From: Philip Homburg <philip@cs.vu.nl>
Date: Mon, 27 Nov 2006 14:21:43 +0000 (+0000)
Subject: First cut at 64-bit file offsets in block devices for mkfs/fsck.
X-Git-Tag: v3.1.3~137
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/soc.html?a=commitdiff_plain;h=bafc45a3099f1270b17df9260d5bd7b05540754b;p=minix.git

First cut at 64-bit file offsets in block devices for mkfs/fsck.
---

diff --git a/commands/simple/fsck.c b/commands/simple/fsck.c
index c23bbc21e..5135de513 100755
--- a/commands/simple/fsck.c
+++ b/commands/simple/fsck.c
@@ -47,6 +47,7 @@
 #include <minix/config.h>
 #include <minix/const.h>
 #include <minix/type.h>
+#include <minix/u64.h>
 #include "../../servers/mfs/const.h"
 #include "../../servers/mfs/inode.h"
 #include "../../servers/mfs/type.h"
@@ -93,10 +94,10 @@ static struct super_block sb;
 #define STICKY_BIT	01000	/* not defined anywhere else */
 
 /* Ztob gives the block address of a zone
- * btoa gives the byte address of a block
+ * btoa64 gives the byte address of a block
  */
 #define ztob(z)		((block_nr) (z) << sb.s_log_zone_size)
-#define btoa(b)		((long) (b) * block_size)
+#define btoa64(b)	(mul64u(b, block_size))
 #define SCALE		((int) ztob(1))	/* # blocks in a zone */
 #define FIRST		((zone_nr) sb.s_firstdatazone)	/* as the name says */
 
@@ -116,8 +117,8 @@ static struct super_block sb;
 #define NLEVEL		(NR_ZONE_NUMS - NR_DZONE_NUM + 1)
 
 /* Byte address of a zone/of an inode */
-#define zaddr(z)	btoa(ztob(z))
-#define cinoaddr(i)	((long) (i - 1) * INODE_SIZE + (long) btoa(BLK_ILIST))
+#define cinoblock(i)	(((i - 1)*INODE_SIZE) / block_size + BLK_ILIST)
+#define cinooff(i)	(((i - 1)*INODE_SIZE) % block_size)
 #define INDCHUNK	((int) (CINDIR * ZONE_NUM_SIZE))
 #define DIRCHUNK	((int) (CDIRECT * DIR_ENTRY_SIZE))
 
@@ -166,8 +167,8 @@ _PROTOTYPE(void printpath, (int mode, int nlcr));
 _PROTOTYPE(void devopen, (void));
 _PROTOTYPE(void devclose, (void));
 _PROTOTYPE(void devio, (block_nr bno, int dir));
-_PROTOTYPE(void devread, (long offset, char *buf, int size));
-_PROTOTYPE(void devwrite, (long offset, char *buf, int size));
+_PROTOTYPE(void devread, (long block, long offset, char *buf, int size));
+_PROTOTYPE(void devwrite, (long block, long offset, char *buf, int size));
 _PROTOTYPE(void pr, (char *fmt, int cnt, char *s, char *p));
 _PROTOTYPE(void lpr, (char *fmt, long cnt, char *s, char *p));
 _PROTOTYPE(bit_nr getnumber, (char *s));
@@ -394,6 +395,8 @@ void devio(bno, dir)
 block_nr bno;
 int dir;
 {
+  int r;
+
   if(!block_size) fatal("devio() with unknown block size");
   if (dir == READING && bno == thisblk) return;
   thisblk = bno;
@@ -401,7 +404,9 @@ int dir;
 #if 0
 printf("%s at block %5d\n", dir == READING ? "reading " : "writing", bno);
 #endif
-  lseek(dev, (off_t) btoa(bno), SEEK_SET);
+  r= lseek64(dev, btoa64(bno), SEEK_SET, NULL);
+  if (r != 0)
+	fatal("lseek64 failed");
   if (dir == READING) {
 	if (read(dev, rwbuf, block_size) == block_size)
 		return;
@@ -420,28 +425,44 @@ printf("%s at block %5d\n", dir == READING ? "reading " : "writing", bno);
   fatal("");
 }
 
-/* Read `size' bytes from the disk starting at byte `offset'. */
-void devread(offset, buf, size)
+/* Read `size' bytes from the disk starting at block 'block' and
+ * byte `offset'.
+ */
+void devread(block, offset, buf, size)
+long block;
 long offset;
 char *buf;
 int size;
 {
   if(!block_size) fatal("devread() with unknown block size");
-  devio((block_nr) (offset / block_size), READING);
-  memmove(buf, &rwbuf[(int) (offset % block_size)], (size_t)size);  /* lint but OK */
+  if (offset >= block_size)
+  {
+	block += offset/block_size;
+	offset %= block_size;
+  }
+  devio(block, READING);
+  memmove(buf, &rwbuf[offset], size);
 }
 
-/* Write `size' bytes to the disk starting at byte `offset'. */
-void devwrite(offset, buf, size)
+/* Write `size' bytes to the disk starting at block 'block' and
+ * byte `offset'.
+ */
+void devwrite(block, offset, buf, size)
+long block;
 long offset;
 char *buf;
 int size;
 {
   if(!block_size) fatal("devwrite() with unknown block size");
   if (!repair) fatal("internal error (devwrite)");
-  if (size != block_size) devio((block_nr) (offset / block_size), READING);
-  memmove(&rwbuf[(int) (offset % block_size)], buf, (size_t)size);  /* lint but OK */
-  devio((block_nr) (offset / block_size), WRITING);
+  if (offset >= block_size)
+  {
+	block += offset/block_size;
+	offset %= block_size;
+  }
+  if (size != block_size) devio(block, READING);
+  memmove(&rwbuf[offset], buf, size);
+  devio(block, WRITING);
   changed = 1;
 }
 
@@ -518,7 +539,7 @@ void lsuper()
 	printf("block size    = %ld", sb.s_block_size);
 	if (input(buf, 80)) sb.s_block_size = atol(buf);
 	if (yes("ok now")) {
-		devwrite(OFFSET_SUPER_BLOCK, (char *) &sb, sizeof(sb));
+		devwrite(0, OFFSET_SUPER_BLOCK, (char *) &sb, sizeof(sb));
 		return;
 	}
   } while (yes("Do you want to try again"));
@@ -601,10 +622,17 @@ void chksuper()
   }
 }
 
-int inoaddr(int inn)
+int inoblock(int inn)
+{
+	int a;
+	a = cinoblock(inn);
+	return a;
+}
+
+int inooff(int inn)
 {
 	int a;
-	a = cinoaddr(inn);
+	a = cinooff(inn);
 	return a;
 }
 
@@ -624,7 +652,7 @@ char **clist;
 	setbit(spec_imap, bit);
 	ino = bit;
 	do {
-		devread(inoaddr(ino), (char *) ip, INODE_SIZE);
+		devread(inoblock(ino), inooff(ino), (char *) ip, INODE_SIZE);
 		printf("inode %u:\n", ino);
 		printf("    mode   = %6o", ip->i_mode);
 		if (input(buf, 80)) ip->i_mode = atoo(buf);
@@ -633,7 +661,8 @@ char **clist;
 		printf("    size   = %6ld", ip->i_size);
 		if (input(buf, 80)) ip->i_size = atol(buf);
 		if (yes("Write this back")) {
-			devwrite(inoaddr(ino), (char *) ip, INODE_SIZE);
+			devwrite(inoblock(ino), inooff(ino), (char *) ip,
+				INODE_SIZE);
 			break;
 		}
 	} while (yes("Do you want to change it again"));
@@ -662,7 +691,7 @@ int nblk;
 
   p = bitmap;
   for (i = 0; i < nblk; i++, bno++, p += WORDS_PER_BLOCK)
-	devread(btoa(bno), (char *) p, block_size);
+	devread(bno, 0, (char *) p, block_size);
   *bitmap |= 1;
 }
 
@@ -676,7 +705,7 @@ int nblk;
   register bitchunk_t *p = bitmap;
 
   for (i = 0; i < nblk; i++, bno++, p += WORDS_PER_BLOCK)
-	devwrite(btoa(bno), (char *) p, block_size);
+	devwrite(bno, 0, (char *) p, block_size);
 }
 
 /* Set the bits given by `list' in the bitmap. */
@@ -787,11 +816,12 @@ void chkilist()
   printf("Checking inode list\n");
   do
 	if (!bitset(imap, (bit_nr) ino)) {
-		devread(inoaddr(ino), (char *) &mode, sizeof(mode));
+		devread(inoblock(ino), inooff(ino), (char *) &mode,
+			sizeof(mode));
 		if (mode != I_NOT_ALLOC) {
 			printf("mode inode %u not cleared", ino);
-			if (yes(". clear")) devwrite(inoaddr(ino), nullbuf,
-					 INODE_SIZE);
+			if (yes(". clear")) devwrite(inoblock(ino),
+				inooff(ino), nullbuf, INODE_SIZE);
 		}
 	}
   while (++ino <= sb.s_ninodes && ino != 0);
@@ -814,7 +844,7 @@ ino_t ino;
 	printf("INODE NLINK COUNT\n");
 	firstcnterr = 0;
   }
-  devread(inoaddr(ino), (char *) &inode, INODE_SIZE);
+  devread(inoblock(ino), inooff(ino), (char *) &inode, INODE_SIZE);
   count[ino] += inode.i_nlinks;	/* it was already subtracted; add it back */
   printf("%5u %5u %5u", ino, (unsigned) inode.i_nlinks, count[ino]);
   if (yes(" adjust")) {
@@ -823,7 +853,7 @@ ino_t ino;
 		inode.i_mode = I_NOT_ALLOC;
 		clrbit(imap, (bit_nr) ino);
 	}
-	devwrite(inoaddr(ino), (char *) &inode, INODE_SIZE);
+	devwrite(inoblock(ino), inooff(ino), (char *) &inode, INODE_SIZE);
   }
 }
 
@@ -1083,12 +1113,13 @@ zone_nr zno;
   dir_struct dirblk[CDIRECT];
   register dir_struct *dp;
   register n, dirty;
-  register long offset = zaddr(zno);
+  long block= ztob(zno);
+  register long offset = 0;
   register off_t size = 0;
   n = SCALE * (NR_DIR_ENTRIES(block_size) / CDIRECT);
 
   do {
-	devread(offset, (char *) dirblk, DIRCHUNK);
+	devread(block, offset, (char *) dirblk, DIRCHUNK);
 	dirty = 0;
 	for (dp = dirblk; dp < &dirblk[CDIRECT]; dp++) {
 		if (dp->d_inum != NO_ENTRY && !chkentry(ino, pos, dp))
@@ -1096,7 +1127,7 @@ zone_nr zno;
 		pos += DIR_ENTRY_SIZE;
 		if (dp->d_inum != NO_ENTRY) size = pos;
 	}
-	if (dirty) devwrite(offset, (char *) dirblk, DIRCHUNK);
+	if (dirty) devwrite(block, offset, (char *) dirblk, DIRCHUNK);
 	offset += DIRCHUNK;
 	n--;
   } while (n > 0);
@@ -1107,7 +1138,7 @@ zone_nr zno;
 	if (yes(". extend")) {
 		setbit(spec_imap, (bit_nr) ino);
 		ip->i_size = size;
-		devwrite(inoaddr(ino), (char *) ip, INODE_SIZE);
+		devwrite(inoblock(ino), inooff(ino), (char *) ip, INODE_SIZE);
 	}
   }
   return(1);
@@ -1120,14 +1151,14 @@ d_inode *ip;
 off_t pos;
 zone_nr zno;
 {
-	long offset;
+	long block;
 	size_t len;
 	char target[PATH_MAX+1];
 
