Add support for on-line resizing to resize2fs

If the filesystem is mounted, attempt to use the on-line resizing
ioctls to resize the filesystem.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>


diff --git a/lib/ext2fs/ChangeLog b/lib/ext2fs/ChangeLog
index f2cd2fb..eb8c09c 100644
--- a/lib/ext2fs/ChangeLog
+++ b/lib/ext2fs/ChangeLog
@@ -1,3 +1,9 @@
+2006-03-17  Theodore Ts'o  <tytso@mit.edu>
+
+	* ext2_fs.h (EXT2_IOC_GETVERSION_NEW, EXT2_IOC_SETVERSION_NEW,
+		EXT2_IOC_GROUP_EXTEND, EXT2_IOC_GROUP_ADD): Add ioctl
+		definitions
+
 2005-12-10  Theodore Ts'o  <tytso@mit.edu>
 
 	* Makefile.in: Add a dependency to make sure that the
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index ff615c4..e427add 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -242,10 +242,26 @@
 /*
  * ioctl commands
  */
+
+/* Used for online resize */
+struct ext2_new_group_input {
+	__u32 group;		/* Group number for this data */
+	__u32 block_bitmap;	/* Absolute block number of block bitmap */
+	__u32 inode_bitmap;	/* Absolute block number of inode bitmap */
+	__u32 inode_table;	/* Absolute block number of inode table start */
+	__u32 blocks_count;	/* Total number of blocks in this group */
+	__u16 reserved_blocks;	/* Number of reserved blocks in this group */
+	__u16 unused;		/* Number of reserved GDT blocks in group */
+};
+
 #define EXT2_IOC_GETFLAGS		_IOR('f', 1, long)
 #define EXT2_IOC_SETFLAGS		_IOW('f', 2, long)
 #define EXT2_IOC_GETVERSION		_IOR('v', 1, long)
 #define EXT2_IOC_SETVERSION		_IOW('v', 2, long)
+#define EXT2_IOC_GETVERSION_NEW		_IOR('f', 3, long)
+#define EXT2_IOC_SETVERSION_NEW		_IOW('f', 4, long)
+#define EXT2_IOC_GROUP_EXTEND		_IOW('f', 7, unsigned long)
+#define EXT2_IOC_GROUP_ADD		_IOW('f', 8,struct ext2_new_group_input)
 
 /*
  * Structure of an inode on the disk
diff --git a/resize/ChangeLog b/resize/ChangeLog
index a6b2ac3..07ca8f4 100644
--- a/resize/ChangeLog
+++ b/resize/ChangeLog
@@ -1,3 +1,24 @@
+2006-03-17  Theodore Ts'o  <tytso@mit.edu>
+
+	* resize2fs.8.in: Update manpage to document that that resize2fs
+		can expand a mounted filesystem.
+
+	* online.c (online_resize_fs): New file which contains the on-line
+		resizing code.
+
+	* main.c (main): If the filesystem to be resized is already
+		mounted, determine the mountpoint, and call online_resize_fs().
+
+	* resize2fs.c (adjust_fs_info, adjust_superblock): Factor out code
+		which only adjusts the in-memory data structures from the
+		code which writes to the disk, since the former can be
+		used by the on-line resizing code.
+
+	* resize2fs.h: Add function prototypes for online_resize_fs() and 
+		adjust_fs_info().
+
+	* Makefile.in (RESIZE_OBJS): Add online.o to list of files to be built.
+
 2005-12-29  Theodore Ts'o  <tytso@mit.edu>
 
 	* resize2fs.c (mark_table_blocks): Remove unused variables to
diff --git a/resize/Makefile.in b/resize/Makefile.in
index ebf3e72..6758912 100644
--- a/resize/Makefile.in
+++ b/resize/Makefile.in
@@ -16,13 +16,14 @@
 TEST_PROGS=	test_extent
 MANPAGES=	resize2fs.8
 
