Import work done under project/nand (@235533) into head.

The NAND Flash environment consists of several distinct components:
  - NAND framework (drivers harness for NAND controllers and NAND chips)
  - NAND simulator (NANDsim)
  - NAND file system (NAND FS)
  - Companion tools and utilities
  - Documentation (manual pages)

This work is still experimental. Please use with caution.

Obtained from: Semihalf
Supported by:  FreeBSD Foundation, Juniper Networks

1 files changed, 1590 insertions, 0 deletions

diff --git a/sys/fs/nandfs/nandfs_vfsops.c b/sys/fs/nandfs/nandfs_vfsops.c
new file mode 100644
index 0000000..ba53546
--- /dev/null
+++ b/sys/fs/nandfs/nandfs_vfsops.c
@@ -0,0 +1,1590 @@
+/*-
+ * Copyright (c) 2010-2012 Semihalf
+ * Copyright (c) 2008, 2009 Reinoud Zandijk
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * From: NetBSD: nilfs_vfsops.c,v 1.1 2009/07/18 16:31:42 reinoud Exp
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/fcntl.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mount.h>
+#include <sys/namei.h>
+#include <sys/proc.h>
+#include <sys/priv.h>
+#include <sys/vnode.h>
+#include <sys/buf.h>
+#include <sys/sysctl.h>
+#include <sys/libkern.h>
+
+#include <geom/geom.h>
+#include <geom/geom_vfs.h>
+
+#include <machine/_inttypes.h>
+
+#include <fs/nandfs/nandfs_mount.h>
+#include <fs/nandfs/nandfs.h>
+#include <fs/nandfs/nandfs_subr.h>
+
+static MALLOC_DEFINE(M_NANDFSMNT, "nandfs_mount", "NANDFS mount structure");
+
+#define	NANDFS_SET_SYSTEMFILE(vp) {	\
+	(vp)->v_vflag |= VV_SYSTEM;	\
+	vref(vp);			\
+	vput(vp); }
+
+#define	NANDFS_UNSET_SYSTEMFILE(vp) {	\
+	VOP_LOCK(vp, LK_EXCLUSIVE);	\
+	MPASS(vp->v_bufobj.bo_dirty.bv_cnt == 0); \
+	(vp)->v_vflag &= ~VV_SYSTEM;	\
+	vgone(vp);			\
+	vput(vp); }
+
+/* Globals */
+struct _nandfs_devices nandfs_devices;
+
+/* Parameters */
+int nandfs_verbose = 0;
+
+static void
+nandfs_tunable_init(void *arg)
+{
+
+	TUNABLE_INT_FETCH("vfs.nandfs.verbose", &nandfs_verbose);
+}
+SYSINIT(nandfs_tunables, SI_SUB_VFS, SI_ORDER_ANY, nandfs_tunable_init, NULL);
+
+static SYSCTL_NODE(_vfs, OID_AUTO, nandfs, CTLFLAG_RD, 0, "NAND filesystem");
+static SYSCTL_NODE(_vfs_nandfs, OID_AUTO, mount, CTLFLAG_RD, 0,
+    "NANDFS mountpoints");
+SYSCTL_INT(_vfs_nandfs, OID_AUTO, verbose, CTLFLAG_RW, &nandfs_verbose, 0, "");
+
+#define NANDFS_CONSTR_INTERVAL	5
+int nandfs_sync_interval = NANDFS_CONSTR_INTERVAL; /* sync every 5 seconds */
+SYSCTL_UINT(_vfs_nandfs, OID_AUTO, sync_interval, CTLFLAG_RW,
+    &nandfs_sync_interval, 0, "");
+
+#define NANDFS_MAX_DIRTY_SEGS	5
+int nandfs_max_dirty_segs = NANDFS_MAX_DIRTY_SEGS; /* sync when 5 dirty seg */
+SYSCTL_UINT(_vfs_nandfs, OID_AUTO, max_dirty_segs, CTLFLAG_RW,
+    &nandfs_max_dirty_segs, 0, "");
+
+#define NANDFS_CPS_BETWEEN_SBLOCKS 5
+int nandfs_cps_between_sblocks = NANDFS_CPS_BETWEEN_SBLOCKS; /* write superblock every 5 checkpoints */
+SYSCTL_UINT(_vfs_nandfs, OID_AUTO, cps_between_sblocks, CTLFLAG_RW,
+    &nandfs_cps_between_sblocks, 0, "");
+
+#define NANDFS_CLEANER_ENABLE 1
+int nandfs_cleaner_enable = NANDFS_CLEANER_ENABLE;
+SYSCTL_UINT(_vfs_nandfs, OID_AUTO, cleaner_enable, CTLFLAG_RW,
+    &nandfs_cleaner_enable, 0, "");
+
+#define NANDFS_CLEANER_INTERVAL 5
+int nandfs_cleaner_interval = NANDFS_CLEANER_INTERVAL;
+SYSCTL_UINT(_vfs_nandfs, OID_AUTO, cleaner_interval, CTLFLAG_RW,
+    &nandfs_cleaner_interval, 0, "");
+
+#define NANDFS_CLEANER_SEGMENTS 5
+int nandfs_cleaner_segments = NANDFS_CLEANER_SEGMENTS;
+SYSCTL_UINT(_vfs_nandfs, OID_AUTO, cleaner_segments, CTLFLAG_RW,
+    &nandfs_cleaner_segments, 0, "");
+
+static int nandfs_mountfs(struct vnode *devvp, struct mount *mp);
+static vfs_mount_t	nandfs_mount;
+static vfs_root_t	nandfs_root;
+static vfs_statfs_t	nandfs_statfs;
+static vfs_unmount_t	nandfs_unmount;
+static vfs_vget_t	nandfs_vget;
+static vfs_sync_t	nandfs_sync;
+static const char *nandfs_opts[] = {
+	"snap", "from", "noatime", NULL
+};
+
+/* System nodes */
+static int
+nandfs_create_system_nodes(struct nandfs_device *nandfsdev)
+{
+	int error;
+
+	error = nandfs_get_node_raw(nandfsdev, NULL, NANDFS_DAT_INO,
+	    &nandfsdev->nd_super_root.sr_dat, &nandfsdev->nd_dat_node);
+	if (error)
+		goto errorout;
+
+	error = nandfs_get_node_raw(nandfsdev, NULL, NANDFS_CPFILE_INO,
+	    &nandfsdev->nd_super_root.sr_cpfile, &nandfsdev->nd_cp_node);
+	if (error)
+		goto errorout;
+
+	error = nandfs_get_node_raw(nandfsdev, NULL, NANDFS_SUFILE_INO,
+	    &nandfsdev->nd_super_root.sr_sufile, &nandfsdev->nd_su_node);
+	if (error)
+		goto errorout;
+
+	error = nandfs_get_node_raw(nandfsdev, NULL, NANDFS_GC_INO,
+	    NULL, &nandfsdev->nd_gc_node);
+	if (error)
+		goto errorout;
+
+	NANDFS_SET_SYSTEMFILE(NTOV(nandfsdev->nd_dat_node));
+	NANDFS_SET_SYSTEMFILE(NTOV(nandfsdev->nd_cp_node));
+	NANDFS_SET_SYSTEMFILE(NTOV(nandfsdev->nd_su_node));
+	NANDFS_SET_SYSTEMFILE(NTOV(nandfsdev->nd_gc_node));
+
+	DPRINTF(VOLUMES, ("System vnodes: dat: %p cp: %p su: %p\n",
+	    NTOV(nandfsdev->nd_dat_node), NTOV(nandfsdev->nd_cp_node),
+	    NTOV(nandfsdev->nd_su_node)));
+	return (0);
+
+errorout:
+	nandfs_dispose_node(&nandfsdev->nd_gc_node);
+	nandfs_dispose_node(&nandfsdev->nd_dat_node);
+	nandfs_dispose_node(&nandfsdev->nd_cp_node);