 	if (ip->i_size > PATH_MAX)
 		fatal("chksymlinkzone: fsck program inconsistency\n");
-	offset = zaddr(zno);
-	devread(offset, target, ip->i_size);
+	block= ztob(zno);
+	devread(block, 0, target, ip->i_size);
 	target[ip->i_size]= '\0';
 	len= strlen(target);
 	if (len != ip->i_size)
@@ -1138,7 +1169,8 @@ zone_nr zno;
 		if (yes(". update")) {
 			setbit(spec_imap, (bit_nr) ino);
 			ip->i_size = len;
-			devwrite(inoaddr(ino), (char *) ip, INODE_SIZE);
+			devwrite(inoblock(ino), inooff(ino), 
+				(char *) ip, INODE_SIZE);
 		}
 	}
 	return 1;
@@ -1201,10 +1233,11 @@ int level;
 {
   zone_nr indirect[CINDIR];
   register n = NR_INDIRECTS / CINDIR;
-  register long offset = zaddr(zno);
+  long block= ztob(zno);
+  register long offset = 0;
 
   do {
-	devread(offset, (char *) indirect, INDCHUNK);
+	devread(block, offset, (char *) indirect, INDCHUNK);
 	if (!chkzones(ino, ip, pos, indirect, CINDIR, level - 1)) return(0);
 	offset += INDCHUNK;
   } while (--n && *pos < ip->i_size);
@@ -1442,14 +1475,15 @@ dir_struct *dp;
   }
   visited = bitset(imap, (bit_nr) ino);
   if (!visited || listing) {
-	devread(inoaddr(ino), (char *) &inode, INODE_SIZE);
+	devread(inoblock(ino), inooff(ino), (char *) &inode, INODE_SIZE);
 	if (listing) list(ino, &inode);
 	if (!visited && !chkinode(ino, &inode)) {
 		setbit(spec_imap, (bit_nr) ino);
 		if (yes("remove")) {
 			count[ino] += inode.i_nlinks - 1;
 			clrbit(imap, (bit_nr) ino);
-			devwrite(inoaddr(ino), nullbuf, INODE_SIZE);
+			devwrite(inoblock(ino), inooff(ino),
+				nullbuf, INODE_SIZE);
 			memset((void *) dp, 0, sizeof(dir_struct));
 			ftop = ftop->st_next;
 			return(0);
diff --git a/commands/simple/mkfs.c b/commands/simple/mkfs.c
index de7882489..a36a6a580 100755
--- a/commands/simple/mkfs.c
+++ b/commands/simple/mkfs.c
@@ -317,12 +317,6 @@ char *argv[];
 	simple = 1;
   }
 
-  if(ULONG_MAX / block_size <= blocks-1) {
-  	fprintf(stderr, "Warning: too big for filesystem to currently\n");
-  	fprintf(stderr, "run on (max 4GB), truncating.\n");
-  	blocks = ULONG_MAX / block_size;
-  }
-
   nrblocks = blocks;
   nrinodes = inodes;
 
@@ -337,7 +331,7 @@ char *argv[];
 	testb = (short *) alloc_block();
 
 	/* Try writing the last block of partition or diskette. */
-	if(lseek(fd, (off_t) (blocks - 1) * block_size, SEEK_SET) < 0) {
+	if(lseek64(fd, mul64u(blocks - 1, block_size), SEEK_SET, NULL) < 0) {
 		pexit("couldn't seek to last block to test size (1)");
 	}
 	testb[0] = 0x3245;
@@ -349,7 +343,7 @@ char *argv[];
 		pexit("File system is too big for minor device (write)");
 	}
 	sync();			/* flush write, so if error next read fails */
-	if(lseek(fd, (off_t) (blocks - 1) * block_size, SEEK_SET) < 0) {
+	if(lseek64(fd, mul64u(blocks - 1, block_size), SEEK_SET, NULL) < 0) {
 		pexit("couldn't seek to last block to test size (2)");
 	}
 	testb[0] = 0;
@@ -358,9 +352,11 @@ char *argv[];
 	if (nread != block_size || testb[0] != 0x3245 || testb[1] != 0x11FF ||
 		testb[block_size-1] != 0x1F2F) {
 		if(nread < 0) perror("read");
+printf("nread = %d\n", nread);
+printf("testb = 0x%x 0x%x 0x%x\n", testb[0], testb[1], testb[block_size-1]);
 		pexit("File system is too big for minor device (read)");
 	}
-	lseek(fd, (off_t) (blocks - 1) * block_size, SEEK_SET);
+	lseek64(fd, mul64u(blocks - 1, block_size), SEEK_SET, NULL);
 	testb[0] = 0;
 	testb[1] = 0;
 	if (write(fd, (char *) testb, block_size) != block_size)
@@ -1536,7 +1532,7 @@ char *buf;
 	copy(zero, buf, block_size);
 	return;
   }
-  lseek(fd, (off_t) n * block_size, SEEK_SET);
+  lseek64(fd, mul64u(n, block_size), SEEK_SET, NULL);
   k = read(fd, buf, block_size);
   if (k != block_size) {
 	pexit("get_block couldn't read");
@@ -1569,7 +1565,7 @@ char *buf;
   (void) read_and_set(n);
 
   /* XXX - check other lseeks too. */
-  if (lseek(fd, (off_t) n * block_size, SEEK_SET) == (off_t) -1) {
+  if (lseek64(fd, mul64u(n, block_size), SEEK_SET, NULL) == (off_t) -1) {
 	pexit("put_block couldn't seek");
   }
   if (write(fd, buf, block_size) != block_size) {
diff --git a/drivers/at_wini/at_wini.c b/drivers/at_wini/at_wini.c
index 3ea656f19..b7ed00cbc 100644
--- a/drivers/at_wini/at_wini.c
+++ b/drivers/at_wini/at_wini.c
@@ -346,7 +346,7 @@ FORWARD _PROTOTYPE( int w_identify, (void) 				);
 FORWARD _PROTOTYPE( char *w_name, (void) 				);
 FORWARD _PROTOTYPE( int w_specify, (void) 				);
 FORWARD _PROTOTYPE( int w_io_test, (void) 				);
-FORWARD _PROTOTYPE( int w_transfer, (int proc_nr, int opcode, off_t position,
+FORWARD _PROTOTYPE( int w_transfer, (int proc_nr, int opcode, u64_t position,
 				iovec_t *iov, unsigned nr_req, int safe));
 FORWARD _PROTOTYPE( int com_out, (struct command *cmd) 			);
 FORWARD _PROTOTYPE( int com_out_ext, (struct command *cmd)		);
@@ -371,7 +371,7 @@ FORWARD _PROTOTYPE( int atapi_intr_wait, (void) 			);
 FORWARD _PROTOTYPE( int atapi_open, (void) 				);
 FORWARD _PROTOTYPE( void atapi_close, (void) 				);
 FORWARD _PROTOTYPE( int atapi_transfer, (int proc_nr, int opcode,
-		off_t position, iovec_t *iov, unsigned nr_req, int safe));
+		u64_t position, iovec_t *iov, unsigned nr_req, int safe));
 #endif
 
 /* Entry points to this driver. */
@@ -806,11 +806,13 @@ PRIVATE int w_identify()
 	if ((s=sys_insw(wn->base_cmd + REG_DATA, SELF, tmp_buf, SECTOR_SIZE)) != OK)
 		panic(w_name(),"Call to sys_insw() failed", s);
 
+#if 0
 	if (id_word(0) & ID_GEN_NOT_ATA)
 	{
 		printf("%s: not an ATA device?\n", w_name());
 		return ERR;
 	}
+#endif
 
 	/* This is an ATA device. */
 	wn->state |= SMART;
@@ -1049,7 +1051,7 @@ PRIVATE int w_io_test(void)
  	if (w_prepare(w_drive * DEV_PER_DRIVE) == NIL_DEV)
  		panic(w_name(), "Couldn't switch devices", NO_NUM);
 
-	r = w_transfer(SELF, DEV_GATHER, 0, &iov, 1, 0);
+	r = w_transfer(SELF, DEV_GATHER, cvu64(0), &iov, 1, 0);
 
 	/* Switch back. */
  	if (w_prepare(save_dev) == NIL_DEV)
@@ -1192,7 +1194,7 @@ PRIVATE int do_transfer(struct wini *wn, unsigned int precomp,
 PRIVATE int w_transfer(proc_nr, opcode, position, iov, nr_req, safe)
 int proc_nr;			/* process doing the request */
 int opcode;			/* DEV_GATHER or DEV_SCATTER */
-off_t position;			/* offset on device to read or write */
+u64_t position;			/* offset on device to read or write */
 iovec_t *iov;			/* pointer to read or write request vector */
 unsigned nr_req;		/* length of request vector */
 int safe;			/* iov contains addresses (0) or grants? */
@@ -1201,7 +1203,7 @@ int safe;			/* iov contains addresses (0) or grants? */
   iovec_t *iop, *iov_end = iov + nr_req;
   int n, r, s, errors, do_dma, do_write, do_copyout;
   unsigned long v, block, w_status;
-  unsigned long dv_size = cv64ul(w_dv->dv_size);
+  u64_t dv_size = w_dv->dv_size;
   unsigned cylinder, head, sector, nbytes;
   unsigned dma_buf_offset;
   size_t addr_offset = 0;
@@ -1213,7 +1215,7 @@ int safe;			/* iov contains addresses (0) or grants? */
 #endif
 
   /* Check disk address. */
-  if ((position & SECTOR_MASK) != 0) return(EINVAL);
+  if (rem64u(position, SECTOR_SIZE) != 0) return(EINVAL);
 
   errors = 0;
 
@@ -1224,9 +1226,10 @@ int safe;			/* iov contains addresses (0) or grants? */
 	if ((nbytes & SECTOR_MASK) != 0) return(EINVAL);
 
 	/* Which block on disk and how close to EOF? */
-	if (position >= dv_size) return(OK);		/* At EOF */
-	if (position + nbytes > dv_size) nbytes = dv_size - position;
-	block = div64u(add64ul(w_dv->dv_base, position), SECTOR_SIZE);
+	if (cmp64(position, dv_size) >= 0) return(OK);		/* At EOF */
+	if (cmp64(add64ul(position, nbytes), dv_size) > 0)
+		nbytes = diff64(dv_size, position);
+	block = div64u(add64(w_dv->dv_base, position), SECTOR_SIZE);
 
 	do_dma= wn->dma;
 	do_write= (opcode == DEV_SCATTER);
@@ -1338,7 +1341,7 @@ int safe;			/* iov contains addresses (0) or grants? */
 
 			/* Book the bytes successfully transferred. */
 			nbytes -= n;
-			position += n;
+			position= add64ul(position, n);
 			if ((iov->iov_size -= n) == 0) {
 				iov++; nr_req--; addr_offset = 0;
 			}
@@ -1412,7 +1415,7 @@ int safe;			/* iov contains addresses (0) or grants? */
 
