.sb_dblocks;
1158 	do_div(resblks, 20);
1159 	resblks = min_t(__uint64_t, resblks, 1024);
1160 	xfs_reserve_blocks(mp, &resblks, NULL);
1161 
1162 	return 0;
1163 
1164  error4:
1165 	/*
1166 	 * Free up the root inode.
1167 	 */
1168 	VN_RELE(rvp);
1169  error3:
1170 	xfs_log_unmount_dealloc(mp);
1171  error2:
1172 	xfs_ihash_free(mp);
1173 	xfs_chash_free(mp);
1174 	for (agno = 0; agno < sbp->sb_agcount; agno++)
1175 		if (mp->m_perag[agno].pagb_list)
1176 			kmem_free(mp->m_perag[agno].pagb_list,
1177 			  sizeof(xfs_perag_busy_t) * XFS_PAGB_NUM_SLOTS);
1178 	kmem_free(mp->m_perag, sbp->sb_agcount * sizeof(xfs_perag_t));
1179 	mp->m_perag = NULL;
1180 	/* FALLTHROUGH */
1181  error1:
1182 	if (uuid_mounted)
1183 		xfs_uuid_unmount(mp);
1184 	xfs_freesb(mp);
1185 	return error;
1186 }
1187 
1188 /*
1189  * xfs_unmountfs
1190  *
1191  * This flushes out the inodes,dquots and the superblock, unmounts the
1192  * log and makes sure that incore structures are freed.
1193  */
1194 int
1195 xfs_unmountfs(xfs_mount_t *mp, struct cred *cr)
1196 {
1197 	struct bhv_vfs	*vfsp = XFS_MTOVFS(mp);
1198 #if defined(DEBUG) || defined(INDUCE_IO_ERROR)
1199 	int64_t		fsid;
1200 #endif
1201 	__uint64_t	resblks;
1202 
1203 	/*
1204 	 * We can potentially deadlock here if we have an inode cluster
1205 	 * that has been freed has it's buffer still pinned in memory because
1206 	 * the transaction is still sitting in a iclog. The stale inodes
1207 	 * on that buffer will have their flush locks held until the
1208 	 * transaction hits the disk and the callbacks run. the inode
1209 	 * flush takes the flush lock unconditionally and with nothing to
1210 	 * push out the iclog we will never get that unlocked. hence we
1211 	 * need to force the log first.
1212 	 */
1213 	xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE | XFS_LOG_SYNC);
1214 	xfs_iflush_all(mp);
1215 
1216 	XFS_QM_DQPURGEALL(mp, XFS_QMOPT_QUOTALL | XFS_QMOPT_UMOUNTING);
1217 
1218 	/*
1219 	 * Flush out the log synchronously so that we know for sure
1220 	 * that nothing is pinned.  This is important because bflush()
1221 	 * will skip pinned buffers.
1222 	 */
1223 	xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE | XFS_LOG_SYNC);
1224 
1225 	xfs_binval(mp->m_ddev_targp);
1226 	if (mp->m_rtdev_targp) {
1227 		xfs_binval(mp->m_rtdev_targp);
1228 	}
1229 
1230 	/*
1231 	 * Unreserve any blocks we have so that when we unmount we don't account
1232 	 * the reserved free space as used. This is really only necessary for
1233 	 * lazy superblock counting because it trusts the incore superblock
1234 	 * counters to be aboslutely correct on clean unmount.
1235 	 *
1236 	 * We don't bother correcting this elsewhere for lazy superblock
1237 	 * counting because on mount of an unclean filesystem we reconstruct the
1238 	 * correct counter value and this is irrelevant.
1239 	 *
1240 	 * For non-lazy counter filesystems, this doesn't matter at all because
1241 	 * we only every apply deltas to the superblock and hence the incore
1242 	 * value does not matter....
1243 	 */
1244 	resblks = 0;
1245 	xfs_reserve_blocks(mp, &resblks, NULL);
1246 
1247 	xfs_log_sbcount(mp, 1);
1248 	xfs_unmountfs_writesb(mp);
1249 	xfs_unmountfs_wait(mp); 		/* wait for async bufs */
1250 	xfs_log_unmount(mp);			/* Done! No more fs ops. */
1251 
1252 	xfs_freesb(mp);
1253 
1254 	/*
1255 	 * All inodes from this mount point should be freed.
1256 	 */
1257 	ASSERT(mp->m_inodes == NULL);
1258 
1259 	xfs_unmountfs_close(mp, cr);
1260 	if ((mp->m_flags & XFS_MOUNT_NOUUID) == 0)
1261 		xfs_uuid_unmount(mp);
1262 
1263 #if defined(DEBUG) || defined(INDUCE_IO_ERROR)
1264 	/*
1265 	 * clear all error tags on this filesystem
1266 	 */
1267 	memcpy(&fsid, &vfsp->vfs_fsid, sizeof(int64_t));
1268 	xfs_errortag_clearall_umount(fsid, mp->m_fsname, 0);
1269 #endif
1270 	XFS_IODONE(vfsp);
1271 	xfs_mount_free(mp, 1);
1272 	return 0;
1273 }
1274 
1275 void
1276 xfs_unmountfs_close(xfs_mount_t *mp, struct cred *cr)
1277 {
1278 	if (mp->m_logdev_targp != mp->m_ddev_targp)
1279 		xfs_free_buftarg(mp->m_logdev_targp, 1);
1280 	if (mp->m_rtdev_targp)
1281 		xfs_free_buftarg(mp->m_rtdev_targp, 1);
1282 	xfs_free_buftarg(mp->m_ddev_targp, 0);
1283 }
1284 
1285 STATIC void
1286 xfs_unmountfs_wait(xfs_mount_t *mp)
1287 {
1288 	if (mp->m_logdev_targp != mp->m_ddev_targp)
1289 		xfs_wait_buftarg(mp->m_logdev_targp);
1290 	if (mp->m_rtdev_targp)
1291 		xfs_wait_buftarg(mp->m_rtdev_targp);
1292 	xfs_wait_buftarg(mp->m_ddev_targp);
1293 }
1294 
1295 int
1296 xfs_fs_writable(xfs_mount_t *mp)
1297 {
1298 	bhv_vfs_t	*vfsp = XFS_MTOVFS(mp);
1299 
1300 	return !(vfs_test_for_freeze(vfsp) || XFS_FORCED_SHUTDOWN(mp) ||
1301 		(vfsp->vfs_flag & VFS_RDONLY));
1302 }
1303 
1304 /*
1305  * xfs_log_sbcount
1306  *
1307  * Called either periodically to keep the on disk superblock values
1308  * roughly up to date or from unmount to make sure the values are
1309  * correct on a clean unmount.
