xref: /linux/fs/xfs/xfs_mount.c (revision ccea15f45eb0ab12d658f88b5d4be005cb2bb1a7)
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_dir.h"
28 #include "xfs_dir2.h"
29 #include "xfs_dmapi.h"
30 #include "xfs_mount.h"
31 #include "xfs_bmap_btree.h"
32 #include "xfs_alloc_btree.h"
33 #include "xfs_ialloc_btree.h"
34 #include "xfs_dir_sf.h"
35 #include "xfs_dir2_sf.h"
36 #include "xfs_attr_sf.h"
37 #include "xfs_dinode.h"
38 #include "xfs_inode.h"
39 #include "xfs_btree.h"
40 #include "xfs_ialloc.h"
41 #include "xfs_alloc.h"
42 #include "xfs_rtalloc.h"
43 #include "xfs_bmap.h"
44 #include "xfs_error.h"
45 #include "xfs_rw.h"
46 #include "xfs_quota.h"
47 #include "xfs_fsops.h"
48 
49 STATIC void	xfs_mount_log_sbunit(xfs_mount_t *, __int64_t);
50 STATIC int	xfs_uuid_mount(xfs_mount_t *);
51 STATIC void	xfs_uuid_unmount(xfs_mount_t *mp);
52 STATIC void	xfs_unmountfs_wait(xfs_mount_t *);
53 
54 
55 #ifdef HAVE_PERCPU_SB
56 STATIC void	xfs_icsb_destroy_counters(xfs_mount_t *);
57 STATIC void	xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t, int);
58 STATIC void	xfs_icsb_sync_counters(xfs_mount_t *);
59 STATIC int	xfs_icsb_modify_counters(xfs_mount_t *, xfs_sb_field_t,
60 						int, int);
61 STATIC int	xfs_icsb_modify_counters_locked(xfs_mount_t *, xfs_sb_field_t,
62 						int, int);
63 STATIC int	xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);
64 
65 #else
66 
67 #define xfs_icsb_destroy_counters(mp)			do { } while (0)
68 #define xfs_icsb_balance_counter(mp, a, b)		do { } while (0)
69 #define xfs_icsb_sync_counters(mp)			do { } while (0)
70 #define xfs_icsb_modify_counters(mp, a, b, c)		do { } while (0)
71 #define xfs_icsb_modify_counters_locked(mp, a, b, c)	do { } while (0)
72 
73 #endif
74 
75 static const struct {
76 	short offset;
77 	short type;	/* 0 = integer
78 			 * 1 = binary / string (no translation)
79 			 */
80 } xfs_sb_info[] = {
81     { offsetof(xfs_sb_t, sb_magicnum),   0 },
82     { offsetof(xfs_sb_t, sb_blocksize),  0 },
83     { offsetof(xfs_sb_t, sb_dblocks),    0 },
84     { offsetof(xfs_sb_t, sb_rblocks),    0 },
85     { offsetof(xfs_sb_t, sb_rextents),   0 },
86     { offsetof(xfs_sb_t, sb_uuid),       1 },
87     { offsetof(xfs_sb_t, sb_logstart),   0 },
88     { offsetof(xfs_sb_t, sb_rootino),    0 },
89     { offsetof(xfs_sb_t, sb_rbmino),     0 },
90     { offsetof(xfs_sb_t, sb_rsumino),    0 },
91     { offsetof(xfs_sb_t, sb_rextsize),   0 },
92     { offsetof(xfs_sb_t, sb_agblocks),   0 },
93     { offsetof(xfs_sb_t, sb_agcount),    0 },
94     { offsetof(xfs_sb_t, sb_rbmblocks),  0 },
95     { offsetof(xfs_sb_t, sb_logblocks),  0 },
96     { offsetof(xfs_sb_t, sb_versionnum), 0 },
97     { offsetof(xfs_sb_t, sb_sectsize),   0 },
98     { offsetof(xfs_sb_t, sb_inodesize),  0 },
99     { offsetof(xfs_sb_t, sb_inopblock),  0 },
100     { offsetof(xfs_sb_t, sb_fname[0]),   1 },
101     { offsetof(xfs_sb_t, sb_blocklog),   0 },
102     { offsetof(xfs_sb_t, sb_sectlog),    0 },
103     { offsetof(xfs_sb_t, sb_inodelog),   0 },
104     { offsetof(xfs_sb_t, sb_inopblog),   0 },
105     { offsetof(xfs_sb_t, sb_agblklog),   0 },
106     { offsetof(xfs_sb_t, sb_rextslog),   0 },
107     { offsetof(xfs_sb_t, sb_inprogress), 0 },
108     { offsetof(xfs_sb_t, sb_imax_pct),   0 },
109     { offsetof(xfs_sb_t, sb_icount),     0 },
110     { offsetof(xfs_sb_t, sb_ifree),      0 },
111     { offsetof(xfs_sb_t, sb_fdblocks),   0 },
112     { offsetof(xfs_sb_t, sb_frextents),  0 },
113     { offsetof(xfs_sb_t, sb_uquotino),   0 },
114     { offsetof(xfs_sb_t, sb_gquotino),   0 },
115     { offsetof(xfs_sb_t, sb_qflags),     0 },
116     { offsetof(xfs_sb_t, sb_flags),      0 },
117     { offsetof(xfs_sb_t, sb_shared_vn),  0 },
118     { offsetof(xfs_sb_t, sb_inoalignmt), 0 },
119     { offsetof(xfs_sb_t, sb_unit),	 0 },
120     { offsetof(xfs_sb_t, sb_width),	 0 },
121     { offsetof(xfs_sb_t, sb_dirblklog),	 0 },
122     { offsetof(xfs_sb_t, sb_logsectlog), 0 },
123     { offsetof(xfs_sb_t, sb_logsectsize),0 },
124     { offsetof(xfs_sb_t, sb_logsunit),	 0 },
125     { offsetof(xfs_sb_t, sb_features2),	 0 },
126     { sizeof(xfs_sb_t),			 0 }
127 };
128 
129 /*
130  * Return a pointer to an initialized xfs_mount structure.
131  */
132 xfs_mount_t *
133 xfs_mount_init(void)
134 {
135 	xfs_mount_t *mp;
136 
137 	mp = kmem_zalloc(sizeof(xfs_mount_t), KM_SLEEP);
138 
139 	if (xfs_icsb_init_counters(mp)) {
140 		mp->m_flags |= XFS_MOUNT_NO_PERCPU_SB;
141 	}
142 
143 	AIL_LOCKINIT(&mp->m_ail_lock, "xfs_ail");
144 	spinlock_init(&mp->m_sb_lock, "xfs_sb");
145 	mutex_init(&mp->m_ilock);
146 	initnsema(&mp->m_growlock, 1, "xfs_grow");
147 	/*
148 	 * Initialize the AIL.
149 	 */
150 	xfs_trans_ail_init(mp);
151 
152 	atomic_set(&mp->m_active_trans, 0);
153 
154 	return mp;
155 }
156 
157 /*
158  * Free up the resources associated with a mount structure.  Assume that
159  * the structure was initially zeroed, so we can tell which fields got
160  * initialized.
161  */
162 void
163 xfs_mount_free(
164 	xfs_mount_t	*mp,
165 	int		remove_bhv)
166 {
167 	if (mp->m_ihash)
168 		xfs_ihash_free(mp);
169 	if (mp->m_chash)
170 		xfs_chash_free(mp);
171 
172 	if (mp->m_perag) {
173 		int	agno;
174 
175 		for (agno = 0; agno < mp->m_maxagi; agno++)
176 			if (mp->m_perag[agno].pagb_list)
177 				kmem_free(mp->m_perag[agno].pagb_list,
178 						sizeof(xfs_perag_busy_t) *
179 							XFS_PAGB_NUM_SLOTS);
180 		kmem_free(mp->m_perag,
181 			  sizeof(xfs_perag_t) * mp->m_sb.sb_agcount);
182 	}
183 
184 	AIL_LOCK_DESTROY(&mp->m_ail_lock);
185 	spinlock_destroy(&mp->m_sb_lock);
186 	mutex_destroy(&mp->m_ilock);
187 	freesema(&mp->m_growlock);
188 	if (mp->m_quotainfo)
189 		XFS_QM_DONE(mp);
190 
191 	if (mp->m_fsname != NULL)
192 		kmem_free(mp->m_fsname, mp->m_fsname_len);
193 	if (mp->m_rtname != NULL)
194 		kmem_free(mp->m_rtname, strlen(mp->m_rtname) + 1);
195 	if (mp->m_logname != NULL)
196 		kmem_free(mp->m_logname, strlen(mp->m_logname) + 1);
197 
198 	if (remove_bhv) {
199 		struct vfs	*vfsp = XFS_MTOVFS(mp);
200 
201 		bhv_remove_all_vfsops(vfsp, 0);
202 		VFS_REMOVEBHV(vfsp, &mp->m_bhv);
203 	}
204 
205 	xfs_icsb_destroy_counters(mp);
206 	kmem_free(mp, sizeof(xfs_mount_t));
207 }
208 
209 
210 /*
211  * Check the validity of the SB found.
212  */
213 STATIC int
214 xfs_mount_validate_sb(
215 	xfs_mount_t	*mp,
216 	xfs_sb_t	*sbp,
217 	int		flags)
218 {
219 	/*
220 	 * If the log device and data device have the
221 	 * same device number, the log is internal.
222 	 * Consequently, the sb_logstart should be non-zero.  If
223 	 * we have a zero sb_logstart in this case, we may be trying to mount
224 	 * a volume filesystem in a non-volume manner.
225 	 */
226 	if (sbp->sb_magicnum != XFS_SB_MAGIC) {
227 		xfs_fs_mount_cmn_err(flags, "bad magic number");
228 		return XFS_ERROR(EWRONGFS);
229 	}
230 
231 	if (!XFS_SB_GOOD_VERSION(sbp)) {
232 		xfs_fs_mount_cmn_err(flags, "bad version");
233 		return XFS_ERROR(EWRONGFS);
234 	}
235 
236 	if (unlikely(
237 	    sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {
238 		xfs_fs_mount_cmn_err(flags,
239 			"filesystem is marked as having an external log; "
240 			"specify logdev on the\nmount command line.");
241 		return XFS_ERROR(EINVAL);
242 	}
243 
244 	if (unlikely(
245 	    sbp->sb_logstart != 0 && mp->m_logdev_targp != mp->m_ddev_targp)) {
246 		xfs_fs_mount_cmn_err(flags,
247 			"filesystem is marked as having an internal log; "
248 			"do not specify logdev on\nthe mount command line.");
249 		return XFS_ERROR(EINVAL);
250 	}
251 
252 	/*
253 	 * More sanity checking. These were stolen directly from
254 	 * xfs_repair.