 		/* Book the bytes successfully transferred. */
 		nbytes -= SECTOR_SIZE;
-		position += SECTOR_SIZE;
+		position= add64u(position, SECTOR_SIZE);
 		addr_offset += SECTOR_SIZE;
 		if ((iov->iov_size -= SECTOR_SIZE) == 0) {
 			iov++;
@@ -2113,7 +2116,7 @@ void sense_request(void)
 PRIVATE int atapi_transfer(proc_nr, opcode, position, iov, nr_req, safe)
 int proc_nr;			/* process doing the request */
 int opcode;			/* DEV_GATHER or DEV_SCATTER */
-off_t position;			/* offset on device to read or write */
+u64_t position;			/* offset on device to read or write */
 iovec_t *iov;			/* pointer to read or write request vector */
 unsigned nr_req;		/* length of request vector */
 int safe;			/* use safecopies? */
@@ -2123,7 +2126,7 @@ int safe;			/* use safecopies? */
   int r, s, errors, fresh;
   u64_t pos;
   unsigned long block;
-  unsigned long dv_size = cv64ul(w_dv->dv_size);
+  u64_t dv_size = w_dv->dv_size;
   unsigned nbytes, nblocks, count, before, chunk;
   static u8_t packet[ATAPI_PACKETSIZE];
   size_t addr_offset = 0;
@@ -2134,7 +2137,7 @@ int safe;			/* use safecopies? */
 	/* The Minix block size is smaller than the CD block size, so we
 	 * may have to read extra before or after the good data.
 	 */
-	pos = add64ul(w_dv->dv_base, position);
+	pos = add64(w_dv->dv_base, position);
 	block = div64u(pos, CD_SECTOR_SIZE);
 	before = rem64u(pos, CD_SECTOR_SIZE);
 
@@ -2152,8 +2155,9 @@ int safe;			/* use safecopies? */
 	if ((before | nbytes) & 1) return(EINVAL);
 
 	/* Which block on disk and how close to EOF? */
-	if (position >= dv_size) return(OK);		/* At EOF */
-	if (position + nbytes > dv_size) nbytes = dv_size - position;
+	if (cmp64(position, dv_size) >= 0) return(OK);		/* At EOF */
+	if (cmp64(add64ul(position, nbytes), dv_size) > 0)
+		nbytes = diff64(dv_size, position);
 
 	nblocks = (before + nbytes + CD_SECTOR_SIZE - 1) / CD_SECTOR_SIZE;
 	if (ATAPI_DEBUG) {
@@ -2214,7 +2218,7 @@ int safe;			/* use safecopies? */
 			}
 			if (s != OK)
 				panic(w_name(),"Call to sys_insw() failed", s);
-			position += chunk;
+			position= add64ul(position, chunk);
 			nbytes -= chunk;
 			count -= chunk;
 			addr_offset += chunk;
diff --git a/drivers/bios_wini/bios_wini.c b/drivers/bios_wini/bios_wini.c
index dbc8593f5..f6f4565d2 100644
--- a/drivers/bios_wini/bios_wini.c
+++ b/drivers/bios_wini/bios_wini.c
@@ -68,7 +68,7 @@ PRIVATE cp_grant_id_t my_bios_grant_id;
 _PROTOTYPE(int main, (void) );
 FORWARD _PROTOTYPE( struct device *w_prepare, (int device) );
 FORWARD _PROTOTYPE( char *w_name, (void) );
-FORWARD _PROTOTYPE( int w_transfer, (int proc_nr, int opcode, off_t position,
+FORWARD _PROTOTYPE( int w_transfer, (int proc_nr, int opcode, u64_t position,
 				iovec_t *iov, unsigned nr_req, int safe) );
 FORWARD _PROTOTYPE( int w_do_open, (struct driver *dp, message *m_ptr) );
 FORWARD _PROTOTYPE( int w_do_close, (struct driver *dp, message *m_ptr) );
@@ -199,10 +199,10 @@ size_t size;
 /*===========================================================================*
  *				w_transfer				     *
  *===========================================================================*/
-PRIVATE int w_transfer(proc_nr, opcode, position, iov, nr_req, safe)
+PRIVATE int w_transfer(proc_nr, opcode, pos64, iov, nr_req, safe)
 int proc_nr;			/* process doing the request */
 int opcode;			/* DEV_GATHER or DEV_SCATTER */
-off_t position;			/* offset on device to read or write */
+u64_t pos64;			/* offset on device to read or write */
 iovec_t *iov;			/* pointer to read or write request vector */
 unsigned nr_req;		/* length of request vector */
 int safe;			/* use safecopies? */
@@ -216,6 +216,7 @@ int safe;			/* use safecopies? */
   size_t vir_offset = 0;
   unsigned long dv_size = cv64ul(w_dv->dv_size);
   unsigned secspcyl = wn->heads * wn->sectors;
+  off_t position;
   struct int13ext_rw {
 	u8_t	len;
 	u8_t	res1;
@@ -225,6 +226,10 @@ int safe;			/* use safecopies? */
   } i13e_rw;
   struct reg86u reg86;
 
+  if (ex64hi(pos64))
+	panic(__FILE__, "should handle 64-bit offsets", NO_NUM);
+  position= ex64lo(pos64);
+
   /* Check disk address. */
   if ((position & SECTOR_MASK) != 0) return(EINVAL);
 
diff --git a/drivers/floppy/floppy.c b/drivers/floppy/floppy.c
index 120722b3a..1d9f59938 100644
--- a/drivers/floppy/floppy.c
+++ b/drivers/floppy/floppy.c
@@ -247,7 +247,7 @@ FORWARD _PROTOTYPE( void f_timeout, (timer_t *tp) 			);
 FORWARD _PROTOTYPE( struct device *f_prepare, (int device) 		);
 FORWARD _PROTOTYPE( char *f_name, (void) 				);
 FORWARD _PROTOTYPE( void f_cleanup, (void) 				);
-FORWARD _PROTOTYPE( int f_transfer, (int proc_nr, int opcode, off_t position,
+FORWARD _PROTOTYPE( int f_transfer, (int proc_nr, int opcode, u64_t position,
 					iovec_t *iov, unsigned nr_req, int) 	);
 FORWARD _PROTOTYPE( int dma_setup, (int opcode) 			);
 FORWARD _PROTOTYPE( void start_motor, (void) 				);
@@ -433,10 +433,10 @@ PRIVATE void f_cleanup()
 /*===========================================================================*
  *				f_transfer				     *
  *===========================================================================*/
-PRIVATE int f_transfer(proc_nr, opcode, position, iov, nr_req, safe)
+PRIVATE int f_transfer(proc_nr, opcode, pos64, iov, nr_req, safe)
 int proc_nr;			/* process doing the request */
 int opcode;			/* DEV_GATHER or DEV_SCATTER */
-off_t position;			/* offset on device to read or write */
+u64_t pos64;			/* offset on device to read or write */
 iovec_t *iov;			/* pointer to read or write request vector */
 unsigned nr_req;		/* length of request vector */
 int safe;
@@ -449,10 +449,15 @@ int safe;
   unsigned nbytes, count, chunk, sector;
   unsigned long dv_size = cv64ul(f_dv->dv_size);
   vir_bytes user_offset, iov_offset = 0, iop_offset;
+  off_t position;
   signed long uoffsets[MAX_SECTORS], *up;
   cp_grant_id_t ugrants[MAX_SECTORS], *ug;
   u8_t cmd[3];
 
+  if (ex64hi(pos64) != 0)
+	return OK;	/* Way beyond EOF */
+  position= cv64ul(pos64);
+
   /* Check disk address. */
   if ((position & SECTOR_MASK) != 0) return(EINVAL);
 
@@ -1307,7 +1312,7 @@ int density;
   position = (off_t) f_dp->test << SECTOR_SHIFT;
   iovec1.iov_addr = (vir_bytes) tmp_buf;
   iovec1.iov_size = SECTOR_SIZE;
-  result = f_transfer(SELF, DEV_GATHER, position, &iovec1, 1, 0);
+  result = f_transfer(SELF, DEV_GATHER, cvul64(position), &iovec1, 1, 0);
 
   if (iovec1.iov_size != 0) return(EIO);
 
diff --git a/drivers/libdriver/driver.c b/drivers/libdriver/driver.c
index 60a8161d7..58e7f5929 100644
--- a/drivers/libdriver/driver.c
+++ b/drivers/libdriver/driver.c
@@ -182,6 +182,7 @@ int safe;			/* use safecopies? */
   iovec_t iovec1;
   int r, opcode;
   phys_bytes phys_addr;
+  u64_t position;
 
   /* Disk address?  Address and length of the user buffer? */
   if (mp->COUNT < 0) return(EINVAL);
@@ -203,7 +204,8 @@ int safe;			/* use safecopies? */
   iovec1.iov_size = mp->COUNT;
 
   /* Transfer bytes from/to the device. */
-  r = (*dp->dr_transfer)(mp->IO_ENDPT, opcode, mp->POSITION, &iovec1, 1, safe);
+  position= make64(mp->POSITION, mp->HIGHPOS);
+  r = (*dp->dr_transfer)(mp->IO_ENDPT, opcode, position, &iovec1, 1, safe);
 
   /* Return the number of bytes transferred or an error code. */
   return(r == OK ? (mp->COUNT - iovec1.iov_size) : r);
@@ -226,7 +228,7 @@ int safe;		/* use safecopies? */
   phys_bytes iovec_size;
   unsigned nr_req;
   int r, j, opcode;
-
+  u64_t position;
 
   nr_req = mp->COUNT;	/* Length of I/O vector */
 
@@ -257,7 +259,8 @@ int safe;		/* use safecopies? */
   opcode = mp->m_type;
   if(opcode == DEV_GATHER_S) opcode = DEV_GATHER;
   if(opcode == DEV_SCATTER_S) opcode = DEV_SCATTER;
-  r = (*dp->dr_transfer)(mp->IO_ENDPT, opcode, mp->POSITION, iov,
+  position= make64(mp->POSITION, mp->HIGHPOS);
+  r = (*dp->dr_transfer)(mp->IO_ENDPT, opcode, position, iov,
 	nr_req, safe);
 
   /* Copy the I/O vector back to the caller. */
diff --git a/drivers/libdriver/driver.h b/drivers/libdriver/driver.h
index 3507e9695..1d71672ab 100644
--- a/drivers/libdriver/driver.h
+++ b/drivers/libdriver/driver.h
@@ -33,8 +33,8 @@ struct driver {
   _PROTOTYPE( int (*dr_close), (struct driver *dp, message *m_ptr) );
   _PROTOTYPE( int (*dr_ioctl), (struct driver *dp, message *m_ptr, int safe) );
   _PROTOTYPE( struct device *(*dr_prepare), (int device) );
-  _PROTOTYPE( int (*dr_transfer), (int proc_nr, int opcode, off_t position,
-					iovec_t *iov, unsigned nr_req, int safe) );
+  _PROTOTYPE( int (*dr_transfer), (int proc_nr, int opcode, u64_t position,
+				iovec_t *iov, unsigned nr_req, int safe) );
   _PROTOTYPE( void (*dr_cleanup), (void) );
   _PROTOTYPE( void (*dr_geometry), (struct partition *entry) );
   _PROTOTYPE( void (*dr_signal), (struct driver *dp, message *m_ptr) );
diff --git a/drivers/libdriver/drvlib.c b/drivers/libdriver/drvlib.c
index 6135896ad..1e1bc8ab7 100644
--- a/drivers/libdriver/drvlib.c
+++ b/drivers/libdriver/drvlib.c
@@ -157,10 +157,10 @@ struct part_entry *table;	/* four entries */
  * errors.
  */
   iovec_t iovec1;
-  off_t position;
+  u64_t position;
   static unsigned char partbuf[CD_SECTOR_SIZE];
 
-  position = offset << SECTOR_SHIFT;
+  position = mul64u(offset, SECTOR_SIZE);
   iovec1.iov_addr = (vir_bytes) partbuf;
   iovec1.iov_size = CD_SECTOR_SIZE;
   if ((*dp->dr_prepare)(device) != NIL_DEV) {
diff --git a/drivers/log/log.c b/drivers/log/log.c
index 6fed82bd8..043fa55ad 100644
--- a/drivers/log/log.c
+++ b/drivers/log/log.c
@@ -25,7 +25,7 @@ PRIVATE int log_device = -1;	 		/* current device */
 
