PageRenderTime 112ms CodeModel.GetById 3ms app.highlight 94ms RepoModel.GetById 1ms app.codeStats 0ms

/sys/ufs/ffs/ffs_snapshot.c

https://bitbucket.org/gthummalapalle/minix
C | 2331 lines | 1743 code | 118 blank | 470 comment | 498 complexity | 27ec15d6707848c853fe2beb84891c55 MD5 | raw file

Large files files are truncated, but you can click here to view the full file

   1/*	$NetBSD: ffs_snapshot.c,v 1.118 2011/10/07 09:35:06 hannken Exp $	*/
   2
   3/*
   4 * Copyright 2000 Marshall Kirk McKusick. All Rights Reserved.
   5 *
   6 * Further information about snapshots can be obtained from:
   7 *
   8 *	Marshall Kirk McKusick		http://www.mckusick.com/softdep/
   9 *	1614 Oxford Street		mckusick@mckusick.com
  10 *	Berkeley, CA 94709-1608		+1-510-843-9542
  11 *	USA
  12 *
  13 * Redistribution and use in source and binary forms, with or without
  14 * modification, are permitted provided that the following conditions
  15 * are met:
  16 *
  17 * 1. Redistributions of source code must retain the above copyright
  18 *    notice, this list of conditions and the following disclaimer.
  19 * 2. Redistributions in binary form must reproduce the above copyright
  20 *    notice, this list of conditions and the following disclaimer in the
  21 *    documentation and/or other materials provided with the distribution.
  22 *
  23 * THIS SOFTWARE IS PROVIDED BY MARSHALL KIRK MCKUSICK ``AS IS'' AND ANY
  24 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  25 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  26 * DISCLAIMED.  IN NO EVENT SHALL MARSHALL KIRK MCKUSICK BE LIABLE FOR
  27 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33 * SUCH DAMAGE.
  34 *
  35 *	@(#)ffs_snapshot.c	8.11 (McKusick) 7/23/00
  36 *
  37 *	from FreeBSD: ffs_snapshot.c,v 1.79 2004/02/13 02:02:06 kuriyama Exp
  38 */
  39
  40#include <sys/cdefs.h>
  41__KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.118 2011/10/07 09:35:06 hannken Exp $");
  42
  43#if defined(_KERNEL_OPT)
  44#include "opt_ffs.h"
  45#include "opt_quota.h"
  46#endif
  47
  48#include <sys/param.h>
  49#include <sys/kernel.h>
  50#include <sys/systm.h>
  51#include <sys/conf.h>
  52#include <sys/buf.h>
  53#include <sys/proc.h>
  54#include <sys/namei.h>
  55#include <sys/sched.h>
  56#include <sys/stat.h>
  57#include <sys/malloc.h>
  58#include <sys/mount.h>
  59#include <sys/resource.h>
  60#include <sys/resourcevar.h>
  61#include <sys/vnode.h>
  62#include <sys/kauth.h>
  63#include <sys/fstrans.h>
  64#include <sys/wapbl.h>
  65
  66#include <miscfs/specfs/specdev.h>
  67
  68#include <ufs/ufs/quota.h>
  69#include <ufs/ufs/ufsmount.h>
  70#include <ufs/ufs/inode.h>
  71#include <ufs/ufs/ufs_extern.h>
  72#include <ufs/ufs/ufs_bswap.h>
  73#include <ufs/ufs/ufs_wapbl.h>
  74
  75#include <ufs/ffs/fs.h>
  76#include <ufs/ffs/ffs_extern.h>
  77
  78#include <uvm/uvm.h>
  79
  80struct snap_info {
  81	kmutex_t si_lock;			/* Lock this snapinfo */
  82	kmutex_t si_snaplock;			/* Snapshot vnode common lock */
  83	lwp_t *si_owner;			/* Sanplock owner */
  84	TAILQ_HEAD(inodelst, inode) si_snapshots; /* List of active snapshots */
  85	daddr_t *si_snapblklist;		/* Snapshot block hints list */
  86	uint32_t si_gen;			/* Incremented on change */
  87};
  88
  89#if !defined(FFS_NO_SNAPSHOT)
  90typedef int (*acctfunc_t)
  91    (struct vnode *, void *, int, int, struct fs *, daddr_t, int);
  92
  93static int snapshot_setup(struct mount *, struct vnode *);
  94static int snapshot_copyfs(struct mount *, struct vnode *, void **);
  95static int snapshot_expunge(struct mount *, struct vnode *,
  96    struct fs *, daddr_t *, daddr_t **);
  97static int snapshot_expunge_snap(struct mount *, struct vnode *,
  98    struct fs *, daddr_t);
  99static int snapshot_writefs(struct mount *, struct vnode *, void *);
 100static int cgaccount(struct vnode *, int, int *);
 101static int cgaccount1(int, struct vnode *, void *, int);
 102static int expunge(struct vnode *, struct inode *, struct fs *,
 103    acctfunc_t, int);
 104static int indiracct(struct vnode *, struct vnode *, int, daddr_t,
 105    daddr_t, daddr_t, daddr_t, daddr_t, struct fs *, acctfunc_t, int);
 106static int fullacct(struct vnode *, void *, int, int, struct fs *,
 107    daddr_t, int);
 108static int snapacct(struct vnode *, void *, int, int, struct fs *,
 109    daddr_t, int);
 110static int mapacct(struct vnode *, void *, int, int, struct fs *,
 111    daddr_t, int);
 112#endif /* !defined(FFS_NO_SNAPSHOT) */
 113
 114static int ffs_copyonwrite(void *, struct buf *, bool);
 115static int snapblkaddr(struct vnode *, daddr_t, daddr_t *);
 116static int rwfsblk(struct vnode *, int, void *, daddr_t);
 117static int syncsnap(struct vnode *);
 118static int wrsnapblk(struct vnode *, void *, daddr_t);
 119#if !defined(FFS_NO_SNAPSHOT)
 120static int blocks_in_journal(struct fs *);
 121#endif
 122
 123static inline bool is_active_snapshot(struct snap_info *, struct inode *);
 124static inline daddr_t db_get(struct inode *, int);
 125static inline void db_assign(struct inode *, int, daddr_t);
 126static inline daddr_t ib_get(struct inode *, int);
 127static inline void ib_assign(struct inode *, int, daddr_t);
 128static inline daddr_t idb_get(struct inode *, void *, int);
 129static inline void idb_assign(struct inode *, void *, int, daddr_t);
 130
 131#ifdef DEBUG
 132static int snapdebug = 0;
 133#endif
 134
 135int
 136ffs_snapshot_init(struct ufsmount *ump)
 137{
 138	struct snap_info *si;
 139
 140	si = ump->um_snapinfo = kmem_alloc(sizeof(*si), KM_SLEEP);
 141	if (si == NULL)
 142		return ENOMEM;
 143
 144	TAILQ_INIT(&si->si_snapshots);
 145	mutex_init(&si->si_lock, MUTEX_DEFAULT, IPL_NONE);
 146	mutex_init(&si->si_snaplock, MUTEX_DEFAULT, IPL_NONE);
 147	si->si_owner = NULL;
 148	si->si_gen = 0;
 149	si->si_snapblklist = NULL;
 150
 151	return 0;
 152}
 153
 154void
 155ffs_snapshot_fini(struct ufsmount *ump)
 156{
 157	struct snap_info *si;
 158
 159	si = ump->um_snapinfo;
 160	ump->um_snapinfo = NULL;
 161
 162	KASSERT(TAILQ_EMPTY(&si->si_snapshots));
 163	mutex_destroy(&si->si_lock);
 164	mutex_destroy(&si->si_snaplock);
 165	KASSERT(si->si_snapblklist == NULL);
 166	kmem_free(si, sizeof(*si));
 167}
 168
 169/*
 170 * Create a snapshot file and initialize it for the filesystem.
 171 * Vnode is locked on entry and return.
 172 */
 173int
 174ffs_snapshot(struct mount *mp, struct vnode *vp, struct timespec *ctime)
 175{
 176#if defined(FFS_NO_SNAPSHOT)
 177	return EOPNOTSUPP;
 178}
 179#else /* defined(FFS_NO_SNAPSHOT) */
 180	bool suspended = false;
 181	int error, redo = 0, snaploc;
 182	void *sbbuf = NULL;
 183	daddr_t *snaplist = NULL, snaplistsize = 0;
 184	struct buf *bp, *nbp;
 185	struct fs *copy_fs = NULL;
 186	struct fs *fs = VFSTOUFS(mp)->um_fs;
 187	struct inode *ip = VTOI(vp);
 188	struct lwp *l = curlwp;
 189	struct snap_info *si = VFSTOUFS(mp)->um_snapinfo;
 190	struct timespec ts;
 191	struct timeval starttime;
 192#ifdef DEBUG
 193	struct timeval endtime;
 194#endif
 195	struct vnode *devvp = ip->i_devvp;
 196
 197	/*
 198	 * If the vnode already is a snapshot, return.
 199	 */
 200	if ((VTOI(vp)->i_flags & SF_SNAPSHOT)) {
 201		if ((VTOI(vp)->i_flags & SF_SNAPINVAL))
 202			return EINVAL;
 203		if (ctime) {
 204			ctime->tv_sec = DIP(VTOI(vp), mtime);
 205			ctime->tv_nsec = DIP(VTOI(vp), mtimensec);
 206		}
 207		return 0;
 208	}
 209	/*
 210	 * Check for free snapshot slot in the superblock.
 211	 */
 212	for (snaploc = 0; snaploc < FSMAXSNAP; snaploc++)
 213		if (fs->fs_snapinum[snaploc] == 0)
 214			break;
 215	if (snaploc == FSMAXSNAP)
 216		return (ENOSPC);
 217	/*
 218	 * Prepare the vnode to become a snapshot.