+	nandfs_dispose_node(&nandfsdev->nd_su_node);
+
+	return (error);
+}
+
+static void
+nandfs_release_system_nodes(struct nandfs_device *nandfsdev)
+{
+
+	if (!nandfsdev)
+		return;
+	if (nandfsdev->nd_refcnt > 0)
+		return;
+
+	if (nandfsdev->nd_gc_node)
+		NANDFS_UNSET_SYSTEMFILE(NTOV(nandfsdev->nd_gc_node));
+	if (nandfsdev->nd_dat_node)
+		NANDFS_UNSET_SYSTEMFILE(NTOV(nandfsdev->nd_dat_node));
+	if (nandfsdev->nd_cp_node)
+		NANDFS_UNSET_SYSTEMFILE(NTOV(nandfsdev->nd_cp_node));
+	if (nandfsdev->nd_su_node)
+		NANDFS_UNSET_SYSTEMFILE(NTOV(nandfsdev->nd_su_node));
+}
+
+static int
+nandfs_check_fsdata_crc(struct nandfs_fsdata *fsdata)
+{
+	uint32_t fsdata_crc, comp_crc;
+
+	if (fsdata->f_magic != NANDFS_FSDATA_MAGIC)
+		return (0);
+
+	/* Preserve CRC */
+	fsdata_crc = fsdata->f_sum;
+
+	/* Calculate */
+	fsdata->f_sum = (0);
+	comp_crc = crc32((uint8_t *)fsdata, fsdata->f_bytes);
+
+	/* Restore */
+	fsdata->f_sum = fsdata_crc;
+
+	/* Check CRC */
+	return (fsdata_crc == comp_crc);
+}
+
+static int
+nandfs_check_superblock_crc(struct nandfs_fsdata *fsdata,
+    struct nandfs_super_block *super)
+{
+	uint32_t super_crc, comp_crc;
+
+	/* Check super block magic */
+	if (super->s_magic != NANDFS_SUPER_MAGIC)
+		return (0);
+
+	/* Preserve CRC */
+	super_crc = super->s_sum;
+
+	/* Calculate */
+	super->s_sum = (0);
+	comp_crc = crc32((uint8_t *)super, fsdata->f_sbbytes);
+
+	/* Restore */
+	super->s_sum = super_crc;
+
+	/* Check CRC */
+	return (super_crc == comp_crc);
+}
+
+static void
+nandfs_calc_superblock_crc(struct nandfs_fsdata *fsdata,
+    struct nandfs_super_block *super)
+{
+	uint32_t comp_crc;
+
+	/* Calculate */
+	super->s_sum = 0;
+	comp_crc = crc32((uint8_t *)super, fsdata->f_sbbytes);
+
+	/* Restore */
+	super->s_sum = comp_crc;
+}
+
+static int
+nandfs_is_empty(u_char *area, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		if (area[i] != 0xff)
+			return (0);
+
+	return (1);
+}
+
+static __inline int
+nandfs_sblocks_in_esize(struct nandfs_device *fsdev)
+{
+
+	return ((fsdev->nd_erasesize - NANDFS_SBLOCK_OFFSET_BYTES) /
+	    sizeof(struct nandfs_super_block));
+}
+
+static __inline int
+nandfs_max_sblocks(struct nandfs_device *fsdev)
+{
+
+	return (NANDFS_NFSAREAS * nandfs_sblocks_in_esize(fsdev));
+}
+
+static __inline int
+nandfs_sblocks_in_block(struct nandfs_device *fsdev)
+{
+
+	return (fsdev->nd_devblocksize / sizeof(struct nandfs_super_block));
+}
+
+static __inline int
+nandfs_sblocks_in_first_block(struct nandfs_device *fsdev)
+{
+	int n;
+
+	n = nandfs_sblocks_in_block(fsdev) -
+	    NANDFS_SBLOCK_OFFSET_BYTES / sizeof(struct nandfs_super_block);
+	if (n < 0)
+		n = 0;
+
+	return (n);
+}
+
+static int
+nandfs_write_superblock_at(struct nandfs_device *fsdev,
+    struct nandfs_fsarea *fstp)
+{
+	struct nandfs_super_block *super, *supert;
+	struct buf *bp;
+	int sb_per_sector, sbs_in_fsd, read_block;
+	int index, pos, error;
+	off_t offset;
+
+	DPRINTF(SYNC, ("%s: last_used %d nandfs_sblocks_in_esize %d\n",
+	    __func__, fstp->last_used, nandfs_sblocks_in_esize(fsdev)));
+	if (fstp->last_used == nandfs_sblocks_in_esize(fsdev) - 1)
+		index = 0;
+	else
+		index = fstp->last_used + 1;
+
+	super = &fsdev->nd_super;
+	supert = NULL;
+
+	sb_per_sector = nandfs_sblocks_in_block(fsdev);
+	sbs_in_fsd = sizeof(struct nandfs_fsdata) /
+	    sizeof(struct nandfs_super_block);
+	index += sbs_in_fsd;
+	offset = fstp->offset;
+
+	DPRINTF(SYNC, ("%s: offset %#jx s_last_pseg %#jx s_last_cno %#jx "
+	    "s_last_seq %#jx wtime %jd index %d\n", __func__, offset,
+	    super->s_last_pseg, super->s_last_cno, super->s_last_seq,
+	    super->s_wtime, index));
+
+	read_block = btodb(offset + ((index / sb_per_sector) * sb_per_sector)
+	    * sizeof(struct nandfs_super_block));
+
+	DPRINTF(SYNC, ("%s: read_block %#x\n", __func__, read_block));
+
+	if (index == sbs_in_fsd) {
+		error = nandfs_erase(fsdev, offset, fsdev->nd_erasesize);
+		if (error)
+			return (error);
+
+		error = bread(fsdev->nd_devvp, btodb(offset),
+		    fsdev->nd_devblocksize, NOCRED, &bp);
+		if (error) {
+			printf("NANDFS: couldn't read initial data: %d\n",
+			    error);
+			brelse(bp);
+			return (error);
+		}
+		memcpy(bp->b_data, &fsdev->nd_fsdata, sizeof(fsdev->nd_fsdata));
+		/*
+		 * 0xff-out the rest. This bp could be cached, so potentially
+		 * b_data contains stale super blocks.
+		 *
+		 * We don't mind cached bp since most of the time we just add
+		 * super blocks to already 0xff-out b_data and don't need to
+		 * perform actual read.
+		 */
+		if (fsdev->nd_devblocksize > sizeof(fsdev->nd_fsdata))
+			memset(bp->b_data + sizeof(fsdev->nd_fsdata), 0xff,
+			    fsdev->nd_devblocksize - sizeof(fsdev->nd_fsdata));
+		error = bwrite(bp);
+		if (error) {
+			printf("NANDFS: cannot rewrite initial data at %jx\n",
+			    offset);
+			return (error);
+		}
+	}
+
+	error = bread(fsdev->nd_devvp, read_block, fsdev->nd_devblocksize,
+	    NOCRED, &bp);
+	if (error) {
+		brelse(bp);
+		return (error);
+	}
+
+	supert = (struct nandfs_super_block *)(bp->b_data);
+	pos = index % sb_per_sector;
+
+	DPRINTF(SYNC, ("%s: storing at %d\n", __func__, pos));
+	memcpy(&supert[pos], super, sizeof(struct nandfs_super_block));
+
+	/*
+	 * See comment above in code that performs erase.