1310  *
1311  * Note this code can be called during the process of freezing, so
1312  * we may need to use the transaction allocator which does not not
1313  * block when the transaction subsystem is in its frozen state.
1314  */
1315 int
1316 xfs_log_sbcount(
1317 	xfs_mount_t	*mp,
1318 	uint		sync)
1319 {
1320 	xfs_trans_t	*tp;
1321 	int		error;
1322 
1323 	if (!xfs_fs_writable(mp))
1324 		return 0;
1325 
1326 	xfs_icsb_sync_counters(mp);
1327 
1328 	/*
1329 	 * we don't need to do this if we are updating the superblock
1330 	 * counters on every modification.
1331 	 */
1332 	if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
1333 		return 0;
1334 
1335 	tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT);
1336 	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
1337 					XFS_DEFAULT_LOG_COUNT);
1338 	if (error) {
1339 		xfs_trans_cancel(tp, 0);
1340 		return error;
1341 	}
1342 
1343 	xfs_mod_sb(tp, XFS_SB_IFREE | XFS_SB_ICOUNT | XFS_SB_FDBLOCKS);
1344 	if (sync)
1345 		xfs_trans_set_sync(tp);
1346 	xfs_trans_commit(tp, 0);
1347 
1348 	return 0;
1349 }
1350 
1351 int
1352 xfs_unmountfs_writesb(xfs_mount_t *mp)
1353 {
1354 	xfs_buf_t	*sbp;
1355 	xfs_sb_t	*sb;
1356 	int		error = 0;
1357 
1358 	/*
1359 	 * skip superblock write if fs is read-only, or
1360 	 * if we are doing a forced umount.
1361 	 */
1362 	if (!(XFS_MTOVFS(mp)->vfs_flag & VFS_RDONLY ||
1363 		XFS_FORCED_SHUTDOWN(mp))) {
1364 
1365 		sbp = xfs_getsb(mp, 0);
1366  		sb = XFS_BUF_TO_SBP(sbp);
1367 
1368 		/*
1369 		 * mark shared-readonly if desired
1370 		 */
1371 		if (mp->m_mk_sharedro) {
1372 			if (!(sb->sb_flags & XFS_SBF_READONLY))
1373 				sb->sb_flags |= XFS_SBF_READONLY;
1374 			if (!XFS_SB_VERSION_HASSHARED(sb))
1375 				XFS_SB_VERSION_ADDSHARED(sb);
1376 			xfs_fs_cmn_err(CE_NOTE, mp,
1377 				"Unmounting, marking shared read-only");
1378 		}
1379 
1380 		XFS_BUF_UNDONE(sbp);
1381 		XFS_BUF_UNREAD(sbp);
1382 		XFS_BUF_UNDELAYWRITE(sbp);
1383 		XFS_BUF_WRITE(sbp);
1384 		XFS_BUF_UNASYNC(sbp);
1385 		ASSERT(XFS_BUF_TARGET(sbp) == mp->m_ddev_targp);
1386 		xfsbdstrat(mp, sbp);
1387 		/* Nevermind errors we might get here. */
1388 		error = xfs_iowait(sbp);
1389 		if (error)
1390 			xfs_ioerror_alert("xfs_unmountfs_writesb",
1391 					  mp, sbp, XFS_BUF_ADDR(sbp));
1392 		if (error && mp->m_mk_sharedro)
1393 			xfs_fs_cmn_err(CE_ALERT, mp, "Superblock write error detected while unmounting.  Filesystem may not be marked shared readonly");
1394 		xfs_buf_relse(sbp);
1395 	}
1396 	return error;
1397 }
1398 
1399 /*
1400  * xfs_mod_sb() can be used to copy arbitrary changes to the
1401  * in-core superblock into the superblock buffer to be logged.
1402  * It does not provide the higher level of locking that is
1403  * needed to protect the in-core superblock from concurrent
1404  * access.
1405  */
1406 void
1407 xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
1408 {
1409 	xfs_buf_t	*bp;
1410 	int		first;
1411 	int		last;
1412 	xfs_mount_t	*mp;
1413 	xfs_sb_t	*sbp;
1414 	xfs_sb_field_t	f;
1415 
1416 	ASSERT(fields);
1417 	if (!fields)
1418 		return;
1419 	mp = tp->t_mountp;
1420 	bp = xfs_trans_getsb(tp, mp, 0);
1421 	sbp = XFS_BUF_TO_SBP(bp);
1422 	first = sizeof(xfs_sb_t);
1423 	last = 0;
1424 
1425 	/* translate/copy */
1426 
1427 	xfs_xlatesb(XFS_BUF_PTR(bp), &(mp->m_sb), -1, fields);
1428 
1429 	/* find modified range */
1430 
1431 	f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
1432 	ASSERT((1LL << f) & XFS_SB_MOD_BITS);
1433 	first = xfs_sb_info[f].offset;
1434 
1435 	f = (xfs_sb_field_t)xfs_highbit64((__uint64_t)fields);
1436 	ASSERT((1LL << f) & XFS_SB_MOD_BITS);
1437 	last = xfs_sb_info[f + 1].offset - 1;
1438 
1439 	xfs_trans_log_buf(tp, bp, first, last);
1440 }
1441 
1442 
1443 /*
1444  * xfs_mod_incore_sb_unlocked() is a utility routine common used to apply
1445  * a delta to a specified field in the in-core superblock.  Simply
1446  * switch on the field indicated and apply the delta to that field.
1447  * Fields are not allowed to dip below zero, so if the delta would
1448  * do this do not apply it and return EINVAL.
1449  *
1450  * The SB_LOCK must be held when this routine is called.