 219	 */
 220	error = snapshot_setup(mp, vp);
 221	if (error)
 222		goto out;
 223
 224	/*
 225	 * Copy all the cylinder group maps. Although the
 226	 * filesystem is still active, we hope that only a few
 227	 * cylinder groups will change between now and when we
 228	 * suspend operations. Thus, we will be able to quickly
 229	 * touch up the few cylinder groups that changed during
 230	 * the suspension period.
 231	 */
 232	error = cgaccount(vp, 1, NULL);
 233	if (error)
 234		goto out;
 235
 236	/*
 237	 * snapshot is now valid
 238	 */
 239	ip->i_flags &= ~SF_SNAPINVAL;
 240	DIP_ASSIGN(ip, flags, ip->i_flags);
 241	ip->i_flag |= IN_CHANGE | IN_UPDATE;
 242
 243	/*
 244	 * Ensure that the snapshot is completely on disk.
 245	 * Since we have marked it as a snapshot it is safe to
 246	 * unlock it as no process will be allowed to write to it.
 247	 */
 248	error = VOP_FSYNC(vp, l->l_cred, FSYNC_WAIT, 0, 0);
 249	if (error)
 250		goto out;
 251	VOP_UNLOCK(vp);
 252	/*
 253	 * All allocations are done, so we can now suspend the filesystem.
 254	 */
 255	error = vfs_suspend(vp->v_mount, 0);
 256	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 257	if (error)
 258		goto out;
 259	suspended = true;
 260	getmicrotime(&starttime);
 261	/*
 262	 * First, copy all the cylinder group maps that have changed.
 263	 */
 264	error = cgaccount(vp, 2, &redo);
 265	if (error)
 266		goto out;
 267	/*
 268	 * Create a copy of the superblock and its summary information.
 269	 */
 270	error = snapshot_copyfs(mp, vp, &sbbuf);
 271	copy_fs = (struct fs *)((char *)sbbuf + blkoff(fs, fs->fs_sblockloc));
 272	if (error)
 273		goto out;
 274	/*
 275	 * Expunge unlinked files from our view.
 276	 */
 277	error = snapshot_expunge(mp, vp, copy_fs, &snaplistsize, &snaplist);
 278	if (error)
 279		goto out;
 280	/*
 281	 * Record snapshot inode. Since this is the newest snapshot,
 282	 * it must be placed at the end of the list.
 283	 */
 284	if (ip->i_nlink > 0)
 285		fs->fs_snapinum[snaploc] = ip->i_number;
 286
 287	mutex_enter(&si->si_lock);
 288	if (is_active_snapshot(si, ip))
 289		panic("ffs_snapshot: %"PRIu64" already on list", ip->i_number);
 290	TAILQ_INSERT_TAIL(&si->si_snapshots, ip, i_nextsnap);
 291	if (TAILQ_FIRST(&si->si_snapshots) == ip) {
 292		/*
 293		 * If this is the first snapshot on this filesystem, put the
 294		 * preliminary list in place and establish the cow handler.
 295		 */
 296		si->si_snapblklist = snaplist;
 297		fscow_establish(mp, ffs_copyonwrite, devvp);
 298	}
 299	si->si_gen++;
 300	mutex_exit(&si->si_lock);
 301
 302	vp->v_vflag |= VV_SYSTEM;
 303	/*
 304	 * Set the mtime to the time the snapshot has been taken.
 305	 */
 306	TIMEVAL_TO_TIMESPEC(&starttime, &ts);
 307	if (ctime)
 308		*ctime = ts;
 309	DIP_ASSIGN(ip, mtime, ts.tv_sec);
 310	DIP_ASSIGN(ip, mtimensec, ts.tv_nsec);
 311	ip->i_flag |= IN_CHANGE | IN_UPDATE;
 312	/*
 313	 * Copy allocation information from all snapshots and then
 314	 * expunge them from our view.
 315	 */
 316	error = snapshot_expunge_snap(mp, vp, copy_fs, snaplistsize);
 317	if (error)
 318		goto out;
 319	/*
 320	 * Write the superblock and its summary information to the snapshot.
 321	 */
 322	error = snapshot_writefs(mp, vp, sbbuf);
 323	if (error)
 324		goto out;
 325	/*
 326	 * We're nearly done, ensure that the snapshot is completely on disk.
 327	 */
 328	error = VOP_FSYNC(vp, l->l_cred, FSYNC_WAIT, 0, 0);
 329	if (error)
 330		goto out;
 331	/*
 332	 * Invalidate and free all pages on the snapshot vnode.
 333	 * We will read and write through the buffercache.
 334	 */
 335	mutex_enter(vp->v_interlock);
 336	error = VOP_PUTPAGES(vp, 0, 0,
 337		    PGO_ALLPAGES | PGO_CLEANIT | PGO_SYNCIO | PGO_FREE);
 338	if (error)
 339		goto out;
 340	/*
 341	 * Invalidate short ( < fs_bsize ) buffers.  We will always read
 342	 * full size buffers later.
 343	 */
 344	mutex_enter(&bufcache_lock);
 345	KASSERT(LIST_FIRST(&vp->v_dirtyblkhd) == NULL);
 346	for (bp = LIST_FIRST(&vp->v_cleanblkhd); bp; bp = nbp) {
 347		nbp = LIST_NEXT(bp, b_vnbufs);
 348		KASSERT((bp->b_cflags & BC_BUSY) == 0);
 349		if (bp->b_bcount < fs->fs_bsize) {
 350			bp->b_cflags |= BC_BUSY;
 351			brelsel(bp, BC_INVAL | BC_VFLUSH);
 352		}
 353	}
 354	mutex_exit(&bufcache_lock);
 355
 356out:
 357	if (sbbuf != NULL) {
 358		free(copy_fs->fs_csp, M_UFSMNT);
 359		free(sbbuf, M_UFSMNT);
 360	}
 361	if (fs->fs_active != NULL) {
 362		free(fs->fs_active, M_DEVBUF);
 363		fs->fs_active = NULL;
 364	}
 365
 366	mutex_enter(&si->si_lock);
 367	if (snaplist != NULL) {
 368		if (si->si_snapblklist == snaplist)
 369			si->si_snapblklist = NULL;
 370		free(snaplist, M_UFSMNT);
 371	}
 372	if (error) {
 373		fs->fs_snapinum[snaploc] = 0;
 374	} else {
 375		/*
 376		 * As this is the newest list, it is the most inclusive, so
 377		 * should replace the previous list.
 378		 */
 379		si->si_snapblklist = ip->i_snapblklist;
 380	}
 381	si->si_gen++;
 382	mutex_exit(&si->si_lock);
 383
 384	if (suspended) {
 385		VOP_UNLOCK(vp);
 386		vfs_resume(vp->v_mount);
 387		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 388#ifdef DEBUG
 389		getmicrotime(&endtime);
 390		timersub(&endtime, &starttime, &endtime);
 391		printf("%s: suspended %lld.%03d sec, redo %d of %d\n",
 392		    mp->mnt_stat.f_mntonname, (long long)endtime.tv_sec,
 393		    endtime.tv_usec / 1000, redo, fs->fs_ncg);
 394#endif
 395	}
 396	if (error) {
 397		if (!UFS_WAPBL_BEGIN(mp)) {
 398			(void) ffs_truncate(vp, (off_t)0, 0, NOCRED);
 399			UFS_WAPBL_END(mp);
 400		}
 401	} else if (ip->i_nlink > 0)
 402		vref(vp);
 403	return (error);
 404}
 405
 406/*
 407 * Prepare vnode to become a snapshot.
 408 */
 409static int
 410snapshot_setup(struct mount *mp, struct vnode *vp)
 411{
 412	int error, n, len, loc, cg;
 413	daddr_t blkno, numblks;
 414	struct buf *ibp, *nbp;
 415	struct fs *fs = VFSTOUFS(mp)->um_fs;
 416	struct lwp *l = curlwp;
 417	const int wbreak = blocks_in_journal(fs)/8;
 418	struct inode *ip = VTOI(vp);
 419
 420	/*
 421	 * Check mount, exclusive reference and owner.
 422	 */
 423	if (vp->v_mount != mp)
 424		return EXDEV;
 425	if (vp->v_usecount != 1 || vp->v_writecount != 0)
 426		return EBUSY;
 427	if (kauth_authorize_generic(l->l_cred, KAUTH_GENERIC_ISSUSER,
 428	    NULL) != 0 &&
 429	    VTOI(vp)->i_uid != kauth_cred_geteuid(l->l_cred))
 430		return EACCES;
 431
 432	if (vp->v_size != 0) {
 433		error = ffs_truncate(vp, 0, 0, NOCRED);
 434		if (error)
 435			return error;
 436	}
 437
 438	/* Change inode to snapshot type file. */
 439	error = UFS_WAPBL_BEGIN(mp);
 440	if (error)
 441		return error;
 442#if defined(QUOTA) || defined(QUOTA2)
 443	/* shapshot inodes are not accounted in quotas */
 444	chkiq(ip, -1, l->l_cred, 0);
 445#endif
 446	ip->i_flags |= (SF_SNAPSHOT | SF_SNAPINVAL);
 447	DIP_ASSIGN(ip, flags, ip->i_flags);
 448	ip->i_flag |= IN_CHANGE | IN_UPDATE;
 449	ffs_update(vp, NULL, NULL, UPDATE_WAIT);
 450	UFS_WAPBL_END(mp);
 451
 452	KASSERT(ip->i_flags & SF_SNAPSHOT);
 453	/*
 454	 * Write an empty list of preallocated blocks to the end of
 455	 * the snapshot to set size to at least that of the filesystem.
