diff --git a/misc/Makefile.in b/misc/Makefile.in
index 58b35519..b4c39eec 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -40,7 +40,7 @@ UUIDD_OBJS=	uuidd.o
 DUMPE2FS_OBJS=	dumpe2fs.o
 BADBLOCKS_OBJS=	badblocks.o
 E2IMAGE_OBJS=	e2image.o
-FSCK_OBJS=	fsck.o base_device.o
+FSCK_OBJS=	fsck.o base_device.o ismounted.o
 BLKID_OBJS=	blkid.o
 FILEFRAG_OBJS=	filefrag.o
 
@@ -51,7 +51,7 @@ SRCS=	$(srcdir)/tune2fs.c $(srcdir)/mklost+found.c $(srcdir)/mke2fs.c \
 		$(srcdir)/badblocks.c $(srcdir)/fsck.c $(srcdir)/util.c \
 		$(srcdir)/uuidgen.c $(srcdir)/blkid.c $(srcdir)/logsave.c \
 		$(srcdir)/filefrag.c $(srcdir)/base_device.c \
-		$(srcdir)/../e2fsck/profile.c
+		$(srcdir)/ismounted.c $(srcdir)/../e2fsck/profile.c
 
 LIBS= $(LIBEXT2FS) $(LIBCOM_ERR) 
 DEPLIBS= $(LIBEXT2FS) $(LIBCOM_ERR) 
@@ -173,6 +173,10 @@ filefrag: $(FILEFRAG_OBJS)
 	@echo "	LD $@"
 	@$(CC) $(ALL_LDFLAGS) -o filefrag $(FILEFRAG_OBJS) 
 
+tst_ismounted: $(srcdir)/ismounted.c $(STATIC_LIBEXT2FS)
+	@echo "	LD $@"
+	$(CC) -o tst_ismounted $(srcdir)/ismounted.c -DDEBUG $(ALL_CFLAGS) $(LIBCOM_ERR)
+
 tune2fs.8: $(DEP_SUBSTITUTE) $(srcdir)/tune2fs.8.in
 	@echo "	SUBST $@"
 	@$(SUBSTITUTE_UPTIME) $(srcdir)/tune2fs.8.in tune2fs.8
@@ -368,7 +372,7 @@ clean:
 		$(FMANPAGES) \
 		base_device base_device.out mke2fs.static filefrag \
 		e2initrd_helper partinfo prof_err.[ch] default_profile.c \
-		uuidd e2image \#* *.s *.o *.a *~ core 
+		uuidd e2image tst_ismounted \#* *.s *.o *.a *~ core
 
 mostlyclean: clean
 distclean: clean
@@ -444,5 +448,6 @@ blkid.o: $(srcdir)/blkid.c $(top_srcdir)/lib/blkid/blkid.h \
 logsave.o: $(srcdir)/logsave.c
 filefrag.o: $(srcdir)/filefrag.c
 base_device.o: $(srcdir)/base_device.c $(srcdir)/fsck.h
+ismounted.o: $(srcdir)/ismounted.c $(top_srcdir)/lib/et/com_err.h
 profile.o: $(srcdir)/../e2fsck/profile.c $(top_srcdir)/lib/et/com_err.h \
  $(srcdir)/../e2fsck/profile.h prof_err.h
diff --git a/misc/fsck.8.in b/misc/fsck.8.in
index aa5fd05f..50fd8cef 100644
--- a/misc/fsck.8.in
+++ b/misc/fsck.8.in
@@ -8,7 +8,7 @@ fsck \- check and repair a Linux file system
 .SH SYNOPSIS
 .B fsck
 [
-.B \-sAVRTNP
+.B \-sAVRTMNP
 ]
 [
 .B \-C
@@ -233,6 +233,10 @@ a progress bar at a time.  GUI front-ends may specify a file descriptor
 .IR fd ,
 in which case the progress bar information will be sent to that file descriptor.
 .TP
+.B \-M
+Do not check mounted filesystems and return an exit code of 0
+for mounted filesystems.
+.TP
 .B \-N
 Don't execute, just show what would be done.
 .TP
diff --git a/misc/fsck.c b/misc/fsck.c
index 5cf1a1c8..24c095a4 100644
--- a/misc/fsck.c
+++ b/misc/fsck.c
@@ -102,7 +102,7 @@ int doall = 0;
 int noexecute = 0;
 int serialize = 0;
 int skip_root = 0;
-int like_mount = 0;
+int ignore_mounted = 0;
 int notitle = 0;
 int parallel_root = 0;
 int progress = 0;
@@ -973,7 +973,8 @@ static int check_all(NOARGS)
 				break;
 		}
 		if (fs) {
-			if (!skip_root && !ignore(fs)) {
+			if (!skip_root && !ignore(fs) &&
+			    !(ignore_mounted && is_mounted(fs->device))) {
 				fsck_device(fs, 1);
 				status |= wait_many(FLAG_WAIT_ALL);
 				if (status > EXIT_NONDESTRUCT)
@@ -1009,6 +1010,10 @@ static int check_all(NOARGS)
 				not_done_yet++;
 				continue;
 			}
+			if (ignore_mounted && is_mounted(fs->device)) {
+				fs->flags |= FLAG_DONE;
+				continue;
+			}
 			/*
 			 * If a filesystem on a particular device has
 			 * already been spawned, then we need to defer
@@ -1058,7 +1063,7 @@ static int check_all(NOARGS)
 