1451  */
1452 int
1453 xfs_mod_incore_sb_unlocked(
1454 	xfs_mount_t	*mp,
1455 	xfs_sb_field_t	field,
1456 	int64_t		delta,
1457 	int		rsvd)
1458 {
1459 	int		scounter;	/* short counter for 32 bit fields */
1460 	long long	lcounter;	/* long counter for 64 bit fields */
1461 	long long	res_used, rem;
1462 
1463 	/*
1464 	 * With the in-core superblock spin lock held, switch
1465 	 * on the indicated field.  Apply the delta to the
1466 	 * proper field.  If the fields value would dip below
1467 	 * 0, then do not apply the delta and return EINVAL.
1468 	 */
1469 	switch (field) {
1470 	case XFS_SBS_ICOUNT:
1471 		lcounter = (long long)mp->m_sb.sb_icount;
1472 		lcounter += delta;
1473 		if (lcounter < 0) {
1474 			ASSERT(0);
1475 			return XFS_ERROR(EINVAL);
1476 		}
1477 		mp->m_sb.sb_icount = lcounter;
1478 		return 0;
1479 	case XFS_SBS_IFREE:
1480 		lcounter = (long long)mp->m_sb.sb_ifree;
1481 		lcounter += delta;
1482 		if (lcounter < 0) {
1483 			ASSERT(0);
1484 			return XFS_ERROR(EINVAL);
1485 		}
1486 		mp->m_sb.sb_ifree = lcounter;
1487 		return 0;
1488 	case XFS_SBS_FDBLOCKS:
1489 		lcounter = (long long)
1490 			mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
1491 		res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
1492 
1493 		if (delta > 0) {		/* Putting blocks back */
1494 			if (res_used > delta) {
1495 				mp->m_resblks_avail += delta;
1496 			} else {
1497 				rem = delta - res_used;
1498 				mp->m_resblks_avail = mp->m_resblks;
1499 				lcounter += rem;
1500 			}
1501 		} else {				/* Taking blocks away */
1502 
1503 			lcounter += delta;
1504 
1505 		/*
1506 		 * If were out of blocks, use any available reserved blocks if
1507 		 * were allowed to.
1508 		 */
1509 
1510 			if (lcounter < 0) {
1511 				if (rsvd) {
1512 					lcounter = (long long)mp->m_resblks_avail + delta;
1513 					if (lcounter < 0) {
1514 						return XFS_ERROR(ENOSPC);
1515 					}
1516 					mp->m_resblks_avail = lcounter;
1517 					return 0;
1518 				} else {	/* not reserved */
1519 					return XFS_ERROR(ENOSPC);
1520 				}
1521 			}
1522 		}
1523 
1524 		mp->m_sb.sb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
1525 		return 0;
1526 	case XFS_SBS_FREXTENTS:
1527 		lcounter = (long long)mp->m_sb.sb_frextents;
1528 		lcounter += delta;
1529 		if (lcounter < 0) {
1530 			return XFS_ERROR(ENOSPC);
1531 		}
1532 		mp->m_sb.sb_frextents = lcounter;
1533 		return 0;
1534 	case XFS_SBS_DBLOCKS:
1535 		lcounter = (long long)mp->m_sb.sb_dblocks;
1536 		lcounter += delta;
1537 		if (lcounter < 0) {
1538 			ASSERT(0);
1539 			return XFS_ERROR(EINVAL);
1540 		}
1541 		mp->m_sb.sb_dblocks = lcounter;
1542 		return 0;
1543 	case XFS_SBS_AGCOUNT:
1544 		scounter = mp->m_sb.sb_agcount;
1545 		scounter += delta;
1546 		if (scounter < 0) {
1547 			ASSERT(0);
1548 			return XFS_ERROR(EINVAL);
1549 		}
1550 		mp->m_sb.sb_agcount = scounter;
1551 		return 0;
1552 	case XFS_SBS_IMAX_PCT:
1553 		scounter = mp->m_sb.sb_imax_pct;
1554 		scounter += delta;
1555 		if (scounter < 0) {
1556 			ASSERT(0);
1557 			return XFS_ERROR(EINVAL);
1558 		}
1559 		mp->m_sb.sb_imax_pct = scounter;
1560 		return 0;
1561 	case XFS_SBS_REXTSIZE:
1562 		scounter = mp->m_sb.sb_rextsize;
1563 		scounter += delta;
1564 		if (scounter < 0) {
1565 			ASSERT(0);
1566 			return XFS_ERROR(EINVAL);
1567 		}
1568 		mp->m_sb.sb_rextsize = scounter;
1569 		return 0;
1570 	case XFS_SBS_RBMBLOCKS:
1571 		scounter = mp->m_sb.sb_rbmblocks;
1572 		scounter += delta;
1573 		if (scounter < 0) {
1574 			ASSERT(0);
1575 			return XFS_ERROR(EINVAL);
1576 		}
1577 		mp->m_sb.sb_rbmblocks = scounter;
1578 		return 0;
1579 	case XFS_SBS_RBLOCKS:
1580 		lcounter = (long long)mp->m_sb.sb_rblocks;
1581 		lcounter += delta;
1582 		if (lcounter < 0) {
1583 			ASSERT(0);
1584 			return XFS_ERROR(EINVAL);
1585 		}
1586 		mp->m_sb.sb_rblocks = lcounter;
1587 		return 0;
1588 	case XFS_SBS_REXTENTS:
1589 		lcounter = (long long)mp->m_sb.sb_rextents;
1590 		lcounter += delta;
1591 		if (lcounter < 0) {
1592 			ASSERT(0);
1593 			return XFS_ERROR(EINVAL);
1594 		}
1595 		mp->m_sb.sb_rextents = lcounter;
1596 		return 0;
1597 	case XFS_SBS_REXTSLOG:
1598 		scounter = mp->m_sb.sb_rextslog;
1599 		scounter += delta;
1600 		if (scounter < 0) {
1601 			ASSERT(0);
1602 			return XFS_ERROR(EINVAL);
1603 		}
1604 		mp->m_sb.sb_rextslog = scounter;
1605 		return 0;
1606 	default:
1607 		ASSERT(0);
1608 		return XFS_ERROR(EINVAL);
1609 	}
1610 }
1611 
1612 /*
1613  * xfs_mod_incore_sb() is used to change a field in the in-core
1614  * superblock structure by the specified delta.  This modification
1615  * is protected by the SB_LOCK.  Just use the xfs_mod_incore_sb_unlocked()
1616  * routine to do the work.