 FORWARD _PROTOTYPE( char *log_name, (void) );
 FORWARD _PROTOTYPE( struct device *log_prepare, (int device) );
-FORWARD _PROTOTYPE( int log_transfer, (int proc_nr, int opcode, off_t position,
+FORWARD _PROTOTYPE( int log_transfer, (int proc_nr, int opcode, u64_t position,
 			iovec_t *iov, unsigned nr_req, int safe) );
 FORWARD _PROTOTYPE( int log_do_open, (struct driver *dp, message *m_ptr) );
 FORWARD _PROTOTYPE( int log_cancel, (struct driver *dp, message *m_ptr) );
@@ -227,7 +227,7 @@ subread(struct logdevice *log, int count, int proc_nr,
 PRIVATE int log_transfer(proc_nr, opcode, position, iov, nr_req, safe)
 int proc_nr;			/* process doing the request */
 int opcode;			/* DEV_GATHER or DEV_SCATTER */
-off_t position;			/* offset on device to read or write */
+u64_t position;			/* offset on device to read or write */
 iovec_t *iov;			/* pointer to read or write request vector */
 unsigned nr_req;		/* length of request vector */
 int safe;			/* safe copies? */
diff --git a/drivers/memory/memory.c b/drivers/memory/memory.c
index 906699e8a..d4b165942 100644
--- a/drivers/memory/memory.c
+++ b/drivers/memory/memory.c
@@ -43,7 +43,7 @@ extern int errno;			/* error number for PM calls */
 
 FORWARD _PROTOTYPE( char *m_name, (void) 				);
 FORWARD _PROTOTYPE( struct device *m_prepare, (int device) 		);
-FORWARD _PROTOTYPE( int m_transfer, (int proc_nr, int opcode, off_t position,
+FORWARD _PROTOTYPE( int m_transfer, (int proc_nr, int opcode, u64_t position,
 				iovec_t *iov, unsigned nr_req, int safe));
 FORWARD _PROTOTYPE( int m_do_open, (struct driver *dp, message *m_ptr) 	);
 FORWARD _PROTOTYPE( void m_init, (void) );
@@ -119,10 +119,10 @@ int device;
 /*===========================================================================*
  *				m_transfer				     *
  *===========================================================================*/
-PRIVATE int m_transfer(proc_nr, opcode, position, iov, nr_req, safe)
+PRIVATE int m_transfer(proc_nr, opcode, pos64, iov, nr_req, safe)
 int proc_nr;			/* process doing the request */
 int opcode;			/* DEV_GATHER or DEV_SCATTER */
-off_t position;			/* offset on device to read or write */
+u64_t pos64;			/* offset on device to read or write */
 iovec_t *iov;			/* pointer to read or write request vector */
 unsigned nr_req;		/* length of request vector */
 int safe;			/* safe copies */
@@ -136,9 +136,14 @@ int safe;			/* safe copies */
   struct device *dv;
   unsigned long dv_size;
   int s, r;
+  off_t position;
 
   static int n = 0;
 
+  if (ex64hi(pos64) != 0)
+	return OK;	/* Beyond EOF */
+  position= cv64ul(pos64);
+
   /* Get minor device number and check for /dev/null. */
   dv = &m_geom[m_device];
   dv_size = cv64ul(dv->dv_size);
diff --git a/include/minix/const.h b/include/minix/const.h
index 4e18ead18..57d35deb3 100755
--- a/include/minix/const.h
+++ b/include/minix/const.h
@@ -111,7 +111,7 @@
 #define MAX_BLOCK_NR  ((block_t) 077777777)	/* largest block number */
 #define HIGHEST_ZONE   ((zone_t) 077777777)	/* largest zone number */
 #define MAX_INODE_NR ((ino_t) 037777777777)	/* largest inode number */
-#define MAX_FILE_POS ((off_t) 037777777777)	/* largest legal file offset */
+#define MAX_FILE_POS ((off_t) 0x7FFFFFFF)	/* largest legal file offset */
 
 #define MAX_SYM_LOOPS	8	/* how many symbolic links are recursed */
 
diff --git a/include/minix/vfsif.h b/include/minix/vfsif.h
index 0f55eadce..5409f0d30 100644
--- a/include/minix/vfsif.h
+++ b/include/minix/vfsif.h
@@ -52,9 +52,15 @@
 #define REQ_FD_START             m2_i2
 #define REQ_FD_END               m2_i3
 
-#define REQ_FD_BLOCK_SIZE        m2_s1
 #define REQ_FD_BDRIVER_E         m2_i1
-#define REQ_FD_BDEV              m2_l2
+
+#define REQ_XFD_BDEV              m2_i1
+#define REQ_XFD_WHO_E             m2_i2
+#define REQ_XFD_NBYTES            m2_i3
+#define REQ_XFD_POS_LO            m2_l1
+#define REQ_XFD_POS_HI            m2_l2
+#define REQ_XFD_USER_ADDR         m2_p1
+#define REQ_XFD_BLOCK_SIZE        m2_s1
 
 /* For REQ_GETDENTS */
 #define REQ_GDE_INODE		 m2_i1
@@ -82,6 +88,10 @@
 #define RES_FD_CUM_IO            m2_i2
 #define RES_FD_SIZE              m2_i3
 
+#define RES_XFD_POS_LO           m2_l1
+#define RES_XFD_POS_HI           m2_l2
+#define RES_XFD_CUM_IO           m2_i1
+
 #define RES_DIR                  m6_l1
 #define RES_FILE                 m6_l2
 
@@ -135,10 +145,10 @@
 
 #define REQ_BREAD                38
 #define REQ_BWRITE               39
-
 #define REQ_GETDENTS		 40
+#define REQ_FLUSH		 41
 
-#define NREQS                    41
+#define NREQS                    42
 
 #define FS_READY                 57
 
diff --git a/include/sys/types.h b/include/sys/types.h
index 6c222f25c..06b553e59 100755
--- a/include/sys/types.h
+++ b/include/sys/types.h
@@ -52,7 +52,7 @@ typedef char           gid_t;	   /* group id */
 typedef unsigned long  ino_t; 	   /* i-node number (V3 filesystem) */
 typedef unsigned short mode_t;	   /* file type and permissions bits */
 typedef short        nlink_t;	   /* number of links to a file */
-typedef unsigned long  off_t;	   /* offset within a file */
+typedef long	       off_t;	   /* offset within a file */
 typedef int            pid_t;	   /* process id (must be signed) */
 typedef short          uid_t;	   /* user id */
 typedef unsigned long zone_t;	   /* zone number */
diff --git a/servers/mfs/cache.c b/servers/mfs/cache.c
index 02e2a8c2c..5f5b85e1e 100644
--- a/servers/mfs/cache.c
+++ b/servers/mfs/cache.c
@@ -16,6 +16,7 @@
 
 #include "fs.h"
 #include <minix/com.h>
+#include <minix/u64.h>
 #include "buf.h"
 #include "super.h"
 
@@ -259,14 +260,14 @@ int rw_flag;			/* READING or WRITING */
  * from the cache, it is not clear what the caller could do about it anyway.
  */
   int r, op;
-  off_t pos;
+  u64_t pos;
   dev_t dev;
   int block_size;
 
   block_size = get_block_size(bp->b_dev);
 
   if ( (dev = bp->b_dev) != NO_DEV) {
-	  pos = (off_t) bp->b_blocknr * block_size;
+	  pos = mul64u(bp->b_blocknr, block_size);
 	  op = (rw_flag == READING ? DEV_READ : DEV_WRITE);
 	  r = block_dev_io(op, dev, SELF_E, bp->b_data, pos, block_size, 0);
 	  if (r != block_size) {
@@ -374,7 +375,7 @@ int rw_flag;			/* READING or WRITING */
 	}
 	r = block_dev_io(rw_flag == WRITING ? DEV_SCATTER : DEV_GATHER,
 		dev, SELF_E, iovec,
-		(off_t) bufq[0]->b_blocknr * block_size, j, 0);
+		mul64u(bufq[0]->b_blocknr, block_size), j, 0);
 
 	/* Harvest the results.  Dev_io reports the first error it may have
 	 * encountered, but we only care if it's the first block that failed.
diff --git a/servers/mfs/device.c b/servers/mfs/device.c
index 5a8662a20..5d6acd83e 100644
--- a/servers/mfs/device.c
+++ b/servers/mfs/device.c
@@ -7,6 +7,7 @@
 #include <minix/endpoint.h>
 #include <minix/ioctl.h>
 #include <minix/safecopies.h>
+#include <minix/u64.h>
 #include <string.h>
 #include "inode.h"
 #include "super.h"
@@ -19,7 +20,7 @@ PRIVATE int dummyproc;
 
 FORWARD _PROTOTYPE( int safe_io_conversion, (endpoint_t,
   cp_grant_id_t *, int *, cp_grant_id_t *, int, endpoint_t *,
-  void **, int *, vir_bytes, off_t *));
+  void **, int *, vir_bytes));
 FORWARD _PROTOTYPE( void safe_io_cleanup, (cp_grant_id_t, cp_grant_id_t *,
 	int));
 
@@ -65,7 +66,7 @@ PUBLIC int fs_new_driver(void)
  *				safe_io_conversion			     *
  *===========================================================================*/
 PRIVATE int safe_io_conversion(driver, gid, op, gids, gids_size,
-	io_ept, buf, vec_grants, bytes, pos)
+	io_ept, buf, vec_grants, bytes)
 endpoint_t driver;
 cp_grant_id_t *gid;
 int *op;
@@ -75,7 +76,6 @@ endpoint_t *io_ept;
 void **buf;
 int *vec_grants;
 vir_bytes bytes;
-off_t *pos;
 {
 	int access = 0, size;
 	int j;
@@ -135,21 +135,6 @@ off_t *pos;
 			/* Set user's vector to the new one. */
 			*buf = new_iovec;
 			break;
-		/*	
-		case DEV_IOCTL:
-			*pos = *io_ept;	
-			*op = DEV_IOCTL_S;
-			if(_MINIX_IOCTL_IOR(m_in.REQUEST)) access |= CPF_WRITE;
-			if(_MINIX_IOCTL_IOW(m_in.REQUEST)) access |= CPF_READ;
-			size = _MINIX_IOCTL_SIZE(m_in.REQUEST);
-
-			if((*gid=cpf_grant_magic(driver, *io_ept,
-				(vir_bytes) *buf, size, access)) < 0) {
-				panic(__FILE__,
-				"cpf_grant_magic failed (ioctl)\n",
-				NO_NUM);
-			}
-		*/
 	}
 
 	/* If we have converted to a safe operation, I/O
@@ -193,7 +178,7 @@ int op;				/* DEV_READ, DEV_WRITE, DEV_IOCTL, etc. */
 dev_t dev;			/* major-minor device number */
 int proc_e;			/* in whose address space is buf? */
 void *buf;			/* virtual address of the buffer */
-off_t pos;			/* byte position */
+u64_t pos;			/* byte position */
 int bytes;			/* how many bytes to transfer */
 int flags;			/* special flags, like O_NONBLOCK */
 {
@@ -208,7 +193,7 @@ int flags;			/* special flags, like O_NONBLOCK */
   void *buf_used;
   static cp_grant_id_t gids[NR_IOREQS];
   endpoint_t driver_e;
- 
+
   /* Determine driver endpoint for this device */
   driver_e = driver_endpoints[(dev >> MAJOR) & BYTE].driver_e;
   
@@ -233,16 +218,16 @@ int flags;			/* special flags, like O_NONBLOCK */
   op_used = op;
   safe = safe_io_conversion(driver_e, &gid,
           &op_used, gids, NR_IOREQS, &m.IO_ENDPT, &buf_used,
-          &vec_grants, bytes, &pos);
+          &vec_grants, bytes);
 