-RESIZE_OBJS= extent.o resize2fs.o main.o sim_progress.o 
+RESIZE_OBJS= extent.o resize2fs.o main.o online.o sim_progress.o 
 
 TEST_EXTENT_OBJS= extent.o test_extent.o
 
 SRCS= $(srcdir)/extent.c \
 	$(srcdir)/resize2fs.c \
 	$(srcdir)/main.c \
+	$(srcdir)/online.c \
 	$(srcdir)/sim_progress.c
 
 LIBS= $(LIBE2P) $(LIBEXT2FS) $(LIBCOM_ERR) $(LIBINTL)
@@ -159,6 +160,11 @@
  $(top_srcdir)/lib/et/com_err.h $(top_srcdir)/lib/ext2fs/ext2_io.h \
  $(top_builddir)/lib/ext2fs/ext2_err.h $(top_srcdir)/lib/ext2fs/bitops.h \
  $(top_srcdir)/version.h
+online.o: $(srcdir)/online.c $(srcdir)/resize2fs.h \
+ $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
+ $(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/lib/ext2fs/ext2_fs.h \
+ $(top_srcdir)/lib/et/com_err.h $(top_srcdir)/lib/ext2fs/ext2_io.h \
+ $(top_builddir)/lib/ext2fs/ext2_err.h $(top_srcdir)/lib/ext2fs/bitops.h
 sim_progress.o: $(srcdir)/sim_progress.c $(srcdir)/resize2fs.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
  $(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/lib/ext2fs/ext2_fs.h \
diff --git a/resize/main.c b/resize/main.c
index 1142c9c..d6ddaa7 100644
--- a/resize/main.c
+++ b/resize/main.c
@@ -94,26 +94,6 @@
 	return 0;
 }
 
-static void check_mount(char *device)
-{
-	errcode_t	retval;
-	int		mount_flags;
-
-	retval = ext2fs_check_if_mounted(device, &mount_flags);
-	if (retval) {
-		com_err("ext2fs_check_if_mount", retval,
-			_("while determining whether %s is mounted."),
-			device);
-		return;
-	}
-	if (!(mount_flags & EXT2_MF_MOUNTED))
-		return;
-	
-	fprintf(stderr, _("%s is mounted; can't resize a "
-		"mounted filesystem!\n\n"), device);
-	exit(1);
-}
-
 int main (int argc, char ** argv)
 {
 	errcode_t	retval;
@@ -135,6 +115,8 @@
 	__s64		new_file_size;
 	unsigned int	sys_page_size = 4096;
 	long		sysval;
+	int		len, mount_flags;
+	char		*mtpt;
 
 #ifdef ENABLE_NLS
 	setlocale(LC_MESSAGES, "");
@@ -184,7 +166,29 @@
 	if (io_options)
 		*io_options++ = 0;
 
-	check_mount(device_name);
+	/*
+	 * Figure out whether or not the device is mounted, and if it is
+	 * where it is mounted.
+	 */
+	len=80;
+	while (1) {
+		mtpt = malloc(len);
+		if (!mtpt)
+			return ENOMEM;
+		mtpt[len-1] = 0;
+		retval = ext2fs_check_mount_point(device_name, &mount_flags, 
+						  mtpt, len);
+		if (retval) {
+			com_err("ext2fs_check_mount_point", retval,
+				_("while determining whether %s is mounted."),
+				device_name);
+			exit(1);
+		}
+		if (!(mount_flags & EXT2_MF_MOUNTED) || (mtpt[len-1] == 0))
+			break;
+		free(mtpt);
+		len = 2 * len;
+	}
 