255 	 */
256 	if (unlikely(
257 	    sbp->sb_agcount <= 0					||
258 	    sbp->sb_sectsize < XFS_MIN_SECTORSIZE			||
259 	    sbp->sb_sectsize > XFS_MAX_SECTORSIZE			||
260 	    sbp->sb_sectlog < XFS_MIN_SECTORSIZE_LOG			||
261 	    sbp->sb_sectlog > XFS_MAX_SECTORSIZE_LOG			||
262 	    sbp->sb_blocksize < XFS_MIN_BLOCKSIZE			||
263 	    sbp->sb_blocksize > XFS_MAX_BLOCKSIZE			||
264 	    sbp->sb_blocklog < XFS_MIN_BLOCKSIZE_LOG			||
265 	    sbp->sb_blocklog > XFS_MAX_BLOCKSIZE_LOG			||
266 	    sbp->sb_inodesize < XFS_DINODE_MIN_SIZE			||
267 	    sbp->sb_inodesize > XFS_DINODE_MAX_SIZE			||
268 	    sbp->sb_inodelog < XFS_DINODE_MIN_LOG			||
269 	    sbp->sb_inodelog > XFS_DINODE_MAX_LOG			||
270 	    (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog)	||
271 	    (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE)	||
272 	    (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE)	||
273 	    (sbp->sb_imax_pct > 100 /* zero sb_imax_pct is valid */))) {
274 		xfs_fs_mount_cmn_err(flags, "SB sanity check 1 failed");
275 		return XFS_ERROR(EFSCORRUPTED);
276 	}
277 
278 	/*
279 	 * Sanity check AG count, size fields against data size field
280 	 */
281 	if (unlikely(
282 	    sbp->sb_dblocks == 0 ||
283 	    sbp->sb_dblocks >
284 	     (xfs_drfsbno_t)sbp->sb_agcount * sbp->sb_agblocks ||
285 	    sbp->sb_dblocks < (xfs_drfsbno_t)(sbp->sb_agcount - 1) *
286 			      sbp->sb_agblocks + XFS_MIN_AG_BLOCKS)) {
287 		xfs_fs_mount_cmn_err(flags, "SB sanity check 2 failed");
288 		return XFS_ERROR(EFSCORRUPTED);
289 	}
290 
291 	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
292 	ASSERT(sbp->sb_blocklog >= BBSHIFT);
293 
294 #if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
295 	if (unlikely(
296 	    (sbp->sb_dblocks >> (PAGE_SHIFT - sbp->sb_blocklog)) > ULONG_MAX ||
297 	    (sbp->sb_rblocks >> (PAGE_SHIFT - sbp->sb_blocklog)) > ULONG_MAX)) {
298 #else                  /* Limited by UINT_MAX of sectors */
299 	if (unlikely(
300 	    (sbp->sb_dblocks << (sbp->sb_blocklog - BBSHIFT)) > UINT_MAX ||
301 	    (sbp->sb_rblocks << (sbp->sb_blocklog - BBSHIFT)) > UINT_MAX)) {
302 #endif
303 		xfs_fs_mount_cmn_err(flags,
304 			"file system too large to be mounted on this system.");
305 		return XFS_ERROR(E2BIG);
306 	}
307 
308 	if (unlikely(sbp->sb_inprogress)) {
309 		xfs_fs_mount_cmn_err(flags, "file system busy");
310 		return XFS_ERROR(EFSCORRUPTED);
311 	}
312 
313 	/*
314 	 * Version 1 directory format has never worked on Linux.
315 	 */
316 	if (unlikely(!XFS_SB_VERSION_HASDIRV2(sbp))) {
317 		xfs_fs_mount_cmn_err(flags,
318 			"file system using version 1 directory format");
319 		return XFS_ERROR(ENOSYS);
320 	}
321 
322 	/*
323 	 * Until this is fixed only page-sized or smaller data blocks work.
324 	 */
325 	if (unlikely(sbp->sb_blocksize > PAGE_SIZE)) {
326 		xfs_fs_mount_cmn_err(flags,
327 			"file system with blocksize %d bytes",
328 			sbp->sb_blocksize);
329 		xfs_fs_mount_cmn_err(flags,
330 			"only pagesize (%ld) or less will currently work.",
331 			PAGE_SIZE);
332 		return XFS_ERROR(ENOSYS);
333 	}
334 
335 	return 0;
336 }
337 
338 xfs_agnumber_t
339 xfs_initialize_perag(
340 	struct vfs	*vfs,
341 	xfs_mount_t	*mp,
342 	xfs_agnumber_t	agcount)
343 {
344 	xfs_agnumber_t	index, max_metadata;
345 	xfs_perag_t	*pag;
346 	xfs_agino_t	agino;
347 	xfs_ino_t	ino;
348 	xfs_sb_t	*sbp = &mp->m_sb;
349 	xfs_ino_t	max_inum = XFS_MAXINUMBER_32;
350 
351 	/* Check to see if the filesystem can overflow 32 bit inodes */
352 	agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
353 	ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
354 
355 	/* Clear the mount flag if no inode can overflow 32 bits
356 	 * on this filesystem, or if specifically requested..
357 	 */
358 	if ((vfs->vfs_flag & VFS_32BITINODES) && ino > max_inum) {
359 		mp->m_flags |= XFS_MOUNT_32BITINODES;
360 	} else {
361 		mp->m_flags &= ~XFS_MOUNT_32BITINODES;
362 	}
363 
364 	/* If we can overflow then setup the ag headers accordingly */
365 	if (mp->m_flags & XFS_MOUNT_32BITINODES) {
366 		/* Calculate how much should be reserved for inodes to
367 		 * meet the max inode percentage.
368 		 */
369 		if (mp->m_maxicount) {
370 			__uint64_t	icount;
371 
372 			icount = sbp->sb_dblocks * sbp->sb_imax_pct;
373 			do_div(icount, 100);
374 			icount += sbp->sb_agblocks - 1;
375 			do_div(icount, sbp->sb_agblocks);
376 			max_metadata = icount;
377 		} else {
378 			max_metadata = agcount;
379 		}
380 		for (index = 0; index < agcount; index++) {
381 			ino = XFS_AGINO_TO_INO(mp, index, agino);
382 			if (ino > max_inum) {
383 				index++;
384 				break;
385 			}
386 
387 			/* This ag is preferred for inodes */
388 			pag = &mp->m_perag[index];
389 			pag->pagi_inodeok = 1;
390 			if (index < max_metadata)
391 				pag->pagf_metadata = 1;
392 		}
393 	} else {
394 		/* Setup default behavior for smaller filesystems */
395 		for (index = 0; index < agcount; index++) {
396 			pag = &mp->m_perag[index];
397 			pag->pagi_inodeok = 1;
398 		}
399 	}
400 	return index;
401 }
402 
403 /*
404  * xfs_xlatesb
405  *
406  *     data       - on disk version of sb
407  *     sb         - a superblock
408  *     dir        - conversion direction: <0 - convert sb to buf
409  *                                        >0 - convert buf to sb
410  *     fields     - which fields to copy (bitmask)
411  */
412 void
413 xfs_xlatesb(
414 	void		*data,
415 	xfs_sb_t	*sb,
416 	int		dir,
417 	__int64_t	fields)
418 {
419 	xfs_caddr_t	buf_ptr;
420 	xfs_caddr_t	mem_ptr;
421 	xfs_sb_field_t	f;
422 	int		first;
423 	int		size;
424 
425 	ASSERT(dir);
426 	ASSERT(fields);
427 
428 	if (!fields)
429 		return;
430 
431 	buf_ptr = (xfs_caddr_t)data;
432 	mem_ptr = (xfs_caddr_t)sb;
433 
434 	while (fields) {
435 		f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
436 		first = xfs_sb_info[f].offset;
437 		size = xfs_sb_info[f + 1].offset - first;
438 
439 		ASSERT(xfs_sb_info[f].type == 0 || xfs_sb_info[f].type == 1);
440 
441 		if (size == 1 || xfs_sb_info[f].type == 1) {
442 			if (dir > 0) {
443 				memcpy(mem_ptr + first, buf_ptr + first, size);
444 			} else {
445 				memcpy(buf_ptr + first, mem_ptr + first, size);
446 			}
447 		} else {
448 			switch (size) {
449 			case 2:
450 				INT_XLATE(*(__uint16_t*)(buf_ptr+first),
451 					  *(__uint16_t*)(mem_ptr+first),
452 					  dir, ARCH_CONVERT);
453 				break;
454 			case 4:
455 				INT_XLATE(*(__uint32_t*)(buf_ptr+first),
456 					  *(__uint32_t*)(mem_ptr+first),
457 					  dir, ARCH_CONVERT);
458 				break;
459 			case 8:
460 				INT_XLATE(*(__uint64_t*)(buf_ptr+first),
461 					  *(__uint64_t*)(mem_ptr+first), dir, ARCH_CONVERT);
462 				break;
463 			default:
464 				ASSERT(0);
465 			}
466 		}
467 
468 		fields &= ~(1LL << f);
469 	}
470 }
471 
472 /*
473  * xfs_readsb
474  *
475  * Does the initial read of the superblock.
476  */
477 int
478 xfs_readsb(xfs_mount_t *mp, int flags)
479 {
480 	unsigned int	sector_size;
481 	unsigned int	extra_flags;
482 	xfs_buf_t	*bp;
483 	xfs_sb_t	*sbp;
484 	int		error;
485 
486 	ASSERT(mp->m_sb_bp == NULL);
487 	ASSERT(mp->m_ddev_targp != NULL);
488 
489 	/*
490 	 * Allocate a (locked) buffer to hold the superblock.
491 	 * This will be kept around at all times to optimize
492 	 * access to the superblock.
493 	 */
494 	sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
495 	extra_flags = XFS_BUF_LOCK | XFS_BUF_MANAGE | XFS_BUF_MAPPED;
496 
497 	bp = xfs_buf_read_flags(mp->m_ddev_targp, XFS_SB_DADDR,
498 				BTOBB(sector_size), extra_flags);
499 	if (!bp || XFS_BUF_ISERROR(bp)) {
500 		xfs_fs_mount_cmn_err(flags, "SB read failed");
501 		error = bp ? XFS_BUF_GETERROR(bp) : ENOMEM;
502 		goto fail;
503 	}
504 	ASSERT(XFS_BUF_ISBUSY(bp));
505 	ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
506 
507 	/*
508 	 * Initialize the mount structure from the superblock.
509 	 * But first do some basic consistency checking.
510 	 */
511 	sbp = XFS_BUF_TO_SBP(bp);
512 	xfs_xlatesb(XFS_BUF_PTR(bp), &(mp->m_sb), 1, XFS_SB_ALL_BITS);
513 
514 	error = xfs_mount_validate_sb(mp, &(mp->m_sb), flags);
515 	if (error) {
516 		xfs_fs_mount_cmn_err(flags, "SB validate failed");
517 		goto fail;
518 	}
519 
520 	/*
521 	 * We must be able to do sector-sized and sector-aligned IO.