 456	 */
 457	numblks = howmany(fs->fs_size, fs->fs_frag);
 458	blkno = 1;
 459	blkno = ufs_rw64(blkno, UFS_FSNEEDSWAP(fs));
 460	error = vn_rdwr(UIO_WRITE, vp,
 461	    (void *)&blkno, sizeof(blkno), lblktosize(fs, (off_t)numblks),
 462	    UIO_SYSSPACE, IO_NODELOCKED|IO_UNIT, l->l_cred, NULL, NULL);
 463	if (error)
 464		return error;
 465	/*
 466	 * Preallocate critical data structures so that we can copy
 467	 * them in without further allocation after we suspend all
 468	 * operations on the filesystem. We would like to just release
 469	 * the allocated buffers without writing them since they will
 470	 * be filled in below once we are ready to go, but this upsets
 471	 * the soft update code, so we go ahead and write the new buffers.
 472	 *
 473	 * Allocate all indirect blocks and mark all of them as not
 474	 * needing to be copied.
 475	 */
 476	error = UFS_WAPBL_BEGIN(mp);
 477	if (error)
 478		return error;
 479	for (blkno = NDADDR, n = 0; blkno < numblks; blkno += NINDIR(fs)) {
 480		error = ffs_balloc(vp, lblktosize(fs, (off_t)blkno),
 481		    fs->fs_bsize, l->l_cred, B_METAONLY, &ibp);
 482		if (error)
 483			goto out;
 484		brelse(ibp, 0);
 485		if (wbreak > 0 && (++n % wbreak) == 0) {
 486			UFS_WAPBL_END(mp);
 487			error = UFS_WAPBL_BEGIN(mp);
 488			if (error)
 489				return error;
 490		}
 491	}
 492	/*
 493	 * Allocate copies for the superblock and its summary information.
 494	 */
 495	error = ffs_balloc(vp, fs->fs_sblockloc, fs->fs_sbsize, l->l_cred,
 496	    0, &nbp);
 497	if (error)
 498		goto out;
 499	bawrite(nbp);
 500	blkno = fragstoblks(fs, fs->fs_csaddr);
 501	len = howmany(fs->fs_cssize, fs->fs_bsize);
 502	for (loc = 0; loc < len; loc++) {
 503		error = ffs_balloc(vp, lblktosize(fs, (off_t)(blkno + loc)),
 504		    fs->fs_bsize, l->l_cred, 0, &nbp);
 505		if (error)
 506			goto out;
 507		bawrite(nbp);
 508		if (wbreak > 0 && (++n % wbreak) == 0) {
 509			UFS_WAPBL_END(mp);
 510			error = UFS_WAPBL_BEGIN(mp);
 511			if (error)
 512				return error;
 513		}
 514	}
 515	/*
 516	 * Allocate all cylinder group blocks.
 517	 */
 518	for (cg = 0; cg < fs->fs_ncg; cg++) {
 519		error = ffs_balloc(vp, lfragtosize(fs, cgtod(fs, cg)),
 520		    fs->fs_bsize, l->l_cred, 0, &nbp);
 521		if (error)
 522			goto out;
 523		bawrite(nbp);
 524		if (wbreak > 0 && (++n % wbreak) == 0) {
 525			UFS_WAPBL_END(mp);
 526			error = UFS_WAPBL_BEGIN(mp);
 527			if (error)
 528				return error;
 529		}
 530	}
 531
 532out:
 533	UFS_WAPBL_END(mp);
 534	return error;
 535}
 536
 537/*
 538 * Create a copy of the superblock and its summary information.
 539 * It is up to the caller to free copyfs and copy_fs->fs_csp.
 540 */
 541static int
 542snapshot_copyfs(struct mount *mp, struct vnode *vp, void **sbbuf)
 543{
 544	int error, i, len, loc, size;
 545	void *space;
 546	int32_t *lp;
 547	struct buf *bp;
 548	struct fs *copyfs, *fs = VFSTOUFS(mp)->um_fs;
 549	struct lwp *l = curlwp;
 550	struct vnode *devvp = VTOI(vp)->i_devvp;
 551
 552	/*
 553	 * Grab a copy of the superblock and its summary information.
 554	 * We delay writing it until the suspension is released below.
 555	 */
 556	*sbbuf = malloc(fs->fs_bsize, M_UFSMNT, M_WAITOK);
 557	loc = blkoff(fs, fs->fs_sblockloc);
 558	if (loc > 0)
 559		memset(*sbbuf, 0, loc);
 560	copyfs = (struct fs *)((char *)(*sbbuf) + loc);
 561	memcpy(copyfs, fs, fs->fs_sbsize);
 562	size = fs->fs_bsize < SBLOCKSIZE ? fs->fs_bsize : SBLOCKSIZE;
 563	if (fs->fs_sbsize < size)
 564		memset((char *)(*sbbuf) + loc + fs->fs_sbsize, 0, 
 565		    size - fs->fs_sbsize);
 566	size = blkroundup(fs, fs->fs_cssize);
 567	if (fs->fs_contigsumsize > 0)
 568		size += fs->fs_ncg * sizeof(int32_t);
 569	space = malloc(size, M_UFSMNT, M_WAITOK);
 570	copyfs->fs_csp = space;
 571	memcpy(copyfs->fs_csp, fs->fs_csp, fs->fs_cssize);
 572	space = (char *)space + fs->fs_cssize;
 573	loc = howmany(fs->fs_cssize, fs->fs_fsize);
 574	i = fs->fs_frag - loc % fs->fs_frag;
 575	len = (i == fs->fs_frag) ? 0 : i * fs->fs_fsize;
 576	if (len > 0) {
 577		if ((error = bread(devvp, fsbtodb(fs, fs->fs_csaddr + loc),
 578		    len, l->l_cred, 0, &bp)) != 0) {
 579			brelse(bp, 0);
 580			free(copyfs->fs_csp, M_UFSMNT);
 581			free(*sbbuf, M_UFSMNT);
 582			*sbbuf = NULL;
 583			return error;
 584		}
 585		memcpy(space, bp->b_data, (u_int)len);
 586		space = (char *)space + len;
 587		brelse(bp, BC_INVAL | BC_NOCACHE);
 588	}
 589	if (fs->fs_contigsumsize > 0) {
 590		copyfs->fs_maxcluster = lp = space;
 591		for (i = 0; i < fs->fs_ncg; i++)
 592			*lp++ = fs->fs_contigsumsize;
 593	}
 594	if (mp->mnt_wapbl)
 595		copyfs->fs_flags &= ~FS_DOWAPBL;
 596	return 0;
 597}
 598
 599/*
 600 * We must check for active files that have been unlinked (e.g., with a zero
 601 * link count). We have to expunge all trace of these files from the snapshot
 602 * so that they are not reclaimed prematurely by fsck or unnecessarily dumped.
 603 * Note that we skip unlinked snapshot files as they will be handled separately.
 604 * Calculate the snapshot list size and create a preliminary list.
 605 */
 606static int
 607snapshot_expunge(struct mount *mp, struct vnode *vp, struct fs *copy_fs,
 608    daddr_t *snaplistsize, daddr_t **snaplist)
 609{
 610	int cg, error = 0, len, loc;
 611	daddr_t blkno, *blkp;
 612	struct fs *fs = VFSTOUFS(mp)->um_fs;
 613	struct inode *xp;
 614	struct lwp *l = curlwp;
 615	struct vattr vat;
 616	struct vnode *logvp = NULL, *mvp = NULL, *xvp;
 617
 618	*snaplist = NULL;
 619	/*
 620	 * Get the log inode if any.
 621	 */
 622	if ((fs->fs_flags & FS_DOWAPBL) &&
 623	    fs->fs_journal_location == UFS_WAPBL_JOURNALLOC_IN_FILESYSTEM) {
 624		error = VFS_VGET(mp,
 625		    fs->fs_journallocs[UFS_WAPBL_INFS_INO], &logvp);
 626		if (error)
 627			goto out;
 628	}
 629	/*
 630	 * Allocate a marker vnode.
 631	 */
 632	mvp = vnalloc(mp);
 633	/*
 634	 * We also calculate the needed size for the snapshot list.
 635	 */
 636	*snaplistsize = fs->fs_ncg + howmany(fs->fs_cssize, fs->fs_bsize) +
 637	    FSMAXSNAP + 1 /* superblock */ + 1 /* last block */ + 1 /* size */;
 638	mutex_enter(&mntvnode_lock);
 639	/*
 640	 * NOTE: not using the TAILQ_FOREACH here since in this loop vgone()
 641	 * and vclean() can be called indirectly
 642	 */
 643	for (xvp = TAILQ_FIRST(&mp->mnt_vnodelist); xvp; xvp = vunmark(mvp)) {
 644		vmark(mvp, xvp);
 645		/*
 646		 * Make sure this vnode wasn't reclaimed in getnewvnode().
 647		 * Start over if it has (it won't be on the list anymore).
 648		 */
 649		if (xvp->v_mount != mp || vismarker(xvp))
 650			continue;
 651		mutex_enter(xvp->v_interlock);
 652		if ((xvp->v_iflag & VI_XLOCK) ||
 653		    xvp->v_usecount == 0 || xvp->v_type == VNON ||
 654		    VTOI(xvp) == NULL ||
 655		    (VTOI(xvp)->i_flags & SF_SNAPSHOT)) {
 656			mutex_exit(xvp->v_interlock);
 657			continue;
 658		}
 659		mutex_exit(&mntvnode_lock);
 660		/*
 661		 * XXXAD should increase vnode ref count to prevent it
 662		 * disappearing or being recycled.