 #ifdef HAVE_OPEN64
 	fd = open64(device_name, O_RDWR);
@@ -314,18 +318,23 @@
 			"long.  Nothing to do!\n\n"), new_size);
 		exit(0);
 	}
-	if (!force && ((fs->super->s_lastcheck < fs->super->s_mtime) ||
-		       (fs->super->s_state & EXT2_ERROR_FS) ||
-		       ((fs->super->s_state & EXT2_VALID_FS) == 0))) {
-		fprintf(stderr, _("Please run 'e2fsck -f %s' first.\n\n"),
-			device_name);
-		exit(1);
+	if (mount_flags & EXT2_MF_MOUNTED) {
+		retval = online_resize_fs(fs, mtpt, &new_size, flags);
+	} else {
+		if (!force && ((fs->super->s_lastcheck < fs->super->s_mtime) ||
+			       (fs->super->s_state & EXT2_ERROR_FS) ||
+			       ((fs->super->s_state & EXT2_VALID_FS) == 0))) {
+			fprintf(stderr, 
+				_("Please run 'e2fsck -f %s' first.\n\n"),
+				device_name);
+			exit(1);
+		}
+		printf("Resizing the filesystem on %s to %d (%dk) blocks.\n",
+		       device_name, new_size, fs->blocksize / 1024);
+		retval = resize_fs(fs, &new_size, flags,
+				   ((flags & RESIZE_PERCENT_COMPLETE) ?
+				    resize_progress_func : 0));
 	}
-	printf("Resizing the filesystem on %s to %d (%dk) blocks.\n",
-	       device_name, new_size, fs->blocksize / 1024);
-	retval = resize_fs(fs, &new_size, flags,
-			   ((flags & RESIZE_PERCENT_COMPLETE) ?
-			    resize_progress_func : 0));
 	if (retval) {
 		com_err(program_name, retval, _("while trying to resize %s"),
 			device_name);
diff --git a/resize/online.c b/resize/online.c
new file mode 100644
index 0000000..45262b1
--- /dev/null
+++ b/resize/online.c
@@ -0,0 +1,141 @@
+/*
+ * online.c --- Do on-line resizing of the ext3 filesystem
+ *
+ * Copyright (C) 2006 by Theodore Ts'o 
+ * 
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#include "resize2fs.h"
+#ifdef HAVE_SYS_IOCTL_H
+#include <sys/ioctl.h>
+#endif
+#include <sys/stat.h>
+#include <fcntl.h>
+
+extern char *program_name;
+
+errcode_t online_resize_fs(ext2_filsys fs, const char *mtpt, 
+			   blk_t *new_size, int flags)
+{
+	struct ext2_new_group_input input;
+	struct ext2_super_block *sb = fs->super;
+	ext2_filsys 		new_fs;
+	errcode_t 		retval;
+	dgrp_t			i;
+	blk_t			size;
+	int			fd, r_frac, overhead;
+
+	printf(_("Filesystem at %s is mounted on %s; "
+		 "on-line resizing required\n"), fs->device_name, mtpt);
+
+	if (*new_size < sb->s_blocks_count) {
+		printf(_("On-line shrinking from %u to %u not supported.\n"),
+		       sb->s_blocks_count, *new_size);
+		exit(1);
+	}
+
+	fd = open(mtpt, O_RDONLY);
+	if (fd < 0) {
+		com_err(program_name, errno, 
+			_("while trying to open mountpoint %s"), mtpt);
+		exit(1);
+	}
+
+	size=sb->s_blocks_count;
+	if (ioctl(fd, EXT2_IOC_GROUP_EXTEND, &size)) {
+		if (errno == EPERM)
+			com_err(program_name, 0, 
+				_("Permission denied to resize filesystem"));
+		else if (errno == ENOTTY)
+			com_err(program_name, 0, 
+			_("Filesystem does not support online resizing"));
+		else 
+			com_err(program_name, errno, 
+			_("While checking for on-line resizing support"));
+		exit(1);
+	}
+
+	r_frac = ((100 * sb->s_r_blocks_count) + sb->s_blocks_count-1) /
+		sb->s_blocks_count;
+
+	retval = ext2fs_read_bitmaps(fs);
+	if (retval)
+		return retval;
+
+	retval = ext2fs_dup_handle(fs, &new_fs);
+	if (retval)
+		return retval;
+
+	retval = adjust_fs_info(new_fs, fs, *new_size);
+	if (retval)
+		return retval;
+
+	printf(_("Performing an on-line resize of %s to %d (%dk) blocks.\n"), 
+	       fs->device_name, *new_size, fs->blocksize / 1024);
+
+	size = fs->group_desc_count * sb->s_blocks_per_group + 
+		sb->s_first_data_block;
+	if (size > *new_size)
+		size = *new_size;
+
+	if (ioctl(fd, EXT2_IOC_GROUP_EXTEND, &size)) {
+		com_err(program_name, errno, 
+			_("While trying to extend the last group"));
+		exit(1);
+	}
+
+	for (i = fs->group_desc_count;
+	     i < new_fs->group_desc_count; i++) {
+
+		overhead = (int) (2 + new_fs->inode_blocks_per_group);
+
+		if (ext2fs_bg_has_super(new_fs, new_fs->group_desc_count - 1))
+			overhead += 1 + new_fs->desc_blocks + 
+				new_fs->super->s_reserved_gdt_blocks;
+
+		input.group = i;
+		input.block_bitmap = new_fs->group_desc[i].bg_block_bitmap;
+		input.inode_bitmap = new_fs->group_desc[i].bg_inode_bitmap;
+		input.inode_table = new_fs->group_desc[i].bg_inode_table;
+		input.blocks_count = sb->s_blocks_per_group;
+		if (i == new_fs->group_desc_count-1) {
+			input.blocks_count = new_fs->super->s_blocks_count -
+				sb->s_first_data_block - 
+				(i * sb->s_blocks_per_group);
+		}
+		input.reserved_blocks = input.blocks_count * r_frac / 100;
+
+#if 0
+		printf("new block bitmap is at 0x%04x\n", input.block_bitmap);
+		printf("new inode bitmap is at 0x%04x\n", input.inode_bitmap);
+		printf("new inode table is at 0x%04x-0x%04x\n", 
+		       input.inode_table,
+		       input.inode_table + new_fs->inode_blocks_per_group-1);
+		printf("new group has %d blocks\n", input.blocks_count);
+		printf("new group will reserve %d blocks\n", 
+		       input.reserved_blocks);
+		printf("new group has %d free blocks\n", 
+		       new_fs->group_desc[i].bg_free_blocks_count);
+		printf("new group has %d free inodes (%d blocks)\n",
+		       new_fs->group_desc[i].bg_free_inodes_count, 
+		       new_fs->inode_blocks_per_group);
+		printf("Adding group #%d\n", input.group);
+#endif
+
+		if (ioctl(fd, EXT2_IOC_GROUP_ADD, &input) < 0) {
+			com_err(program_name, errno, 
+				_("While trying to add group #%d"), 
+				input.group);
+			exit(1);
+		}
+	}
+
+	ext2fs_free(new_fs);
+	close(fd);
+
+	return 0;
+}
diff --git a/resize/resize2fs.8.in b/resize/resize2fs.8.in
index 81a5135..426c3ce 100644
--- a/resize/resize2fs.8.in
+++ b/resize/resize2fs.8.in
@@ -28,8 +28,13 @@
 The 
 .B resize2fs 
 program will resize ext2 file systems.  It can be used to enlarge or
-shrink an ext2 file system located on 
+shrink an unmounted ext2 file system located on 
 .IR device .
+If the filesystem is mounted, it can be used to expand the size of the
+mounted filesystem, assuming the kernel supports on-line resizing.  (As
+of this writing, the Linux 2.6 kernel supports on-line resize for
+filesystems mounted using ext3 only.).
+.PP
 The 
 .I size
 parameter specifies the requested new size of the filesystem.
diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index 4eefd0d..d920bef 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -172,27 +172,22 @@
  */
 
