- Improved /etc/mtab lock
- fix for the mount command and am-utils using different mtab locking

--- util-linux-2.12p/mount/fstab.c.mtab-lock	2005-03-22 14:05:22.481297072 +0100
+++ util-linux-2.12p/mount/fstab.c	2005-03-22 14:50:55.719781664 +0100
@@ -395,6 +395,7 @@
 
 /* Flag for already existing lock file. */
 static int we_created_lockfile = 0;
+static int lockfile_fd = -1;
 
 /* Flag to indicate that signals have been set up. */
 static int signals_have_been_setup = 0;
@@ -416,6 +417,8 @@
 void
 unlock_mtab (void) {
 	if (we_created_lockfile) {
+		close(lockfile_fd);
+		lockfile_fd = -1;
 		unlink (MOUNTED_LOCK);
 		we_created_lockfile = 0;
 	}
@@ -443,7 +446,7 @@
 
 void
 lock_mtab (void) {
-	int tries = 3;
+	int tries = 100000, i;
 	char linktargetfile[MOUNTLOCK_LINKTARGET_LTH];
 
 	at_die = unlock_mtab;
@@ -469,45 +472,48 @@
 
 	sprintf(linktargetfile, MOUNTLOCK_LINKTARGET, getpid ());
 
+	i = open (linktargetfile, O_WRONLY|O_CREAT, 0);
+	if (i < 0) {
+		int errsv = errno;
+		/* linktargetfile does not exist (as a file)
+		   and we cannot create it. Read-only filesystem?
+		   Too many files open in the system?
+		   Filesystem full? */
+		die (EX_FILEIO, _("can't create lock file %s: %s "
+						  "(use -n flag to override)"),
+			 linktargetfile, strerror (errsv));
+	}
+	close(i);
+	
 	/* Repeat until it was us who made the link */
 	while (!we_created_lockfile) {
 		struct flock flock;
-		int errsv, fd, i, j;
-
-		i = open (linktargetfile, O_WRONLY|O_CREAT, 0);
-		if (i < 0) {
-			int errsv = errno;
-			/* linktargetfile does not exist (as a file)
-			   and we cannot create it. Read-only filesystem?
-			   Too many files open in the system?
-			   Filesystem full? */
-			die (EX_FILEIO, _("can't create lock file %s: %s "
-			     "(use -n flag to override)"),
-			     linktargetfile, strerror (errsv));
-		}
-		close(i);
+		int errsv, j;
 
 		j = link(linktargetfile, MOUNTED_LOCK);
 		errsv = errno;
 
-		(void) unlink(linktargetfile);
-
 		if (j == 0)
 			we_created_lockfile = 1;
 
 		if (j < 0 && errsv != EEXIST) {
+			(void) unlink(linktargetfile);
 			die (EX_FILEIO, _("can't link lock file %s: %s "
 			     "(use -n flag to override)"),
 			     MOUNTED_LOCK, strerror (errsv));
 		}
 
-		fd = open (MOUNTED_LOCK, O_WRONLY);
+		lockfile_fd = open (MOUNTED_LOCK, O_WRONLY);
 
-		if (fd < 0) {
+		if (lockfile_fd < 0) {
 			int errsv = errno;
 			/* Strange... Maybe the file was just deleted? */
-			if (errno == ENOENT && tries-- > 0)
+			if (errno == ENOENT && tries-- > 0) {
+				if (tries % 200 == 0)
+					usleep(30);
 				continue;
+			}
+			(void) unlink(linktargetfile);
 			die (EX_FILEIO, _("can't open lock file %s: %s "
 			     "(use -n flag to override)"),
 			     MOUNTED_LOCK, strerror (errsv));
@@ -520,7 +526,7 @@
 
 		if (j == 0) {
 			/* We made the link. Now claim the lock. */
-			if (fcntl (fd, F_SETLK, &flock) == -1) {
+			if (fcntl (lockfile_fd, F_SETLK, &flock) == -1) {
 				if (verbose) {
 				    int errsv = errno;
 				    printf(_("Can't lock lock file %s: %s\n"),
@@ -528,13 +534,15 @@
 				}
 				/* proceed anyway */
 			}
+			(void) unlink(linktargetfile);
 		} else {
 			static int tries = 0;
 
 			/* Someone else made the link. Wait. */
 			alarm(LOCK_TIMEOUT);
-			if (fcntl (fd, F_SETLKW, &flock) == -1) {
+			if (fcntl (lockfile_fd, F_SETLKW, &flock) == -1) {
 				int errsv = errno;
+				(void) unlink(linktargetfile);
 				die (EX_FILEIO, _("can't lock lock file %s: %s"),
 				     MOUNTED_LOCK, (errno == EINTR) ?
 				     _("timed out") : strerror (errsv));
@@ -542,16 +550,18 @@
 			alarm(0);
 			/* Limit the number of iterations - maybe there
 			   still is some old /etc/mtab~ */
-			if (tries++ > 3) {
-				if (tries > 5)
-					die (EX_FILEIO, _("Cannot create link %s\n"
-					    "Perhaps there is a stale lock file?\n"),
-					     MOUNTED_LOCK);
-				sleep(1);
-			}
+			++tries;
+			if (tries % 200 == 0)
+			   usleep(30);
+			if (tries > 100000) {
+				(void) unlink(linktargetfile);
+				close(lockfile_fd);
+				die (EX_FILEIO, _("Cannot create link %s\n"
+						  "Perhaps there is a stale lock file?\n"),
+					 MOUNTED_LOCK);
+ 			}
+			close(lockfile_fd);
 		}
-
-		close(fd);
 	}
 }