 663		 */
 664		mutex_exit(xvp->v_interlock);
 665#ifdef DEBUG
 666		if (snapdebug)
 667			vprint("ffs_snapshot: busy vnode", xvp);
 668#endif
 669		xp = VTOI(xvp);
 670		if (xvp != logvp) {
 671			if (VOP_GETATTR(xvp, &vat, l->l_cred) == 0 &&
 672			    vat.va_nlink > 0) {
 673				mutex_enter(&mntvnode_lock);
 674				continue;
 675			}
 676			if (ffs_checkfreefile(copy_fs, vp, xp->i_number)) {
 677				mutex_enter(&mntvnode_lock);
 678				continue;
 679			}
 680		}
 681		/*
 682		 * If there is a fragment, clear it here.
 683		 */
 684		blkno = 0;
 685		loc = howmany(xp->i_size, fs->fs_bsize) - 1;
 686		if (loc < NDADDR) {
 687			len = fragroundup(fs, blkoff(fs, xp->i_size));
 688			if (len > 0 && len < fs->fs_bsize) {
 689				error = UFS_WAPBL_BEGIN(mp);
 690				if (error) {
 691					(void)vunmark(mvp);
 692					goto out;
 693				}
 694				ffs_blkfree_snap(copy_fs, vp, db_get(xp, loc),
 695				    len, xp->i_number);
 696				blkno = db_get(xp, loc);
 697				db_assign(xp, loc, 0);
 698				UFS_WAPBL_END(mp);
 699			}
 700		}
 701		*snaplistsize += 1;
 702		error = expunge(vp, xp, copy_fs, fullacct, BLK_NOCOPY);
 703		if (blkno)
 704			db_assign(xp, loc, blkno);
 705		if (!error) {
 706			error = UFS_WAPBL_BEGIN(mp);
 707			if (!error) {
 708				error = ffs_freefile_snap(copy_fs, vp,
 709				    xp->i_number, xp->i_mode);
 710				UFS_WAPBL_END(mp);
 711			}
 712		}
 713		if (error) {
 714			(void)vunmark(mvp);
 715			goto out;
 716		}
 717		mutex_enter(&mntvnode_lock);
 718	}
 719	mutex_exit(&mntvnode_lock);
 720	/*
 721	 * Create a preliminary list of preallocated snapshot blocks.
 722	 */
 723	*snaplist = malloc(*snaplistsize * sizeof(daddr_t), M_UFSMNT, M_WAITOK);
 724	blkp = &(*snaplist)[1];
 725	*blkp++ = lblkno(fs, fs->fs_sblockloc);
 726	blkno = fragstoblks(fs, fs->fs_csaddr);
 727	for (cg = 0; cg < fs->fs_ncg; cg++) {
 728		if (fragstoblks(fs, cgtod(fs, cg)) > blkno)
 729			break;
 730		*blkp++ = fragstoblks(fs, cgtod(fs, cg));
 731	}
 732	len = howmany(fs->fs_cssize, fs->fs_bsize);
 733	for (loc = 0; loc < len; loc++)
 734		*blkp++ = blkno + loc;
 735	for (; cg < fs->fs_ncg; cg++)
 736		*blkp++ = fragstoblks(fs, cgtod(fs, cg));
 737	(*snaplist)[0] = blkp - &(*snaplist)[0];
 738
 739out:
 740	if (mvp != NULL)
 741		vnfree(mvp);
 742	if (logvp != NULL)
 743		vput(logvp);
 744	if (error && *snaplist != NULL) {
 745		free(*snaplist, M_UFSMNT);
 746		*snaplist = NULL;
 747	}
 748
 749	return error;
 750}
 751
 752/*
 753 * Copy allocation information from all the snapshots in this snapshot and
 754 * then expunge them from its view. Also, collect the list of allocated
 755 * blocks in i_snapblklist.
 756 */
 757static int
 758snapshot_expunge_snap(struct mount *mp, struct vnode *vp,
 759    struct fs *copy_fs, daddr_t snaplistsize)
 760{
 761	int error = 0, i;
 762	daddr_t numblks, *snaplist = NULL;
 763	struct fs *fs = VFSTOUFS(mp)->um_fs;
 764	struct inode *ip = VTOI(vp), *xp;
 765	struct lwp *l = curlwp;
 766	struct snap_info *si = VFSTOUFS(mp)->um_snapinfo;
 767
 768	TAILQ_FOREACH(xp, &si->si_snapshots, i_nextsnap) {
 769		if (xp != ip) {
 770			error = expunge(vp, xp, fs, snapacct, BLK_SNAP);
 771			if (error)
 772				break;
 773		}
 774		if (xp->i_nlink != 0)
 775			continue;
 776		error = UFS_WAPBL_BEGIN(mp);
 777		if (error)
 778			break;
 779		error = ffs_freefile_snap(copy_fs, vp, xp->i_number, xp->i_mode);
 780		UFS_WAPBL_END(mp);
 781		if (error)
 782			break;
 783	}
 784	if (error)
 785		goto out;
 786	/*
 787	 * Allocate space for the full list of preallocated snapshot blocks.
 788	 */
 789	snaplist = malloc(snaplistsize * sizeof(daddr_t), M_UFSMNT, M_WAITOK);
 790	ip->i_snapblklist = &snaplist[1];
 791	/*
 792	 * Expunge the blocks used by the snapshots from the set of
 793	 * blocks marked as used in the snapshot bitmaps. Also, collect
 794	 * the list of allocated blocks in i_snapblklist.
 795	 */
 796	error = expunge(vp, ip, copy_fs, mapacct, BLK_SNAP);
 797	if (error)
 798		goto out;
 799	if (snaplistsize < ip->i_snapblklist - snaplist)
 800		panic("ffs_snapshot: list too small");
 801	snaplistsize = ip->i_snapblklist - snaplist;
 802	snaplist[0] = snaplistsize;
 803	ip->i_snapblklist = &snaplist[0];
 804	/*
 805	 * Write out the list of allocated blocks to the end of the snapshot.
 806	 */
 807	numblks = howmany(fs->fs_size, fs->fs_frag);
 808	for (i = 0; i < snaplistsize; i++)
 809		snaplist[i] = ufs_rw64(snaplist[i], UFS_FSNEEDSWAP(fs));
 810	error = vn_rdwr(UIO_WRITE, vp, (void *)snaplist,
 811	    snaplistsize * sizeof(daddr_t), lblktosize(fs, (off_t)numblks),
 812	    UIO_SYSSPACE, IO_NODELOCKED | IO_UNIT, l->l_cred, NULL, NULL);
 813	for (i = 0; i < snaplistsize; i++)
 814		snaplist[i] = ufs_rw64(snaplist[i], UFS_FSNEEDSWAP(fs));
 815out:
 816	if (error && snaplist != NULL) {
 817		free(snaplist, M_UFSMNT);
 818		ip->i_snapblklist = NULL;
 819	}
 820	return error;
 821}
 822
 823/*
 824 * Write the superblock and its summary information to the snapshot.
 825 * Make sure, the first NDADDR blocks get copied to the snapshot.
 826 */
 827static int
 828snapshot_writefs(struct mount *mp, struct vnode *vp, void *sbbuf)
 829{
 830	int error, len, loc;
 831	void *space;
 832	daddr_t blkno;
 833	struct buf *bp;
 834	struct fs *copyfs, *fs = VFSTOUFS(mp)->um_fs;
 835	struct inode *ip = VTOI(vp);
 836	struct lwp *l = curlwp;
 837
 838	copyfs = (struct fs *)((char *)sbbuf + blkoff(fs, fs->fs_sblockloc));
 839
 840	/*
 841	 * Write the superblock and its summary information
 842	 * to the snapshot.
 843	 */
 844	blkno = fragstoblks(fs, fs->fs_csaddr);
 845	len = howmany(fs->fs_cssize, fs->fs_bsize);
 846	space = copyfs->fs_csp;
 847#ifdef FFS_EI
 848	if (UFS_FSNEEDSWAP(fs)) {
 849		ffs_sb_swap(copyfs, copyfs);
 850		ffs_csum_swap(space, space, fs->fs_cssize);
 851	}
 852#endif
 853	error = UFS_WAPBL_BEGIN(mp);
 854	if (error)
 855		return error;
 856	for (loc = 0; loc < len; loc++) {
 857		error = bread(vp, blkno + loc, fs->fs_bsize, l->l_cred,
 858		    B_MODIFY, &bp);
 859		if (error) {
 860			brelse(bp, 0);
 861			break;
 862		}
 863		memcpy(bp->b_data, space, fs->fs_bsize);
 864		space = (char *)space + fs->fs_bsize;
 865		bawrite(bp);
 866	}
 867	if (error)
 868		goto out;
 869	error = bread(vp, lblkno(fs, fs->fs_sblockloc),
 870	    fs->fs_bsize, l->l_cred, B_MODIFY, &bp);
 871	if (error) {
 872		brelse(bp, 0);
 873		goto out;
 874	} else {
 875		memcpy(bp->b_data, sbbuf, fs->fs_bsize);
 876		bawrite(bp);
 877	}
 878	/*
 879	 * Copy the first NDADDR blocks to the snapshot so ffs_copyonwrite()
 880	 * and ffs_snapblkfree() will always work on indirect blocks.