   /* Set up rest of the message. */
   if (safe) m.IO_GRANT = (char *) gid;
 
   m.m_type   = op_used;
   m.DEVICE   = (dev >> MINOR) & BYTE;
-  m.POSITION = pos;
+  m.POSITION = ex64lo(pos);
   m.COUNT    = bytes;
-  m.HIGHPOS  = 0;
+  m.HIGHPOS  = ex64hi(pos);
 
   /* Call the task. */
   r = sendrec(driver_e, &m);
diff --git a/servers/mfs/misc.c b/servers/mfs/misc.c
index 3613fc71f..b6e296fa5 100644
--- a/servers/mfs/misc.c
+++ b/servers/mfs/misc.c
@@ -1,6 +1,7 @@
 
 #include "fs.h"
 #include <fcntl.h>
+#include <minix/vfsif.h>
 
 #include "buf.h"
 #include "inode.h"
@@ -32,3 +33,26 @@ PUBLIC int fs_sync()
 }
 
 
+/*===========================================================================*
+ *				fs_flush				     *
+ *===========================================================================*/
+PUBLIC int fs_flush()
+{
+/* Flush the blocks of a device from the cache after writing any dirty blocks
+ * to disk.
+ */
+  dev_t dev;
+
+  dev= fs_m_in.REQ_DEV;
+  if (dev == fs_dev)
+  {
+	printf("fs_flush: not flushing block for mounted filsystem\n");
+	return EBUSY;
+  }
+  flushall(dev);
+  invalidate(dev);
+
+  return(OK);
+}
+
+
diff --git a/servers/mfs/proto.h b/servers/mfs/proto.h
index dd3fbb1ca..e8aef47d9 100644
--- a/servers/mfs/proto.h
+++ b/servers/mfs/proto.h
@@ -47,6 +47,7 @@ int fs_slink(void);
 int fs_rdlink(void);
 int fs_breadwrite(void);
 int fs_getdents(void);
+int fs_flush(void);
 
 void init_inode_cache(void);
 
@@ -70,7 +71,7 @@ _PROTOTYPE( void invalidate2, (Dev_t device)				);
 
 /* device.c */
 _PROTOTYPE( int block_dev_io, (int op, Dev_t dev, int proc, void *buf,
-			off_t pos, int bytes, int flags)		);
+			u64_t pos, int bytes, int flags)		);
 
 
 /* inode.c */
@@ -146,7 +147,7 @@ _PROTOTYPE( int read_only, (struct inode *ip)				);
 /* read.c */
 _PROTOTYPE( int do_read, (void)						);
 _PROTOTYPE( struct buf *rahead, (struct inode *rip, block_t baseblock,
-			off_t position, unsigned bytes_ahead)		);
+			u64_t position, unsigned bytes_ahead)		);
 _PROTOTYPE( void read_ahead, (void)					);
 _PROTOTYPE( block_t read_map, (struct inode *rip, off_t pos)		);
 _PROTOTYPE( int read_write, (int rw_flag)				);
diff --git a/servers/mfs/read.c b/servers/mfs/read.c
index 920c22c1b..453a226ef 100644
--- a/servers/mfs/read.c
+++ b/servers/mfs/read.c
@@ -6,6 +6,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include "buf.h"
 #include "inode.h"
 #include "super.h"
@@ -14,7 +15,7 @@
 
 
 
-FORWARD _PROTOTYPE( int rw_chunk, (struct inode *rip, off_t position,
+FORWARD _PROTOTYPE( int rw_chunk, (struct inode *rip, u64_t position,
 	unsigned off, int chunk, unsigned left, int rw_flag,
 	char *buff, int seg, int usr, int block_size, int *completed));
 
@@ -98,7 +99,7 @@ PUBLIC int fs_readwrite(void)
       }
 
       /* Read or write 'chunk' bytes. */
-      r = rw_chunk(rip, position, off, chunk, (unsigned) nrbytes,
+      r = rw_chunk(rip, cvul64(position), off, chunk, (unsigned) nrbytes,
               rw_flag, user_addr, seg, usr, block_size, &completed);
 
       if (r != OK) break;	/* EOF reached */
@@ -166,7 +167,7 @@ PUBLIC int fs_breadwrite(void)
 {
   int r, usr, rw_flag, chunk, block_size;
   int nrbytes;
-  off_t position, f_size, bytes_left;
+  u64_t position;
   unsigned int off, cum_io;
   mode_t mode_word;
   int completed, r2 = OK;
@@ -176,37 +177,30 @@ PUBLIC int fs_breadwrite(void)
   struct inode rip;
   
   r = OK;
-  f_size = ULONG_MAX;
   
   /* Get the values from the request message */ 
   rw_flag = (fs_m_in.m_type == REQ_BREAD ? READING : WRITING);
-  usr = fs_m_in.REQ_FD_WHO_E;
-  position = fs_m_in.REQ_FD_POS;
-  nrbytes = (unsigned) fs_m_in.REQ_FD_NBYTES;
-  user_addr = fs_m_in.REQ_FD_USER_ADDR;
+  usr = fs_m_in.REQ_XFD_WHO_E;
+  position = make64(fs_m_in.REQ_XFD_POS_LO, fs_m_in.REQ_XFD_POS_HI);
+  nrbytes = (unsigned) fs_m_in.REQ_XFD_NBYTES;
+  user_addr = fs_m_in.REQ_XFD_USER_ADDR;
   
-  block_size = get_block_size(fs_m_in.REQ_FD_BDEV);
+  block_size = get_block_size(fs_m_in.REQ_XFD_BDEV);
 
-  rip.i_zone[0] = fs_m_in.REQ_FD_BDEV;
+  rip.i_zone[0] = fs_m_in.REQ_XFD_BDEV;
   rip.i_mode = I_BLOCK_SPECIAL;
-  rip.i_size = f_size;
+  rip.i_size = 0;
 
   rdwt_err = OK;		/* set to EIO if disk error occurs */
   
   cum_io = 0;
   /* Split the transfer into chunks that don't span two blocks. */
   while (nrbytes != 0) {
-      off = (unsigned int) (position % block_size);/* offset in blk*/
+      off = rem64u(position, block_size);	/* offset in blk*/
         
       chunk = MIN(nrbytes, block_size - off);
       if (chunk < 0) chunk = block_size - off;
 
-      if (rw_flag == READING) {
-          bytes_left = f_size - position;
-          if (position >= f_size) break;	/* we are beyond EOF */
-          if (chunk > bytes_left) chunk = (int) bytes_left;
-      }
-
       /* Read or write 'chunk' bytes. */
       r = rw_chunk(&rip, position, off, chunk, (unsigned) nrbytes,
               rw_flag, user_addr, D, usr, block_size, &completed);
@@ -218,16 +212,16 @@ PUBLIC int fs_breadwrite(void)
       user_addr += chunk;	/* user buffer address */
       nrbytes -= chunk;	        /* bytes yet to be read */
       cum_io += chunk;	        /* bytes read so far */
-      position += chunk;	/* position within the file */
+      position= add64ul(position, chunk);	/* position within the file */
   }
   
-  fs_m_out.RES_FD_POS = position; 
+  fs_m_out.RES_XFD_POS_LO = ex64lo(position); 
+  fs_m_out.RES_XFD_POS_HI = ex64hi(position); 
   
   if (rdwt_err != OK) r = rdwt_err;	/* check for disk error */
   if (rdwt_err == END_OF_FILE) r = OK;
 
-  fs_m_out.RES_FD_CUM_IO = cum_io;
-  fs_m_out.RES_FD_SIZE = rip.i_size;
+  fs_m_out.RES_XFD_CUM_IO = cum_io;
   
   return(r);
 }
@@ -239,7 +233,7 @@ PUBLIC int fs_breadwrite(void)
 PRIVATE int rw_chunk(rip, position, off, chunk, left, rw_flag, buff,
  seg, usr, block_size, completed)
 register struct inode *rip;	/* pointer to inode for file to be rd/wr */
-off_t position;			/* position within file to read or write */
+u64_t position;			/* position within file to read or write */
 unsigned off;			/* off within the current block */
 int chunk;			/* number of bytes to read or write */
 unsigned left;			/* max number of bytes wanted after position */
@@ -263,11 +257,13 @@ int *completed;			/* number of bytes copied */
   block_spec = (rip->i_mode & I_TYPE) == I_BLOCK_SPECIAL;
 
   if (block_spec) {
-	b = position/block_size;
+	b = div64u(position, block_size);
 	dev = (dev_t) rip->i_zone[0];
   } 
   else {
-	b = read_map(rip, position);
+	if (ex64hi(position) != 0)
+		panic(__FILE__, "rw_chunk: position too high", NO_NUM);
+	b = read_map(rip, ex64lo(position));
 	dev = rip->i_dev;
   }
 
@@ -279,7 +275,8 @@ int *completed;			/* number of bytes copied */
 	} 
         else {
 		/* Writing to a nonexistent block. Create and enter in inode.*/
-		if ((bp= new_block(rip, position)) == NIL_BUF)return(err_code);
+		if ((bp= new_block(rip, ex64lo(position))) == NIL_BUF)
+			return(err_code);
 	}
   } 
   else if (rw_flag == READING) {
@@ -292,7 +289,8 @@ int *completed;			/* number of bytes copied */
 	 * the cache, acquire it, otherwise just acquire a free buffer.
 	 */
 	n = (chunk == block_size ? NO_READ : NORMAL);
-	if (!block_spec && off == 0 && position >= rip->i_size) n = NO_READ;
+	if (!block_spec && off == 0 && ex64lo(position) >= rip->i_size) 
+		n = NO_READ;
 	bp = get_block(dev, b, n);
   }
 
@@ -302,7 +300,7 @@ int *completed;			/* number of bytes copied */
   }
   
   if (rw_flag == WRITING && chunk != block_size && !block_spec &&
-					position >= rip->i_size && off == 0) {
+				ex64lo(position) >= rip->i_size && off == 0) {
 	zero_block(bp);
   }
 
@@ -439,7 +437,7 @@ PUBLIC void read_ahead()
   block_size = get_block_size(rip->i_dev);
   rdahed_inode = NIL_INODE;	/* turn off read ahead */
   if ( (b = read_map(rip, rdahedpos)) == NO_BLOCK) return;	/* at EOF */
-  bp = rahead(rip, b, rdahedpos, block_size);
+  bp = rahead(rip, b, cvul64(rdahedpos), block_size);
   put_block(bp, PARTIAL_DATA_BLOCK);
 }
 
@@ -449,7 +447,7 @@ PUBLIC void read_ahead()
 PUBLIC struct buf *rahead(rip, baseblock, position, bytes_ahead)
 register struct inode *rip;	/* pointer to inode for file to be read */
 block_t baseblock;		/* block at current position */
-off_t position;			/* position within file */
+u64_t position;			/* position within file */
 unsigned bytes_ahead;		/* bytes beyond position for immediate use */
 {
 /* Fetch a block from the cache or the device.  If a physical read is
@@ -502,8 +500,8 @@ unsigned bytes_ahead;		/* bytes beyond position for immediate use */
    * indirect blocks (but don't call read_map!).
    */
 
-  fragment = position % block_size;
-  position -= fragment;
+  fragment = rem64u(position, block_size);
+  position= sub64u(position, fragment);
   bytes_ahead += fragment;
 
   blocks_ahead = (bytes_ahead + block_size - 1) / block_size;
@@ -511,13 +509,14 @@ unsigned bytes_ahead;		/* bytes beyond position for immediate use */
   if (block_spec && rip->i_size == 0) {
 	blocks_left = NR_IOREQS;
   } else {
-	blocks_left = (rip->i_size - position + block_size - 1) / block_size;
+	blocks_left = (rip->i_size - ex64lo(position) + block_size - 1) /
+		block_size;
 