 /*
- * This routine adjusts the superblock and other data structures...
+ * This routine is shared by the online and offline resize routines.
+ * All of the information which is adjusted in memory is done here.
  */
-static errcode_t adjust_superblock(ext2_resize_t rfs, blk_t new_size)
+errcode_t adjust_fs_info(ext2_filsys fs, ext2_filsys old_fs, blk_t new_size)
 {
-	ext2_filsys fs;
-	int		overhead = 0;
-	int		rem, adj = 0;
 	errcode_t	retval;
-	ext2_ino_t	real_end;
+	int		overhead = 0;
+	int		rem;
 	blk_t		blk, group_block;
-	unsigned long	i, j, old_desc_blocks;
-	int		old_numblocks, numblocks, adjblocks;
+	ext2_ino_t	real_end;
+	int		adj, old_numblocks, numblocks, adjblocks;
+	unsigned long	i, j, old_desc_blocks, max_group;
 	unsigned int	meta_bg, meta_bg_size;
 	int		has_super;
-	unsigned long	max_group;
-	
-	fs = rfs->new_fs;
+
 	fs->super->s_blocks_count = new_size;
-	ext2fs_mark_super_dirty(fs);
-	ext2fs_mark_bb_dirty(fs);
-	ext2fs_mark_ib_dirty(fs);
 