 881	 */
 882	for (loc = 0; loc < NDADDR; loc++) {
 883		if (db_get(ip, loc) != 0)
 884			continue;
 885		error = ffs_balloc(vp, lblktosize(fs, (off_t)loc),
 886		    fs->fs_bsize, l->l_cred, 0, &bp);
 887		if (error)
 888			break;
 889		error = rwfsblk(vp, B_READ, bp->b_data, loc);
 890		if (error) {
 891			brelse(bp, 0);
 892			break;
 893		}
 894		bawrite(bp);
 895	}
 896
 897out:
 898	UFS_WAPBL_END(mp);
 899	return error;
 900}
 901
 902/*
 903 * Copy all cylinder group maps.
 904 */
 905static int
 906cgaccount(struct vnode *vp, int passno, int *redo)
 907{
 908	int cg, error = 0;
 909	struct buf *nbp;
 910	struct fs *fs = VTOI(vp)->i_fs;
 911
 912	if (redo != NULL)
 913		*redo = 0;
 914	if (passno == 1)
 915		fs->fs_active = malloc(howmany(fs->fs_ncg, NBBY),
 916		    M_DEVBUF, M_WAITOK | M_ZERO);
 917	for (cg = 0; cg < fs->fs_ncg; cg++) {
 918		if (passno == 2 && ACTIVECG_ISSET(fs, cg))
 919			continue;
 920
 921		if (redo != NULL)
 922			*redo += 1;
 923		error = UFS_WAPBL_BEGIN(vp->v_mount);
 924		if (error)
 925			return error;
 926		error = ffs_balloc(vp, lfragtosize(fs, cgtod(fs, cg)),
 927		    fs->fs_bsize, curlwp->l_cred, 0, &nbp);
 928		if (error) {
 929			UFS_WAPBL_END(vp->v_mount);
 930			break;
 931		}
 932		error = cgaccount1(cg, vp, nbp->b_data, passno);
 933		bawrite(nbp);
 934		UFS_WAPBL_END(vp->v_mount);
 935		if (error)
 936			break;
 937	}
 938	return error;
 939}
 940
 941/*
 942 * Copy a cylinder group map. All the unallocated blocks are marked
 943 * BLK_NOCOPY so that the snapshot knows that it need not copy them
 944 * if they are later written. If passno is one, then this is a first
 945 * pass, so only setting needs to be done. If passno is 2, then this
 946 * is a revision to a previous pass which must be undone as the
 947 * replacement pass is done.
 948 */
 949static int
 950cgaccount1(int cg, struct vnode *vp, void *data, int passno)
 951{
 952	struct buf *bp, *ibp;
 953	struct inode *ip;
 954	struct cg *cgp;
 955	struct fs *fs;
 956	struct lwp *l = curlwp;
 957	daddr_t base, numblks;
 958	int error, len, loc, ns, indiroff;
 959
 960	ip = VTOI(vp);
 961	fs = ip->i_fs;
 962	ns = UFS_FSNEEDSWAP(fs);
 963	error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)),
 964		(int)fs->fs_cgsize, l->l_cred, 0, &bp);
 965	if (error) {
 966		brelse(bp, 0);
 967		return (error);
 968	}
 969	cgp = (struct cg *)bp->b_data;
 970	if (!cg_chkmagic(cgp, ns)) {
 971		brelse(bp, 0);
 972		return (EIO);
 973	}
 974	ACTIVECG_SET(fs, cg);
 975
 976	memcpy(data, bp->b_data, fs->fs_cgsize);
 977	brelse(bp, 0);
 978	if (fs->fs_cgsize < fs->fs_bsize)
 979		memset((char *)data + fs->fs_cgsize, 0,
 980		    fs->fs_bsize - fs->fs_cgsize);
 981	numblks = howmany(fs->fs_size, fs->fs_frag);
 982	len = howmany(fs->fs_fpg, fs->fs_frag);
 983	base = cg * fs->fs_fpg / fs->fs_frag;
 984	if (base + len >= numblks)
 985		len = numblks - base - 1;
 986	loc = 0;
 987	if (base < NDADDR) {
 988		for ( ; loc < NDADDR; loc++) {
 989			if (ffs_isblock(fs, cg_blksfree(cgp, ns), loc))
 990				db_assign(ip, loc, BLK_NOCOPY);
 991			else if (db_get(ip, loc) == BLK_NOCOPY) {
 992				if (passno == 2)
 993					db_assign(ip, loc, 0);
 994				else if (passno == 1)
 995					panic("ffs_snapshot: lost direct block");
 996			}
 997		}
 998	}
 999	if ((error = ffs_balloc(vp, lblktosize(fs, (off_t)(base + loc)),
1000	    fs->fs_bsize, l->l_cred, B_METAONLY, &ibp)) != 0)
1001		return (error);
1002	indiroff = (base + loc - NDADDR) % NINDIR(fs);
1003	for ( ; loc < len; loc++, indiroff++) {
1004		if (indiroff >= NINDIR(fs)) {
1005			bawrite(ibp);
1006			if ((error = ffs_balloc(vp,
1007			    lblktosize(fs, (off_t)(base + loc)),
1008			    fs->fs_bsize, l->l_cred, B_METAONLY, &ibp)) != 0)
1009				return (error);
1010			indiroff = 0;
1011		}
1012		if (ffs_isblock(fs, cg_blksfree(cgp, ns), loc))
1013			idb_assign(ip, ibp->b_data, indiroff, BLK_NOCOPY);
1014		else if (idb_get(ip, ibp->b_data, indiroff) == BLK_NOCOPY) {
1015			if (passno == 2)
1016				idb_assign(ip, ibp->b_data, indiroff, 0);
1017			else if (passno == 1)
1018				panic("ffs_snapshot: lost indirect block");
1019		}
1020	}
1021	bdwrite(ibp);
1022	return (0);
1023}
1024
1025/*
1026 * Before expunging a snapshot inode, note all the
1027 * blocks that it claims with BLK_SNAP so that fsck will
1028 * be able to account for those blocks properly and so
1029 * that this snapshot knows that it need not copy them
1030 * if the other snapshot holding them is freed.
1031 */
1032static int
1033expunge(struct vnode *snapvp, struct inode *cancelip, struct fs *fs,
1034    acctfunc_t acctfunc, int expungetype)
1035{
1036	int i, error, ns;
1037	daddr_t lbn, rlbn;
1038	daddr_t len, blkno, numblks, blksperindir;
1039	struct ufs1_dinode *dip1;
1040	struct ufs2_dinode *dip2;
1041	struct lwp *l = curlwp;
1042	void *bap;
1043	struct buf *bp;
1044	struct mount *mp;
1045
1046	ns = UFS_FSNEEDSWAP(fs);
1047	mp = snapvp->v_mount;
1048
1049	error = UFS_WAPBL_BEGIN(mp);
1050	if (error)
1051		return error;
1052	/*
1053	 * Prepare to expunge the inode. If its inode block has not
1054	 * yet been copied, then allocate and fill the copy.
1055	 */
1056	lbn = fragstoblks(fs, ino_to_fsba(fs, cancelip->i_number));
1057	error = snapblkaddr(snapvp, lbn, &blkno);
1058	if (error)
1059		return error;
1060	if (blkno != 0) {
1061		error = bread(snapvp, lbn, fs->fs_bsize, l->l_cred,
1062		    B_MODIFY, &bp);
1063	} else {
1064		error = ffs_balloc(snapvp, lblktosize(fs, (off_t)lbn),
1065		    fs->fs_bsize, l->l_cred, 0, &bp);
1066		if (! error)
1067			error = rwfsblk(snapvp, B_READ, bp->b_data, lbn);
1068	}
1069	if (error) {
1070		UFS_WAPBL_END(mp);
1071		return error;
1072	}
1073	/*
1074	 * Set a snapshot inode to be a zero length file, regular files
1075	 * or unlinked snapshots to be completely unallocated.
1076	 */
1077	if (fs->fs_magic == FS_UFS1_MAGIC) {
1078		dip1 = (struct ufs1_dinode *)bp->b_data +
1079		    ino_to_fsbo(fs, cancelip->i_number);
1080		if (cancelip->i_flags & SF_SNAPSHOT) {
1081			dip1->di_flags =
1082			    ufs_rw32(ufs_rw32(dip1->di_flags, ns) |
1083			    SF_SNAPINVAL, ns);
1084		}
1085		if (expungetype == BLK_NOCOPY || cancelip->i_nlink == 0)
1086			dip1->di_mode = 0;
1087		dip1->di_size = 0;
1088		dip1->di_blocks = 0;
1089		memset(&dip1->di_db[0], 0, (NDADDR + NIADDR) * sizeof(int32_t));
1090	} else {
1091		dip2 = (struct ufs2_dinode *)bp->b_data +
1092		    ino_to_fsbo(fs, cancelip->i_number);
1093		if (cancelip->i_flags & SF_SNAPSHOT) {
1094			dip2->di_flags =
1095			    ufs_rw32(ufs_rw32(dip2->di_flags, ns) |
1096			    SF_SNAPINVAL, ns);
1097		}
1098		if (expungetype == BLK_NOCOPY || cancelip->i_nlink == 0)
1099			dip2->di_mode = 0;
1100		dip2->di_size = 0;
1101		dip2->di_blocks = 0;
1102		memset(&dip2->di_db[0], 0, (NDADDR + NIADDR) * sizeof(int64_t));
1103	}
1104	bdwrite(bp);
1105	UFS_WAPBL_END(mp);
1106	/*
1107	 * Now go through and expunge all the blocks in the file
1108	 * using the function requested.