1617  */
1618 int
1619 xfs_mod_incore_sb(
1620 	xfs_mount_t	*mp,
1621 	xfs_sb_field_t	field,
1622 	int64_t		delta,
1623 	int		rsvd)
1624 {
1625 	unsigned long	s;
1626 	int	status;
1627 
1628 	/* check for per-cpu counters */
1629 	switch (field) {
1630 #ifdef HAVE_PERCPU_SB
1631 	case XFS_SBS_ICOUNT:
1632 	case XFS_SBS_IFREE:
1633 	case XFS_SBS_FDBLOCKS:
1634 		if (!(mp->m_flags & XFS_MOUNT_NO_PERCPU_SB)) {
1635 			status = xfs_icsb_modify_counters(mp, field,
1636 							delta, rsvd);
1637 			break;
1638 		}
1639 		/* FALLTHROUGH */
1640 #endif
1641 	default:
1642 		s = XFS_SB_LOCK(mp);
1643 		status = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
1644 		XFS_SB_UNLOCK(mp, s);
1645 		break;
1646 	}
1647 
1648 	return status;
1649 }
1650 
1651 /*
1652  * xfs_mod_incore_sb_batch() is used to change more than one field
1653  * in the in-core superblock structure at a time.  This modification
1654  * is protected by a lock internal to this module.  The fields and
1655  * changes to those fields are specified in the array of xfs_mod_sb
1656  * structures passed in.
1657  *
1658  * Either all of the specified deltas will be applied or none of
1659  * them will.  If any modified field dips below 0, then all modifications
1660  * will be backed out and EINVAL will be returned.
1661  */
1662 int
1663 xfs_mod_incore_sb_batch(xfs_mount_t *mp, xfs_mod_sb_t *msb, uint nmsb, int rsvd)
1664 {
1665 	unsigned long	s;
1666 	int		status=0;
1667 	xfs_mod_sb_t	*msbp;
1668 
1669 	/*
1670 	 * Loop through the array of mod structures and apply each
1671 	 * individually.  If any fail, then back out all those
1672 	 * which have already been applied.  Do all of this within
1673 	 * the scope of the SB_LOCK so that all of the changes will
1674 	 * be atomic.
1675 	 */
1676 	s = XFS_SB_LOCK(mp);
1677 	msbp = &msb[0];
1678 	for (msbp = &msbp[0]; msbp < (msb + nmsb); msbp++) {
1679 		/*
1680 		 * Apply the delta at index n.  If it fails, break
1681 		 * from the loop so we'll fall into the undo loop
1682 		 * below.
1683 		 */
1684 		switch (msbp->msb_field) {
1685 #ifdef HAVE_PERCPU_SB
1686 		case XFS_SBS_ICOUNT:
1687 		case XFS_SBS_IFREE:
1688 		case XFS_SBS_FDBLOCKS:
1689 			if (!(mp->m_flags & XFS_MOUNT_NO_PERCPU_SB)) {
1690 				XFS_SB_UNLOCK(mp, s);
1691 				status = xfs_icsb_modify_counters(mp,
1692 							msbp->msb_field,
1693 							msbp->msb_delta, rsvd);
1694 				s = XFS_SB_LOCK(mp);
1695 				break;
1696 			}
1697 			/* FALLTHROUGH */
1698 #endif
1699 		default:
1700 			status = xfs_mod_incore_sb_unlocked(mp,
1701 						msbp->msb_field,
1702 						msbp->msb_delta, rsvd);
1703 			break;
1704 		}
1705 
1706 		if (status != 0) {
1707 			break;
1708 		}
1709 	}
1710 
1711 	/*
1712 	 * If we didn't complete the loop above, then back out
1713 	 * any changes made to the superblock.  If you add code
1714 	 * between the loop above and here, make sure that you
1715 	 * preserve the value of status. Loop back until
1716 	 * we step below the beginning of the array.  Make sure
1717 	 * we don't touch anything back there.
1718 	 */
1719 	if (status != 0) {
1720 		msbp--;
1721 		while (msbp >= msb) {
1722 			switch (msbp->msb_field) {
1723 #ifdef HAVE_PERCPU_SB
1724 			case XFS_SBS_ICOUNT:
1725 			case XFS_SBS_IFREE:
1726 			case XFS_SBS_FDBLOCKS:
1727 				if (!(mp->m_flags & XFS_MOUNT_NO_PERCPU_SB)) {
1728 					XFS_SB_UNLOCK(mp, s);
1729 					status = xfs_icsb_modify_counters(mp,
1730 							msbp->msb_field,
1731 							-(msbp->msb_delta),
1732 							rsvd);
1733 					s = XFS_SB_LOCK(mp);
1734 					break;
1735 				}
1736 				/* FALLTHROUGH */
1737 #endif
1738 			default:
1739 				status = xfs_mod_incore_sb_unlocked(mp,
1740 							msbp->msb_field,
1741 							-(msbp->msb_delta),
1742 							rsvd);
1743 				break;
1744 			}
1745 			ASSERT(status == 0);
1746 			msbp--;
1747 		}
1748 	}
1749 	XFS_SB_UNLOCK(mp, s);
1750 	return status;
1751 }
1752 
1753 /*
1754  * xfs_getsb() is called to obtain the buffer for the superblock.
1755  * The buffer is returned locked and read in from disk.
1756  * The buffer should be released with a call to xfs_brelse().
1757  *
1758  * If the flags parameter is BUF_TRYLOCK, then we'll only return
1759  * the superblock buffer if it can be locked without sleeping.
1760  * If it can't then we'll return NULL.
1761  */
1762 xfs_buf_t *
1763 xfs_getsb(
1764 	xfs_mount_t	*mp,
1765 	int		flags)
1766 {
1767 	xfs_buf_t	*bp;
1768 
1769 	ASSERT(mp->m_sb_bp != NULL);
1770 	bp = mp->m_sb_bp;
1771 	if (flags & XFS_BUF_TRYLOCK) {
1772 		if (!XFS_BUF_CPSEMA(bp)) {
1773 			return NULL;
1774 		}
1775 	} else {
1776 		XFS_BUF_PSEMA(bp, PRIBIO);
1777 	}
1778 	XFS_BUF_HOLD(bp);
1779 	ASSERT(XFS_BUF_ISDONE(bp));
1780 	return bp;
1781 }
1782 
1783 /*
1784  * Used to free the superblock along various error paths.