 	/* Go for the first indirect block if we are in its neighborhood. */
 	if (!block_spec) {
 		scale = rip->i_sp->s_log_zone_size;
 		ind1_pos = (off_t) rip->i_ndzones * (block_size << scale);
-		if (position <= ind1_pos && rip->i_size > ind1_pos) {
+		if (ex64lo(position) <= ind1_pos && rip->i_size > ind1_pos) {
 			blocks_ahead++;
 			blocks_left++;
 		}
diff --git a/servers/mfs/super.c b/servers/mfs/super.c
index bc94da198..23272ef3a 100644
--- a/servers/mfs/super.c
+++ b/servers/mfs/super.c
@@ -14,6 +14,7 @@
 #include "fs.h"
 #include <string.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include "buf.h"
 #include "inode.h"
 #include "super.h"
@@ -224,7 +225,7 @@ register struct super_block *sp; /* pointer to a superblock */
   	panic(__FILE__,"request for super_block of NO_DEV", NO_NUM);
   
   r = block_dev_io(DEV_READ, dev, SELF_E,
-  	sbbuf, SUPER_BLOCK_BYTES, _MIN_BLOCK_SIZE, 0);
+  	sbbuf, cvu64(SUPER_BLOCK_BYTES), _MIN_BLOCK_SIZE, 0);
   if (r != _MIN_BLOCK_SIZE) {
 printf("MFSread_super r != _MIN_BLOCK_SIZE\n");
   	return EINVAL;
@@ -312,6 +313,13 @@ printf("MFSread_super block_sizr % INODE_SIZE notOK \n");
   	return EINVAL;
   }
 
+  /* Limit s_max_size to LONG_MAX */
+  if ((unsigned long)sp->s_max_size > LONG_MAX)
+  {
+	printf("read_super: reducing s_max_size to LONG_MAX\n");
+	sp->s_max_size= LONG_MAX;
+  }
+
   sp->s_isearch = 0;		/* inode searches initially start at 0 */
   sp->s_zsearch = 0;		/* zone searches initially start at 0 */
   sp->s_version = version;
diff --git a/servers/mfs/table.c b/servers/mfs/table.c
index 1db0b907d..a86739fb9 100644
--- a/servers/mfs/table.c
+++ b/servers/mfs/table.c
@@ -59,5 +59,6 @@ PUBLIC _PROTOTYPE (int (*fs_call_vec[]), (void) ) = {
         fs_breadwrite,       /* 38  */
         fs_breadwrite,       /* 39  */
         fs_getdents,	     /* 40  */
+        fs_flush,	     /* 41  */
 };
 
diff --git a/servers/vfs/device.c b/servers/vfs/device.c
index 914af39b0..efe4441e6 100644
--- a/servers/vfs/device.c
+++ b/servers/vfs/device.c
@@ -24,6 +24,7 @@
 #include <minix/com.h>
 #include <minix/endpoint.h>
 #include <minix/ioctl.h>
+#include <minix/u64.h>
 #include "file.h"
 #include "fproc.h"
 
@@ -415,17 +416,18 @@ int bytes;			/* how many bytes to transfer */
 /*===========================================================================*
  *				dev_io					     *
  *===========================================================================*/
-PUBLIC int dev_io(op, dev, proc_e, buf, pos, bytes, flags)
+PUBLIC int dev_io(op, dev, proc_e, buf, posX, bytes, flags)
 int op;				/* DEV_READ, DEV_WRITE, DEV_IOCTL, etc. */
 dev_t dev;			/* major-minor device number */
 int proc_e;			/* in whose address space is buf? */
 void *buf;			/* virtual address of the buffer */
-off_t pos;			/* byte position */
+u64_t posX;			/* byte position */
 int bytes;			/* how many bytes to transfer */
 int flags;			/* special flags, like O_NONBLOCK */
 {
 /* Read or write from a device.  The parameter 'dev' tells which one. */
   struct dmap *dp;
+  off_t pos;
   message dev_mess;
   cp_grant_id_t gid = GRANT_INVALID;
   static cp_grant_id_t gids[NR_IOREQS];
@@ -433,6 +435,10 @@ int flags;			/* special flags, like O_NONBLOCK */
   void *buf_used;
   endpoint_t ioproc;
 
+  if (ex64hi(posX) != 0)
+	panic(__FILE__, "dev_io: postition too high", NO_NUM);
+  pos= ex64lo(posX);
+
   /* Determine task dmap. */
   dp = &dmap[(dev >> MAJOR) & BYTE];
   orig_op = op;
@@ -648,7 +654,7 @@ PUBLIC int do_ioctl()
 	&& (vp->v_mode & I_TYPE) != I_BLOCK_SPECIAL) return(ENOTTY);
   dev = (dev_t) vp->v_sdev;
 
-  return(dev_io(DEV_IOCTL, dev, who_e, m_in.ADDRESS, 0L, 
+  return(dev_io(DEV_IOCTL, dev, who_e, m_in.ADDRESS, cvu64(0), 
   	m_in.REQUEST, f->filp_flags));
 }
 
diff --git a/servers/vfs/exec.c b/servers/vfs/exec.c
index 10ca92d90..6b2174a6f 100644
--- a/servers/vfs/exec.c
+++ b/servers/vfs/exec.c
@@ -22,6 +22,7 @@
 #include <minix/callnr.h>
 #include <minix/endpoint.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include <a.out.h>
 #include <signal.h>
 #include <string.h>
@@ -400,7 +401,7 @@ int *hdrlenp;
   req.inode_nr = vp->v_inode_nr;
   req.user_e = FS_PROC_NR;
   req.seg = D;
-  req.pos = pos;
+  req.pos = cvul64(pos);
   req.num_of_bytes = sizeof(hdr);
   req.user_addr = (char*)&hdr;
   req.inode_index = vp->v_index;
@@ -475,7 +476,7 @@ vir_bytes *stk_bytes;		/* size of initial stack */
   req.inode_nr = vp->v_inode_nr;
   req.user_e = FS_PROC_NR;
   req.seg = D;
-  req.pos = pos;
+  req.pos = cvul64(pos);
   req.num_of_bytes = _MAX_BLOCK_SIZE;
   req.user_addr = buf;
   req.inode_index = vp->v_index;
@@ -636,7 +637,7 @@ phys_bytes seg_bytes;		/* how much is to be transferred? */
   req.inode_nr = vp->v_inode_nr;
   req.user_e = proc_e;
   req.seg = seg;
-  req.pos = off;
+  req.pos = cvul64(off);
   req.num_of_bytes = seg_bytes;
   req.user_addr = 0;
   req.inode_index = vp->v_index;
diff --git a/servers/vfs/file.h b/servers/vfs/file.h
index 4b1e692f4..74552a58e 100644
--- a/servers/vfs/file.h
+++ b/servers/vfs/file.h
@@ -10,7 +10,7 @@ EXTERN struct filp {
 
   struct vnode *filp_vno;
   
-  off_t filp_pos;		/* file position */
+  u64_t filp_pos;		/* file position */
 
   /* the following fields are for select() and are owned by the generic
    * select() code (i.e., fd-type-specific select() code can't touch these).
diff --git a/servers/vfs/filedes.c b/servers/vfs/filedes.c
index 4b137c969..b070e517d 100644
--- a/servers/vfs/filedes.c
+++ b/servers/vfs/filedes.c
@@ -9,6 +9,7 @@
  */
 
 #include <sys/select.h>
+#include <minix/u64.h>
 
 #include "fs.h"
 #include "file.h"
@@ -47,7 +48,7 @@ PUBLIC int get_fd(int start, mode_t bits, int *k, struct filp **fpt)
   for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
 	if (f->filp_count == 0) {
 		f->filp_mode = bits;
-		f->filp_pos = 0L;
+		f->filp_pos = cvu64(0);
 		f->filp_selectors = 0;
 		f->filp_select_ops = 0;
 		f->filp_pipe_select_ops = 0;
diff --git a/servers/vfs/lock.c b/servers/vfs/lock.c
index d8e93cb49..6a3233a1c 100644
--- a/servers/vfs/lock.c
+++ b/servers/vfs/lock.c
@@ -7,6 +7,7 @@
 
 #include "fs.h"
 #include <minix/com.h>
+#include <minix/u64.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include "file.h"
@@ -50,7 +51,13 @@ int req;			/* either F_SETLK or F_SETLKW */
   /* Compute the first and last bytes in the lock region. */
   switch (flock.l_whence) {
 	case SEEK_SET:	first = 0; break;
-	case SEEK_CUR:	first = f->filp_pos; break;
+	case SEEK_CUR:
+		if (ex64hi(f->filp_pos) != 0)
+		{
+			panic(__FILE__, "lock_op: position in file too high",
+				NO_NUM);
+		}
+		first = ex64lo(f->filp_pos); break;
 	case SEEK_END:	first = f->filp_vno->v_size; break;
 	default:	return(EINVAL);
   }
diff --git a/servers/vfs/misc.c b/servers/vfs/misc.c
index 7ad28ca57..87729f0ae 100644
--- a/servers/vfs/misc.c
+++ b/servers/vfs/misc.c
@@ -26,6 +26,7 @@
 #include <minix/safecopies.h>
 #include <minix/endpoint.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include <sys/ptrace.h>
 #include <sys/svrctl.h>
 #include "file.h"
@@ -231,7 +232,14 @@ PUBLIC int do_fcntl()
 	/* Figure out starting position base. */
 	switch(flock_arg.l_whence) {
 		case SEEK_SET: start = 0; if(offset < 0) return EINVAL; break;
-		case SEEK_CUR: start = f->filp_pos; break;
+		case SEEK_CUR:
+			if (ex64hi(f->filp_pos) != 0)
+			{
+				panic(__FILE__,
+					"do_fcntl: position in file too high",
+					NO_NUM);
+			}
+			start = ex64lo(f->filp_pos); break;
 		case SEEK_END: start = f->filp_vno->v_size; break;
 		default: return EINVAL;
 	}
diff --git a/servers/vfs/mount.c b/servers/vfs/mount.c
index fd59686f1..5639da98d 100644
--- a/servers/vfs/mount.c
+++ b/servers/vfs/mount.c
@@ -77,7 +77,7 @@ PUBLIC int do_mount()
 	
   /* FS process' endpoint number */ 
   fs_e = (unsigned long)m_in.m1_p3;
-  
+
   /* Do the actual job */
   r = mount_fs(fs_e);
 
diff --git a/servers/vfs/open.c b/servers/vfs/open.c
index cd8a0ea1b..a8966d592 100644
--- a/servers/vfs/open.c
+++ b/servers/vfs/open.c
@@ -20,6 +20,7 @@
 #include <unistd.h>
 #include <minix/callnr.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include "file.h"
 #include "fproc.h"
 #include "lock.h"
@@ -30,7 +31,8 @@
 #include "vnode.h"
 #include "vmnt.h"
 