1109	 */
1110	numblks = howmany(cancelip->i_size, fs->fs_bsize);
1111	if (fs->fs_magic == FS_UFS1_MAGIC)
1112		bap = &cancelip->i_ffs1_db[0];
1113	else
1114		bap = &cancelip->i_ffs2_db[0];
1115	error = (*acctfunc)(snapvp, bap, 0, NDADDR, fs, 0, expungetype);
1116	if (error)
1117		return (error);
1118	if (fs->fs_magic == FS_UFS1_MAGIC)
1119		bap = &cancelip->i_ffs1_ib[0];
1120	else
1121		bap = &cancelip->i_ffs2_ib[0];
1122	error = (*acctfunc)(snapvp, bap, 0, NIADDR, fs, -1, expungetype);
1123	if (error)
1124		return (error);
1125	blksperindir = 1;
1126	lbn = -NDADDR;
1127	len = numblks - NDADDR;
1128	rlbn = NDADDR;
1129	for (i = 0; len > 0 && i < NIADDR; i++) {
1130		error = indiracct(snapvp, ITOV(cancelip), i,
1131		    ib_get(cancelip, i), lbn, rlbn, len,
1132		    blksperindir, fs, acctfunc, expungetype);
1133		if (error)
1134			return (error);
1135		blksperindir *= NINDIR(fs);
1136		lbn -= blksperindir + 1;
1137		len -= blksperindir;
1138		rlbn += blksperindir;
1139	}
1140	return (0);
1141}
1142
1143/*
1144 * Descend an indirect block chain for vnode cancelvp accounting for all
1145 * its indirect blocks in snapvp.
1146 */
1147static int
1148indiracct(struct vnode *snapvp, struct vnode *cancelvp, int level,
1149    daddr_t blkno, daddr_t lbn, daddr_t rlbn, daddr_t remblks,
1150    daddr_t blksperindir, struct fs *fs, acctfunc_t acctfunc, int expungetype)
1151{
1152	int error, num, i;
1153	daddr_t subblksperindir;
1154	struct indir indirs[NIADDR + 2];
1155	daddr_t last;
1156	void *bap;
1157	struct buf *bp;
1158
1159	if (blkno == 0) {
1160		if (expungetype == BLK_NOCOPY)
1161			return (0);
1162		panic("indiracct: missing indir");
1163	}
1164	if ((error = ufs_getlbns(cancelvp, rlbn, indirs, &num)) != 0)
1165		return (error);
1166	if (lbn != indirs[num - 1 - level].in_lbn || num < 2)
1167		panic("indiracct: botched params");
1168	/*
1169	 * We have to expand bread here since it will deadlock looking
1170	 * up the block number for any blocks that are not in the cache.
1171	 */
1172	error = ffs_getblk(cancelvp, lbn, fsbtodb(fs, blkno), fs->fs_bsize,
1173	    false, &bp);
1174	if (error)
1175		return error;
1176	if ((bp->b_oflags & (BO_DONE | BO_DELWRI)) == 0 && (error =
1177	    rwfsblk(bp->b_vp, B_READ, bp->b_data, fragstoblks(fs, blkno)))) {
1178		brelse(bp, 0);
1179		return (error);
1180	}
1181	/*
1182	 * Account for the block pointers in this indirect block.
1183	 */
1184	last = howmany(remblks, blksperindir);
1185	if (last > NINDIR(fs))
1186		last = NINDIR(fs);
1187	bap = malloc(fs->fs_bsize, M_DEVBUF, M_WAITOK | M_ZERO);
1188	memcpy((void *)bap, bp->b_data, fs->fs_bsize);
1189	brelse(bp, 0);
1190	error = (*acctfunc)(snapvp, bap, 0, last,
1191	    fs, level == 0 ? rlbn : -1, expungetype);
1192	if (error || level == 0)
1193		goto out;
1194	/*
1195	 * Account for the block pointers in each of the indirect blocks
1196	 * in the levels below us.
1197	 */
1198	subblksperindir = blksperindir / NINDIR(fs);
1199	for (lbn++, level--, i = 0; i < last; i++) {
1200		error = indiracct(snapvp, cancelvp, level,
1201		    idb_get(VTOI(snapvp), bap, i), lbn, rlbn, remblks,
1202		    subblksperindir, fs, acctfunc, expungetype);
1203		if (error)
1204			goto out;
1205		rlbn += blksperindir;
1206		lbn -= blksperindir;
1207		remblks -= blksperindir;
1208	}
1209out:
1210	free(bap, M_DEVBUF);
1211	return (error);
1212}
1213
1214/*
1215 * Do both snap accounting and map accounting.
1216 */
1217static int
1218fullacct(struct vnode *vp, void *bap, int oldblkp, int lastblkp,
1219    struct fs *fs, daddr_t lblkno,
1220    int exptype /* BLK_SNAP or BLK_NOCOPY */)
1221{
1222	int error;
1223
1224	if ((error = snapacct(vp, bap, oldblkp, lastblkp, fs, lblkno, exptype)))
1225		return (error);
1226	return (mapacct(vp, bap, oldblkp, lastblkp, fs, lblkno, exptype));
1227}
1228
1229/*
1230 * Identify a set of blocks allocated in a snapshot inode.
1231 */
1232static int
1233snapacct(struct vnode *vp, void *bap, int oldblkp, int lastblkp,
1234    struct fs *fs, daddr_t lblkno,
1235    int expungetype /* BLK_SNAP or BLK_NOCOPY */)
1236{
1237	struct inode *ip = VTOI(vp);
1238	struct lwp *l = curlwp;
1239	struct mount *mp = vp->v_mount;
1240	daddr_t blkno;
1241	daddr_t lbn;
1242	struct buf *ibp;
1243	int error, n;
1244	const int wbreak = blocks_in_journal(VFSTOUFS(mp)->um_fs)/8;
1245
1246	error = UFS_WAPBL_BEGIN(mp);
1247	if (error)
1248		return error;
1249	for ( n = 0; oldblkp < lastblkp; oldblkp++) {
1250		blkno = idb_get(ip, bap, oldblkp);
1251		if (blkno == 0 || blkno == BLK_NOCOPY || blkno == BLK_SNAP)
1252			continue;
1253		lbn = fragstoblks(fs, blkno);
1254		if (lbn < NDADDR) {
1255			blkno = db_get(ip, lbn);
1256			ip->i_flag |= IN_CHANGE | IN_UPDATE;
1257		} else {
1258			error = ffs_balloc(vp, lblktosize(fs, (off_t)lbn),
1259			    fs->fs_bsize, l->l_cred, B_METAONLY, &ibp);
1260			if (error)
1261				break;
1262			blkno = idb_get(ip, ibp->b_data,
1263			    (lbn - NDADDR) % NINDIR(fs));
1264		}
1265		/*
1266		 * If we are expunging a snapshot vnode and we
1267		 * find a block marked BLK_NOCOPY, then it is
1268		 * one that has been allocated to this snapshot after
1269		 * we took our current snapshot and can be ignored.
1270		 */
1271		if (expungetype == BLK_SNAP && blkno == BLK_NOCOPY) {
1272			if (lbn >= NDADDR)
1273				brelse(ibp, 0);
1274		} else {
1275			if (blkno != 0)
1276				panic("snapacct: bad block");
1277			if (lbn < NDADDR)
1278				db_assign(ip, lbn, expungetype);
1279			else {
1280				idb_assign(ip, ibp->b_data,
1281				    (lbn - NDADDR) % NINDIR(fs), expungetype);
1282				bdwrite(ibp);
1283			}
1284		}
1285		if (wbreak > 0 && (++n % wbreak) == 0) {
1286			UFS_WAPBL_END(mp);
1287			error = UFS_WAPBL_BEGIN(mp);
1288			if (error)
1289				return error;
1290		}
1291	}
1292	UFS_WAPBL_END(mp);
1293	return error;
1294}
1295
1296/*
1297 * Account for a set of blocks allocated in a snapshot inode.
1298 */
1299static int
1300mapacct(struct vnode *vp, void *bap, int oldblkp, int lastblkp,
1301    struct fs *fs, daddr_t lblkno, int expungetype)
1302{
1303	daddr_t blkno;
1304	struct inode *ip;
1305	struct mount *mp = vp->v_mount;
1306	ino_t inum;
1307	int acctit, error, n;
1308	const int wbreak = blocks_in_journal(VFSTOUFS(mp)->um_fs)/8;
1309
1310	error = UFS_WAPBL_BEGIN(mp);
1311	if (error)
1312		return error;
1313	ip = VTOI(vp);
1314	inum = ip->i_number;
1315	if (lblkno == -1)
1316		acctit = 0;
1317	else
1318		acctit = 1;
1319	for ( n = 0; oldblkp < lastblkp; oldblkp++, lblkno++) {
1320		blkno = idb_get(ip, bap, oldblkp);
1321		if (blkno == 0 || blkno == BLK_NOCOPY)
1322			continue;
1323		if (acctit && expungetype == BLK_SNAP && blkno != BLK_SNAP)
1324			*ip->i_snapblklist++ = lblkno;
1325		if (blkno == BLK_SNAP)
1326			blkno = blkstofrags(fs, lblkno);
1327		ffs_blkfree_snap(fs, vp, blkno, fs->fs_bsize, inum);
1328		if (wbreak > 0 && (++n % wbreak) == 0) {
1329			UFS_WAPBL_END(mp);
1330			error = UFS_WAPBL_BEGIN(mp);
1331			if (error)
1332				return error;
1333		}
1334	}
1335	UFS_WAPBL_END(mp);
1336	return (0);
1337}
1338
1339/*
1340 * Number of blocks that fit into the journal or zero if not logging.