1785  */
1786 void
1787 xfs_freesb(
1788 	xfs_mount_t	*mp)
1789 {
1790 	xfs_buf_t	*bp;
1791 
1792 	/*
1793 	 * Use xfs_getsb() so that the buffer will be locked
1794 	 * when we call xfs_buf_relse().
1795 	 */
1796 	bp = xfs_getsb(mp, 0);
1797 	XFS_BUF_UNMANAGE(bp);
1798 	xfs_buf_relse(bp);
1799 	mp->m_sb_bp = NULL;
1800 }
1801 
1802 /*
1803  * See if the UUID is unique among mounted XFS filesystems.
1804  * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
1805  */
1806 STATIC int
1807 xfs_uuid_mount(
1808 	xfs_mount_t	*mp)
1809 {
1810 	if (uuid_is_nil(&mp->m_sb.sb_uuid)) {
1811 		cmn_err(CE_WARN,
1812 			"XFS: Filesystem %s has nil UUID - can't mount",
1813 			mp->m_fsname);
1814 		return -1;
1815 	}
1816 	if (!uuid_table_insert(&mp->m_sb.sb_uuid)) {
1817 		cmn_err(CE_WARN,
1818 			"XFS: Filesystem %s has duplicate UUID - can't mount",
1819 			mp->m_fsname);
1820 		return -1;
1821 	}
1822 	return 0;
1823 }
1824 
1825 /*
1826  * Remove filesystem from the UUID table.
1827  */
1828 STATIC void
1829 xfs_uuid_unmount(
1830 	xfs_mount_t	*mp)
1831 {
1832 	uuid_table_remove(&mp->m_sb.sb_uuid);
1833 }
1834 
1835 /*
1836  * Used to log changes to the superblock unit and width fields which could
1837  * be altered by the mount options. Only the first superblock is updated.
1838  */
1839 STATIC void
1840 xfs_mount_log_sbunit(
1841 	xfs_mount_t	*mp,
1842 	__int64_t	fields)
1843 {
1844 	xfs_trans_t	*tp;
1845 
1846 	ASSERT(fields & (XFS_SB_UNIT|XFS_SB_WIDTH|XFS_SB_UUID));
1847 
1848 	tp = xfs_trans_alloc(mp, XFS_TRANS_SB_UNIT);
1849 	if (xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
1850 				XFS_DEFAULT_LOG_COUNT)) {
1851 		xfs_trans_cancel(tp, 0);
1852 		return;
1853 	}
1854 	xfs_mod_sb(tp, fields);
1855 	xfs_trans_commit(tp, 0);
1856 }
1857 
1858 
1859 #ifdef HAVE_PERCPU_SB
1860 /*
1861  * Per-cpu incore superblock counters
1862  *
1863  * Simple concept, difficult implementation
1864  *
1865  * Basically, replace the incore superblock counters with a distributed per cpu
1866  * counter for contended fields (e.g.  free block count).
1867  *
1868  * Difficulties arise in that the incore sb is used for ENOSPC checking, and
1869  * hence needs to be accurately read when we are running low on space. Hence
1870  * there is a method to enable and disable the per-cpu counters based on how
1871  * much "stuff" is available in them.
1872  *
1873  * Basically, a counter is enabled if there is enough free resource to justify
1874  * running a per-cpu fast-path. If the per-cpu counter runs out (i.e. a local
1875  * ENOSPC), then we disable the counters to synchronise all callers and
1876  * re-distribute the available resources.
1877  *
1878  * If, once we redistributed the available resources, we still get a failure,
1879  * we disable the per-cpu counter and go through the slow path.
1880  *
1881  * The slow path is the current xfs_mod_incore_sb() function.  This means that
1882  * when we disable a per-cpu counter, we need to drain it's resources back to
1883  * the global superblock. We do this after disabling the counter to prevent
1884  * more threads from queueing up on the counter.
1885  *
1886  * Essentially, this means that we still need a lock in the fast path to enable
1887  * synchronisation between the global counters and the per-cpu counters. This
1888  * is not a problem because the lock will be local to a CPU almost all the time
1889  * and have little contention except when we get to ENOSPC conditions.
1890  *
1891  * Basically, this lock becomes a barrier that enables us to lock out the fast
1892  * path while we do things like enabling and disabling counters and
1893  * synchronising the counters.
1894  *
1895  * Locking rules:
1896  *
1897  * 	1. XFS_SB_LOCK() before picking up per-cpu locks
1898  * 	2. per-cpu locks always picked up via for_each_online_cpu() order
1899  * 	3. accurate counter sync requires XFS_SB_LOCK + per cpu locks
1900  * 	4. modifying per-cpu counters requires holding per-cpu lock
1901  * 	5. modifying global counters requires holding XFS_SB_LOCK
1902  *	6. enabling or disabling a counter requires holding the XFS_SB_LOCK
1903  *	   and _none_ of the per-cpu locks.
1904  *
1905  * Disabled counters are only ever re-enabled by a balance operation
1906  * that results in more free resources per CPU than a given threshold.
1907  * To ensure counters don't remain disabled, they are rebalanced when
1908  * the global resource goes above a higher threshold (i.e. some hysteresis
1909  * is present to prevent thrashing).
1910  */
1911 
1912 #ifdef CONFIG_HOTPLUG_CPU
1913 /*
1914  * hot-plug CPU notifier support.
1915  *
1916  * We need a notifier per filesystem as we need to be able to identify
1917  * the filesystem to balance the counters out. This is achieved by
1918  * having a notifier block embedded in the xfs_mount_t and doing pointer
1919  * magic to get the mount pointer from the notifier block address.