+	 */
+	if (pos == 0)
+		memset(&supert[1], 0xff,
+		    (sb_per_sector - 1) * sizeof(struct nandfs_super_block));
+
+	error = bwrite(bp);
+	if (error) {
+		printf("NANDFS: cannot update superblock at %jx\n", offset);
+		return (error);
+	}
+
+	DPRINTF(SYNC, ("%s: fstp->last_used %d -> %d\n", __func__,
+	    fstp->last_used, index - sbs_in_fsd));
+	fstp->last_used = index - sbs_in_fsd;
+
+	return (0);
+}
+
+int
+nandfs_write_superblock(struct nandfs_device *fsdev)
+{
+	struct nandfs_super_block *super;
+	struct timespec ts;
+	int error;
+	int i, j;
+
+	vfs_timestamp(&ts);
+
+	super = &fsdev->nd_super;
+
+	super->s_last_pseg = fsdev->nd_last_pseg;
+	super->s_last_cno = fsdev->nd_last_cno;
+	super->s_last_seq = fsdev->nd_seg_sequence;
+	super->s_wtime = ts.tv_sec;
+
+	nandfs_calc_superblock_crc(&fsdev->nd_fsdata, super);
+
+	error = 0;
+	for (i = 0, j = fsdev->nd_last_fsarea; i < NANDFS_NFSAREAS;
+	    i++, j = (j + 1 % NANDFS_NFSAREAS)) {
+		if (fsdev->nd_fsarea[j].flags & NANDFS_FSSTOR_FAILED) {
+			DPRINTF(SYNC, ("%s: skipping %d\n", __func__, j));
+			continue;
+		}
+		error = nandfs_write_superblock_at(fsdev, &fsdev->nd_fsarea[j]);
+		if (error) {
+			printf("NANDFS: writing superblock at offset %d failed:"
+			    "%d\n", j * fsdev->nd_erasesize, error);
+			fsdev->nd_fsarea[j].flags |= NANDFS_FSSTOR_FAILED;
+		} else
+			break;
+	}
+
+	if (i == NANDFS_NFSAREAS) {
+		printf("NANDFS: superblock was not written\n");
+		/*
+		 * TODO: switch to read-only?
+		 */
+		return (error);
+	} else
+		fsdev->nd_last_fsarea = (j + 1) % NANDFS_NFSAREAS;
+
+	return (0);
+}
+
+static int
+nandfs_select_fsdata(struct nandfs_device *fsdev,
+    struct nandfs_fsdata *fsdatat, struct nandfs_fsdata **fsdata, int nfsds)
+{
+	int i;
+
+	*fsdata = NULL;
+	for (i = 0; i < nfsds; i++) {
+		DPRINTF(VOLUMES, ("%s: i %d f_magic %x f_crc %x\n", __func__,
+		    i, fsdatat[i].f_magic, fsdatat[i].f_sum));
+		if (!nandfs_check_fsdata_crc(&fsdatat[i]))
+			continue;
+		*fsdata = &fsdatat[i];
+		break;
+	}
+
+	return (*fsdata != NULL ? 0 : EINVAL);
+}
+
+static int
+nandfs_select_sb(struct nandfs_device *fsdev,
+    struct nandfs_super_block *supert, struct nandfs_super_block **super,
+    int nsbs)
+{
+	int i;
+
+	*super = NULL;
+	for (i = 0; i < nsbs; i++) {
+		if (!nandfs_check_superblock_crc(&fsdev->nd_fsdata, &supert[i]))
+			continue;
+		DPRINTF(SYNC, ("%s: i %d s_last_cno %jx s_magic %x "
+		    "s_wtime %jd\n", __func__, i, supert[i].s_last_cno,
+		    supert[i].s_magic, supert[i].s_wtime));
+		if (*super == NULL || supert[i].s_last_cno >
+		    (*super)->s_last_cno)
+			*super = &supert[i];
+	}
+
+	return (*super != NULL ? 0 : EINVAL);
+}
+
+static int
+nandfs_read_structures_at(struct nandfs_device *fsdev,
+    struct nandfs_fsarea *fstp, struct nandfs_fsdata *fsdata,
+    struct nandfs_super_block *super)
+{
+	struct nandfs_super_block *tsuper, *tsuperd;
+	struct buf *bp;
+	int error, read_size;
+	int i;
+	int offset;
+
+	offset = fstp->offset;
+
+	if (fsdev->nd_erasesize > MAXBSIZE)
+		read_size = MAXBSIZE;
+	else
+		read_size = fsdev->nd_erasesize;
+
+	error = bread(fsdev->nd_devvp, btodb(offset), read_size, NOCRED, &bp);
+	if (error) {
+		printf("couldn't read: %d\n", error);
+		brelse(bp);
+		fstp->flags |= NANDFS_FSSTOR_FAILED;
+		return (error);
+	}
+
+	tsuper = super;
+
+	memcpy(fsdata, bp->b_data, sizeof(struct nandfs_fsdata));
+	memcpy(tsuper, (bp->b_data + sizeof(struct nandfs_fsdata)),
+	    read_size - sizeof(struct nandfs_fsdata));
+	brelse(bp);
+
+	tsuper += (read_size - sizeof(struct nandfs_fsdata)) /
+	    sizeof(struct nandfs_super_block);
+
+	for (i = 1; i < fsdev->nd_erasesize / read_size; i++) {
+		error = bread(fsdev->nd_devvp, btodb(offset + i * read_size),
+		    read_size, NOCRED, &bp);
+		if (error) {
+			printf("couldn't read: %d\n", error);
+			brelse(bp);
+			fstp->flags |= NANDFS_FSSTOR_FAILED;
+			return (error);
+		}
+		memcpy(tsuper, bp->b_data, read_size);
+		tsuper += read_size / sizeof(struct nandfs_super_block);
+		brelse(bp);
+	}
+
+	tsuper -= 1;
+	fstp->last_used = nandfs_sblocks_in_esize(fsdev) - 1;
+	for (tsuperd = super - 1; (tsuper != tsuperd); tsuper -= 1) {
+		if (nandfs_is_empty((u_char *)tsuper, sizeof(*tsuper)))
+			fstp->last_used--;
+		else
+			break;
+	}
+
+	DPRINTF(VOLUMES, ("%s: last_used %d\n", __func__, fstp->last_used));
+
+	return (0);
+}
+
+static int
+nandfs_read_structures(struct nandfs_device *fsdev)
+{
+	struct nandfs_fsdata *fsdata, *fsdatat;
+	struct nandfs_super_block *sblocks, *ssblock;
+	int nsbs, nfsds, i;
+	int error = 0;
+	int nrsbs;
+
+	nfsds = NANDFS_NFSAREAS;
+	nsbs = nandfs_max_sblocks(fsdev);
+
+	fsdatat = malloc(sizeof(struct nandfs_fsdata) * nfsds, M_NANDFSTEMP,
+	    M_WAITOK | M_ZERO);
+	sblocks = malloc(sizeof(struct nandfs_super_block) * nsbs, M_NANDFSTEMP,
+	    M_WAITOK | M_ZERO);
+
+	nrsbs = 0;
+	for (i = 0; i < NANDFS_NFSAREAS; i++) {
+		fsdev->nd_fsarea[i].offset = i * fsdev->nd_erasesize;
+		error = nandfs_read_structures_at(fsdev, &fsdev->nd_fsarea[i],
+		    &fsdatat[i], sblocks + nrsbs);
+		if (error)
+			continue;
+		nrsbs += (fsdev->nd_fsarea[i].last_used + 1);
+		if (fsdev->nd_fsarea[fsdev->nd_last_fsarea].last_used >
+		    fsdev->nd_fsarea[i].last_used)
+			fsdev->nd_last_fsarea = i;
+	}
+
+	if (nrsbs == 0) {
+		printf("nandfs: no valid superblocks found\n");
+		error = EINVAL;
+		goto out;
+	}
+
+	error = nandfs_select_fsdata(fsdev, fsdatat, &fsdata, nfsds);
+	if (error)
+		goto out;
+	memcpy(&fsdev->nd_fsdata, fsdata, sizeof(struct nandfs_fsdata));
+
+	error = nandfs_select_sb(fsdev, sblocks, &ssblock, nsbs);
+	if (error)
+		goto out;
+
+	memcpy(&fsdev->nd_super, ssblock, sizeof(struct nandfs_super_block));
+out:
+	free(fsdatat, M_NANDFSTEMP);
+	free(sblocks, M_NANDFSTEMP);
+
+	if (error == 0)
+		DPRINTF(VOLUMES, ("%s: selected sb with w_time %jd "
+		    "last_pseg %#jx\n", __func__, fsdev->nd_super.s_wtime,
+		    fsdev->nd_super.s_last_pseg));
+
+	return (error);
+}
+
+static void
+nandfs_unmount_base(struct nandfs_device *nandfsdev)
+{
+	int error;
+
+	if (!nandfsdev)
+		return;
+
+	/* Remove all our information */
+	error = vinvalbuf(nandfsdev->nd_devvp, V_SAVE, 0, 0);
+	if (error) {
+		/*
+		 * Flushing buffers failed when fs was umounting, can't do
+		 * much now, just printf error and continue with umount.