522 	 */
523 	if (sector_size > mp->m_sb.sb_sectsize) {
524 		xfs_fs_mount_cmn_err(flags,
525 			"device supports only %u byte sectors (not %u)",
526 			sector_size, mp->m_sb.sb_sectsize);
527 		error = ENOSYS;
528 		goto fail;
529 	}
530 
531 	/*
532 	 * If device sector size is smaller than the superblock size,
533 	 * re-read the superblock so the buffer is correctly sized.
534 	 */
535 	if (sector_size < mp->m_sb.sb_sectsize) {
536 		XFS_BUF_UNMANAGE(bp);
537 		xfs_buf_relse(bp);
538 		sector_size = mp->m_sb.sb_sectsize;
539 		bp = xfs_buf_read_flags(mp->m_ddev_targp, XFS_SB_DADDR,
540 					BTOBB(sector_size), extra_flags);
541 		if (!bp || XFS_BUF_ISERROR(bp)) {
542 			xfs_fs_mount_cmn_err(flags, "SB re-read failed");
543 			error = bp ? XFS_BUF_GETERROR(bp) : ENOMEM;
544 			goto fail;
545 		}
546 		ASSERT(XFS_BUF_ISBUSY(bp));
547 		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
548 	}
549 
550 	xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
551 	xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
552 	xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
553 
554 	mp->m_sb_bp = bp;
555 	xfs_buf_relse(bp);
556 	ASSERT(XFS_BUF_VALUSEMA(bp) > 0);
557 	return 0;
558 
559  fail:
560 	if (bp) {
561 		XFS_BUF_UNMANAGE(bp);
562 		xfs_buf_relse(bp);
563 	}
564 	return error;
565 }
566 
567 
568 /*
569  * xfs_mount_common
570  *
571  * Mount initialization code establishing various mount
572  * fields from the superblock associated with the given
573  * mount structure
574  */
575 STATIC void
576 xfs_mount_common(xfs_mount_t *mp, xfs_sb_t *sbp)
577 {
578 	int	i;
579 
580 	mp->m_agfrotor = mp->m_agirotor = 0;
581 	spinlock_init(&mp->m_agirotor_lock, "m_agirotor_lock");
582 	mp->m_maxagi = mp->m_sb.sb_agcount;
583 	mp->m_blkbit_log = sbp->sb_blocklog + XFS_NBBYLOG;
584 	mp->m_blkbb_log = sbp->sb_blocklog - BBSHIFT;
585 	mp->m_sectbb_log = sbp->sb_sectlog - BBSHIFT;
586 	mp->m_agno_log = xfs_highbit32(sbp->sb_agcount - 1) + 1;
587 	mp->m_agino_log = sbp->sb_inopblog + sbp->sb_agblklog;
588 	mp->m_litino = sbp->sb_inodesize -
589 		((uint)sizeof(xfs_dinode_core_t) + (uint)sizeof(xfs_agino_t));
590 	mp->m_blockmask = sbp->sb_blocksize - 1;
591 	mp->m_blockwsize = sbp->sb_blocksize >> XFS_WORDLOG;
592 	mp->m_blockwmask = mp->m_blockwsize - 1;
593 	INIT_LIST_HEAD(&mp->m_del_inodes);
594 
595 	/*
596 	 * Setup for attributes, in case they get created.
597 	 * This value is for inodes getting attributes for the first time,
598 	 * the per-inode value is for old attribute values.
599 	 */
600 	ASSERT(sbp->sb_inodesize >= 256 && sbp->sb_inodesize <= 2048);
601 	switch (sbp->sb_inodesize) {
602 	case 256:
603 		mp->m_attroffset = XFS_LITINO(mp) -
604 				   XFS_BMDR_SPACE_CALC(MINABTPTRS);
605 		break;
606 	case 512:
607 	case 1024:
608 	case 2048:
609 		mp->m_attroffset = XFS_BMDR_SPACE_CALC(6 * MINABTPTRS);
610 		break;
611 	default:
612 		ASSERT(0);
613 	}
614 	ASSERT(mp->m_attroffset < XFS_LITINO(mp));
615 
616 	for (i = 0; i < 2; i++) {
617 		mp->m_alloc_mxr[i] = XFS_BTREE_BLOCK_MAXRECS(sbp->sb_blocksize,
618 			xfs_alloc, i == 0);
619 		mp->m_alloc_mnr[i] = XFS_BTREE_BLOCK_MINRECS(sbp->sb_blocksize,
620 			xfs_alloc, i == 0);
621 	}
622 	for (i = 0; i < 2; i++) {
623 		mp->m_bmap_dmxr[i] = XFS_BTREE_BLOCK_MAXRECS(sbp->sb_blocksize,
624 			xfs_bmbt, i == 0);
625 		mp->m_bmap_dmnr[i] = XFS_BTREE_BLOCK_MINRECS(sbp->sb_blocksize,
626 			xfs_bmbt, i == 0);
627 	}
628 	for (i = 0; i < 2; i++) {
629 		mp->m_inobt_mxr[i] = XFS_BTREE_BLOCK_MAXRECS(sbp->sb_blocksize,
630 			xfs_inobt, i == 0);
631 		mp->m_inobt_mnr[i] = XFS_BTREE_BLOCK_MINRECS(sbp->sb_blocksize,
632 			xfs_inobt, i == 0);
633 	}
634 
635 	mp->m_bsize = XFS_FSB_TO_BB(mp, 1);
636 	mp->m_ialloc_inos = (int)MAX((__uint16_t)XFS_INODES_PER_CHUNK,
637 					sbp->sb_inopblock);
638 	mp->m_ialloc_blks = mp->m_ialloc_inos >> sbp->sb_inopblog;
639 }
640 /*
641  * xfs_mountfs
642  *
643  * This function does the following on an initial mount of a file system:
644  *	- reads the superblock from disk and init the mount struct
645  *	- if we're a 32-bit kernel, do a size check on the superblock
646  *		so we don't mount terabyte filesystems
647  *	- init mount struct realtime fields
648  *	- allocate inode hash table for fs
649  *	- init directory manager
650  *	- perform recovery and init the log manager
651  */
652 int
653 xfs_mountfs(
654 	vfs_t		*vfsp,
655 	xfs_mount_t	*mp,
656 	int		mfsi_flags)
657 {
658 	xfs_buf_t	*bp;
659 	xfs_sb_t	*sbp = &(mp->m_sb);
660 	xfs_inode_t	*rip;
661 	vnode_t		*rvp = NULL;
662 	int		readio_log, writeio_log;
663 	xfs_daddr_t	d;
664 	__uint64_t	ret64;
665 	__int64_t	update_flags;
666 	uint		quotamount, quotaflags;
667 	int		agno;
668 	int		uuid_mounted = 0;
669 	int		error = 0;
670 
671 	if (mp->m_sb_bp == NULL) {
672 		if ((error = xfs_readsb(mp, mfsi_flags))) {
673 			return error;
674 		}
675 	}
676 	xfs_mount_common(mp, sbp);
677 
678 	/*
679 	 * Check if sb_agblocks is aligned at stripe boundary
680 	 * If sb_agblocks is NOT aligned turn off m_dalign since
681 	 * allocator alignment is within an ag, therefore ag has
682 	 * to be aligned at stripe boundary.
683 	 */
684 	update_flags = 0LL;
685 	if (mp->m_dalign && !(mfsi_flags & XFS_MFSI_SECOND)) {
686 		/*
687 		 * If stripe unit and stripe width are not multiples
688 		 * of the fs blocksize turn off alignment.
689 		 */
690 		if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
691 		    (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
692 			if (mp->m_flags & XFS_MOUNT_RETERR) {
693 				cmn_err(CE_WARN,
694 					"XFS: alignment check 1 failed");
695 				error = XFS_ERROR(EINVAL);
696 				goto error1;
697 			}
698 			mp->m_dalign = mp->m_swidth = 0;
699 		} else {
700 			/*
701 			 * Convert the stripe unit and width to FSBs.
702 			 */
703 			mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
704 			if (mp->m_dalign && (sbp->sb_agblocks % mp->m_dalign)) {
705 				if (mp->m_flags & XFS_MOUNT_RETERR) {
706 					error = XFS_ERROR(EINVAL);
707 					goto error1;
708 				}
709 				xfs_fs_cmn_err(CE_WARN, mp,
710 "stripe alignment turned off: sunit(%d)/swidth(%d) incompatible with agsize(%d)",
711 					mp->m_dalign, mp->m_swidth,
712 					sbp->sb_agblocks);
713 
714 				mp->m_dalign = 0;
715 				mp->m_swidth = 0;
716 			} else if (mp->m_dalign) {
717 				mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
718 			} else {
719 				if (mp->m_flags & XFS_MOUNT_RETERR) {
720 					xfs_fs_cmn_err(CE_WARN, mp,
721 "stripe alignment turned off: sunit(%d) less than bsize(%d)",
722                                         	mp->m_dalign,
723 						mp->m_blockmask +1);
724 					error = XFS_ERROR(EINVAL);
725 					goto error1;
726 				}
727 				mp->m_swidth = 0;
728 			}
729 		}
730 
731 		/*
732 		 * Update superblock with new values
733 		 * and log changes
734 		 */
735 		if (XFS_SB_VERSION_HASDALIGN(sbp)) {
736 			if (sbp->sb_unit != mp->m_dalign) {
737 				sbp->sb_unit = mp->m_dalign;
738 				update_flags |= XFS_SB_UNIT;
739 			}
740 			if (sbp->sb_width != mp->m_swidth) {
741 				sbp->sb_width = mp->m_swidth;
742 				update_flags |= XFS_SB_WIDTH;
743 			}
744 		}
745 	} else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
746 		    XFS_SB_VERSION_HASDALIGN(&mp->m_sb)) {
747 			mp->m_dalign = sbp->sb_unit;
748 			mp->m_swidth = sbp->sb_width;
749 	}
750 
751 	xfs_alloc_compute_maxlevels(mp);
752 	xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
753 	xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
754 	xfs_ialloc_compute_maxlevels(mp);
755 
756 	if (sbp->sb_imax_pct) {
757 		__uint64_t	icount;
758 
759 		/* Make sure the maximum inode count is a multiple of the
760 		 * units we allocate inodes in.
761 		 */
762 
763 		icount = sbp->sb_dblocks * sbp->sb_imax_pct;
764 		do_div(icount, 100);
765 		do_div(icount, mp->m_ialloc_blks);
766 		mp->m_maxicount = (icount * mp->m_ialloc_blks)  <<
767 				   sbp->sb_inopblog;
768 	} else
769 		mp->m_maxicount = 0;
770 
771 	mp->m_maxioffset = xfs_max_file_offset(sbp->sb_blocklog);
772 
773 	/*
774 	 * XFS uses the uuid from the superblock as the unique
775 	 * identifier for fsid.  We can not use the uuid from the volume
776 	 * since a single partition filesystem is identical to a single
777 	 * partition volume/filesystem.