1920  */
1921 STATIC int
1922 xfs_icsb_cpu_notify(
1923 	struct notifier_block *nfb,
1924 	unsigned long action,
1925 	void *hcpu)
1926 {
1927 	xfs_icsb_cnts_t *cntp;
1928 	xfs_mount_t	*mp;
1929 	int		s;
1930 
1931 	mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier);
1932 	cntp = (xfs_icsb_cnts_t *)
1933 			per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu);
1934 	switch (action) {
1935 	case CPU_UP_PREPARE:
1936 	case CPU_UP_PREPARE_FROZEN:
1937 		/* Easy Case - initialize the area and locks, and
1938 		 * then rebalance when online does everything else for us. */
1939 		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
1940 		break;
1941 	case CPU_ONLINE:
1942 	case CPU_ONLINE_FROZEN:
1943 		xfs_icsb_lock(mp);
1944 		xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0, 0);
1945 		xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0, 0);
1946 		xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0, 0);
1947 		xfs_icsb_unlock(mp);
1948 		break;
1949 	case CPU_DEAD:
1950 	case CPU_DEAD_FROZEN:
1951 		/* Disable all the counters, then fold the dead cpu's
1952 		 * count into the total on the global superblock and
1953 		 * re-enable the counters. */
1954 		xfs_icsb_lock(mp);
1955 		s = XFS_SB_LOCK(mp);
1956 		xfs_icsb_disable_counter(mp, XFS_SBS_ICOUNT);
1957 		xfs_icsb_disable_counter(mp, XFS_SBS_IFREE);
1958 		xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS);
1959 
1960 		mp->m_sb.sb_icount += cntp->icsb_icount;
1961 		mp->m_sb.sb_ifree += cntp->icsb_ifree;
1962 		mp->m_sb.sb_fdblocks += cntp->icsb_fdblocks;
1963 
1964 		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
1965 
1966 		xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT,
1967 					 XFS_ICSB_SB_LOCKED, 0);
1968 		xfs_icsb_balance_counter(mp, XFS_SBS_IFREE,
1969 					 XFS_ICSB_SB_LOCKED, 0);
1970 		xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS,
1971 					 XFS_ICSB_SB_LOCKED, 0);
1972 		XFS_SB_UNLOCK(mp, s);
1973 		xfs_icsb_unlock(mp);
1974 		break;
1975 	}
1976 
1977 	return NOTIFY_OK;
1978 }
1979 #endif /* CONFIG_HOTPLUG_CPU */
1980 
1981 int
1982 xfs_icsb_init_counters(
1983 	xfs_mount_t	*mp)
1984 {
1985 	xfs_icsb_cnts_t *cntp;
1986 	int		i;
1987 
1988 	mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t);
1989 	if (mp->m_sb_cnts == NULL)
1990 		return -ENOMEM;
1991 
1992 #ifdef CONFIG_HOTPLUG_CPU
1993 	mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify;
1994 	mp->m_icsb_notifier.priority = 0;
1995 	register_hotcpu_notifier(&mp->m_icsb_notifier);
1996 #endif /* CONFIG_HOTPLUG_CPU */
1997 
1998 	for_each_online_cpu(i) {
1999 		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
2000 		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
2001 	}
2002 
2003 	mutex_init(&mp->m_icsb_mutex);
2004 
2005 	/*
2006 	 * start with all counters disabled so that the
2007 	 * initial balance kicks us off correctly
2008 	 */
2009 	mp->m_icsb_counters = -1;
2010 	return 0;
2011 }
2012 
2013 void
2014 xfs_icsb_reinit_counters(
2015 	xfs_mount_t	*mp)
2016 {
2017 	xfs_icsb_lock(mp);
2018 	/*
2019 	 * start with all counters disabled so that the
2020 	 * initial balance kicks us off correctly
2021 	 */
2022 	mp->m_icsb_counters = -1;
2023 	xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0, 0);
2024 	xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0, 0);
2025 	xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0, 0);
2026 	xfs_icsb_unlock(mp);
2027 }
2028 
2029 STATIC void
2030 xfs_icsb_destroy_counters(
2031 	xfs_mount_t	*mp)
2032 {
2033 	if (mp->m_sb_cnts) {
2034 		unregister_hotcpu_notifier(&mp->m_icsb_notifier);
2035 		free_percpu(mp->m_sb_cnts);
2036 	}
2037 	mutex_destroy(&mp->m_icsb_mutex);
2038 }
2039 
2040 STATIC_INLINE void
2041 xfs_icsb_lock_cntr(
2042 	xfs_icsb_cnts_t	*icsbp)
2043 {
2044 	while (test_and_set_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags)) {
2045 		ndelay(1000);
2046 	}
2047 }
2048 
2049 STATIC_INLINE void
2050 xfs_icsb_unlock_cntr(
2051 	xfs_icsb_cnts_t	*icsbp)
2052 {
2053 	clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags);
2054 }
2055 
2056 
2057 STATIC_INLINE void
2058 xfs_icsb_lock_all_counters(
2059 	xfs_mount_t	*mp)
2060 {
2061 	xfs_icsb_cnts_t *cntp;
2062 	int		i;
2063 
2064 	for_each_online_cpu(i) {
2065 		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
2066 		xfs_icsb_lock_cntr(cntp);
2067 	}
2068 }
2069 
2070 STATIC_INLINE void
2071 xfs_icsb_unlock_all_counters(
2072 	xfs_mount_t	*mp)
2073 {
2074 	xfs_icsb_cnts_t *cntp;
2075 	int		i;
2076 
2077 	for_each_online_cpu(i) {
2078 		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
2079 		xfs_icsb_unlock_cntr(cntp);
2080 	}
2081 }
2082 
2083 STATIC void
2084 xfs_icsb_count(
2085 	xfs_mount_t	*mp,
2086 	xfs_icsb_cnts_t	*cnt,
2087 	int		flags)
2088 {
2089 	xfs_icsb_cnts_t *cntp;
2090 	int		i;
2091 
2092 	memset(cnt, 0, sizeof(xfs_icsb_cnts_t));
2093 
2094 	if (!(flags & XFS_ICSB_LAZY_COUNT))
2095 		xfs_icsb_lock_all_counters(mp);
2096 
2097 	for_each_online_cpu(i) {
2098 		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
2099 		cnt->icsb_icount += cntp->icsb_icount;
2100 		cnt->icsb_ifree += cntp->icsb_ifree;
2101 		cnt->icsb_fdblocks += cntp->icsb_fdblocks;
2102 	}
2103 
2104 	if (!(flags & XFS_ICSB_LAZY_COUNT))
2105 		xfs_icsb_unlock_all_counters(mp);
2106 }
2107 
2108 STATIC int
2109 xfs_icsb_counter_disabled(
2110 	xfs_mount_t	*mp,
2111 	xfs_sb_field_t	field)
2112 {
2113 	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
2114 	return test_bit(field, &mp->m_icsb_counters);
2115 }
2116 
2117 STATIC int
2118 xfs_icsb_disable_counter(
2119 	xfs_mount_t	*mp,
2120 	xfs_sb_field_t	field)
2121 {
2122 	xfs_icsb_cnts_t	cnt;
2123 
2124 	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
2125 
2126 	/*
2127 	 * If we are already disabled, then there is nothing to do
2128 	 * here. We check before locking all the counters to avoid
2129 	 * the expensive lock operation when being called in the
2130 	 * slow path and the counter is already disabled. This is
2131 	 * safe because the only time we set or clear this state is under
2132 	 * the m_icsb_mutex.