+		 */
+		nandfs_error("%s(): error:%d when umounting FS\n",
+		    __func__, error);
+	}
+
+	/* Release the device's system nodes */
+	nandfs_release_system_nodes(nandfsdev);
+}
+
+static void
+nandfs_get_ncleanseg(struct nandfs_device *nandfsdev)
+{
+	struct nandfs_seg_stat nss;
+
+	nandfs_get_seg_stat(nandfsdev, &nss);
+	nandfsdev->nd_clean_segs = nss.nss_ncleansegs;
+	DPRINTF(VOLUMES, ("nandfs_mount: clean segs: %jx\n",
+	    (uintmax_t)nandfsdev->nd_clean_segs));
+}
+
+
+static int
+nandfs_mount_base(struct nandfs_device *nandfsdev, struct mount *mp,
+    struct nandfs_args *args)
+{
+	uint32_t log_blocksize;
+	int error;
+
+	/* Flush out any old buffers remaining from a previous use. */
+	if ((error = vinvalbuf(nandfsdev->nd_devvp, V_SAVE, 0, 0)))
+		return (error);
+
+	error = nandfs_read_structures(nandfsdev);
+	if (error) {
+		printf("nandfs: could not get valid filesystem structures\n");
+		return (error);
+	}
+
+	if (nandfsdev->nd_fsdata.f_rev_level != NANDFS_CURRENT_REV) {
+		printf("nandfs: unsupported file system revision: %d "
+		    "(supported is %d).\n", nandfsdev->nd_fsdata.f_rev_level,
+		    NANDFS_CURRENT_REV);
+		return (EINVAL);
+	}
+
+	if (nandfsdev->nd_fsdata.f_erasesize != nandfsdev->nd_erasesize) {
+		printf("nandfs: erasesize mismatch (device %#x, fs %#x)\n",
+		    nandfsdev->nd_erasesize, nandfsdev->nd_fsdata.f_erasesize);
+		return (EINVAL);
+	}
+
+	/* Get our blocksize */
+	log_blocksize = nandfsdev->nd_fsdata.f_log_block_size;
+	nandfsdev->nd_blocksize = (uint64_t) 1 << (log_blocksize + 10);
+	DPRINTF(VOLUMES, ("%s: blocksize:%x\n", __func__,
+	    nandfsdev->nd_blocksize));
+
+	DPRINTF(VOLUMES, ("%s: accepted super block with cp %#jx\n", __func__,
+	    (uintmax_t)nandfsdev->nd_super.s_last_cno));
+
+	/* Calculate dat structure parameters */
+	nandfs_calc_mdt_consts(nandfsdev, &nandfsdev->nd_dat_mdt,
+	    nandfsdev->nd_fsdata.f_dat_entry_size);
+	nandfs_calc_mdt_consts(nandfsdev, &nandfsdev->nd_ifile_mdt,
+	    nandfsdev->nd_fsdata.f_inode_size);
+
+	/* Search for the super root and roll forward when needed */
+	if (nandfs_search_super_root(nandfsdev)) {
+		printf("Cannot find valid SuperRoot\n");
+		return (EINVAL);
+	}
+
+	nandfsdev->nd_mount_state = nandfsdev->nd_super.s_state;
+	if (nandfsdev->nd_mount_state != NANDFS_VALID_FS) {
+		printf("FS is seriously damaged, needs repairing\n");
+		printf("aborting mount\n");
+		return (EINVAL);
+	}
+
+	/*
+	 * FS should be ok now. The superblock and the last segsum could be
+	 * updated from the repair so extract running values again.
+	 */
+	nandfsdev->nd_last_pseg = nandfsdev->nd_super.s_last_pseg;
+	nandfsdev->nd_seg_sequence = nandfsdev->nd_super.s_last_seq;
+	nandfsdev->nd_seg_num = nandfs_get_segnum_of_block(nandfsdev,
+	    nandfsdev->nd_last_pseg);
+	nandfsdev->nd_next_seg_num = nandfs_get_segnum_of_block(nandfsdev,
+	    nandfsdev->nd_last_segsum.ss_next);
+	nandfsdev->nd_ts.tv_sec = nandfsdev->nd_last_segsum.ss_create;
+	nandfsdev->nd_last_cno = nandfsdev->nd_super.s_last_cno;
+	nandfsdev->nd_fakevblk = 1;
+	nandfsdev->nd_last_ino  = NANDFS_USER_INO;
+	DPRINTF(VOLUMES, ("%s: last_pseg %#jx last_cno %#jx last_seq %#jx\n"
+	    "fsdev: last_seg: seq %#jx num %#jx, next_seg_num %#jx\n",
+	    __func__, (uintmax_t)nandfsdev->nd_last_pseg,
+	    (uintmax_t)nandfsdev->nd_last_cno,
+	    (uintmax_t)nandfsdev->nd_seg_sequence,
+	    (uintmax_t)nandfsdev->nd_seg_sequence,
+	    (uintmax_t)nandfsdev->nd_seg_num,
+	    (uintmax_t)nandfsdev->nd_next_seg_num));
+
+	DPRINTF(VOLUMES, ("nandfs_mount: accepted super root\n"));
+
+	/* Create system vnodes for DAT, CP and SEGSUM */
+	error = nandfs_create_system_nodes(nandfsdev);
+	if (error)
+		nandfs_unmount_base(nandfsdev);
+
+	nandfs_get_ncleanseg(nandfsdev);
+
+	return (error);
+}
+
+static void
+nandfs_unmount_device(struct nandfs_device *nandfsdev)
+{
+
+	/* Is there anything? */
+	if (nandfsdev == NULL)
+		return;
+
+	/* Remove the device only if we're the last reference */
+	nandfsdev->nd_refcnt--;
+	if (nandfsdev->nd_refcnt >= 1)
+		return;
+
+	MPASS(nandfsdev->nd_syncer == NULL);
+	MPASS(nandfsdev->nd_cleaner == NULL);
+	MPASS(nandfsdev->nd_free_base == NULL);
+
+	/* Unmount our base */
+	nandfs_unmount_base(nandfsdev);
+
+	/* Remove from our device list */
+	SLIST_REMOVE(&nandfs_devices, nandfsdev, nandfs_device, nd_next_device);
+
+	DROP_GIANT();
+	g_topology_lock();
+	g_vfs_close(nandfsdev->nd_gconsumer);
+	g_topology_unlock();
+	PICKUP_GIANT();
+
+	DPRINTF(VOLUMES, ("closing device\n"));
+
+	/* Clear our mount reference and release device node */
+	vrele(nandfsdev->nd_devvp);
+
+	dev_rel(nandfsdev->nd_devvp->v_rdev);
+
+	/* Free our device info */
+	cv_destroy(&nandfsdev->nd_sync_cv);
+	mtx_destroy(&nandfsdev->nd_sync_mtx);
+	cv_destroy(&nandfsdev->nd_clean_cv);
+	mtx_destroy(&nandfsdev->nd_clean_mtx);
+	mtx_destroy(&nandfsdev->nd_mutex);
+	lockdestroy(&nandfsdev->nd_seg_const);
+	free(nandfsdev, M_NANDFSMNT);
+}
+
+static int