778 	 */
779 	if ((mfsi_flags & XFS_MFSI_SECOND) == 0 &&
780 	    (mp->m_flags & XFS_MOUNT_NOUUID) == 0) {
781 		if (xfs_uuid_mount(mp)) {
782 			error = XFS_ERROR(EINVAL);
783 			goto error1;
784 		}
785 		uuid_mounted=1;
786 		ret64 = uuid_hash64(&sbp->sb_uuid);
787 		memcpy(&vfsp->vfs_fsid, &ret64, sizeof(ret64));
788 	}
789 
790 	/*
791 	 * Set the default minimum read and write sizes unless
792 	 * already specified in a mount option.
793 	 * We use smaller I/O sizes when the file system
794 	 * is being used for NFS service (wsync mount option).
795 	 */
796 	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
797 		if (mp->m_flags & XFS_MOUNT_WSYNC) {
798 			readio_log = XFS_WSYNC_READIO_LOG;
799 			writeio_log = XFS_WSYNC_WRITEIO_LOG;
800 		} else {
801 			readio_log = XFS_READIO_LOG_LARGE;
802 			writeio_log = XFS_WRITEIO_LOG_LARGE;
803 		}
804 	} else {
805 		readio_log = mp->m_readio_log;
806 		writeio_log = mp->m_writeio_log;
807 	}
808 
809 	/*
810 	 * Set the number of readahead buffers to use based on
811 	 * physical memory size.
812 	 */
813 	if (xfs_physmem <= 4096)		/* <= 16MB */
814 		mp->m_nreadaheads = XFS_RW_NREADAHEAD_16MB;
815 	else if (xfs_physmem <= 8192)	/* <= 32MB */
816 		mp->m_nreadaheads = XFS_RW_NREADAHEAD_32MB;
817 	else
818 		mp->m_nreadaheads = XFS_RW_NREADAHEAD_K32;
819 	if (sbp->sb_blocklog > readio_log) {
820 		mp->m_readio_log = sbp->sb_blocklog;
821 	} else {
822 		mp->m_readio_log = readio_log;
823 	}
824 	mp->m_readio_blocks = 1 << (mp->m_readio_log - sbp->sb_blocklog);
825 	if (sbp->sb_blocklog > writeio_log) {
826 		mp->m_writeio_log = sbp->sb_blocklog;
827 	} else {
828 		mp->m_writeio_log = writeio_log;
829 	}
830 	mp->m_writeio_blocks = 1 << (mp->m_writeio_log - sbp->sb_blocklog);
831 
832 	/*
833 	 * Set the inode cluster size based on the physical memory
834 	 * size.  This may still be overridden by the file system
835 	 * block size if it is larger than the chosen cluster size.
836 	 */
837 	if (xfs_physmem <= btoc(32 * 1024 * 1024)) { /* <= 32 MB */
838 		mp->m_inode_cluster_size = XFS_INODE_SMALL_CLUSTER_SIZE;
839 	} else {
840 		mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
841 	}
842 	/*
843 	 * Set whether we're using inode alignment.
844 	 */
845 	if (XFS_SB_VERSION_HASALIGN(&mp->m_sb) &&
846 	    mp->m_sb.sb_inoalignmt >=
847 	    XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size))
848 		mp->m_inoalign_mask = mp->m_sb.sb_inoalignmt - 1;
849 	else
850 		mp->m_inoalign_mask = 0;
851 	/*
852 	 * If we are using stripe alignment, check whether
853 	 * the stripe unit is a multiple of the inode alignment
854 	 */
855 	if (mp->m_dalign && mp->m_inoalign_mask &&
856 	    !(mp->m_dalign & mp->m_inoalign_mask))
857 		mp->m_sinoalign = mp->m_dalign;
858 	else
859 		mp->m_sinoalign = 0;
860 	/*
861 	 * Check that the data (and log if separate) are an ok size.
862 	 */
863 	d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
864 	if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {
865 		cmn_err(CE_WARN, "XFS: size check 1 failed");
866 		error = XFS_ERROR(E2BIG);
867 		goto error1;
868 	}
869 	error = xfs_read_buf(mp, mp->m_ddev_targp,
870 			     d - XFS_FSS_TO_BB(mp, 1),
871 			     XFS_FSS_TO_BB(mp, 1), 0, &bp);
872 	if (!error) {
873 		xfs_buf_relse(bp);
874 	} else {
875 		cmn_err(CE_WARN, "XFS: size check 2 failed");
876 		if (error == ENOSPC) {
877 			error = XFS_ERROR(E2BIG);
878 		}
879 		goto error1;
880 	}
881 
882 	if (((mfsi_flags & XFS_MFSI_CLIENT) == 0) &&
883 	    mp->m_logdev_targp != mp->m_ddev_targp) {
884 		d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
885 		if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {
886 			cmn_err(CE_WARN, "XFS: size check 3 failed");
887 			error = XFS_ERROR(E2BIG);
888 			goto error1;
889 		}
890 		error = xfs_read_buf(mp, mp->m_logdev_targp,
891 				     d - XFS_FSB_TO_BB(mp, 1),
892 				     XFS_FSB_TO_BB(mp, 1), 0, &bp);
893 		if (!error) {
894 			xfs_buf_relse(bp);
895 		} else {
896 			cmn_err(CE_WARN, "XFS: size check 3 failed");
897 			if (error == ENOSPC) {
898 				error = XFS_ERROR(E2BIG);
899 			}
900 			goto error1;
901 		}
902 	}
903 
904 	/*
905 	 * Initialize realtime fields in the mount structure
906 	 */
907 	if ((error = xfs_rtmount_init(mp))) {
908 		cmn_err(CE_WARN, "XFS: RT mount failed");
909 		goto error1;
910 	}
911 
912 	/*
913 	 * For client case we are done now
914 	 */
915 	if (mfsi_flags & XFS_MFSI_CLIENT) {
916 		return 0;
917 	}
918 
919 	/*
920 	 *  Copies the low order bits of the timestamp and the randomly
921 	 *  set "sequence" number out of a UUID.
922 	 */
923 	uuid_getnodeuniq(&sbp->sb_uuid, mp->m_fixedfsid);
924 
925 	/*
926 	 *  The vfs structure needs to have a file system independent
927 	 *  way of checking for the invariant file system ID.  Since it
928 	 *  can't look at mount structures it has a pointer to the data
929 	 *  in the mount structure.
930 	 *
931 	 *  File systems that don't support user level file handles (i.e.
932 	 *  all of them except for XFS) will leave vfs_altfsid as NULL.
933 	 */
934 	vfsp->vfs_altfsid = (xfs_fsid_t *)mp->m_fixedfsid;
935 	mp->m_dmevmask = 0;	/* not persistent; set after each mount */
936 
937 	/*
938 	 * Select the right directory manager.
939 	 */
940 	mp->m_dirops =
941 		XFS_SB_VERSION_HASDIRV2(&mp->m_sb) ?
942 			xfsv2_dirops :
943 			xfsv1_dirops;
944 
945 	/*
946 	 * Initialize directory manager's entries.
947 	 */
948 	XFS_DIR_MOUNT(mp);
949 
950 	/*
951 	 * Initialize the attribute manager's entries.
952 	 */
953 	mp->m_attr_magicpct = (mp->m_sb.sb_blocksize * 37) / 100;
954 
955 	/*
956 	 * Initialize the precomputed transaction reservations values.
957 	 */
958 	xfs_trans_init(mp);
959 
960 	/*
961 	 * Allocate and initialize the inode hash table for this
962 	 * file system.
963 	 */
964 	xfs_ihash_init(mp);
965 	xfs_chash_init(mp);
966 
967 	/*
968 	 * Allocate and initialize the per-ag data.
969 	 */
970 	init_rwsem(&mp->m_peraglock);
971 	mp->m_perag =
972 		kmem_zalloc(sbp->sb_agcount * sizeof(xfs_perag_t), KM_SLEEP);
973 
974 	mp->m_maxagi = xfs_initialize_perag(vfsp, mp, sbp->sb_agcount);
975 
976 	/*
977 	 * log's mount-time initialization. Perform 1st part recovery if needed
978 	 */
979 	if (likely(sbp->sb_logblocks > 0)) {	/* check for volume case */
980 		error = xfs_log_mount(mp, mp->m_logdev_targp,
981 				      XFS_FSB_TO_DADDR(mp, sbp->sb_logstart),
982 				      XFS_FSB_TO_BB(mp, sbp->sb_logblocks));
983 		if (error) {
984 			cmn_err(CE_WARN, "XFS: log mount failed");
985 			goto error2;
986 		}
987 	} else {	/* No log has been defined */
988 		cmn_err(CE_WARN, "XFS: no log defined");
989 		XFS_ERROR_REPORT("xfs_mountfs_int(1)", XFS_ERRLEVEL_LOW, mp);
990 		error = XFS_ERROR(EFSCORRUPTED);
991 		goto error2;
992 	}
993 
994 	/*
995 	 * Get and sanity-check the root inode.
996 	 * Save the pointer to it in the mount structure.
997 	 */
998 	error = xfs_iget(mp, NULL, sbp->sb_rootino, 0, XFS_ILOCK_EXCL, &rip, 0);
999 	if (error) {
1000 		cmn_err(CE_WARN, "XFS: failed to read root inode");
1001 		goto error3;
1002 	}
1003 
1004 	ASSERT(rip != NULL);
1005 	rvp = XFS_ITOV(rip);
1006 
1007 	if (unlikely((rip->i_d.di_mode & S_IFMT) != S_IFDIR)) {
1008 		cmn_err(CE_WARN, "XFS: corrupted root inode");
1009 		prdev("Root inode %llu is not a directory",
1010 		      mp->m_ddev_targp, (unsigned long long)rip->i_ino);
1011 		xfs_iunlock(rip, XFS_ILOCK_EXCL);
1012 		XFS_ERROR_REPORT("xfs_mountfs_int(2)", XFS_ERRLEVEL_LOW,
1013 				 mp);
1014 		error = XFS_ERROR(EFSCORRUPTED);
1015 		goto error4;
1016 	}
1017 	mp->m_rootip = rip;	/* save it */
1018 
1019 	xfs_iunlock(rip, XFS_ILOCK_EXCL);
1020 
1021 	/*
1022 	 * Initialize realtime inode pointers in the mount structure
1023 	 */
1024 	if ((error = xfs_rtmount_inodes(mp))) {
1025 		/*
1026 		 * Free up the root inode.
1027 		 */
1028 		cmn_err(CE_WARN, "XFS: failed to read RT inodes");
1029 		goto error4;
1030 	}
1031 
1032 	/*
1033 	 * If fs is not mounted readonly, then update the superblock
1034 	 * unit and width changes.