2133 	 */
2134 	if (xfs_icsb_counter_disabled(mp, field))
2135 		return 0;
2136 
2137 	xfs_icsb_lock_all_counters(mp);
2138 	if (!test_and_set_bit(field, &mp->m_icsb_counters)) {
2139 		/* drain back to superblock */
2140 
2141 		xfs_icsb_count(mp, &cnt, XFS_ICSB_SB_LOCKED|XFS_ICSB_LAZY_COUNT);
2142 		switch(field) {
2143 		case XFS_SBS_ICOUNT:
2144 			mp->m_sb.sb_icount = cnt.icsb_icount;
2145 			break;
2146 		case XFS_SBS_IFREE:
2147 			mp->m_sb.sb_ifree = cnt.icsb_ifree;
2148 			break;
2149 		case XFS_SBS_FDBLOCKS:
2150 			mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
2151 			break;
2152 		default:
2153 			BUG();
2154 		}
2155 	}
2156 
2157 	xfs_icsb_unlock_all_counters(mp);
2158 
2159 	return 0;
2160 }
2161 
2162 STATIC void
2163 xfs_icsb_enable_counter(
2164 	xfs_mount_t	*mp,
2165 	xfs_sb_field_t	field,
2166 	uint64_t	count,
2167 	uint64_t	resid)
2168 {
2169 	xfs_icsb_cnts_t	*cntp;
2170 	int		i;
2171 
2172 	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
2173 
2174 	xfs_icsb_lock_all_counters(mp);
2175 	for_each_online_cpu(i) {
2176 		cntp = per_cpu_ptr(mp->m_sb_cnts, i);
2177 		switch (field) {
2178 		case XFS_SBS_ICOUNT:
2179 			cntp->icsb_icount = count + resid;
2180 			break;
2181 		case XFS_SBS_IFREE:
2182 			cntp->icsb_ifree = count + resid;
2183 			break;
2184 		case XFS_SBS_FDBLOCKS:
2185 			cntp->icsb_fdblocks = count + resid;
2186 			break;
2187 		default:
2188 			BUG();
2189 			break;
2190 		}
2191 		resid = 0;
2192 	}
2193 	clear_bit(field, &mp->m_icsb_counters);
2194 	xfs_icsb_unlock_all_counters(mp);
2195 }
2196 
2197 void
2198 xfs_icsb_sync_counters_flags(
2199 	xfs_mount_t	*mp,
2200 	int		flags)
2201 {
2202 	xfs_icsb_cnts_t	cnt;
2203 	int		s;
2204 
2205 	/* Pass 1: lock all counters */
2206 	if ((flags & XFS_ICSB_SB_LOCKED) == 0)
2207 		s = XFS_SB_LOCK(mp);
2208 
2209 	xfs_icsb_count(mp, &cnt, flags);
2210 
2211 	/* Step 3: update mp->m_sb fields */
2212 	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_ICOUNT))
2213 		mp->m_sb.sb_icount = cnt.icsb_icount;
2214 	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_IFREE))
2215 		mp->m_sb.sb_ifree = cnt.icsb_ifree;
2216 	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_FDBLOCKS))
2217 		mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
2218 
2219 	if ((flags & XFS_ICSB_SB_LOCKED) == 0)
2220 		XFS_SB_UNLOCK(mp, s);
2221 }
2222 
2223 /*
2224  * Accurate update of per-cpu counters to incore superblock
2225  */
2226 STATIC void
2227 xfs_icsb_sync_counters(
2228 	xfs_mount_t	*mp)
2229 {
2230 	xfs_icsb_sync_counters_flags(mp, 0);
2231 }
2232 
2233 /*
2234  * Balance and enable/disable counters as necessary.
2235  *
2236  * Thresholds for re-enabling counters are somewhat magic.  inode counts are
2237  * chosen to be the same number as single on disk allocation chunk per CPU, and
2238  * free blocks is something far enough zero that we aren't going thrash when we
2239  * get near ENOSPC. We also need to supply a minimum we require per cpu to
2240  * prevent looping endlessly when xfs_alloc_space asks for more than will
2241  * be distributed to a single CPU but each CPU has enough blocks to be
2242  * reenabled.
2243  *
2244  * Note that we can be called when counters are already disabled.
2245  * xfs_icsb_disable_counter() optimises the counter locking in this case to
2246  * prevent locking every per-cpu counter needlessly.
