Allow symlink creation to be disabled from command line or mdadm.conf

ChangeLog

@@ -1,3 +1,8 @@
+Changes Priot to this release
+    -   When creating devices in /dev/md/ create matching symlinks
+	from /dev.  e.g. /dev/md0 -> /dev/md/0.
+	Allow this to be disabled in mdadm.conf or on command line.
+
 Changes Prior to 2.5.3 release
     -   Document v0.91 superblocks in md.4
     -   Make GPL explicit in man pages.

ReadMe.c

@@ -139,6 +139,7 @@ struct option long_options[] = {
     {"re-add",    0, 0,  ReAdd},
     {"homehost",  1, 0,  HomeHost},
     {"auto-update-homehost", 0, 0, AutoHomeHost},
+    {"symlinks",  1, 0,  Symlinks},
 
     /* For assemble */
     {"uuid",      1, 0, 'u'},

config.c

@@ -255,6 +255,7 @@ mddev_dev_t load_partitions(void)
 }
 
 struct createinfo createinfo = {
+	.symlinks = 1,
 #ifdef DEBIAN
 	.gid = 6, /* disk */
 	.mode = 0660,
@@ -364,8 +365,11 @@ static void createline(char *line)
 			if (!createinfo.supertype)
 				fprintf(stderr, Name ": metadata format %s unknown, ignoring\n",
 					w+9);
-
-		} else {
+		} else if (strncasecmp(w, "symlinks=yes", 12) == 0)
+			createinfo.symlinks = 1;
+		else if  (strncasecmp(w, "symlinks=no", 11) == 0)
+			createinfo.symlinks = 0;
+		else {
 			fprintf(stderr, Name ": unrecognised word on CREATE line: %s\n",
 				w);
 		}

mdadm.8

@@ -594,6 +594,28 @@ number will be considered unused if there is no active array for that
 number, and there is no entry in /dev for that number and with a
 non-standard name.
 
+.TP
+.BR --symlink = no
+Normally when
+.B --auto
+causes
+.I mdadm
+to create devices in
+.B /dev/md/
+it will also create symlinks from
+.B /dev/
+with names starting with
+.B md
+or
+.BR md_ .
+Use
+.B --symlink=no
+to suppress this, or
+.B --symlink=yes
+to enforce this even if it is suppressing
+.IR mdadm.conf .
+
+
 .SH For assemble:
 
 .TP

mdadm.c

@@ -75,6 +75,7 @@ int main(int argc, char *argv[])
 	int force = 0;
 	int test = 0;
 	int assume_clean = 0;
+	char *symlinks = NULL;
 	/* autof indicates whether and how to create device node.
 	 * bottom 3 bits are style.  Rest (when shifted) are number of parts
 	 * 0  - unset
@@ -499,6 +500,12 @@ int main(int argc, char *argv[])
 			autof = parse_auto(optarg, "--auto flag", 0);
 			continue;
 
+		case O(CREATE,Symlinks):
+		case O(BUILD,Symlinks):
+		case O(ASSEMBLE,Symlinks): /* auto creation of symlinks in /dev to /dev/md */
+			symlinks = optarg;
+			continue;
+
 		case O(BUILD,'f'): /* force honouring '-n 1' */
 		case O(GROW,'f'): /* ditto */
 		case O(CREATE,'f'): /* force honouring of device list */
@@ -858,6 +865,19 @@ int main(int argc, char *argv[])
 		fputs(Usage, stderr);
 		exit(2);
 	}
+
+	if (symlinks) {
+		struct createinfo *ci = conf_get_create_info();
+
+		if (strcasecmp(symlinks, "yes") == 0)
+			ci->symlinks = 1;
+		else if (strcasecmp(symlinks, "no") == 0)
+			ci->symlinks = 0;
+		else {
+			fprintf(stderr, Name ": option --symlinks must be 'no' or 'yes'\n");
+			exit(2);
+		}
+	}
 	/* Ok, got the option parsing out of the way
 	 * hopefully it's mostly right but there might be some stuff
 	 * missing

mdadm.conf.5

@@ -273,6 +273,20 @@ missing device entries should be created.
 The name of the metadata format to use if none is explicitly given.
 This can be useful to impose a system-wide default of version-1 superblocks.
 
+.TP
+.B symlinks=no
+Normally when creating devices in
+.B /dev/md/
+.I mdadm
+will create a matching symlink from
+.B /dev/
+with a name starting
+.B md
+or
+.BR md_ .
+Give
+.B symlinked=no
+to suppress this symlink creation.
 .RE
 
 

mdadm.h

@@ -132,6 +132,7 @@ struct createinfo {
 	int	gid;
 	int	autof;
 	int	mode;
+	int	symlinks;
 	struct supertype *supertype;
 };
 
@@ -167,6 +168,7 @@ enum special_options {
 	BackupFile,
 	HomeHost,
 	AutoHomeHost,
+	Symlinks,
 };
 
 /* structures read from config file */

mdopen.c

@@ -48,7 +48,7 @@ void make_dev_symlink(char *dev)
 }
 
 
-void make_parts(char *dev, int cnt)
+void make_parts(char *dev, int cnt, int symlinks)
 {
 	/* make 'cnt' partition devices for 'dev'
 	 * We use the major/minor from dev and add 1..cnt
@@ -88,7 +88,7 @@ void make_parts(char *dev, int cnt)
 			perror("chown");
 		if (chmod(name, stb2.st_mode & 07777))
 			perror("chmod");
-		if (strncmp(name, "/dev/md/", 8) == 0)
+		if (symlinks && strncmp(name, "/dev/md/", 8) == 0)
 			make_dev_symlink(name);
 		stat(name, &stb2);
 		add_dev(name, &stb2, 0, NULL);
@@ -192,7 +192,7 @@ int open_mddev(char *dev, int autof)
 				return -1;
 			} else {
 				if (major != MD_MAJOR && parts > 0)
-					make_parts(dev, parts);
+					make_parts(dev, parts, ci->symlinks);
 				return mdfd;
 			}
 		}
@@ -279,10 +279,10 @@ int open_mddev(char *dev, int autof)
 			}
 			stat(dev, &stb);
 			add_dev(dev, &stb, 0, NULL);
-			if (strncmp(dev, "/dev/md/", 8) == 0)
+			if (ci->symlinks && strncmp(dev, "/dev/md/", 8) == 0)
 				make_dev_symlink(dev);
 			if (major != MD_MAJOR)
-				make_parts(dev,parts);
+				make_parts(dev,parts, ci->symlinks);
 		}
 	}
 	mdfd = open(dev, O_RDWR, 0);