1035 	 */
1036 	if (update_flags && !(vfsp->vfs_flag & VFS_RDONLY))
1037 		xfs_mount_log_sbunit(mp, update_flags);
1038 
1039 	/*
1040 	 * Initialise the XFS quota management subsystem for this mount
1041 	 */
1042 	if ((error = XFS_QM_INIT(mp, &quotamount, &quotaflags)))
1043 		goto error4;
1044 
1045 	/*
1046 	 * Finish recovering the file system.  This part needed to be
1047 	 * delayed until after the root and real-time bitmap inodes
1048 	 * were consistently read in.
1049 	 */
1050 	error = xfs_log_mount_finish(mp, mfsi_flags);
1051 	if (error) {
1052 		cmn_err(CE_WARN, "XFS: log mount finish failed");
1053 		goto error4;
1054 	}
1055 
1056 	/*
1057 	 * Complete the quota initialisation, post-log-replay component.
1058 	 */
1059 	if ((error = XFS_QM_MOUNT(mp, quotamount, quotaflags, mfsi_flags)))
1060 		goto error4;
1061 
1062 	return 0;
1063 
1064  error4:
1065 	/*
1066 	 * Free up the root inode.
1067 	 */
1068 	VN_RELE(rvp);
1069  error3:
1070 	xfs_log_unmount_dealloc(mp);
1071  error2:
1072 	xfs_ihash_free(mp);
1073 	xfs_chash_free(mp);
1074 	for (agno = 0; agno < sbp->sb_agcount; agno++)
1075 		if (mp->m_perag[agno].pagb_list)
1076 			kmem_free(mp->m_perag[agno].pagb_list,
1077 			  sizeof(xfs_perag_busy_t) * XFS_PAGB_NUM_SLOTS);
1078 	kmem_free(mp->m_perag, sbp->sb_agcount * sizeof(xfs_perag_t));
1079 	mp->m_perag = NULL;
1080 	/* FALLTHROUGH */
1081  error1:
1082 	if (uuid_mounted)
1083 		xfs_uuid_unmount(mp);
1084 	xfs_freesb(mp);
1085 	return error;
1086 }
1087 
1088 /*
1089  * xfs_unmountfs
1090  *
1091  * This flushes out the inodes,dquots and the superblock, unmounts the
1092  * log and makes sure that incore structures are freed.
1093  */
1094 int
1095 xfs_unmountfs(xfs_mount_t *mp, struct cred *cr)
1096 {
1097 	struct vfs	*vfsp = XFS_MTOVFS(mp);
1098 #if defined(DEBUG) || defined(INDUCE_IO_ERROR)
1099 	int64_t		fsid;
1100 #endif
1101 
1102 	xfs_iflush_all(mp);
1103 
1104 	XFS_QM_DQPURGEALL(mp, XFS_QMOPT_QUOTALL | XFS_QMOPT_UMOUNTING);
1105 
1106 	/*
1107 	 * Flush out the log synchronously so that we know for sure
1108 	 * that nothing is pinned.  This is important because bflush()
1109 	 * will skip pinned buffers.
1110 	 */
1111 	xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE | XFS_LOG_SYNC);
1112 
1113 	xfs_binval(mp->m_ddev_targp);
1114 	if (mp->m_rtdev_targp) {
1115 		xfs_binval(mp->m_rtdev_targp);
1116 	}
1117 
1118 	xfs_unmountfs_writesb(mp);
1119 
1120 	xfs_unmountfs_wait(mp); 		/* wait for async bufs */
1121 
1122 	xfs_log_unmount(mp);			/* Done! No more fs ops. */
1123 
1124 	xfs_freesb(mp);
1125 
1126 	/*
1127 	 * All inodes from this mount point should be freed.
1128 	 */
1129 	ASSERT(mp->m_inodes == NULL);
1130 
1131 	xfs_unmountfs_close(mp, cr);
1132 	if ((mp->m_flags & XFS_MOUNT_NOUUID) == 0)
1133 		xfs_uuid_unmount(mp);
1134 
1135 #if defined(DEBUG) || defined(INDUCE_IO_ERROR)
1136 	/*
1137 	 * clear all error tags on this filesystem
1138 	 */
1139 	memcpy(&fsid, &vfsp->vfs_fsid, sizeof(int64_t));
1140 	xfs_errortag_clearall_umount(fsid, mp->m_fsname, 0);
1141 #endif
1142 	XFS_IODONE(vfsp);
1143 	xfs_mount_free(mp, 1);
1144 	return 0;
1145 }
1146 
1147 void
1148 xfs_unmountfs_close(xfs_mount_t *mp, struct cred *cr)
1149 {
1150 	if (mp->m_logdev_targp != mp->m_ddev_targp)
1151 		xfs_free_buftarg(mp->m_logdev_targp, 1);
1152 	if (mp->m_rtdev_targp)
1153 		xfs_free_buftarg(mp->m_rtdev_targp, 1);
1154 	xfs_free_buftarg(mp->m_ddev_targp, 0);
1155 }
1156 
1157 STATIC void
1158 xfs_unmountfs_wait(xfs_mount_t *mp)
1159 {
1160 	if (mp->m_logdev_targp != mp->m_ddev_targp)
1161 		xfs_wait_buftarg(mp->m_logdev_targp);
1162 	if (mp->m_rtdev_targp)
1163 		xfs_wait_buftarg(mp->m_rtdev_targp);
1164 	xfs_wait_buftarg(mp->m_ddev_targp);
1165 }
1166 
1167 int
1168 xfs_unmountfs_writesb(xfs_mount_t *mp)
1169 {
1170 	xfs_buf_t	*sbp;
1171 	xfs_sb_t	*sb;
1172 	int		error = 0;
1173 
1174 	/*
1175 	 * skip superblock write if fs is read-only, or
1176 	 * if we are doing a forced umount.
1177 	 */
1178 	sbp = xfs_getsb(mp, 0);
1179 	if (!(XFS_MTOVFS(mp)->vfs_flag & VFS_RDONLY ||
1180 		XFS_FORCED_SHUTDOWN(mp))) {
1181 
1182 		xfs_icsb_sync_counters(mp);
1183 
1184 		/*
1185 		 * mark shared-readonly if desired
1186 		 */
1187 		sb = XFS_BUF_TO_SBP(sbp);
1188 		if (mp->m_mk_sharedro) {
1189 			if (!(sb->sb_flags & XFS_SBF_READONLY))
1190 				sb->sb_flags |= XFS_SBF_READONLY;
1191 			if (!XFS_SB_VERSION_HASSHARED(sb))
1192 				XFS_SB_VERSION_ADDSHARED(sb);
1193 			xfs_fs_cmn_err(CE_NOTE, mp,
1194 				"Unmounting, marking shared read-only");
1195 		}
1196 		XFS_BUF_UNDONE(sbp);
1197 		XFS_BUF_UNREAD(sbp);
1198 		XFS_BUF_UNDELAYWRITE(sbp);
1199 		XFS_BUF_WRITE(sbp);
1200 		XFS_BUF_UNASYNC(sbp);
1201 		ASSERT(XFS_BUF_TARGET(sbp) == mp->m_ddev_targp);
1202 		xfsbdstrat(mp, sbp);
1203 		/* Nevermind errors we might get here. */
1204 		error = xfs_iowait(sbp);
1205 		if (error)
1206 			xfs_ioerror_alert("xfs_unmountfs_writesb",
1207 					  mp, sbp, XFS_BUF_ADDR(sbp));
1208 		if (error && mp->m_mk_sharedro)
1209 			xfs_fs_cmn_err(CE_ALERT, mp, "Superblock write error detected while unmounting.  Filesystem may not be marked shared readonly");
1210 	}
1211 	xfs_buf_relse(sbp);
1212 	return error;
1213 }
1214 
1215 /*
1216  * xfs_mod_sb() can be used to copy arbitrary changes to the
1217  * in-core superblock into the superblock buffer to be logged.
1218  * It does not provide the higher level of locking that is
1219  * needed to protect the in-core superblock from concurrent
1220  * access.
1221  */
1222 void
1223 xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
1224 {
1225 	xfs_buf_t	*bp;
1226 	int		first;
1227 	int		last;
1228 	xfs_mount_t	*mp;
1229 	xfs_sb_t	*sbp;
1230 	xfs_sb_field_t	f;
1231 
1232 	ASSERT(fields);
1233 	if (!fields)
1234 		return;
1235 	mp = tp->t_mountp;
1236 	bp = xfs_trans_getsb(tp, mp, 0);
1237 	sbp = XFS_BUF_TO_SBP(bp);
1238 	first = sizeof(xfs_sb_t);
1239 	last = 0;
1240 
1241 	/* translate/copy */
1242 
1243 	xfs_xlatesb(XFS_BUF_PTR(bp), &(mp->m_sb), -1, fields);
1244 
1245 	/* find modified range */
1246 
1247 	f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
1248 	ASSERT((1LL << f) & XFS_SB_MOD_BITS);
1249 	first = xfs_sb_info[f].offset;
1250 
1251 	f = (xfs_sb_field_t)xfs_highbit64((__uint64_t)fields);
1252 	ASSERT((1LL << f) & XFS_SB_MOD_BITS);
1253 	last = xfs_sb_info[f + 1].offset - 1;
1254 
1255 	xfs_trans_log_buf(tp, bp, first, last);
1256 }
1257 /*
1258  * xfs_mod_incore_sb_unlocked() is a utility routine common used to apply
1259  * a delta to a specified field in the in-core superblock.  Simply
1260  * switch on the field indicated and apply the delta to that field.
1261  * Fields are not allowed to dip below zero, so if the delta would
1262  * do this do not apply it and return EINVAL.
1263  *
1264  * The SB_LOCK must be held when this routine is called.
1265  */
1266 int
1267 xfs_mod_incore_sb_unlocked(xfs_mount_t *mp, xfs_sb_field_t field,
1268 			int delta, int rsvd)
1269 {
1270 	int		scounter;	/* short counter for 32 bit fields */
1271 	long long	lcounter;	/* long counter for 64 bit fields */
1272 	long long	res_used, rem;
1273 
1274 	/*
1275 	 * With the in-core superblock spin lock held, switch
1276 	 * on the indicated field.  Apply the delta to the
1277 	 * proper field.  If the fields value would dip below
1278 	 * 0, then do not apply the delta and return EINVAL.
1279 	 */
1280 	switch (field) {
1281 	case XFS_SBS_ICOUNT:
1282 		lcounter = (long long)mp->m_sb.sb_icount;
1283 		lcounter += delta;
1284 		if (lcounter < 0) {
1285 			ASSERT(0);
1286 			return XFS_ERROR(EINVAL);
1287 		}
1288 		mp->m_sb.sb_icount = lcounter;
1289 		return 0;
1290 	case XFS_SBS_IFREE:
1291 		lcounter = (long long)mp->m_sb.sb_ifree;
1292 		lcounter += delta;
1293 		if (lcounter < 0) {
1294 			ASSERT(0);
1295 			return XFS_ERROR(EINVAL);
1296 		}
1297 		mp->m_sb.sb_ifree = lcounter;
1298 		return 0;
1299 	case XFS_SBS_FDBLOCKS:
1300 
1301 		lcounter = (long long)mp->m_sb.sb_fdblocks;
1302 		res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
1303 
1304 		if (delta > 0) {		/* Putting blocks back */
1305 			if (res_used > delta) {
1306 				mp->m_resblks_avail += delta;
1307 			} else {
1308 				rem = delta - res_used;
1309 				mp->m_resblks_avail = mp->m_resblks;
1310 				lcounter += rem;
1311 			}
1312 		} else {				/* Taking blocks away */
1313 
1314 			lcounter += delta;
1315 
1316 		/*
1317 		 * If were out of blocks, use any available reserved blocks if
1318 		 * were allowed to.