+nandfs_check_mounts(struct nandfs_device *nandfsdev, struct mount *mp,
+    struct nandfs_args *args)
+{
+	struct nandfsmount *nmp;
+	uint64_t last_cno;
+
+	/* no double-mounting of the same checkpoint */
+	STAILQ_FOREACH(nmp, &nandfsdev->nd_mounts, nm_next_mount) {
+		if (nmp->nm_mount_args.cpno == args->cpno)
+			return (EBUSY);
+	}
+
+	/* Allow readonly mounts without questioning here */
+	if (mp->mnt_flag & MNT_RDONLY)
+		return (0);
+
+	/* Read/write mount */
+	STAILQ_FOREACH(nmp, &nandfsdev->nd_mounts, nm_next_mount) {
+		/* Only one RW mount on this device! */
+		if ((nmp->nm_vfs_mountp->mnt_flag & MNT_RDONLY)==0)
+			return (EROFS);
+		/* RDONLY on last mountpoint is device busy */
+		last_cno = nmp->nm_nandfsdev->nd_super.s_last_cno;
+		if (nmp->nm_mount_args.cpno == last_cno)
+			return (EBUSY);
+	}
+
+	/* OK for now */
+	return (0);
+}
+
+static int
+nandfs_mount_device(struct vnode *devvp, struct mount *mp,
+    struct nandfs_args *args, struct nandfs_device **nandfsdev_p)
+{
+	struct nandfs_device *nandfsdev;
+	struct g_provider *pp;
+	struct g_consumer *cp;
+	struct cdev *dev;
+	uint32_t erasesize;
+	int error, size;
+	int ronly;
+
+	DPRINTF(VOLUMES, ("Mounting NANDFS device\n"));
+
+	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
+
+	/* Look up device in our nandfs_mountpoints */
+	*nandfsdev_p = NULL;
+	SLIST_FOREACH(nandfsdev, &nandfs_devices, nd_next_device)
+		if (nandfsdev->nd_devvp == devvp)
+			break;
+
+	if (nandfsdev) {
+		DPRINTF(VOLUMES, ("device already mounted\n"));
+		error = nandfs_check_mounts(nandfsdev, mp, args);
+		if (error)
+			return error;
+		nandfsdev->nd_refcnt++;
+		*nandfsdev_p = nandfsdev;
+
+		if (!ronly) {
+			DROP_GIANT();
+			g_topology_lock();
+			error = g_access(nandfsdev->nd_gconsumer, 0, 1, 0);
+			g_topology_unlock();
+			PICKUP_GIANT();
+		}
+		return (error);
+	}
+
+	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
+	dev = devvp->v_rdev;
+	dev_ref(dev);
+	DROP_GIANT();
+	g_topology_lock();
+	error = g_vfs_open(devvp, &cp, "nandfs", ronly ? 0 : 1);
+	pp = g_dev_getprovider(dev);
+	g_topology_unlock();
+	PICKUP_GIANT();
+	VOP_UNLOCK(devvp, 0);
+	if (error) {
+		dev_rel(dev);
+		return (error);
+	}
+
+	nandfsdev = malloc(sizeof(struct nandfs_device), M_NANDFSMNT, M_WAITOK | M_ZERO);
+
+	/* Initialise */
+	nandfsdev->nd_refcnt = 1;
+	nandfsdev->nd_devvp = devvp;
+	nandfsdev->nd_syncing = 0;
+	nandfsdev->nd_cleaning = 0;
+	nandfsdev->nd_gconsumer = cp;
+	cv_init(&nandfsdev->nd_sync_cv, "nandfssync");
+	mtx_init(&nandfsdev->nd_sync_mtx, "nffssyncmtx", NULL, MTX_DEF);
+	cv_init(&nandfsdev->nd_clean_cv, "nandfsclean");
+	mtx_init(&nandfsdev->nd_clean_mtx, "nffscleanmtx", NULL, MTX_DEF);
+	mtx_init(&nandfsdev->nd_mutex, "nandfsdev lock", NULL, MTX_DEF);
+	lockinit(&nandfsdev->nd_seg_const, PVFS, "nffssegcon", VLKTIMEOUT,
+	    LK_CANRECURSE);
+	STAILQ_INIT(&nandfsdev->nd_mounts);
+
+	nandfsdev->nd_devsize = pp->mediasize;
+	nandfsdev->nd_devblocksize = pp->sectorsize;
+
+	size = sizeof(erasesize);
+	error = g_io_getattr("NAND::blocksize", nandfsdev->nd_gconsumer, &size,
+	    &erasesize);
+	if (error) {
+		DPRINTF(VOLUMES, ("couldn't get erasesize: %d\n", error));
+
+		if (error == ENOIOCTL || error == EOPNOTSUPP) {
+			/*
+			 * We conclude that this is not NAND storage
+			 */
+			nandfsdev->nd_erasesize = NANDFS_DEF_ERASESIZE;
+			nandfsdev->nd_is_nand = 0;
+		} else {
+			DROP_GIANT();
+			g_topology_lock();
+			g_vfs_close(nandfsdev->nd_gconsumer);
+			g_topology_unlock();
+			PICKUP_GIANT();
+			dev_rel(dev);
+			free(nandfsdev, M_NANDFSMNT);
+			return (error);
+		}
+	} else {
+		nandfsdev->nd_erasesize = erasesize;
+		nandfsdev->nd_is_nand = 1;
+	}
+
+	DPRINTF(VOLUMES, ("%s: erasesize %x\n", __func__,
+	    nandfsdev->nd_erasesize));
+
+	/* Register nandfs_device in list */
+	SLIST_INSERT_HEAD(&nandfs_devices, nandfsdev, nd_next_device);
+
+	error = nandfs_mount_base(nandfsdev, mp, args);
+	if (error) {
+		/* Remove all our information */
+		nandfs_unmount_device(nandfsdev);
+		return (EINVAL);
+	}
+
+	nandfsdev->nd_maxfilesize = nandfs_get_maxfilesize(nandfsdev);
+
+	*nandfsdev_p = nandfsdev;
+	DPRINTF(VOLUMES, ("NANDFS device mounted ok\n"));
+
+	return (0);
+}
+
+static int
+nandfs_mount_checkpoint(struct nandfsmount *nmp)
+{
+	struct nandfs_cpfile_header *cphdr;
+	struct nandfs_checkpoint *cp;
+	struct nandfs_inode ifile_inode;
+	struct nandfs_node *cp_node;
+	struct buf *bp;
+	uint64_t ncp, nsn, cpno, fcpno, blocknr, last_cno;
+	uint32_t off, dlen;
+	int cp_per_block, error;
+
+	cpno = nmp->nm_mount_args.cpno;
+	if (cpno == 0)
+		cpno = nmp->nm_nandfsdev->nd_super.s_last_cno;
+
+	DPRINTF(VOLUMES, ("%s: trying to mount checkpoint number %"PRIu64"\n",
+	    __func__, cpno));
+
+	cp_node = nmp->nm_nandfsdev->nd_cp_node;
+
+	VOP_LOCK(NTOV(cp_node), LK_SHARED);
+	/* Get cpfile header from 1st block of cp file */
+	error = nandfs_bread(cp_node, 0, NOCRED, 0, &bp);
+	if (error) {
+		brelse(bp);