 static void usage(NOARGS)
 {
-	fputs(_("Usage: fsck [-ANPRTV] [ -C [ fd ] ] [-t fstype] [fs-options] [filesys ...]\n"), stderr);
+	fputs(_("Usage: fsck [-AMNPRTV] [ -C [ fd ] ] [-t fstype] [fs-options] [filesys ...]\n"), stderr);
 	exit(EXIT_USAGE);
 }
 
@@ -1181,7 +1186,7 @@ static void PRS(int argc, char *argv[])
 				notitle++;
 				break;
 			case 'M':
-				like_mount++;
+				ignore_mounted++;
 				break;
 			case 'P':
 				parallel_root++;
@@ -1303,6 +1308,8 @@ int main(int argc, char *argv[])
 			if (!fs)
 				continue;
 		}
+		if (ignore_mounted && is_mounted(fs->device))
+			continue;
 		fsck_device(fs, interactive);
 		if (serialize ||
 		    (max_running && (num_running >= max_running))) {
diff --git a/misc/ismounted.c b/misc/ismounted.c
new file mode 100644
index 00000000..72f4cbae
--- /dev/null
+++ b/misc/ismounted.c
@@ -0,0 +1,212 @@
+/*
+ * ismounted.c --- Check to see if the filesystem was mounted
+ *
+ * Copyright (C) 1995,1996,1997,1998,1999,2000,2008 Theodore Ts'o.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#include <stdio.h>
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+#if HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <fcntl.h>
+#ifdef HAVE_LINUX_FD_H
+#include <linux/fd.h>
+#endif
+#ifdef HAVE_MNTENT_H
+#include <mntent.h>
+#endif
+#include <string.h>
+#include <sys/stat.h>
+
+/*
+ * ext2fs_check_if_mounted flags
+ */
+#define MF_MOUNTED		1
+
+#include "et/com_err.h"
+
+static char *skip_over_blank(char *cp)
+{
+	while (*cp && isspace(*cp))
+		cp++;
+	return cp;
+}
+
+static char *skip_over_word(char *cp)
+{
+	while (*cp && !isspace(*cp))
+		cp++;
+	return cp;
+}
+
+static char *parse_word(char **buf)
+{
+	char *word, *next;
+
+	word = *buf;
+	if (*word == 0)
+		return 0;
+
+	word = skip_over_blank(word);
+	next = skip_over_word(word);
+	if (*next)
+		*next++ = 0;
+	*buf = next;
+	return word;
+}
+
+/*
+ * Helper function which checks a file in /etc/mtab format to see if a
+ * filesystem is mounted.  Returns an error if the file doesn't exist
+ * or can't be opened.
+ */
+static errcode_t check_mntent_file(const char *mtab_file, const char *file,
+				   int *mount_flags)
+{
+	struct stat	st_buf;
+	errcode_t	retval = 0;
+	dev_t		file_dev=0, file_rdev=0;
+	ino_t		file_ino=0;
+	FILE 		*f;
+	char		buf[1024], *device = 0, *mnt_dir = 0, *cp;
+	int		fd;
+
+	*mount_flags = 0;
+	if ((f = fopen(mtab_file, "r")) == NULL)
+		return errno;
+
+	if ((f = setmntent (mtab_file, "r")) == NULL)
+		return errno;
+	if (stat(file, &st_buf) == 0) {
+		if (S_ISBLK(st_buf.st_mode)) {
+#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
+			file_rdev = st_buf.st_rdev;
+#endif	/* __GNU__ */
+		} else {
+			file_dev = st_buf.st_dev;
+			file_ino = st_buf.st_ino;