1319 		 */
1320 
1321 			if (lcounter < 0) {
1322 				if (rsvd) {
1323 					lcounter = (long long)mp->m_resblks_avail + delta;
1324 					if (lcounter < 0) {
1325 						return XFS_ERROR(ENOSPC);
1326 					}
1327 					mp->m_resblks_avail = lcounter;
1328 					return 0;
1329 				} else {	/* not reserved */
1330 					return XFS_ERROR(ENOSPC);
1331 				}
1332 			}
1333 		}
1334 
1335 		mp->m_sb.sb_fdblocks = lcounter;
1336 		return 0;
1337 	case XFS_SBS_FREXTENTS:
1338 		lcounter = (long long)mp->m_sb.sb_frextents;
1339 		lcounter += delta;
1340 		if (lcounter < 0) {
1341 			return XFS_ERROR(ENOSPC);
1342 		}
1343 		mp->m_sb.sb_frextents = lcounter;
1344 		return 0;
1345 	case XFS_SBS_DBLOCKS:
1346 		lcounter = (long long)mp->m_sb.sb_dblocks;
1347 		lcounter += delta;
1348 		if (lcounter < 0) {
1349 			ASSERT(0);
1350 			return XFS_ERROR(EINVAL);
1351 		}
1352 		mp->m_sb.sb_dblocks = lcounter;
1353 		return 0;
1354 	case XFS_SBS_AGCOUNT:
1355 		scounter = mp->m_sb.sb_agcount;
1356 		scounter += delta;
1357 		if (scounter < 0) {
1358 			ASSERT(0);
1359 			return XFS_ERROR(EINVAL);
1360 		}
1361 		mp->m_sb.sb_agcount = scounter;
1362 		return 0;
1363 	case XFS_SBS_IMAX_PCT:
1364 		scounter = mp->m_sb.sb_imax_pct;
1365 		scounter += delta;
1366 		if (scounter < 0) {
1367 			ASSERT(0);
1368 			return XFS_ERROR(EINVAL);
1369 		}
1370 		mp->m_sb.sb_imax_pct = scounter;
1371 		return 0;
1372 	case XFS_SBS_REXTSIZE:
1373 		scounter = mp->m_sb.sb_rextsize;
1374 		scounter += delta;
1375 		if (scounter < 0) {
1376 			ASSERT(0);
1377 			return XFS_ERROR(EINVAL);
1378 		}
1379 		mp->m_sb.sb_rextsize = scounter;
1380 		return 0;
1381 	case XFS_SBS_RBMBLOCKS:
1382 		scounter = mp->m_sb.sb_rbmblocks;
1383 		scounter += delta;
1384 		if (scounter < 0) {
1385 			ASSERT(0);
1386 			return XFS_ERROR(EINVAL);
1387 		}
1388 		mp->m_sb.sb_rbmblocks = scounter;
1389 		return 0;
1390 	case XFS_SBS_RBLOCKS:
1391 		lcounter = (long long)mp->m_sb.sb_rblocks;
1392 		lcounter += delta;
1393 		if (lcounter < 0) {
1394 			ASSERT(0);
1395 			return XFS_ERROR(EINVAL);
1396 		}
1397 		mp->m_sb.sb_rblocks = lcounter;
1398 		return 0;
1399 	case XFS_SBS_REXTENTS:
1400 		lcounter = (long long)mp->m_sb.sb_rextents;
1401 		lcounter += delta;
1402 		if (lcounter < 0) {
1403 			ASSERT(0);
1404 			return XFS_ERROR(EINVAL);
1405 		}
1406 		mp->m_sb.sb_rextents = lcounter;
1407 		return 0;
1408 	case XFS_SBS_REXTSLOG:
1409 		scounter = mp->m_sb.sb_rextslog;
1410 		scounter += delta;
1411 		if (scounter < 0) {
1412 			ASSERT(0);
1413 			return XFS_ERROR(EINVAL);
1414 		}
1415 		mp->m_sb.sb_rextslog = scounter;
1416 		return 0;
1417 	default:
1418 		ASSERT(0);
1419 		return XFS_ERROR(EINVAL);
1420 	}
1421 }
1422 
1423 /*
1424  * xfs_mod_incore_sb() is used to change a field in the in-core
1425  * superblock structure by the specified delta.  This modification
1426  * is protected by the SB_LOCK.  Just use the xfs_mod_incore_sb_unlocked()
1427  * routine to do the work.
1428  */
1429 int
1430 xfs_mod_incore_sb(xfs_mount_t *mp, xfs_sb_field_t field, int delta, int rsvd)
1431 {
1432 	unsigned long	s;
1433 	int	status;
1434 
1435 	/* check for per-cpu counters */
1436 	switch (field) {
1437 #ifdef HAVE_PERCPU_SB
1438 	case XFS_SBS_ICOUNT:
1439 	case XFS_SBS_IFREE:
1440 	case XFS_SBS_FDBLOCKS:
1441 		if (!(mp->m_flags & XFS_MOUNT_NO_PERCPU_SB)) {
1442 			status = xfs_icsb_modify_counters(mp, field,
1443 							delta, rsvd);
1444 			break;
1445 		}
1446 		/* FALLTHROUGH */
1447 #endif
1448 	default:
1449 		s = XFS_SB_LOCK(mp);
1450 		status = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
1451 		XFS_SB_UNLOCK(mp, s);
1452 		break;
1453 	}
1454 
1455 	return status;
1456 }
1457 
1458 /*
1459  * xfs_mod_incore_sb_batch() is used to change more than one field
1460  * in the in-core superblock structure at a time.  This modification
1461  * is protected by a lock internal to this module.  The fields and
1462  * changes to those fields are specified in the array of xfs_mod_sb
1463  * structures passed in.
1464  *
1465  * Either all of the specified deltas will be applied or none of
1466  * them will.  If any modified field dips below 0, then all modifications
1467  * will be backed out and EINVAL will be returned.
1468  */
1469 int
1470 xfs_mod_incore_sb_batch(xfs_mount_t *mp, xfs_mod_sb_t *msb, uint nmsb, int rsvd)
1471 {
1472 	unsigned long	s;
1473 	int		status=0;
1474 	xfs_mod_sb_t	*msbp;
1475 
1476 	/*
1477 	 * Loop through the array of mod structures and apply each
1478 	 * individually.  If any fail, then back out all those
1479 	 * which have already been applied.  Do all of this within
1480 	 * the scope of the SB_LOCK so that all of the changes will
1481 	 * be atomic.
1482 	 */
1483 	s = XFS_SB_LOCK(mp);
1484 	msbp = &msb[0];
1485 	for (msbp = &msbp[0]; msbp < (msb + nmsb); msbp++) {
1486 		/*
1487 		 * Apply the delta at index n.  If it fails, break
1488 		 * from the loop so we'll fall into the undo loop
1489 		 * below.
1490 		 */
1491 		switch (msbp->msb_field) {
1492 #ifdef HAVE_PERCPU_SB
1493 		case XFS_SBS_ICOUNT:
1494 		case XFS_SBS_IFREE:
1495 		case XFS_SBS_FDBLOCKS:
1496 			if (!(mp->m_flags & XFS_MOUNT_NO_PERCPU_SB)) {
1497 				status = xfs_icsb_modify_counters_locked(mp,
1498 							msbp->msb_field,
1499 							msbp->msb_delta, rsvd);
1500 				break;
1501 			}
1502 			/* FALLTHROUGH */
1503 #endif
1504 		default:
1505 			status = xfs_mod_incore_sb_unlocked(mp,
1506 						msbp->msb_field,
1507 						msbp->msb_delta, rsvd);
1508 			break;
1509 		}
1510 
1511 		if (status != 0) {
1512 			break;
1513 		}
1514 	}
1515 
1516 	/*
1517 	 * If we didn't complete the loop above, then back out
1518 	 * any changes made to the superblock.  If you add code
1519 	 * between the loop above and here, make sure that you
1520 	 * preserve the value of status. Loop back until
1521 	 * we step below the beginning of the array.  Make sure
1522 	 * we don't touch anything back there.
1523 	 */
1524 	if (status != 0) {
1525 		msbp--;
1526 		while (msbp >= msb) {
1527 			switch (msbp->msb_field) {
1528 #ifdef HAVE_PERCPU_SB
1529 			case XFS_SBS_ICOUNT:
1530 			case XFS_SBS_IFREE:
1531 			case XFS_SBS_FDBLOCKS:
1532 				if (!(mp->m_flags & XFS_MOUNT_NO_PERCPU_SB)) {
1533 					status =
1534 					    xfs_icsb_modify_counters_locked(mp,
1535 							msbp->msb_field,
1536 							-(msbp->msb_delta),
1537 							rsvd);
1538 					break;
1539 				}
1540 				/* FALLTHROUGH */
1541 #endif
1542 			default:
1543 				status = xfs_mod_incore_sb_unlocked(mp,
1544 							msbp->msb_field,
1545 							-(msbp->msb_delta),
1546 							rsvd);
1547 				break;
1548 			}
1549 			ASSERT(status == 0);
1550 			msbp--;
1551 		}
1552 	}
1553 	XFS_SB_UNLOCK(mp, s);
1554 	return status;
1555 }
1556 
1557 /*
1558  * xfs_getsb() is called to obtain the buffer for the superblock.
1559  * The buffer is returned locked and read in from disk.
1560  * The buffer should be released with a call to xfs_brelse().
1561  *
1562  * If the flags parameter is BUF_TRYLOCK, then we'll only return
1563  * the superblock buffer if it can be locked without sleeping.
1564  * If it can't then we'll return NULL.
1565  */
1566 xfs_buf_t *
1567 xfs_getsb(
1568 	xfs_mount_t	*mp,
1569 	int		flags)
1570 {
1571 	xfs_buf_t	*bp;
1572 
1573 	ASSERT(mp->m_sb_bp != NULL);
1574 	bp = mp->m_sb_bp;
1575 	if (flags & XFS_BUF_TRYLOCK) {
1576 		if (!XFS_BUF_CPSEMA(bp)) {
1577 			return NULL;
1578 		}
1579 	} else {
1580 		XFS_BUF_PSEMA(bp, PRIBIO);
1581 	}
1582 	XFS_BUF_HOLD(bp);
1583 	ASSERT(XFS_BUF_ISDONE(bp));
1584 	return bp;
1585 }
1586 
1587 /*
1588  * Used to free the superblock along various error paths.