1341 */
1342static int
1343blocks_in_journal(struct fs *fs)
1344{
1345	off_t bpj;
1346
1347	if ((fs->fs_flags & FS_DOWAPBL) == 0)
1348		return 0;
1349	bpj = 1;
1350	if (fs->fs_journal_version == UFS_WAPBL_VERSION) {
1351		switch (fs->fs_journal_location) {
1352		case UFS_WAPBL_JOURNALLOC_END_PARTITION:
1353			bpj = (off_t)fs->fs_journallocs[UFS_WAPBL_EPART_BLKSZ]*
1354			    fs->fs_journallocs[UFS_WAPBL_EPART_COUNT];
1355			break;
1356		case UFS_WAPBL_JOURNALLOC_IN_FILESYSTEM:
1357			bpj = (off_t)fs->fs_journallocs[UFS_WAPBL_INFS_BLKSZ]*
1358			    fs->fs_journallocs[UFS_WAPBL_INFS_COUNT];
1359			break;
1360		}
1361	}
1362	bpj /= fs->fs_bsize;
1363	return (bpj > 0 ? bpj : 1);
1364}
1365#endif /* defined(FFS_NO_SNAPSHOT) */
1366
1367/*
1368 * Decrement extra reference on snapshot when last name is removed.
1369 * It will not be freed until the last open reference goes away.
1370 */
1371void
1372ffs_snapgone(struct inode *ip)
1373{
1374	struct mount *mp = ip->i_devvp->v_specmountpoint;
1375	struct inode *xp;
1376	struct fs *fs;
1377	struct snap_info *si;
1378	int snaploc;
1379
1380	si = VFSTOUFS(mp)->um_snapinfo;
1381
1382	/*
1383	 * Find snapshot in incore list.
1384	 */
1385	mutex_enter(&si->si_lock);
1386	TAILQ_FOREACH(xp, &si->si_snapshots, i_nextsnap)
1387		if (xp == ip)
1388			break;
1389	mutex_exit(&si->si_lock);
1390	if (xp != NULL)
1391		vrele(ITOV(ip));
1392#ifdef DEBUG
1393	else if (snapdebug)
1394		printf("ffs_snapgone: lost snapshot vnode %llu\n",
1395		    (unsigned long long)ip->i_number);
1396#endif
1397	/*
1398	 * Delete snapshot inode from superblock. Keep list dense.
1399	 */
1400	mutex_enter(&si->si_lock);
1401	fs = ip->i_fs;
1402	for (snaploc = 0; snaploc < FSMAXSNAP; snaploc++)
1403		if (fs->fs_snapinum[snaploc] == ip->i_number)
1404			break;
1405	if (snaploc < FSMAXSNAP) {
1406		for (snaploc++; snaploc < FSMAXSNAP; snaploc++) {
1407			if (fs->fs_snapinum[snaploc] == 0)
1408				break;
1409			fs->fs_snapinum[snaploc - 1] = fs->fs_snapinum[snaploc];
1410		}
1411		fs->fs_snapinum[snaploc - 1] = 0;
1412	}
1413	si->si_gen++;
1414	mutex_exit(&si->si_lock);
1415}
1416
1417/*
1418 * Prepare a snapshot file for being removed.
1419 */
1420void
1421ffs_snapremove(struct vnode *vp)
1422{
1423	struct inode *ip = VTOI(vp), *xp;
1424	struct vnode *devvp = ip->i_devvp;
1425	struct fs *fs = ip->i_fs;
1426	struct mount *mp = devvp->v_specmountpoint;
1427	struct buf *ibp;
1428	struct snap_info *si;
1429	struct lwp *l = curlwp;
1430	daddr_t numblks, blkno, dblk;
1431	int error, loc, last;
1432
1433	si = VFSTOUFS(mp)->um_snapinfo;
1434	/*
1435	 * If active, delete from incore list (this snapshot may
1436	 * already have been in the process of being deleted, so
1437	 * would not have been active).
1438	 *
1439	 * Clear copy-on-write flag if last snapshot.
1440	 */
1441	mutex_enter(&si->si_snaplock);
1442	mutex_enter(&si->si_lock);
1443	if (is_active_snapshot(si, ip)) {
1444		TAILQ_REMOVE(&si->si_snapshots, ip, i_nextsnap);
1445		if (TAILQ_FIRST(&si->si_snapshots) != 0) {
1446			/* Roll back the list of preallocated blocks. */
1447			xp = TAILQ_LAST(&si->si_snapshots, inodelst);
1448			si->si_snapblklist = xp->i_snapblklist;
1449			si->si_gen++;
1450			mutex_exit(&si->si_lock);
1451			mutex_exit(&si->si_snaplock);
1452		} else {
1453			si->si_snapblklist = 0;
1454			si->si_gen++;
1455			mutex_exit(&si->si_lock);
1456			mutex_exit(&si->si_snaplock);
1457			fscow_disestablish(mp, ffs_copyonwrite, devvp);
1458		}
1459		if (ip->i_snapblklist != NULL) {
1460			free(ip->i_snapblklist, M_UFSMNT);
1461			ip->i_snapblklist = NULL;
1462		}
1463	} else {
1464		mutex_exit(&si->si_lock);
1465		mutex_exit(&si->si_snaplock);
1466	}
1467	/*
1468	 * Clear all BLK_NOCOPY fields. Pass any block claims to other
1469	 * snapshots that want them (see ffs_snapblkfree below).
1470	 */
1471	for (blkno = 1; blkno < NDADDR; blkno++) {
1472		dblk = db_get(ip, blkno);
1473		if (dblk == BLK_NOCOPY || dblk == BLK_SNAP)
1474			db_assign(ip, blkno, 0);
1475		else if ((dblk == blkstofrags(fs, blkno) &&
1476		     ffs_snapblkfree(fs, ip->i_devvp, dblk, fs->fs_bsize,
1477		     ip->i_number))) {
1478			DIP_ADD(ip, blocks, -btodb(fs->fs_bsize));
1479			db_assign(ip, blkno, 0);
1480		}
1481	}
1482	numblks = howmany(ip->i_size, fs->fs_bsize);
1483	for (blkno = NDADDR; blkno < numblks; blkno += NINDIR(fs)) {
1484		error = ffs_balloc(vp, lblktosize(fs, (off_t)blkno),
1485		    fs->fs_bsize, l->l_cred, B_METAONLY, &ibp);
1486		if (error)
1487			continue;
1488		if (fs->fs_size - blkno > NINDIR(fs))
1489			last = NINDIR(fs);
1490		else
1491			last = fs->fs_size - blkno;
1492		for (loc = 0; loc < last; loc++) {
1493			dblk = idb_get(ip, ibp->b_data, loc);
1494			if (dblk == BLK_NOCOPY || dblk == BLK_SNAP)
1495				idb_assign(ip, ibp->b_data, loc, 0);
1496			else if (dblk == blkstofrags(fs, blkno) &&
1497			    ffs_snapblkfree(fs, ip->i_devvp, dblk,
1498			    fs->fs_bsize, ip->i_number)) {
1499				DIP_ADD(ip, blocks, -btodb(fs->fs_bsize));
1500				idb_assign(ip, ibp->b_data, loc, 0);
1501			}
1502		}
1503		bawrite(ibp);
1504		UFS_WAPBL_END(mp);
1505		error = UFS_WAPBL_BEGIN(mp);
1506		KASSERT(error == 0);
1507	}
1508	/*
1509	 * Clear snapshot flag and drop reference.
1510	 */
1511	ip->i_flags &= ~(SF_SNAPSHOT | SF_SNAPINVAL);
1512	DIP_ASSIGN(ip, flags, ip->i_flags);
1513	ip->i_flag |= IN_CHANGE | IN_UPDATE;
1514#if defined(QUOTA) || defined(QUOTA2)
1515	chkdq(ip, DIP(ip, blocks), l->l_cred, FORCE);
1516	chkiq(ip, 1, l->l_cred, FORCE);
1517#endif
1518}
1519
1520/*
1521 * Notification that a block is being freed. Return zero if the free
1522 * should be allowed to proceed. Return non-zero if the snapshot file
1523 * wants to claim the block. The block will be claimed if it is an
1524 * uncopied part of one of the snapshots. It will be freed if it is
1525 * either a BLK_NOCOPY or has already been copied in all of the snapshots.
1526 * If a fragment is being freed, then all snapshots that care about
1527 * it must make a copy since a snapshot file can only claim full sized
1528 * blocks. Note that if more than one snapshot file maps the block,
1529 * we can pick one at random to claim it. Since none of the snapshots
1530 * can change, we are assurred that they will all see the same unmodified
1531 * image. When deleting a snapshot file (see ffs_snapremove above), we
1532 * must push any of these claimed blocks to one of the other snapshots
1533 * that maps it. These claimed blocks are easily identified as they will
1534 * have a block number equal to their logical block number within the
1535 * snapshot. A copied block can never have this property because they
1536 * must always have been allocated from a BLK_NOCOPY location.
1537 */
1538int
1539ffs_snapblkfree(struct fs *fs, struct vnode *devvp, daddr_t bno,
1540    long size, ino_t inum)
1541{
1542	struct mount *mp = devvp->v_specmountpoint;
1543	struct buf *ibp;
1544	struct inode *ip;
1545	struct vnode *vp = NULL;
1546	struct snap_info *si;
1547	void *saved_data = NULL;
1548	daddr_t lbn;
1549	daddr_t blkno;
1550	uint32_t gen;
1551	int indiroff = 0, error = 0, claimedblk = 0;
1552
1553	si = VFSTOUFS(mp)->um_snapinfo;
1554	lbn = fragstoblks(fs, bno);
1555	mutex_enter(&si->si_snaplock);
1556	mutex_enter(&si->si_lock);
1557	si->si_owner = curlwp;
1558		
1559retry:
1560	gen = si->si_gen;
1561	TAILQ_FOREACH(ip, &si->si_snapshots, i_nextsnap) {
1562		vp = ITOV(ip);
1563		/*
1564		 * Lookup block being written.