-#define offset m2_l1
+#define offset_lo	m2_l1
+#define offset_high	m2_l2
  
 
 FORWARD _PROTOTYPE( int common_open, (int oflags, mode_t omode)		);
@@ -248,9 +250,9 @@ printf("the root FS...\n");
                   /* Nobody else found.  Restore filp. */
                   fil_ptr->filp_count = 1;
 		  if (fil_ptr->filp_mode == R_BIT)
-			fil_ptr->filp_pos = vp->v_pipe_rd_pos; 
+			fil_ptr->filp_pos = cvul64(vp->v_pipe_rd_pos);
 		  else
-			fil_ptr->filp_pos = vp->v_pipe_wr_pos;
+			fil_ptr->filp_pos = cvul64(vp->v_pipe_wr_pos);
               }
           }
           break;
@@ -399,7 +401,61 @@ PUBLIC int do_lseek()
 {
 /* Perform the lseek(ls_fd, offset, whence) system call. */
   register struct filp *rfilp;
-  register off_t pos;
+  int r;
+  long offset;
+  u64_t pos, newpos;
+  struct node_req req;
+
+  /* Check to see if the file descriptor is valid. */
+  if ( (rfilp = get_filp(m_in.ls_fd)) == NIL_FILP) return(err_code);
+
+  /* No lseek on pipes. */
+  if (rfilp->filp_vno->v_pipe == I_PIPE) return(ESPIPE);
+
+  /* The value of 'whence' determines the start position to use. */
+  switch(m_in.whence) {
+      case SEEK_SET: pos = cvu64(0);	break;
+      case SEEK_CUR: pos = rfilp->filp_pos;	break;
+      case SEEK_END: pos = cvul64(rfilp->filp_vno->v_size);	break;
+      default: return(EINVAL);
+  }
+
+  offset= m_in.offset_lo;
+  if (offset >= 0)
+	newpos= add64ul(pos, offset);
+  else
+	newpos= sub64ul(pos, -offset);
+
+  /* Check for overflow. */
+  if (ex64hi(newpos) != 0)
+	return EINVAL;
+
+  if (cmp64(newpos, rfilp->filp_pos) != 0) { /* Inhibit read ahead request */
+      /* Fill in request message */
+      req.fs_e = rfilp->filp_vno->v_fs_e;
+      req.inode_nr = rfilp->filp_vno->v_inode_nr;
+
+      /* Issue request */
+      if ((r = req_inhibread(&req)) != OK) return r;
+  }
+
+  rfilp->filp_pos = newpos;
+
+  /* insert the new position into the output message */
+  m_out.reply_l1 = ex64lo(newpos);
+
+  return(OK);
+}
+
+
+/*===========================================================================*
+ *				do_llseek				     *
+ *===========================================================================*/
+PUBLIC int do_llseek()
+{
+/* Perform the llseek(ls_fd, offset, whence) system call. */
+  register struct filp *rfilp;
+  u64_t pos, newpos;
   struct node_req req;
   int r;
 
@@ -411,20 +467,21 @@ PUBLIC int do_lseek()
 
   /* The value of 'whence' determines the start position to use. */
   switch(m_in.whence) {
-      case SEEK_SET: pos = 0;	break;
+      case SEEK_SET: pos = cvu64(0);	break;
       case SEEK_CUR: pos = rfilp->filp_pos;	break;
-      case SEEK_END: pos = rfilp->filp_vno->v_size;	break;
+      case SEEK_END: pos = cvul64(rfilp->filp_vno->v_size);	break;
       default: return(EINVAL);
   }
 
+  newpos= add64(pos, make64(m_in.offset_lo, m_in.offset_high));
+
   /* Check for overflow. */
-  if (((long)m_in.offset > 0) && ((long)(pos + m_in.offset) < (long)pos)) 
+  if (((long)m_in.offset_high > 0) && cmp64(newpos, pos) < 0) 
       return(EINVAL);
-  if (((long)m_in.offset < 0) && ((long)(pos + m_in.offset) > (long)pos)) 
+  if (((long)m_in.offset_high < 0) && cmp64(newpos, pos) > 0) 
       return(EINVAL);
-  pos = pos + m_in.offset;
 
-  if (pos != rfilp->filp_pos) {         /* Inhibit read ahead request */
+  if (cmp64(newpos, rfilp->filp_pos) != 0) { /* Inhibit read ahead request */
       /* Fill in request message */
       req.fs_e = rfilp->filp_vno->v_fs_e;
       req.inode_nr = rfilp->filp_vno->v_inode_nr;
@@ -433,8 +490,9 @@ PUBLIC int do_lseek()
       if ((r = req_inhibread(&req)) != OK) return r;
   }
 
-  rfilp->filp_pos = pos;
-  m_out.reply_l1 = pos;		/* insert the long into the output message */
+  rfilp->filp_pos = newpos;
+  m_out.reply_l1 = ex64lo(newpos);
+  m_out.reply_l2 = ex64hi(newpos);
   return(OK);
 }
 
@@ -474,11 +532,16 @@ int fd_nr;
 	if (mode_word == I_CHAR_SPECIAL || mode_word == I_BLOCK_SPECIAL) {
 		dev = (dev_t) vp->v_sdev;
 		if (mode_word == I_BLOCK_SPECIAL)  {
-			/* Invalidate cache entries unless special is mounted
-			 * or ROOT
-			 */
-          		req_sync(vp->v_bfs_e);
-printf("VFSclose: closed block spec %d\n", dev);		
+printf("VFSclose: closing block spec 0x%x\n", dev);		
+			if (vp->v_bfs_e == ROOT_FS_E)
+			{
+				/* Invalidate the cache unless the special is
+				 * mounted. Assume that the root filesystem's
+				 * is open only for fsck.
+			 	 */
+printf("VFSclose: flushing block spec 0x%x\n", dev);		
+          			req_flush(vp->v_bfs_e, dev);
+			}
 		}
 		/* Do any special processing on device close. */
 		dev_close(dev);
@@ -498,9 +561,9 @@ printf("VFSclose: closed block spec %d\n", dev);
 		 * The read and write positions are saved separately.  
 		 */
 		if (rfilp->filp_mode == R_BIT)
-			vp->v_pipe_rd_pos = rfilp->filp_pos;
+			vp->v_pipe_rd_pos = ex64lo(rfilp->filp_pos);
 		else
-			vp->v_pipe_wr_pos = rfilp->filp_pos;
+			vp->v_pipe_wr_pos = ex64lo(rfilp->filp_pos);
 		
 	}
 	else {
diff --git a/servers/vfs/pipe.c b/servers/vfs/pipe.c
index 430f97f61..af327dc51 100644
--- a/servers/vfs/pipe.c
+++ b/servers/vfs/pipe.c
@@ -25,6 +25,7 @@
 #include <minix/callnr.h>
 #include <minix/endpoint.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include <sys/select.h>
 #include <sys/time.h>
 #include "file.h"
@@ -136,7 +137,7 @@ register struct vnode *vp;	/* the inode of the pipe */
 int rw_flag;			/* READING or WRITING */
 int oflags;			/* flags set by open or fcntl */
 register int bytes;		/* bytes to be read or written (all chunks) */
-register off_t position;	/* current file position */
+u64_t position;			/* current file position */
 int *canwrite;			/* return: number of bytes we can write */
 int notouch;			/* check only */
 {
@@ -145,10 +146,15 @@ int notouch;			/* check only */
  * and there is no writer, return 0 bytes.  If a process is writing to a
  * pipe and no one is reading from it, give a broken pipe error.
  */
+  off_t pos;
+
+  if (ex64hi(position) != 0)
+	panic(__FILE__, "pipe_check: position too large in pipe", NO_NUM);
+  pos= ex64lo(position);
 
   /* If reading, check for empty pipe. */
   if (rw_flag == READING) {
-	if (position >= vp->v_size) {
+	if (pos >= vp->v_size) {
 		/* Process is reading from an empty pipe. */
 		int r = 0;
 		if (find_filp(vp, W_BIT) != NIL_FILP) {
@@ -176,7 +182,7 @@ int notouch;			/* check only */
 		return(EPIPE);
 	}
 
-	if (position + bytes > PIPE_SIZE(vp->v_vmnt->m_block_size)) {
+	if (pos + bytes > PIPE_SIZE(vp->v_vmnt->m_block_size)) {
 		if ((oflags & O_NONBLOCK)
 		 && bytes <= PIPE_SIZE(vp->v_vmnt->m_block_size)) {
 			return(EAGAIN);
@@ -184,7 +190,7 @@ int notouch;			/* check only */
 		else if ((oflags & O_NONBLOCK)
 		&& bytes > PIPE_SIZE(vp->v_vmnt->m_block_size)) {
 		if ( (*canwrite = (PIPE_SIZE(vp->v_vmnt->m_block_size) 
-			- position)) > 0)  {
+			- pos)) > 0)  {
 				/* Do a partial write. Need to wakeup reader */
 				if (!notouch)
 					release(vp, READ, susp_count);
@@ -195,7 +201,7 @@ int notouch;			/* check only */
 		     }
 		if (bytes > PIPE_SIZE(vp->v_vmnt->m_block_size)) {
 			if ((*canwrite = PIPE_SIZE(vp->v_vmnt->m_block_size) 
-				- position) > 0) {
+				- pos) > 0) {
 				/* Do a partial write. Need to wakeup reader
 				 * since we'll suspend ourself in read_write()
 				 */
@@ -210,7 +216,7 @@ int notouch;			/* check only */
 	}
 
 	/* Writing to an empty pipe.  Search for suspended reader. */
-	if (position == 0 && !notouch)
+	if (pos == 0 && !notouch)
 		release(vp, READ, susp_count);
   }
 
diff --git a/servers/vfs/proto.h b/servers/vfs/proto.h
index f117a2470..c886cea90 100644
--- a/servers/vfs/proto.h
+++ b/servers/vfs/proto.h
@@ -15,7 +15,7 @@ _PROTOTYPE( void dev_close, (Dev_t dev)					);
 _PROTOTYPE( int dev_bio, (int op, Dev_t dev, int proc, void *buf,
 			off_t pos, int bytes)				);
 _PROTOTYPE( int dev_io, (int op, Dev_t dev, int proc, void *buf,
-			off_t pos, int bytes, int flags)		);
+			u64_t pos, int bytes, int flags)		);
 _PROTOTYPE( int gen_opcl, (int op, Dev_t dev, int proc, int flags)	);
 _PROTOTYPE( int gen_io, (int task_nr, message *mess_ptr)		);
 _PROTOTYPE( int no_dev, (int op, Dev_t dev, int proc, int flags)	);
@@ -92,6 +92,7 @@ _PROTOTYPE( int do_close, (void)					);
 _PROTOTYPE( int close_fd, (struct fproc *rfp, int fd_nr)		);
 _PROTOTYPE( int do_creat, (void)					);
 _PROTOTYPE( int do_lseek, (void)					);
+_PROTOTYPE( int do_llseek, (void)					);
 _PROTOTYPE( int do_mknod, (void)					);
 _PROTOTYPE( int do_mkdir, (void)					);
 _PROTOTYPE( int do_open, (void)						);
@@ -105,7 +106,7 @@ _PROTOTYPE( int do_pipe, (void)						);
 _PROTOTYPE( int do_unpause, (void)					);
 _PROTOTYPE( int unpause, (int proc_nr_e)				);
 _PROTOTYPE( int pipe_check, (struct vnode *vp, int rw_flag,
-      int oflags, int bytes, off_t position, int *canwrite, int notouch));
+      int oflags, int bytes, u64_t position, int *canwrite, int notouch));
 _PROTOTYPE( void release, (struct vnode *vp, int call_nr, int count)	);
 _PROTOTYPE( void revive, (int proc_nr, int bytes)			);
 _PROTOTYPE( void suspend, (int task)					);
@@ -168,6 +169,7 @@ _PROTOTYPE( int req_breadwrite, (breadwrite_req_t *req,
             readwrite_res_t *res)                                       );
 _PROTOTYPE( int req_getdents, (endpoint_t fs_e, ino_t inode_nr,
 	off_t pos, cp_grant_id_t gid, size_t size, off_t *pos_change)	);
+_PROTOTYPE( int req_flush, (endpoint_t fs_e, Dev_t)                     );
 