1589  */
1590 void
1591 xfs_freesb(
1592 	xfs_mount_t	*mp)
1593 {
1594 	xfs_buf_t	*bp;
1595 
1596 	/*
1597 	 * Use xfs_getsb() so that the buffer will be locked
1598 	 * when we call xfs_buf_relse().
1599 	 */
1600 	bp = xfs_getsb(mp, 0);
1601 	XFS_BUF_UNMANAGE(bp);
1602 	xfs_buf_relse(bp);
1603 	mp->m_sb_bp = NULL;
1604 }
1605 
1606 /*
1607  * See if the UUID is unique among mounted XFS filesystems.
1608  * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
1609  */
1610 STATIC int
1611 xfs_uuid_mount(
1612 	xfs_mount_t	*mp)
1613 {
1614 	if (uuid_is_nil(&mp->m_sb.sb_uuid)) {
1615 		cmn_err(CE_WARN,
1616 			"XFS: Filesystem %s has nil UUID - can't mount",
1617 			mp->m_fsname);
1618 		return -1;
1619 	}
1620 	if (!uuid_table_insert(&mp->m_sb.sb_uuid)) {
1621 		cmn_err(CE_WARN,
1622 			"XFS: Filesystem %s has duplicate UUID - can't mount",
1623 			mp->m_fsname);
1624 		return -1;
1625 	}
1626 	return 0;
1627 }
1628 
1629 /*
1630  * Remove filesystem from the UUID table.
1631  */
1632 STATIC void
1633 xfs_uuid_unmount(
1634 	xfs_mount_t	*mp)
1635 {
1636 	uuid_table_remove(&mp->m_sb.sb_uuid);
1637 }
1638 
1639 /*
1640  * Used to log changes to the superblock unit and width fields which could
1641  * be altered by the mount options. Only the first superblock is updated.
1642  */
1643 STATIC void
1644 xfs_mount_log_sbunit(
1645 	xfs_mount_t	*mp,
1646 	__int64_t	fields)
1647 {
1648 	xfs_trans_t	*tp;
1649 
1650 	ASSERT(fields & (XFS_SB_UNIT|XFS_SB_WIDTH|XFS_SB_UUID));
1651 
1652 	tp = xfs_trans_alloc(mp, XFS_TRANS_SB_UNIT);
1653 	if (xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
1654 				XFS_DEFAULT_LOG_COUNT)) {
1655 		xfs_trans_cancel(tp, 0);
1656 		return;
1657 	}
1658 	xfs_mod_sb(tp, fields);
1659 	xfs_trans_commit(tp, 0, NULL);
1660 }
1661 
1662 
1663 #ifdef HAVE_PERCPU_SB
1664 /*
1665  * Per-cpu incore superblock counters
1666  *
1667  * Simple concept, difficult implementation
1668  *
1669  * Basically, replace the incore superblock counters with a distributed per cpu
1670  * counter for contended fields (e.g.  free block count).
1671  *
1672  * Difficulties arise in that the incore sb is used for ENOSPC checking, and
1673  * hence needs to be accurately read when we are running low on space. Hence
1674  * there is a method to enable and disable the per-cpu counters based on how
1675  * much "stuff" is available in them.
1676  *
1677  * Basically, a counter is enabled if there is enough free resource to justify
1678  * running a per-cpu fast-path. If the per-cpu counter runs out (i.e. a local
1679  * ENOSPC), then we disable the counters to synchronise all callers and
1680  * re-distribute the available resources.
1681  *
1682  * If, once we redistributed the available resources, we still get a failure,
1683  * we disable the per-cpu counter and go through the slow path.
1684  *
1685  * The slow path is the current xfs_mod_incore_sb() function.  This means that
1686  * when we disable a per-cpu counter, we need to drain it's resources back to
1687  * the global superblock. We do this after disabling the counter to prevent
1688  * more threads from queueing up on the counter.
1689  *
1690  * Essentially, this means that we still need a lock in the fast path to enable
1691  * synchronisation between the global counters and the per-cpu counters. This
1692  * is not a problem because the lock will be local to a CPU almost all the time
1693  * and have little contention except when we get to ENOSPC conditions.
1694  *
1695  * Basically, this lock becomes a barrier that enables us to lock out the fast
1696  * path while we do things like enabling and disabling counters and
1697  * synchronising the counters.
1698  *
1699  * Locking rules:
1700  *
1701  * 	1. XFS_SB_LOCK() before picking up per-cpu locks
1702  * 	2. per-cpu locks always picked up via for_each_online_cpu() order
1703  * 	3. accurate counter sync requires XFS_SB_LOCK + per cpu locks
1704  * 	4. modifying per-cpu counters requires holding per-cpu lock
1705  * 	5. modifying global counters requires holding XFS_SB_LOCK
1706  *	6. enabling or disabling a counter requires holding the XFS_SB_LOCK
1707  *	   and _none_ of the per-cpu locks.
1708  *
1709  * Disabled counters are only ever re-enabled by a balance operation
1710  * that results in more free resources per CPU than a given threshold.
1711  * To ensure counters don't remain disabled, they are rebalanced when
1712  * the global resource goes above a higher threshold (i.e. some hysteresis
1713  * is present to prevent thrashing).
1714  */
1715 
1716 /*
1717  * hot-plug CPU notifier support.
1718  *
1719  * We cannot use the hotcpu_register() function because it does
1720  * not allow notifier instances. We need a notifier per filesystem
1721  * as we need to be able to identify the filesystem to balance
1722  * the counters out. This is achieved by having a notifier block
1723  * embedded in the xfs_mount_t and doing pointer magic to get the
1724  * mount pointer from the notifier block address.
1725  */
1726 STATIC int
1727 xfs_icsb_cpu_notify(
1728 	struct notifier_block *nfb,
1729 	unsigned long action,
1730 	void *hcpu)
1731 {
1732 	xfs_icsb_cnts_t *cntp;
1733 	xfs_mount_t	*mp;
1734 	int		s;
1735 
1736 	mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier);
1737 	cntp = (xfs_icsb_cnts_t *)
1738 			per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu);
1739 	switch (action) {
1740 	case CPU_UP_PREPARE:
1741 		/* Easy Case - initialize the area and locks, and
1742 		 * then rebalance when online does everything else for us. */
1743 		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
1744 		break;
1745 	case CPU_ONLINE:
1746 		xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
1747 		xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
1748 		xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
1749 		break;
1750 	case CPU_DEAD:
1751 		/* Disable all the counters, then fold the dead cpu's
1752 		 * count into the total on the global superblock and
1753 		 * re-enable the counters. */
1754 		s = XFS_SB_LOCK(mp);
1755 		xfs_icsb_disable_counter(mp, XFS_SBS_ICOUNT);
1756 		xfs_icsb_disable_counter(mp, XFS_SBS_IFREE);
1757 		xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS);
1758 
1759 		mp->m_sb.sb_icount += cntp->icsb_icount;
1760 		mp->m_sb.sb_ifree += cntp->icsb_ifree;
1761 		mp->m_sb.sb_fdblocks += cntp->icsb_fdblocks;
1762 
1763 		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
1764 
1765 		xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, XFS_ICSB_SB_LOCKED);
1766 		xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, XFS_ICSB_SB_LOCKED);
1767 		xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, XFS_ICSB_SB_LOCKED);
1768 		XFS_SB_UNLOCK(mp, s);
1769 		break;
1770 	}
1771 
1772 	return NOTIFY_OK;
1773 }
1774 
1775 int
1776 xfs_icsb_init_counters(
1777 	xfs_mount_t	*mp)
1778 {
1779 	xfs_icsb_cnts_t *cntp;
1780 	int		i;
1781 
1782 	mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t);
1783 	if (mp->m_sb_cnts == NULL)
1784 		return -ENOMEM;
1785 
1786 	mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify;
1787 	mp->m_icsb_notifier.priority = 0;
1788 	register_cpu_notifier(&mp->m_icsb_notifier);
1789 
1790 	for_each_online_cpu(i) {
1791 		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
1792 		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
1793 	}
1794 	/*
1795 	 * start with all counters disabled so that the
1796 	 * initial balance kicks us off correctly
1797 	 */
1798 	mp->m_icsb_counters = -1;
1799 	return 0;
1800 }
1801 
1802 STATIC void
1803 xfs_icsb_destroy_counters(
1804 	xfs_mount_t	*mp)
1805 {
1806 	if (mp->m_sb_cnts) {
1807 		unregister_cpu_notifier(&mp->m_icsb_notifier);
1808 		free_percpu(mp->m_sb_cnts);
1809 	}
1810 }
1811 
1812 STATIC inline void
1813 xfs_icsb_lock_cntr(
1814 	xfs_icsb_cnts_t	*icsbp)
1815 {
1816 	while (test_and_set_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags)) {
1817 		ndelay(1000);
1818 	}
1819 }
1820 
1821 STATIC inline void
1822 xfs_icsb_unlock_cntr(
1823 	xfs_icsb_cnts_t	*icsbp)
1824 {
1825 	clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags);
1826 }
1827 
1828 
1829 STATIC inline void
1830 xfs_icsb_lock_all_counters(
1831 	xfs_mount_t	*mp)
1832 {
1833 	xfs_icsb_cnts_t *cntp;
1834 	int		i;
1835 
1836 	for_each_online_cpu(i) {
1837 		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
1838 		xfs_icsb_lock_cntr(cntp);
1839 	}
1840 }
1841 
1842 STATIC inline void
1843 xfs_icsb_unlock_all_counters(
1844 	xfs_mount_t	*mp)
1845 {
1846 	xfs_icsb_cnts_t *cntp;
1847 	int		i;
1848 
1849 	for_each_online_cpu(i) {
1850 		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
1851 		xfs_icsb_unlock_cntr(cntp);