+		VOP_UNLOCK(NTOV(cp_node), 0);
+		return (error);
+	}
+
+	cphdr = (struct nandfs_cpfile_header *) bp->b_data;
+	ncp = cphdr->ch_ncheckpoints;
+	nsn = cphdr->ch_nsnapshots;
+
+	brelse(bp);
+
+	DPRINTF(VOLUMES, ("mount_nandfs: checkpoint header read in\n"));
+	DPRINTF(VOLUMES, ("\tNumber of checkpoints %"PRIu64"\n", ncp));
+	DPRINTF(VOLUMES, ("\tNumber of snapshots %"PRIu64"\n", nsn));
+
+	/* Read in our specified checkpoint */
+	dlen = nmp->nm_nandfsdev->nd_fsdata.f_checkpoint_size;
+	cp_per_block = nmp->nm_nandfsdev->nd_blocksize / dlen;
+
+	fcpno = cpno + NANDFS_CPFILE_FIRST_CHECKPOINT_OFFSET - 1;
+	blocknr = fcpno / cp_per_block;
+	off = (fcpno % cp_per_block) * dlen;
+	error = nandfs_bread(cp_node, blocknr, NOCRED, 0, &bp);
+	if (error) {
+		brelse(bp);
+		VOP_UNLOCK(NTOV(cp_node), 0);
+		printf("mount_nandfs: couldn't read cp block %"PRIu64"\n",
+		    fcpno);
+		return (EINVAL);
+	}
+
+	/* Needs to be a valid checkpoint */
+	cp = (struct nandfs_checkpoint *) ((uint8_t *) bp->b_data + off);
+	if (cp->cp_flags & NANDFS_CHECKPOINT_INVALID) {
+		printf("mount_nandfs: checkpoint marked invalid\n");
+		brelse(bp);
+		VOP_UNLOCK(NTOV(cp_node), 0);
+		return (EINVAL);
+	}
+
+	/* Is this really the checkpoint we want? */
+	if (cp->cp_cno != cpno) {
+		printf("mount_nandfs: checkpoint file corrupt? "
+		    "expected cpno %"PRIu64", found cpno %"PRIu64"\n",
+		    cpno, cp->cp_cno);
+		brelse(bp);
+		VOP_UNLOCK(NTOV(cp_node), 0);
+		return (EINVAL);
+	}
+
+	/* Check if it's a snapshot ! */
+	last_cno = nmp->nm_nandfsdev->nd_super.s_last_cno;
+	if (cpno != last_cno) {
+		/* Only allow snapshots if not mounting on the last cp */
+		if ((cp->cp_flags & NANDFS_CHECKPOINT_SNAPSHOT) == 0) {
+			printf( "mount_nandfs: checkpoint %"PRIu64" is not a "
+			    "snapshot\n", cpno);
+			brelse(bp);
+			VOP_UNLOCK(NTOV(cp_node), 0);
+			return (EINVAL);
+		}
+	}
+
+	ifile_inode = cp->cp_ifile_inode;
+	brelse(bp);
+
+	/* Get ifile inode */
+	error = nandfs_get_node_raw(nmp->nm_nandfsdev, NULL, NANDFS_IFILE_INO,
+	    &ifile_inode, &nmp->nm_ifile_node);
+	if (error) {
+		printf("mount_nandfs: can't read ifile node\n");
+		VOP_UNLOCK(NTOV(cp_node), 0);
+		return (EINVAL);
+	}
+
+	NANDFS_SET_SYSTEMFILE(NTOV(nmp->nm_ifile_node));
+	VOP_UNLOCK(NTOV(cp_node), 0);
+	/* Get root node? */
+
+	return (0);
+}
+
+static void
+free_nandfs_mountinfo(struct mount *mp)
+{
+	struct nandfsmount *nmp = VFSTONANDFS(mp);
+
+	if (nmp == NULL)
+		return;
+
+	free(nmp, M_NANDFSMNT);
+}
+
+void
+nandfs_wakeup_wait_sync(struct nandfs_device *nffsdev, int reason)
+{
+	char *reasons[] = {
+	    "umount",
+	    "vfssync",
+	    "bdflush",
+	    "fforce",
+	    "fsync",
+	    "ro_upd"
+	};
+
+	DPRINTF(SYNC, ("%s: %s\n", __func__, reasons[reason]));
+	mtx_lock(&nffsdev->nd_sync_mtx);
+	if (nffsdev->nd_syncing)
+		cv_wait(&nffsdev->nd_sync_cv, &nffsdev->nd_sync_mtx);
+	if (reason == SYNCER_UMOUNT)
+		nffsdev->nd_syncer_exit = 1;
+	nffsdev->nd_syncing = 1;
+	wakeup(&nffsdev->nd_syncing);
+	cv_wait(&nffsdev->nd_sync_cv, &nffsdev->nd_sync_mtx);
+
+	mtx_unlock(&nffsdev->nd_sync_mtx);
+}
+
+static void
+nandfs_gc_finished(struct nandfs_device *nffsdev, int exit)
+{
+	int error;
+
+	mtx_lock(&nffsdev->nd_sync_mtx);
+	nffsdev->nd_syncing = 0;
+	DPRINTF(SYNC, ("%s: cleaner finish\n", __func__));
+	cv_broadcast(&nffsdev->nd_sync_cv);
+	mtx_unlock(&nffsdev->nd_sync_mtx);
+	if (!exit) {
+		error = tsleep(&nffsdev->nd_syncing, PRIBIO, "-",
+		    hz * nandfs_sync_interval);
+		DPRINTF(SYNC, ("%s: cleaner waked up: %d\n",
+		    __func__, error));
+	}
+}
+
+static void
+nandfs_syncer(struct nandfsmount *nmp)
+{
+	struct nandfs_device *nffsdev;
+	struct mount *mp;
+	int flags, error;
+
+	mp = nmp->nm_vfs_mountp;
+	nffsdev = nmp->nm_nandfsdev;
+	tsleep(&nffsdev->nd_syncing, PRIBIO, "-", hz * nandfs_sync_interval);
+
+	while (!nffsdev->nd_syncer_exit) {
+		DPRINTF(SYNC, ("%s: syncer run\n", __func__));
+		nffsdev->nd_syncing = 1;
+
+		flags = (nmp->nm_flags & (NANDFS_FORCE_SYNCER | NANDFS_UMOUNT));
+
+		error = nandfs_segment_constructor(nmp, flags);
+		if (error)
+			nandfs_error("%s: error:%d when creating segments\n",
+			    __func__, error);
+
+		nmp->nm_flags &= ~flags;
+
+		nandfs_gc_finished(nffsdev, 0);
+	}
+
+	MPASS(nffsdev->nd_cleaner == NULL);
+	error = nandfs_segment_constructor(nmp,
+	    NANDFS_FORCE_SYNCER | NANDFS_UMOUNT);
+	if (error)
+		nandfs_error("%s: error:%d when creating segments\n",
+		    __func__, error);
+	nandfs_gc_finished(nffsdev, 1);
+	nffsdev->nd_syncer = NULL;
+	MPASS(nffsdev->nd_free_base == NULL);
+
+	DPRINTF(SYNC, ("%s: exiting\n", __func__));
+	kthread_exit();
+}
+
+static int
+start_syncer(struct nandfsmount *nmp)
+{
+	int error;
+
+	MPASS(nmp->nm_nandfsdev->nd_syncer == NULL);
+
+	DPRINTF(SYNC, ("%s: start syncer\n", __func__));
+
+	nmp->nm_nandfsdev->nd_syncer_exit = 0;
+
+	error = kthread_add((void(*)(void *))nandfs_syncer, nmp, NULL,
+	    &nmp->nm_nandfsdev->nd_syncer, 0, 0, "nandfs_syncer");