 /* stadir.c */
 _PROTOTYPE( int do_chdir, (void)					);
diff --git a/servers/vfs/read.c b/servers/vfs/read.c
index d860f6ac0..3f755cfeb 100644
--- a/servers/vfs/read.c
+++ b/servers/vfs/read.c
@@ -16,6 +16,7 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include "file.h"
 #include "fproc.h"
 #include "param.h"
@@ -44,7 +45,8 @@ int rw_flag;			/* READING or WRITING */
 /* Perform read(fd, buffer, nbytes) or write(fd, buffer, nbytes) call. */
   register struct filp *f;
   register struct vnode *vp;
-  off_t bytes_left, f_size, position;
+  off_t bytes_left, f_size;
+  u64_t position;
   unsigned int off, cum_io;
   int op, oflags, r, chunk, usr, seg, block_spec, char_spec;
   int regular, partial_pipe = 0, partial_cnt = 0;
@@ -85,10 +87,12 @@ int rw_flag;			/* READING or WRITING */
   /* check if user process has the memory it needs.
    * if not, copying will fail later.
    * do this after 0-check above because umap doesn't want to map 0 bytes. */
-  if ((r = sys_umap(usr, seg, (vir_bytes) m_in.buffer, m_in.nbytes, &p)) != OK) {
+  if ((r = sys_umap(usr, seg, (vir_bytes) m_in.buffer, m_in.nbytes, &p)) != OK)
+  {
       printf("VFS: read_write: umap failed for process %d\n", usr);
       return r;
   }
+
   position = f->filp_pos;
   oflags = f->filp_flags;
 
@@ -129,7 +133,7 @@ int rw_flag;			/* READING or WRITING */
       r = dev_io(op, dev, usr, m_in.buffer, position, m_in.nbytes, oflags);
       if (r >= 0) {
           cum_io = r;
-          position += r;
+          position = add64ul(position, r);
           r = OK;
       }
   } 
@@ -154,12 +158,13 @@ int rw_flag;			/* READING or WRITING */
   /* Regular files */
   else {
       if (rw_flag == WRITING && block_spec == 0) {
+          /* Check for O_APPEND flag. */
+          if (oflags & O_APPEND) position = cvul64(f_size);
+
           /* Check in advance to see if file will grow too big. */
-          if (position > vp->v_vmnt->m_max_file_size - m_in.nbytes) 
+          if (cmp64ul(position, vp->v_vmnt->m_max_file_size - m_in.nbytes) > 0)
               return(EFBIG);
 
-          /* Check for O_APPEND flag. */
-          if (oflags & O_APPEND) position = f_size;
       }
 
       /* Pipes are a little different. Check. */
@@ -190,24 +195,39 @@ int rw_flag;			/* READING or WRITING */
       /* Issue request */
       r = req_readwrite(&req, &res);
 
-      position = res.new_pos;
-      cum_io += res.cum_io;
+      if (r >= 0)
+      {
+	if (ex64hi(res.new_pos))
+		panic(__FILE__, "read_write: bad new pos", NO_NUM);
+
+	position = res.new_pos;
+	cum_io += res.cum_io;
+      }
   }
 
   /* On write, update file size and access time. */
   if (rw_flag == WRITING) {
       if (regular || mode_word == I_DIRECTORY) {
-          if (position > f_size) vp->v_size = position;
+          if (cmp64ul(position, f_size) > 0)
+	  {
+		if (ex64hi(position) != 0)
+		{
+			panic(__FILE__,
+				"read_write: file size too big for v_size",
+				NO_NUM);
+		}
+		vp->v_size = ex64lo(position);
+	  }
       }
   }
   else {
       if (vp->v_pipe == I_PIPE) {
-          if (position >= vp->v_size) {
+          if (cmp64ul(position, vp->v_size) >= 0) {
               /* Reset pipe pointers */
               vp->v_size = 0;
-              position = 0;
+              position = cvu64(0);
               wf = find_filp(vp, W_BIT);
-              if (wf != NIL_FILP) wf->filp_pos = 0;
+              if (wf != NIL_FILP) wf->filp_pos = cvu64(0);
           }
       }
   }
@@ -319,13 +339,16 @@ PUBLIC int do_getdents()
   if (gid < 0) panic(__FILE__, "cpf_grant_magic failed", gid);
 
   /* Issue request */
+  if (ex64hi(rfilp->filp_pos) != 0)
+	panic(__FILE__, "do_getdents: should handle large offsets", NO_NUM);
+	
   r= req_getdents(rfilp->filp_vno->v_fs_e, rfilp->filp_vno->v_inode_nr, 
-	rfilp->filp_pos, gid, m_in.nbytes, &pos_change);
+	ex64lo(rfilp->filp_pos), gid, m_in.nbytes, &pos_change);
 
   cpf_revoke(gid);
 
   if (r > 0)
-	rfilp->filp_pos += pos_change;
+	rfilp->filp_pos= add64ul(rfilp->filp_pos, pos_change);
   return r;
 }
 
diff --git a/servers/vfs/request.c b/servers/vfs/request.c
index cb7bc69a8..28d850f11 100644
--- a/servers/vfs/request.c
+++ b/servers/vfs/request.c
@@ -17,6 +17,7 @@
 #include <minix/keymap.h>
 #include <minix/const.h>
 #include <minix/endpoint.h>
+#include <minix/u64.h>
 #include <unistd.h>
 
 #include <minix/vfsif.h>
@@ -118,13 +119,16 @@ readwrite_res_t *res;
 {
     int r;
     message m;
+
+    if (ex64hi(req->pos) != 0)
+	panic(__FILE__, "req_readwrite: pos too large", NO_NUM);
     
     /* Fill in request message */
     m.m_type = req->rw_flag == READING ? REQ_READ : REQ_WRITE;
     m.REQ_FD_INODE_NR = req->inode_nr;
     m.REQ_FD_WHO_E = req->user_e;
     m.REQ_FD_SEG = req->seg;
-    m.REQ_FD_POS = req->pos;
+    m.REQ_FD_POS = ex64lo(req->pos);
     m.REQ_FD_NBYTES = req->num_of_bytes;
     m.REQ_FD_USER_ADDR = req->user_addr;
     m.REQ_FD_INODE_INDEX = req->inode_index;
@@ -133,7 +137,7 @@ readwrite_res_t *res;
     if ((r = fs_sendrec(req->fs_e, &m)) != OK) return r;
 
     /* Fill in response structure */
-    res->new_pos = m.RES_FD_POS;
+    res->new_pos = cvul64(m.RES_FD_POS);
     res->cum_io = m.RES_FD_CUM_IO;
 
     return OK;
@@ -810,22 +814,23 @@ readwrite_res_t *res;
 {
     int r;
     message m;
-    
+
     /* Fill in request message */
     m.m_type = req->rw_flag == READING ? REQ_BREAD : REQ_BWRITE;
-    m.REQ_FD_BDEV = req->dev;
-    m.REQ_FD_BLOCK_SIZE = req->blocksize;
-    m.REQ_FD_WHO_E = req->user_e;
-    m.REQ_FD_POS = req->pos;
-    m.REQ_FD_NBYTES = req->num_of_bytes;
-    m.REQ_FD_USER_ADDR = req->user_addr;
+    m.REQ_XFD_BDEV = req->dev;
+    m.REQ_XFD_BLOCK_SIZE = req->blocksize;
+    m.REQ_XFD_WHO_E = req->user_e;
+    m.REQ_XFD_POS_LO = ex64lo(req->pos);
+    m.REQ_XFD_POS_HI = ex64hi(req->pos);
+    m.REQ_XFD_NBYTES = req->num_of_bytes;
+    m.REQ_XFD_USER_ADDR = req->user_addr;
     
     /* Send/rec request */
     if ((r = fs_sendrec(req->fs_e, &m)) != OK) return r;
 
     /* Fill in response structure */
-    res->new_pos = m.RES_FD_POS;
-    res->cum_io = m.RES_FD_CUM_IO;
+    res->new_pos = make64(m.RES_XFD_POS_LO, m.RES_XFD_POS_HI);
+    res->cum_io = m.RES_XFD_CUM_IO;
 
     return OK;
 }
@@ -854,6 +859,24 @@ off_t *pos_change;
 }
 
 
+/*===========================================================================*
+ *				req_flush         			     *
+ *===========================================================================*/
+PUBLIC int req_flush(fs_e, dev)
+endpoint_t fs_e; 
+dev_t dev;
+{
+    message m;
+
+    /* Fill in request message */
+    m.m_type = REQ_FLUSH;
+    m.REQ_DEV = dev;
+    
+    /* Send/rec request */
+    return fs_sendrec(fs_e, &m);
+}
+
+
 #if 0           
 /*                 Wrapper pattern:                                          */
 /*===========================================================================*
diff --git a/servers/vfs/request.h b/servers/vfs/request.h
index 16795f342..a41a278f5 100644
--- a/servers/vfs/request.h
+++ b/servers/vfs/request.h
@@ -51,7 +51,7 @@ typedef struct readwrite_req {
 	ino_t inode_nr;
 	unsigned short inode_index;
 	int seg;
-	off_t pos;
+	u64_t pos;
 	unsigned int num_of_bytes;
 	char *user_addr;
 } readwrite_req_t;
@@ -59,7 +59,7 @@ typedef struct readwrite_req {
 
 /* Structure for response of REQ_READ and REQ_WRITE */
 typedef struct readwrite_res {
-	off_t new_pos;
+	u64_t new_pos;
 	unsigned int cum_io;
 } readwrite_res_t;
 
@@ -311,7 +311,7 @@ typedef struct breadwrite_req {
         endpoint_t user_e;
         endpoint_t driver_e;
         dev_t dev;
-	off_t pos;
+	u64_t pos;
 	unsigned int num_of_bytes;
 	char *user_addr;
 } breadwrite_req_t;
diff --git a/servers/vfs/select.c b/servers/vfs/select.c
index 44dd00a67..efb03949d 100644
--- a/servers/vfs/select.c
+++ b/servers/vfs/select.c
@@ -20,6 +20,7 @@
 #include <sys/time.h>
 #include <sys/select.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include <string.h>
 
 /* max. number of simultaneously pending select() calls */
@@ -103,7 +104,8 @@ PRIVATE int select_request_general(struct filp *f, int *ops, int block)
 {
 	int rops = *ops;
 	if (block) rops |= SEL_NOTIFY;
-	*ops = dev_io(DEV_SELECT, f->filp_vno->v_sdev, rops, NULL, 0, 0, 0);
+	*ops = dev_io(DEV_SELECT, f->filp_vno->v_sdev, rops, NULL, cvu64(0),
+		0, 0);
 	if (*ops < 0)
 		return SEL_ERR;
 	return SEL_OK;
diff --git a/servers/vfs/stadir.c b/servers/vfs/stadir.c
index 91d2ee430..40889a3bf 100644
--- a/servers/vfs/stadir.c
+++ b/servers/vfs/stadir.c
@@ -17,6 +17,7 @@
 #include <sys/stat.h>
 #include <sys/statfs.h>
 #include <minix/com.h>
+#include <minix/u64.h>
 #include <string.h>
 #include "file.h"
 #include "fproc.h"
@@ -257,7 +258,12 @@ PUBLIC int do_fstat()
   /* If we read from a pipe, send position too */
   if (rfilp->filp_vno->v_pipe == I_PIPE) {
 	if (rfilp->filp_mode & R_BIT) 
-		pipe_pos = rfilp->filp_pos;
+		if (ex64hi(rfilp->filp_pos) != 0)
+		{
+			panic(__FILE__, "do_fstat: bad position in pipe",
+				NO_NUM);
+		}
+		pipe_pos = ex64lo(rfilp->filp_pos);
   }
 
   /* Fill in request message */