1852 	}
1853 }
1854 
1855 STATIC void
1856 xfs_icsb_count(
1857 	xfs_mount_t	*mp,
1858 	xfs_icsb_cnts_t	*cnt,
1859 	int		flags)
1860 {
1861 	xfs_icsb_cnts_t *cntp;
1862 	int		i;
1863 
1864 	memset(cnt, 0, sizeof(xfs_icsb_cnts_t));
1865 
1866 	if (!(flags & XFS_ICSB_LAZY_COUNT))
1867 		xfs_icsb_lock_all_counters(mp);
1868 
1869 	for_each_online_cpu(i) {
1870 		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
1871 		cnt->icsb_icount += cntp->icsb_icount;
1872 		cnt->icsb_ifree += cntp->icsb_ifree;
1873 		cnt->icsb_fdblocks += cntp->icsb_fdblocks;
1874 	}
1875 
1876 	if (!(flags & XFS_ICSB_LAZY_COUNT))
1877 		xfs_icsb_unlock_all_counters(mp);
1878 }
1879 
1880 STATIC int
1881 xfs_icsb_counter_disabled(
1882 	xfs_mount_t	*mp,
1883 	xfs_sb_field_t	field)
1884 {
1885 	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
1886 	return test_bit(field, &mp->m_icsb_counters);
1887 }
1888 
1889 STATIC int
1890 xfs_icsb_disable_counter(
1891 	xfs_mount_t	*mp,
1892 	xfs_sb_field_t	field)
1893 {
1894 	xfs_icsb_cnts_t	cnt;
1895 
1896 	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
1897 
1898 	xfs_icsb_lock_all_counters(mp);
1899 	if (!test_and_set_bit(field, &mp->m_icsb_counters)) {
1900 		/* drain back to superblock */
1901 
1902 		xfs_icsb_count(mp, &cnt, XFS_ICSB_SB_LOCKED|XFS_ICSB_LAZY_COUNT);
1903 		switch(field) {
1904 		case XFS_SBS_ICOUNT:
1905 			mp->m_sb.sb_icount = cnt.icsb_icount;
1906 			break;
1907 		case XFS_SBS_IFREE:
1908 			mp->m_sb.sb_ifree = cnt.icsb_ifree;
1909 			break;
1910 		case XFS_SBS_FDBLOCKS:
1911 			mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
1912 			break;
1913 		default:
1914 			BUG();
1915 		}
1916 	}
1917 
1918 	xfs_icsb_unlock_all_counters(mp);
1919 
1920 	return 0;
1921 }
1922 
1923 STATIC void
1924 xfs_icsb_enable_counter(
1925 	xfs_mount_t	*mp,
1926 	xfs_sb_field_t	field,
1927 	uint64_t	count,
1928 	uint64_t	resid)
1929 {
1930 	xfs_icsb_cnts_t	*cntp;
1931 	int		i;
1932 
1933 	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
1934 
1935 	xfs_icsb_lock_all_counters(mp);
1936 	for_each_online_cpu(i) {
1937 		cntp = per_cpu_ptr(mp->m_sb_cnts, i);
1938 		switch (field) {
1939 		case XFS_SBS_ICOUNT:
1940 			cntp->icsb_icount = count + resid;
1941 			break;
1942 		case XFS_SBS_IFREE:
1943 			cntp->icsb_ifree = count + resid;
1944 			break;
1945 		case XFS_SBS_FDBLOCKS:
1946 			cntp->icsb_fdblocks = count + resid;
1947 			break;
1948 		default:
1949 			BUG();
1950 			break;
1951 		}
1952 		resid = 0;
1953 	}
1954 	clear_bit(field, &mp->m_icsb_counters);
1955 	xfs_icsb_unlock_all_counters(mp);
1956 }
1957 
1958 STATIC void
1959 xfs_icsb_sync_counters_int(
1960 	xfs_mount_t	*mp,
1961 	int		flags)
1962 {
1963 	xfs_icsb_cnts_t	cnt;
1964 	int		s;
1965 
1966 	/* Pass 1: lock all counters */
1967 	if ((flags & XFS_ICSB_SB_LOCKED) == 0)
1968 		s = XFS_SB_LOCK(mp);
1969 
1970 	xfs_icsb_count(mp, &cnt, flags);
1971 
1972 	/* Step 3: update mp->m_sb fields */
1973 	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_ICOUNT))
1974 		mp->m_sb.sb_icount = cnt.icsb_icount;
1975 	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_IFREE))
1976 		mp->m_sb.sb_ifree = cnt.icsb_ifree;
1977 	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_FDBLOCKS))
1978 		mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
1979 
1980 	if ((flags & XFS_ICSB_SB_LOCKED) == 0)
1981 		XFS_SB_UNLOCK(mp, s);
1982 }
1983 
1984 /*
1985  * Accurate update of per-cpu counters to incore superblock
1986  */
1987 STATIC void
1988 xfs_icsb_sync_counters(
1989 	xfs_mount_t	*mp)
1990 {
1991 	xfs_icsb_sync_counters_int(mp, 0);
1992 }
1993 
1994 /*
1995  * lazy addition used for things like df, background sb syncs, etc
1996  */
1997 void
1998 xfs_icsb_sync_counters_lazy(
1999 	xfs_mount_t	*mp)
2000 {
2001 	xfs_icsb_sync_counters_int(mp, XFS_ICSB_LAZY_COUNT);
2002 }
2003 
2004 /*
2005  * Balance and enable/disable counters as necessary.
2006  *
2007  * Thresholds for re-enabling counters are somewhat magic.
2008  * inode counts are chosen to be the same number as single
2009  * on disk allocation chunk per CPU, and free blocks is
2010  * something far enough zero that we aren't going thrash
2011  * when we get near ENOSPC.
2012  */
2013 #define XFS_ICSB_INO_CNTR_REENABLE	64
2014 #define XFS_ICSB_FDBLK_CNTR_REENABLE	512
2015 STATIC void
2016 xfs_icsb_balance_counter(
2017 	xfs_mount_t	*mp,
2018 	xfs_sb_field_t  field,
2019 	int		flags)
2020 {
2021 	uint64_t	count, resid = 0;
2022 	int		weight = num_online_cpus();
2023 	int		s;
2024 
2025 	if (!(flags & XFS_ICSB_SB_LOCKED))
2026 		s = XFS_SB_LOCK(mp);
2027 
2028 	/* disable counter and sync counter */
2029 	xfs_icsb_disable_counter(mp, field);
2030 
2031 	/* update counters  - first CPU gets residual*/
2032 	switch (field) {
2033 	case XFS_SBS_ICOUNT:
2034 		count = mp->m_sb.sb_icount;
2035 		resid = do_div(count, weight);
2036 		if (count < XFS_ICSB_INO_CNTR_REENABLE)
2037 			goto out;
2038 		break;
2039 	case XFS_SBS_IFREE:
2040 		count = mp->m_sb.sb_ifree;
2041 		resid = do_div(count, weight);
2042 		if (count < XFS_ICSB_INO_CNTR_REENABLE)
2043 			goto out;
2044 		break;
2045 	case XFS_SBS_FDBLOCKS:
2046 		count = mp->m_sb.sb_fdblocks;
2047 		resid = do_div(count, weight);
2048 		if (count < XFS_ICSB_FDBLK_CNTR_REENABLE)
2049 			goto out;
2050 		break;
2051 	default:
2052 		BUG();
2053 		break;
2054 	}
2055 
2056 	xfs_icsb_enable_counter(mp, field, count, resid);
2057 out:
2058 	if (!(flags & XFS_ICSB_SB_LOCKED))
2059 		XFS_SB_UNLOCK(mp, s);
2060 }
2061 
2062 STATIC int
2063 xfs_icsb_modify_counters_int(
2064 	xfs_mount_t	*mp,
2065 	xfs_sb_field_t	field,
2066 	int		delta,
2067 	int		rsvd,
2068 	int		flags)
2069 {
2070 	xfs_icsb_cnts_t	*icsbp;
2071 	long long	lcounter;	/* long counter for 64 bit fields */
2072 	int		cpu, s, locked = 0;
2073 	int		ret = 0, balance_done = 0;
2074 
2075 again:
2076 	cpu = get_cpu();
2077 	icsbp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, cpu),
2078 	xfs_icsb_lock_cntr(icsbp);
2079 	if (unlikely(xfs_icsb_counter_disabled(mp, field)))
2080 		goto slow_path;
2081 
2082 	switch (field) {
2083 	case XFS_SBS_ICOUNT:
2084 		lcounter = icsbp->icsb_icount;
2085 		lcounter += delta;
2086 		if (unlikely(lcounter < 0))
2087 			goto slow_path;
2088 		icsbp->icsb_icount = lcounter;
2089 		break;
2090 
2091 	case XFS_SBS_IFREE:
2092 		lcounter = icsbp->icsb_ifree;
2093 		lcounter += delta;
2094 		if (unlikely(lcounter < 0))
2095 			goto slow_path;
2096 		icsbp->icsb_ifree = lcounter;
2097 		break;
2098 
2099 	case XFS_SBS_FDBLOCKS:
2100 		BUG_ON((mp->m_resblks - mp->m_resblks_avail) != 0);
2101 
2102 		lcounter = icsbp->icsb_fdblocks;
2103 		lcounter += delta;
2104 		if (unlikely(lcounter < 0))
2105 			goto slow_path;
2106 		icsbp->icsb_fdblocks = lcounter;
2107 		break;
2108 	default:
2109 		BUG();
2110 		break;
2111 	}
2112 	xfs_icsb_unlock_cntr(icsbp);
2113 	put_cpu();
2114 	if (locked)
2115 		XFS_SB_UNLOCK(mp, s);
2116 	return 0;
2117 
2118 	/*
2119 	 * The slow path needs to be run with the SBLOCK
2120 	 * held so that we prevent other threads from
2121 	 * attempting to run this path at the same time.
2122 	 * this provides exclusion for the balancing code,
2123 	 * and exclusive fallback if the balance does not
2124 	 * provide enough resources to continue in an unlocked
2125 	 * manner.
2126 	 */
2127 slow_path:
2128 	xfs_icsb_unlock_cntr(icsbp);
2129 	put_cpu();
2130 
2131 	/* need to hold superblock incase we need
2132 	 * to disable a counter */
2133 	if (!(flags & XFS_ICSB_SB_LOCKED)) {
2134 		s = XFS_SB_LOCK(mp);
2135 		locked = 1;
2136 		flags |= XFS_ICSB_SB_LOCKED;
2137 	}
2138 	if (!balance_done) {
2139 		xfs_icsb_balance_counter(mp, field, flags);
2140 		balance_done = 1;
2141 		goto again;
2142 	} else {
2143 		/*
2144 		 * we might not have enough on this local
2145 		 * cpu to allocate for a bulk request.
2146 		 * We need to drain this field from all CPUs
2147 		 * and disable the counter fastpath
2148 		 */
2149 		xfs_icsb_disable_counter(mp, field);
2150 	}
2151 
2152 	ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
2153 
2154 	if (locked)
2155 		XFS_SB_UNLOCK(mp, s);
2156 	return ret;
2157 }
2158 
2159 STATIC int
2160 xfs_icsb_modify_counters(
2161 	xfs_mount_t	*mp,
2162 	xfs_sb_field_t	field,
2163 	int		delta,
2164 	int		rsvd)
2165 {
2166 	return xfs_icsb_modify_counters_int(mp, field, delta, rsvd, 0);
2167 }
2168 
2169 /*
2170  * Called when superblock is already locked
2171  */
2172 STATIC int
2173 xfs_icsb_modify_counters_locked(
2174 	xfs_mount_t	*mp,
2175 	xfs_sb_field_t	field,
2176 	int		delta,
2177 	int		rsvd)
2178 {
2179 	return xfs_icsb_modify_counters_int(mp, field, delta,
2180 						rsvd, XFS_ICSB_SB_LOCKED);
2181 }
2182 #endif
2183