+
+	if (error)
+		printf("nandfs: could not start syncer: %d\n", error);
+
+	return (error);
+}
+
+static int
+stop_syncer(struct nandfsmount *nmp)
+{
+
+	MPASS(nmp->nm_nandfsdev->nd_syncer != NULL);
+
+	nandfs_wakeup_wait_sync(nmp->nm_nandfsdev, SYNCER_UMOUNT);
+
+	DPRINTF(SYNC, ("%s: stop syncer\n", __func__));
+	return (0);
+}
+
+/*
+ * Mount null layer
+ */
+static int
+nandfs_mount(struct mount *mp)
+{
+	struct nandfsmount *nmp;
+	struct vnode *devvp;
+	struct nameidata nd;
+	struct vfsoptlist *opts;
+	struct thread *td;
+	char *from;
+	int error = 0, flags;
+
+	DPRINTF(VOLUMES, ("%s: mp = %p\n", __func__, (void *)mp));
+
+	td = curthread;
+	opts = mp->mnt_optnew;
+
+	if (vfs_filteropt(opts, nandfs_opts))
+		return (EINVAL);
+
+	/*
+	 * Update is a no-op
+	 */
+	if (mp->mnt_flag & MNT_UPDATE) {
+		nmp = VFSTONANDFS(mp);
+		if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) {
+			return (error);
+		}
+		if (!(nmp->nm_ronly) && vfs_flagopt(opts, "ro", NULL, 0)) {
+			vn_start_write(NULL, &mp, V_WAIT);
+			error = VFS_SYNC(mp, MNT_WAIT);
+			if (error)
+				return (error);
+			vn_finished_write(mp);
+
+			flags = WRITECLOSE;
+			if (mp->mnt_flag & MNT_FORCE)
+				flags |= FORCECLOSE;
+
+			nandfs_wakeup_wait_sync(nmp->nm_nandfsdev,
+			    SYNCER_ROUPD);
+			error = vflush(mp, 0, flags, td);
+			if (error)
+				return (error);
+
+			nandfs_stop_cleaner(nmp->nm_nandfsdev);
+			stop_syncer(nmp);
+			DROP_GIANT();
+			g_topology_lock();
+			g_access(nmp->nm_nandfsdev->nd_gconsumer, 0, -1, 0);
+			g_topology_unlock();
+			PICKUP_GIANT();
+			MNT_ILOCK(mp);
+			mp->mnt_flag |= MNT_RDONLY;
+			MNT_IUNLOCK(mp);
+			nmp->nm_ronly = 1;
+
+		} else if ((nmp->nm_ronly) &&
+		    !vfs_flagopt(opts, "ro", NULL, 0)) {
+			/*
+			 * Don't allow read-write snapshots.
+			 */
+			if (nmp->nm_mount_args.cpno != 0)
+				return (EROFS);
+			/*
+			 * If upgrade to read-write by non-root, then verify
+			 * that user has necessary permissions on the device.
+			 */
+			devvp = nmp->nm_nandfsdev->nd_devvp;
+			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
+			error = VOP_ACCESS(devvp, VREAD | VWRITE,
+			    td->td_ucred, td);
+			if (error) {
+				error = priv_check(td, PRIV_VFS_MOUNT_PERM);
+				if (error) {
+					VOP_UNLOCK(devvp, 0);
+					return (error);
+				}
+			}
+
+			VOP_UNLOCK(devvp, 0);
+			DROP_GIANT();
+			g_topology_lock();
+			error = g_access(nmp->nm_nandfsdev->nd_gconsumer, 0, 1,
+			    0);
+			g_topology_unlock();
+			PICKUP_GIANT();
+			if (error)
+				return (error);
+
+			MNT_ILOCK(mp);
+			mp->mnt_flag &= ~MNT_RDONLY;
+			MNT_IUNLOCK(mp);
+			error = start_syncer(nmp);
+			if (error == 0)
+				error = nandfs_start_cleaner(nmp->nm_nandfsdev);
+			if (error) {
+				DROP_GIANT();
+				g_topology_lock();
+				g_access(nmp->nm_nandfsdev->nd_gconsumer, 0, -1,
+				    0);
+				g_topology_unlock();
+				PICKUP_GIANT();
+				return (error);
+			}
+
+			nmp->nm_ronly = 0;
+		}
+		return (0);
+	}
+
+	from = vfs_getopts(opts, "from", &error);
+	if (error)
+		return (error);
+
+	/*
+	 * Find device node
+	 */
+	NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, from, curthread);
+	error = namei(&nd);
+	if (error)
+		return (error);
+	NDFREE(&nd, NDF_ONLY_PNBUF);
+
+	devvp = nd.ni_vp;
+
+	if (!vn_isdisk(devvp, &error)) {
+		vput(devvp);
+		return (error);
+	}
+
+	/* Check the access rights on the mount device */
+	error = VOP_ACCESS(devvp, VREAD, curthread->td_ucred, curthread);
+	if (error)
+		error = priv_check(curthread, PRIV_VFS_MOUNT_PERM);
+	if (error) {
+		vput(devvp);
+		return (error);
+	}
+
+	vfs_getnewfsid(mp);
+
+	error = nandfs_mountfs(devvp, mp);
+	if (error)
+		return (error);
+	vfs_mountedfrom(mp, from);
+
+	return (0);
+}
+
+static int
+nandfs_mountfs(struct vnode *devvp, struct mount *mp)
+{
+	struct nandfsmount *nmp = NULL;
+	struct nandfs_args *args = NULL;
+	struct nandfs_device *nandfsdev;
+	char *from;
+	int error, ronly;
+	char *cpno;
+
+	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
+
+	if (devvp->v_rdev->si_iosize_max != 0)
+		mp->mnt_iosize_max = devvp->v_rdev->si_iosize_max;
+	VOP_UNLOCK(devvp, 0);
+
+	if (mp->mnt_iosize_max > MAXPHYS)
+		mp->mnt_iosize_max = MAXPHYS;
+
+	from = vfs_getopts(mp->mnt_optnew, "from", &error);
+	if (error)
+		goto error;
+
+	error = vfs_getopt(mp->mnt_optnew, "snap", (void **)&cpno, NULL);
+	if (error == ENOENT)
+		cpno = NULL;
+	else if (error)
+		goto error;
+
+	args = (struct nandfs_args *)malloc(sizeof(struct nandfs_args),
+	    M_NANDFSMNT, M_WAITOK | M_ZERO);
+
+	if (cpno != NULL)
+		args->cpno = strtoul(cpno, (char **)NULL, 10);
+	else
+		args->cpno = 0;
+	args->fspec = from;
+
+	if (args->cpno != 0 && !ronly) {
+		error = EROFS;
+		goto error;
+	}
+
+	printf("WARNING: NANDFS is considered to be a highly experimental "
+	    "feature in FreeBSD.\n");
+
+	error = nandfs_mount_device(devvp, mp, args, &nandfsdev);
+	if (error)
+		goto error;
+