1565		 */
1566		if (lbn < NDADDR) {
1567			blkno = db_get(ip, lbn);
1568		} else {
1569			mutex_exit(&si->si_lock);
1570			error = ffs_balloc(vp, lblktosize(fs, (off_t)lbn),
1571			    fs->fs_bsize, FSCRED, B_METAONLY, &ibp);
1572			if (error) {
1573				mutex_enter(&si->si_lock);
1574				break;
1575			}
1576			indiroff = (lbn - NDADDR) % NINDIR(fs);
1577			blkno = idb_get(ip, ibp->b_data, indiroff);
1578			mutex_enter(&si->si_lock);
1579			if (gen != si->si_gen) {
1580				brelse(ibp, 0);
1581				goto retry;
1582			}
1583		}
1584		/*
1585		 * Check to see if block needs to be copied.
1586		 */
1587		if (blkno == 0) {
1588			/*
1589			 * A block that we map is being freed. If it has not
1590			 * been claimed yet, we will claim or copy it (below).
1591			 */
1592			claimedblk = 1;
1593		} else if (blkno == BLK_SNAP) {
1594			/*
1595			 * No previous snapshot claimed the block,
1596			 * so it will be freed and become a BLK_NOCOPY
1597			 * (don't care) for us.
1598			 */
1599			if (claimedblk)
1600				panic("snapblkfree: inconsistent block type");
1601			if (lbn < NDADDR) {
1602				db_assign(ip, lbn, BLK_NOCOPY);
1603				ip->i_flag |= IN_CHANGE | IN_UPDATE;
1604			} else {
1605				idb_assign(ip, ibp->b_data, indiroff,
1606				    BLK_NOCOPY);
1607				mutex_exit(&si->si_lock);
1608				if (ip->i_nlink > 0)
1609					bwrite(ibp);
1610				else
1611					bdwrite(ibp);
1612				mutex_enter(&si->si_lock);
1613				if (gen != si->si_gen)
1614					goto retry;
1615			}
1616			continue;
1617		} else /* BLK_NOCOPY or default */ {
1618			/*
1619			 * If the snapshot has already copied the block
1620			 * (default), or does not care about the block,
1621			 * it is not needed.
1622			 */
1623			if (lbn >= NDADDR)
1624				brelse(ibp, 0);
1625			continue;
1626		}
1627		/*
1628		 * If this is a full size block, we will just grab it
1629		 * and assign it to the snapshot inode. Otherwise we
1630		 * will proceed to copy it. See explanation for this
1631		 * routine as to why only a single snapshot needs to
1632		 * claim this block.
1633		 */
1634		if (size == fs->fs_bsize) {
1635#ifdef DEBUG
1636			if (snapdebug)
1637				printf("%s %llu lbn %" PRId64
1638				    "from inum %llu\n",
1639				    "Grabonremove: snapino",
1640				    (unsigned long long)ip->i_number,
1641				    lbn, (unsigned long long)inum);
1642#endif
1643			mutex_exit(&si->si_lock);
1644			if (lbn < NDADDR) {
1645				db_assign(ip, lbn, bno);
1646			} else {
1647				idb_assign(ip, ibp->b_data, indiroff, bno);
1648				if (ip->i_nlink > 0)
1649					bwrite(ibp);
1650				else
1651					bdwrite(ibp);
1652			}
1653			DIP_ADD(ip, blocks, btodb(size));
1654			ip->i_flag |= IN_CHANGE | IN_UPDATE;
1655			if (ip->i_nlink > 0 && mp->mnt_wapbl)
1656				error = syncsnap(vp);
1657			else
1658				error = 0;
1659			mutex_enter(&si->si_lock);
1660			si->si_owner = NULL;
1661			mutex_exit(&si->si_lock);
1662			mutex_exit(&si->si_snaplock);
1663			return (error == 0);
1664		}
1665		if (lbn >= NDADDR)
1666			brelse(ibp, 0);
1667#ifdef DEBUG
1668		if (snapdebug)
1669			printf("%s%llu lbn %" PRId64 " %s %llu size %ld\n",
1670			    "Copyonremove: snapino ",
1671			    (unsigned long long)ip->i_number,
1672			    lbn, "for inum", (unsigned long long)inum, size);
1673#endif
1674		/*
1675		 * If we have already read the old block contents, then
1676		 * simply copy them to the new block. Note that we need
1677		 * to synchronously write snapshots that have not been
1678		 * unlinked, and hence will be visible after a crash,
1679		 * to ensure their integrity.
1680		 */
1681		mutex_exit(&si->si_lock);
1682		if (saved_data == NULL) {
1683			saved_data = malloc(fs->fs_bsize, M_UFSMNT, M_WAITOK);
1684			error = rwfsblk(vp, B_READ, saved_data, lbn);
1685			if (error) {
1686				free(saved_data, M_UFSMNT);
1687				saved_data = NULL;
1688				mutex_enter(&si->si_lock);
1689				break;
1690			}
1691		}
1692		error = wrsnapblk(vp, saved_data, lbn);
1693		if (error == 0 && ip->i_nlink > 0 && mp->mnt_wapbl)
1694			error = syncsnap(vp);
1695		mutex_enter(&si->si_lock);
1696		if (error)
1697			break;
1698		if (gen != si->si_gen)
1699			goto retry;
1700	}
1701	si->si_owner = NULL;
1702	mutex_exit(&si->si_lock);
1703	mutex_exit(&si->si_snaplock);
1704	if (saved_data)
1705		free(saved_data, M_UFSMNT);
1706	/*
1707	 * If we have been unable to allocate a block in which to do
1708	 * the copy, then return non-zero so that the fragment will
1709	 * not be freed. Although space will be lost, the snapshot
1710	 * will stay consistent.
1711	 */
1712	return (error);
1713}
1714
1715/*
1716 * Associate snapshot files when mounting.
1717 */
1718void
1719ffs_snapshot_mount(struct mount *mp)
1720{
1721	struct vnode *devvp = VFSTOUFS(mp)->um_devvp;
1722	struct fs *fs = VFSTOUFS(mp)->um_fs;
1723	struct lwp *l = curlwp;
1724	struct vnode *vp;
1725	struct inode *ip, *xp;
1726	struct snap_info *si;
1727	daddr_t snaplistsize, *snapblklist;
1728	int i, error, ns, snaploc, loc;
1729
1730	/*
1731	 * No persistent snapshots on apple ufs file systems.
1732	 */
1733	if (UFS_MPISAPPLEUFS(VFSTOUFS(mp)))
1734		return;
1735
1736	si = VFSTOUFS(mp)->um_snapinfo;
1737	ns = UFS_FSNEEDSWAP(fs);
1738	/*
1739	 * XXX The following needs to be set before ffs_truncate or
1740	 * VOP_READ can be called.
1741	 */
1742	mp->mnt_stat.f_iosize = fs->fs_bsize;
1743	/*
1744	 * Process each snapshot listed in the superblock.
1745	 */
1746	vp = NULL;
1747	mutex_enter(&si->si_lock);
1748	for (snaploc = 0; snaploc < FSMAXSNAP; snaploc++) {
1749		if (fs->fs_snapinum[snaploc] == 0)
1750			break;
1751		if ((error = VFS_VGET(mp, fs->fs_snapinum[snaploc],
1752		    &vp)) != 0) {
1753			printf("ffs_snapshot_mount: vget failed %d\n", error);
1754			continue;
1755		}
1756		ip = VTOI(vp);
1757		if ((ip->i_flags & (SF_SNAPSHOT | SF_SNAPINVAL)) !=
1758		    SF_SNAPSHOT) {
1759			printf("ffs_snapshot_mount: non-snapshot inode %d\n",
1760			    fs->fs_snapinum[snaploc]);
1761			vput(vp);
1762			vp = NULL;
1763			for (loc = snaploc + 1; loc < FSMAXSNAP; loc++) {
1764				if (fs->fs_snapinum[loc] == 0)
1765					break;
1766				fs->fs_snapinum[loc - 1] = fs->fs_snapinum[loc];
1767			}
1768			fs->fs_snapinum[loc - 1] = 0;
1769			snaploc--;
1770			continue;
1771		}
1772
1773		/*
1774		 * Read the block hints list. Use an empty list on
1775		 * read errors.
1776		 */
1777		error = vn_rdwr(UIO_READ, vp,
1778		    (void *)&snaplistsize, sizeof(snaplistsize),
1779		    lblktosize(fs, howmany(fs->fs_size, fs->fs_frag)),
1780		    UIO_SYSSPACE, IO_NODELOCKED|IO_UNIT|IO_ALTSEMANTICS,
1781		    l->l_cred, NULL, NULL);
1782		if (error) {
1783			printf("ffs_snapshot_mount: read_1 failed %d\n", error);
1784			snaplistsize = 1;
1785		} else
1786			snaplistsize = ufs_rw64(snaplistsize, ns);
1787		snapblklist = malloc(
1788		    snaplistsize * sizeof(daddr_t), M_UFSMNT, M_WAITOK);
1789		if (error)
1790			snapblklist[0] = 1;
1791		else {
1792			error = vn_rdwr(UIO_READ, vp, (void *)snapblklist,
1793			    snaplistsize * sizeof(daddr_t),
1794			    lblktosize(fs, howmany(fs->fs_size, fs->fs_frag)),
1795			    UIO_SYSSPACE, IO_NODELOCKED|IO_UNIT|IO_ALTSEMANTICS,
1796			    l->l_cred, NULL, NULL);
1797			for (i = 0; i < snaplistsize; i++)

Large files files are truncated, but you can click here to view the full file