 retry:
 	fs->group_desc_count = (fs->super->s_blocks_count -
@@ -239,7 +234,7 @@
 	/*
 	 * Adjust the number of free blocks
 	 */
-	blk = rfs->old_fs->super->s_blocks_count;
+	blk = old_fs->super->s_blocks_count;
 	if (blk > fs->super->s_blocks_count)
 		fs->super->s_free_blocks_count -=
 			(blk - fs->super->s_blocks_count);
@@ -250,8 +245,8 @@
 	/*
 	 * Adjust the number of reserved blocks
 	 */
-	blk = rfs->old_fs->super->s_r_blocks_count * 100 /
-		rfs->old_fs->super->s_blocks_count;
+	blk = old_fs->super->s_r_blocks_count * 100 /
+		old_fs->super->s_blocks_count;
 	fs->super->s_r_blocks_count = ((fs->super->s_blocks_count * blk)
 				       / 100);
 
@@ -274,31 +269,21 @@
 	/*
 	 * Reallocate the group descriptors as necessary.
 	 */
-	if (rfs->old_fs->desc_blocks != fs->desc_blocks) {
-		retval = ext2fs_resize_mem(rfs->old_fs->desc_blocks *
+	if (old_fs->desc_blocks != fs->desc_blocks) {
+		retval = ext2fs_resize_mem(old_fs->desc_blocks *
 					   fs->blocksize,
 					   fs->desc_blocks * fs->blocksize,
 					   &fs->group_desc);
 		if (retval)
 			goto errout;
-		if (fs->desc_blocks > rfs->old_fs->desc_blocks) 
+		if (fs->desc_blocks > old_fs->desc_blocks) 
 			memset((char *) fs->group_desc + 
-			       (rfs->old_fs->desc_blocks * fs->blocksize), 0,
-			       (fs->desc_blocks - rfs->old_fs->desc_blocks) *
+			       (old_fs->desc_blocks * fs->blocksize), 0,
+			       (fs->desc_blocks - old_fs->desc_blocks) *
 			       fs->blocksize);
 	}
 
 	/*
-	 * Check to make sure there are enough inodes
-	 */
-	if ((rfs->old_fs->super->s_inodes_count -
-	     rfs->old_fs->super->s_free_inodes_count) >
-	    rfs->new_fs->super->s_inodes_count) {
-		retval = ENOSPC;
-		goto errout;
-	}
-
-	/*
 	 * If the resize_inode feature is set, and we are changing the
 	 * number of descriptor blocks, then adjust
 	 * s_reserved_gdt_blocks if possible to avoid needing to move
@@ -306,11 +291,11 @@
 	 */
 	if ((fs->super->s_feature_compat & 
 	     EXT2_FEATURE_COMPAT_RESIZE_INODE) &&
-	    (rfs->old_fs->desc_blocks != fs->desc_blocks)) {
+	    (old_fs->desc_blocks != fs->desc_blocks)) {
 		int new;
 