+	nmp = (struct nandfsmount *) malloc(sizeof(struct nandfsmount),
+	    M_NANDFSMNT, M_WAITOK | M_ZERO);
+
+	mp->mnt_data = nmp;
+	nmp->nm_vfs_mountp = mp;
+	nmp->nm_ronly = ronly;
+	MNT_ILOCK(mp);
+	mp->mnt_flag |= MNT_LOCAL;
+	mp->mnt_kern_flag |= MNTK_MPSAFE;
+	MNT_IUNLOCK(mp);
+	nmp->nm_nandfsdev = nandfsdev;
+	/* Add our mountpoint */
+	STAILQ_INSERT_TAIL(&nandfsdev->nd_mounts, nmp, nm_next_mount);
+
+	if (args->cpno > nandfsdev->nd_last_cno) {
+		printf("WARNING: supplied checkpoint number (%jd) is greater "
+		    "than last known checkpoint on filesystem (%jd). Mounting"
+		    " checkpoint %jd\n", (uintmax_t)args->cpno,
+		    (uintmax_t)nandfsdev->nd_last_cno,
+		    (uintmax_t)nandfsdev->nd_last_cno);
+		args->cpno = nandfsdev->nd_last_cno;
+	}
+
+	/* Setting up other parameters */
+	nmp->nm_mount_args = *args;
+	free(args, M_NANDFSMNT);
+	error = nandfs_mount_checkpoint(nmp);
+	if (error) {
+		nandfs_unmount(mp, MNT_FORCE);
+		goto unmounted;
+	}
+
+	if (!ronly) {
+		error = start_syncer(nmp);
+		if (error == 0)
+			error = nandfs_start_cleaner(nmp->nm_nandfsdev);
+		if (error)
+			nandfs_unmount(mp, MNT_FORCE);
+	}
+
+	return (0);
+
+error:
+	if (args != NULL)
+		free(args, M_NANDFSMNT);
+
+	if (nmp != NULL) {
+		free(nmp, M_NANDFSMNT);
+		mp->mnt_data = NULL;
+	}
+unmounted:
+	return (error);
+}
+
+static int
+nandfs_unmount(struct mount *mp, int mntflags)
+{
+	struct nandfs_device *nandfsdev;
+	struct nandfsmount *nmp;
+	int error;
+	int flags = 0;
+
+	DPRINTF(VOLUMES, ("%s: mp = %p\n", __func__, (void *)mp));
+
+	if (mntflags & MNT_FORCE)
+		flags |= FORCECLOSE;
+
+	nmp = mp->mnt_data;
+	nandfsdev = nmp->nm_nandfsdev;
+
+	error = vflush(mp, 0, flags | SKIPSYSTEM, curthread);
+	if (error)
+		return (error);
+
+	if (!(nmp->nm_ronly)) {
+		nandfs_stop_cleaner(nandfsdev);
+		stop_syncer(nmp);
+	}
+
+	if (nmp->nm_ifile_node)
+		NANDFS_UNSET_SYSTEMFILE(NTOV(nmp->nm_ifile_node));
+
+	/* Remove our mount point */
+	STAILQ_REMOVE(&nandfsdev->nd_mounts, nmp, nandfsmount, nm_next_mount);
+
+	/* Unmount the device itself when we're the last one */
+	nandfs_unmount_device(nandfsdev);
+
+	free_nandfs_mountinfo(mp);
+
+	/*
+	 * Finally, throw away the null_mount structure
+	 */
+	mp->mnt_data = 0;
+	MNT_ILOCK(mp);
+	mp->mnt_flag &= ~MNT_LOCAL;
+	MNT_IUNLOCK(mp);
+
+	return (0);
+}
+
+static int
+nandfs_statfs(struct mount *mp, struct statfs *sbp)
+{
+	struct nandfsmount *nmp;
+	struct nandfs_device *nandfsdev;
+	struct nandfs_fsdata *fsdata;
+	struct nandfs_super_block *sb;
+	struct nandfs_block_group_desc *groups;
+	struct nandfs_node *ifile;
+	struct nandfs_mdt *mdt;
+	struct buf *bp;
+	int i, error;
+	uint32_t entries_per_group;
+	uint64_t files = 0;
+
+	nmp = mp->mnt_data;
+	nandfsdev = nmp->nm_nandfsdev;
+	fsdata = &nandfsdev->nd_fsdata;
+	sb = &nandfsdev->nd_super;
+	ifile = nmp->nm_ifile_node;
+	mdt = &nandfsdev->nd_ifile_mdt;
+	entries_per_group = mdt->entries_per_group;
+
+	VOP_LOCK(NTOV(ifile), LK_SHARED);
+	error = nandfs_bread(ifile, 0, NOCRED, 0, &bp);
+	if (error) {
+		brelse(bp);
+		VOP_UNLOCK(NTOV(ifile), 0);
+		return (error);
+	}
+
+	groups = (struct nandfs_block_group_desc *)bp->b_data;
+
+	for (i = 0; i < mdt->groups_per_desc_block; i++)
+		files += (entries_per_group - groups[i].bg_nfrees);
+
+	brelse(bp);
+	VOP_UNLOCK(NTOV(ifile), 0);
+
+	sbp->f_bsize = nandfsdev->nd_blocksize;
+	sbp->f_iosize = sbp->f_bsize;
+	sbp->f_blocks = fsdata->f_blocks_per_segment * fsdata->f_nsegments;
+	sbp->f_bfree = sb->s_free_blocks_count;
+	sbp->f_bavail = sbp->f_bfree;
+	sbp->f_files = files;
+	sbp->f_ffree = 0;
+	return (0);
+}
+
+static int
+nandfs_root(struct mount *mp, int flags, struct vnode **vpp)
+{
+	struct nandfsmount *nmp = VFSTONANDFS(mp);
+	struct nandfs_node *node;
+	int error;
+
+	error = nandfs_get_node(nmp, NANDFS_ROOT_INO, &node);
+	if (error)
+		return (error);
+
+	KASSERT(NTOV(node)->v_vflag & VV_ROOT,
+	    ("root_vp->v_vflag & VV_ROOT"));
+
+	*vpp = NTOV(node);
+
+	return (error);
+}
+
+static int
+nandfs_vget(struct mount *mp, ino_t ino, int flags, struct vnode **vpp)
+{
+	struct nandfsmount *nmp = VFSTONANDFS(mp);
+	struct nandfs_node *node;
+	int error;
+
+	error = nandfs_get_node(nmp, ino, &node);
+	if (node)
+		*vpp = NTOV(node);
+
+	return (error);
+}
+
+static int
+nandfs_sync(struct mount *mp, int waitfor)
+{
+	struct nandfsmount *nmp = VFSTONANDFS(mp);
+
+	DPRINTF(SYNC, ("%s: mp %p waitfor %d\n", __func__, mp, waitfor));
+
+	/*
+	 * XXX: A hack to be removed soon
+	 */
+	if (waitfor == MNT_LAZY)
+		return (0);
+	if (waitfor == MNT_SUSPEND)
+		return (0);
+	nandfs_wakeup_wait_sync(nmp->nm_nandfsdev, SYNCER_VFS_SYNC);
+	return (0);
+}
+
+static struct vfsops nandfs_vfsops = {
+	.vfs_init =		nandfs_init,
+	.vfs_mount =		nandfs_mount,
+	.vfs_root =		nandfs_root,
+	.vfs_statfs =		nandfs_statfs,
+	.vfs_uninit =		nandfs_uninit,
+	.vfs_unmount =		nandfs_unmount,
+	.vfs_vget =		nandfs_vget,
+	.vfs_sync =		nandfs_sync,
+};
+
+VFS_SET(nandfs_vfsops, nandfs, VFCF_LOOPBACK);