+		}
+	}
+	while (1) {
+		if (!fgets(buf, sizeof(buf), f)) {
+			device = mnt_dir = 0;
+			break;
+		}
+		buf[sizeof(buf)-1] = 0;
+
+		cp = buf;
+		device = parse_word(&cp);
+		if (!device || *device == '#')
+			return 0;	/* Ignore blank lines and comments */
+		mnt_dir = parse_word(&cp);
+
+		if (device[0] != '/')
+			continue;
+
+		if (strcmp(file, device) == 0)
+			break;
+		if (stat(device, &st_buf) == 0) {
+			if (S_ISBLK(st_buf.st_mode)) {
+#ifndef __GNU__
+				if (file_rdev && (file_rdev == st_buf.st_rdev))
+					break;
+#endif	/* __GNU__ */
+			} else {
+				if (file_dev && ((file_dev == st_buf.st_dev) &&
+						 (file_ino == st_buf.st_ino)))
+					break;
+			}
+		}
+	}
+
+	if (mnt_dir == 0) {
+#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
+		/*
+		 * Do an extra check to see if this is the root device.  We
+		 * can't trust /etc/mtab, and /proc/mounts will only list
+		 * /dev/root for the root filesystem.  Argh.  Instead we
+		 * check if the given device has the same major/minor number
+		 * as the device that the root directory is on.
+		 */
+		if (file_rdev && (stat("/", &st_buf) == 0) &&
+		    (st_buf.st_dev == file_rdev))
+			*mount_flags = MF_MOUNTED;
+#endif	/* __GNU__ */
+		goto errout;
+	}
+#ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
+	/* Validate the entry in case /etc/mtab is out of date */
+	/*
+	 * We need to be paranoid, because some broken distributions
+	 * (read: Slackware) don't initialize /etc/mtab before checking
+	 * all of the non-root filesystems on the disk.
+	 */
+	if (stat(mnt_dir, &st_buf) < 0) {
+		retval = errno;
+		if (retval == ENOENT) {
+#ifdef DEBUG
+			printf("Bogus entry in %s!  (%s does not exist)\n",
+			       mtab_file, mnt_dir);
+#endif /* DEBUG */
+			retval = 0;
+		}
+		goto errout;
+	}
+	if (file_rdev && (st_buf.st_dev != file_rdev)) {
+#ifdef DEBUG
+		printf("Bogus entry in %s!  (%s not mounted on %s)\n",
+		       mtab_file, file, mnt_dir);
+#endif /* DEBUG */
+		goto errout;
+	}
+#endif /* __GNU__ */
+	*mount_flags = MF_MOUNTED;
+
+	retval = 0;
+errout:
+	endmntent (f);
+	return retval;
+}
+
+int is_mounted(const char *file)
+{
+	errcode_t	retval;
+	int		mount_flags = 0;
+
+#ifdef __linux__
+	retval = check_mntent_file("/proc/mounts", file, &mount_flags);
+	if (retval)
+		return 0;
+	if (mount_flags)
+		return 1;
+#endif /* __linux__ */
+	retval = check_mntent_file("/etc/mtab", file, &mount_flags);
+	if (retval)
+		return 0;
+	return (mount_flags);
+}
+
+#ifdef DEBUG
+int main(int argc, char **argv)
+{
+	if (argc < 2) {
+		fprintf(stderr, "Usage: %s device\n", argv[0]);
+		exit(1);
+	}
+
+	if (is_mounted(argv[1]))
+		printf("\t%s is mounted.\n", argv[1]);
+	exit(0);
+}
+#endif /* DEBUG */