 		new = ((int) fs->super->s_reserved_gdt_blocks) + 
-			(rfs->old_fs->desc_blocks - fs->desc_blocks);
+			(old_fs->desc_blocks - fs->desc_blocks);
 		if (new < 0)
 			new = 0;
 		if (new > fs->blocksize/4)
@@ -325,27 +310,28 @@
 	 * If we are shrinking the number block groups, we're done and
 	 * can exit now.
 	 */
-	if (rfs->old_fs->group_desc_count > fs->group_desc_count) {
+	if (old_fs->group_desc_count > fs->group_desc_count) {
 		retval = 0;
 		goto errout;
 	}
+
 	/*
 	 * Fix the count of the last (old) block group
 	 */
-	old_numblocks = (rfs->old_fs->super->s_blocks_count -
-			 rfs->old_fs->super->s_first_data_block) %
-				 rfs->old_fs->super->s_blocks_per_group;
+	old_numblocks = (old_fs->super->s_blocks_count -
+			 old_fs->super->s_first_data_block) %
+				 old_fs->super->s_blocks_per_group;
 	if (!old_numblocks)
-		old_numblocks = rfs->old_fs->super->s_blocks_per_group;
-	if (rfs->old_fs->group_desc_count == fs->group_desc_count) {
-		numblocks = (rfs->new_fs->super->s_blocks_count -
-			     rfs->new_fs->super->s_first_data_block) %
-				     rfs->new_fs->super->s_blocks_per_group;
+		old_numblocks = old_fs->super->s_blocks_per_group;
+	if (old_fs->group_desc_count == fs->group_desc_count) {
+		numblocks = (fs->super->s_blocks_count -
+			     fs->super->s_first_data_block) %
+			fs->super->s_blocks_per_group;
 		if (!numblocks)
-			numblocks = rfs->new_fs->super->s_blocks_per_group;
+			numblocks = fs->super->s_blocks_per_group;
 	} else
-		numblocks = rfs->new_fs->super->s_blocks_per_group;
-	i = rfs->old_fs->group_desc_count - 1;
+		numblocks = fs->super->s_blocks_per_group;
+	i = old_fs->group_desc_count - 1;
 	fs->group_desc[i].bg_free_blocks_count += (numblocks-old_numblocks);
 		
 	/*
@@ -353,36 +339,25 @@
 	 * done and can exit now.  (If the number block groups is
 	 * shrinking, we had exited earlier.)
 	 */
-	if (rfs->old_fs->group_desc_count >= fs->group_desc_count) {
+	if (old_fs->group_desc_count >= fs->group_desc_count) {
 		retval = 0;
 		goto errout;
 	}
+
 	/*
 	 * Initialize the new block group descriptors
 	 */
-	retval = ext2fs_get_mem(fs->blocksize * fs->inode_blocks_per_group,
-				&rfs->itable_buf);
-	if (retval)
-		goto errout;
-
-	memset(rfs->itable_buf, 0, fs->blocksize * fs->inode_blocks_per_group);
 	group_block = fs->super->s_first_data_block +
-		rfs->old_fs->group_desc_count * fs->super->s_blocks_per_group;
+		old_fs->group_desc_count * fs->super->s_blocks_per_group;
 
-	adj = rfs->old_fs->group_desc_count;
+	adj = old_fs->group_desc_count;
 	max_group = fs->group_desc_count - adj;
-	if (rfs->progress) {
-		retval = rfs->progress(rfs, E2_RSZ_EXTEND_ITABLE_PASS,
-				       0, max_group);
-		if (retval)
-			goto errout;
-	}
 	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 		old_desc_blocks = fs->super->s_first_meta_bg;
 	else
 		old_desc_blocks = fs->desc_blocks + 
 			fs->super->s_reserved_gdt_blocks;
-	for (i = rfs->old_fs->group_desc_count;
+	for (i = old_fs->group_desc_count;
 	     i < fs->group_desc_count; i++) {
 		memset(&fs->group_desc[i], 0,
 		       sizeof(struct ext2_group_desc));
@@ -438,6 +413,87 @@
 		retval = ext2fs_allocate_group_table(fs, i, 0);
 		if (retval) goto errout;
 