2247  */
2248 
2249 #define XFS_ICSB_INO_CNTR_REENABLE	(uint64_t)64
2250 #define XFS_ICSB_FDBLK_CNTR_REENABLE(mp) \
2251 		(uint64_t)(512 + XFS_ALLOC_SET_ASIDE(mp))
2252 STATIC void
2253 xfs_icsb_balance_counter(
2254 	xfs_mount_t	*mp,
2255 	xfs_sb_field_t  field,
2256 	int		flags,
2257 	int		min_per_cpu)
2258 {
2259 	uint64_t	count, resid;
2260 	int		weight = num_online_cpus();
2261 	int		s;
2262 	uint64_t	min = (uint64_t)min_per_cpu;
2263 
2264 	if (!(flags & XFS_ICSB_SB_LOCKED))
2265 		s = XFS_SB_LOCK(mp);
2266 
2267 	/* disable counter and sync counter */
2268 	xfs_icsb_disable_counter(mp, field);
2269 
2270 	/* update counters  - first CPU gets residual*/
2271 	switch (field) {
2272 	case XFS_SBS_ICOUNT:
2273 		count = mp->m_sb.sb_icount;
2274 		resid = do_div(count, weight);
2275 		if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
2276 			goto out;
2277 		break;
2278 	case XFS_SBS_IFREE:
2279 		count = mp->m_sb.sb_ifree;
2280 		resid = do_div(count, weight);
2281 		if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
2282 			goto out;
2283 		break;
2284 	case XFS_SBS_FDBLOCKS:
2285 		count = mp->m_sb.sb_fdblocks;
2286 		resid = do_div(count, weight);
2287 		if (count < max(min, XFS_ICSB_FDBLK_CNTR_REENABLE(mp)))
2288 			goto out;
2289 		break;
2290 	default:
2291 		BUG();
2292 		count = resid = 0;	/* quiet, gcc */
2293 		break;
2294 	}
2295 
2296 	xfs_icsb_enable_counter(mp, field, count, resid);
2297 out:
2298 	if (!(flags & XFS_ICSB_SB_LOCKED))
2299 		XFS_SB_UNLOCK(mp, s);
2300 }
2301 
2302 int
2303 xfs_icsb_modify_counters(
2304 	xfs_mount_t	*mp,
2305 	xfs_sb_field_t	field,
2306 	int64_t		delta,
2307 	int		rsvd)
2308 {
2309 	xfs_icsb_cnts_t	*icsbp;
2310 	long long	lcounter;	/* long counter for 64 bit fields */
2311 	int		cpu, ret = 0, s;
2312 
2313 	might_sleep();
2314 again:
2315 	cpu = get_cpu();
2316 	icsbp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, cpu);
2317 
2318 	/*
2319 	 * if the counter is disabled, go to slow path
2320 	 */
2321 	if (unlikely(xfs_icsb_counter_disabled(mp, field)))
2322 		goto slow_path;
2323 	xfs_icsb_lock_cntr(icsbp);
2324 	if (unlikely(xfs_icsb_counter_disabled(mp, field))) {
2325 		xfs_icsb_unlock_cntr(icsbp);
2326 		goto slow_path;
2327 	}
2328 
2329 	switch (field) {
2330 	case XFS_SBS_ICOUNT:
2331 		lcounter = icsbp->icsb_icount;
2332 		lcounter += delta;
2333 		if (unlikely(lcounter < 0))
2334 			goto balance_counter;
2335 		icsbp->icsb_icount = lcounter;
2336 		break;
2337 
2338 	case XFS_SBS_IFREE:
2339 		lcounter = icsbp->icsb_ifree;
2340 		lcounter += delta;
2341 		if (unlikely(lcounter < 0))
2342 			goto balance_counter;
2343 		icsbp->icsb_ifree = lcounter;
2344 		break;
2345 
2346 	case XFS_SBS_FDBLOCKS:
2347 		BUG_ON((mp->m_resblks - mp->m_resblks_avail) != 0);
2348 
2349 		lcounter = icsbp->icsb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
2350 		lcounter += delta;
2351 		if (unlikely(lcounter < 0))
2352 			goto balance_counter;
2353 		icsbp->icsb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
2354 		break;
2355 	default:
2356 		BUG();
2357 		break;
2358 	}
2359 	xfs_icsb_unlock_cntr(icsbp);
2360 	put_cpu();
2361 	return 0;
2362 
2363 slow_path:
2364 	put_cpu();
2365 
2366 	/*
2367 	 * serialise with a mutex so we don't burn lots of cpu on
2368 	 * the superblock lock. We still need to hold the superblock
2369 	 * lock, however, when we modify the global structures.
2370 	 */
2371 	xfs_icsb_lock(mp);
2372 
2373 	/*
2374 	 * Now running atomically.
2375 	 *
2376 	 * If the counter is enabled, someone has beaten us to rebalancing.
2377 	 * Drop the lock and try again in the fast path....
2378 	 */
2379 	if (!(xfs_icsb_counter_disabled(mp, field))) {
2380 		xfs_icsb_unlock(mp);
2381 		goto again;
2382 	}
2383 
2384 	/*
2385 	 * The counter is currently disabled. Because we are
2386 	 * running atomically here, we know a rebalance cannot
2387 	 * be in progress. Hence we can go straight to operating
2388 	 * on the global superblock. We do not call xfs_mod_incore_sb()
2389 	 * here even though we need to get the SB_LOCK. Doing so
2390 	 * will cause us to re-enter this function and deadlock.
2391 	 * Hence we get the SB_LOCK ourselves and then call
2392 	 * xfs_mod_incore_sb_unlocked() as the unlocked path operates
2393 	 * directly on the global counters.
2394 	 */
2395 	s = XFS_SB_LOCK(mp);
2396 	ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
2397 	XFS_SB_UNLOCK(mp, s);
2398 
2399 	/*
2400 	 * Now that we've modified the global superblock, we
2401 	 * may be able to re-enable the distributed counters
2402 	 * (e.g. lots of space just got freed). After that
2403 	 * we are done.
2404 	 */
2405 	if (ret != ENOSPC)
2406 		xfs_icsb_balance_counter(mp, field, 0, 0);
2407 	xfs_icsb_unlock(mp);
2408 	return ret;
2409 
2410 balance_counter:
2411 	xfs_icsb_unlock_cntr(icsbp);
2412 	put_cpu();
2413 
2414 	/*
2415 	 * We may have multiple threads here if multiple per-cpu
2416 	 * counters run dry at the same time. This will mean we can
2417 	 * do more balances than strictly necessary but it is not
2418 	 * the common slowpath case.
2419 	 */
2420 	xfs_icsb_lock(mp);
2421 
2422 	/*
2423 	 * running atomically.
2424 	 *
2425 	 * This will leave the counter in the correct state for future
2426 	 * accesses. After the rebalance, we simply try again and our retry
2427 	 * will either succeed through the fast path or slow path without
2428 	 * another balance operation being required.
2429 	 */
2430 	xfs_icsb_balance_counter(mp, field, 0, delta);
2431 	xfs_icsb_unlock(mp);
2432 	goto again;
2433 }
2434 
2435 #endif
2436