+		group_block += fs->super->s_blocks_per_group;
+	}
+	retval = 0;
+
+errout:
+	return (retval);
+}
+
+/*
+ * This routine adjusts the superblock and other data structures, both
+ * in disk as well as in memory...
+ */
+static errcode_t adjust_superblock(ext2_resize_t rfs, blk_t new_size)
+{
+	ext2_filsys fs;
+	int		adj = 0;
+	errcode_t	retval;
+	blk_t		group_block;
+	unsigned long	i;
+	unsigned long	max_group;
+	
+	fs = rfs->new_fs;
+	ext2fs_mark_super_dirty(fs);
+	ext2fs_mark_bb_dirty(fs);
+	ext2fs_mark_ib_dirty(fs);
+
+	retval = adjust_fs_info(fs, rfs->old_fs, new_size);
+	if (retval)
+		goto errout;
+
+	/*
+	 * Check to make sure there are enough inodes
+	 */
+	if ((rfs->old_fs->super->s_inodes_count -
+	     rfs->old_fs->super->s_free_inodes_count) >
+	    rfs->new_fs->super->s_inodes_count) {
+		retval = ENOSPC;
+		goto errout;
+	}
+
+	/*
+	 * If we are shrinking the number block groups, we're done and
+	 * can exit now.
+	 */
+	if (rfs->old_fs->group_desc_count > fs->group_desc_count) {
+		retval = 0;
+		goto errout;
+	}
+
+	/*
+	 * If the number of block groups is staying the same, we're
+	 * done and can exit now.  (If the number block groups is
+	 * shrinking, we had exited earlier.)
+	 */
+	if (rfs->old_fs->group_desc_count >= fs->group_desc_count) {
+		retval = 0;
+		goto errout;
+	}
+
+	/*
+	 * Initialize the new block group descriptors
+	 */
+	retval = ext2fs_get_mem(fs->blocksize * fs->inode_blocks_per_group,
+				&rfs->itable_buf);
+	if (retval)
+		goto errout;
+
+	memset(rfs->itable_buf, 0, fs->blocksize * fs->inode_blocks_per_group);
+	group_block = fs->super->s_first_data_block +
+		rfs->old_fs->group_desc_count * fs->super->s_blocks_per_group;
+
+	adj = rfs->old_fs->group_desc_count;
+	max_group = fs->group_desc_count - adj;
+	if (rfs->progress) {
+		retval = rfs->progress(rfs, E2_RSZ_EXTEND_ITABLE_PASS,
+				       0, max_group);
+		if (retval)
+			goto errout;
+	}
+	for (i = rfs->old_fs->group_desc_count;
+	     i < fs->group_desc_count; i++) {
 		/*
 		 * Write out the new inode table
 		 */
diff --git a/resize/resize2fs.h b/resize/resize2fs.h
index 6f262c2..8d325c1 100644
--- a/resize/resize2fs.h
+++ b/resize/resize2fs.h
@@ -125,6 +125,10 @@
 					    int pass, unsigned long cur,
 					    unsigned long max));
 
+extern errcode_t adjust_fs_info(ext2_filsys fs, ext2_filsys old_fs, 
+				blk_t new_size);
+
+
 /* extent.c */
 extern errcode_t ext2fs_create_extent_table(ext2_extent *ret_extent,
 					    int size);
@@ -136,6 +140,10 @@
 extern errcode_t ext2fs_iterate_extent(ext2_extent extent, __u32 *old_loc,
 				       __u32 *new_loc, int *size);
 
+/* online.c */
+extern errcode_t online_resize_fs(ext2_filsys fs, const char *mtpt, 
+				  blk_t *new_size, int flags);
+
 /* sim_progress.c */
 extern errcode_t ext2fs_progress_init(ext2_sim_progmeter *ret_prog,
 				      const char *label,