Use O_EXCL when opening component devices to be assembled into an array

In 2.6, this will fail if the device is already in use, so we can detect this error
more easily.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>

5 files changed, 20 insertions, 8 deletions

diff --git a/Assemble.c b/Assemble.c
index 4e4e123..ace5717 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -193,7 +193,7 @@ int Assemble(char *mddev, int mdfd,
 			continue;
 		}
 		
-		dfd = open(devname, O_RDONLY, 0);
+		dfd = open(devname, O_RDONLY|O_EXCL, 0);
 		if (dfd < 0) {
 			if (inargv || verbose)
 				fprintf(stderr, Name ": cannot open device %s: %s\n",
@@ -326,7 +326,7 @@ int Assemble(char *mddev, int mdfd,
 				super.recovery_cp = 0;
 			}
 			super.sb_csum = calc_sb_csum(&super);
-			dfd = open(devname, O_RDWR, 0);
+			dfd = open(devname, O_RDWR|O_EXCL, 0);
 			if (dfd < 0) 
 				fprintf(stderr, Name ": Cannot open %s for superblock update\n",
 					devname);
@@ -435,7 +435,7 @@ int Assemble(char *mddev, int mdfd,
 			devices[chosen_drive].devname, devices[chosen_drive].raid_disk,
 			(int)(devices[chosen_drive].events),
 			(int)(devices[most_recent].events));
-		fd = open(devices[chosen_drive].devname, O_RDWR);
+		fd = open(devices[chosen_drive].devname, O_RDWR|O_EXCL);
 		if (fd < 0) {
 			fprintf(stderr, Name ": Couldn't open %s for write - not updating\n",
 				devices[chosen_drive].devname);
@@ -484,7 +484,7 @@ int Assemble(char *mddev, int mdfd,
 		if (!devices[j].uptodate)
 			continue;
 		chosen_drive = j;
-		if ((fd=open(devices[j].devname, O_RDONLY))< 0) {
+		if ((fd=open(devices[j].devname, O_RDONLY|O_EXCL))< 0) {
 			fprintf(stderr, Name ": Cannot open %s: %s\n",
 				devices[j].devname, strerror(errno));
 			return 1;
@@ -556,7 +556,7 @@ This doesnt work yet
 	    || (old_linux && (change & 1))) {
 		int fd;
 		super.sb_csum = calc_sb_csum(&super);
-		fd = open(devices[chosen_drive].devname, O_RDWR);
+		fd = open(devices[chosen_drive].devname, O_RDWR|O_EXCL);
 		if (fd < 0) {
 			fprintf(stderr, Name ": Could open %s for write - cannot Assemble array.\n",
 				devices[chosen_drive].devname);
diff --git a/ChangeLog b/ChangeLog
index 7e03a5c..6854858 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Changes Prior to 1.10.0 release
+    -   Fix bug with --config=partitions
+    -   Open sub-devices with O_EXCL to detect if already in use
+
 Changes Prior to 1.9.0 release
     -   Fix rpm build problem (stray %)
     -   Minor manpage updates
diff --git a/Create.c b/Create.c
index 1c814f7..66a88d2 100644
--- a/Create.c
+++ b/Create.c
@@ -187,7 +187,7 @@ int Create(char *mddev, int mdfd,
 		array.working_disks++;
 		if (dnum < raiddisks)
 			array.active_disks++;
-		fd = open(dname, O_RDONLY, 0);
+		fd = open(dname, O_RDONLY|O_EXCL, 0);
 		if (fd <0 ) {
 			fprintf(stderr, Name ": Cannot open %s: %s\n",
 				dname, strerror(errno));
@@ -368,7 +368,7 @@ int Create(char *mddev, int mdfd,
 			disk.minor = 0;
 			disk.state = 1; /* faulty */
 		} else {
-			fd = open(dv->devname, O_RDONLY, 0);
+			fd = open(dv->devname, O_RDONLY|O_EXCL, 0);
 			if (fd < 0) {
 				fprintf(stderr, Name ": failed to open %s after earlier success - aborting\n",
 					dv->devname);
diff --git a/Kill.c b/Kill.c
index a57bdf8..9441f73 100644
--- a/Kill.c
+++ b/Kill.c
@@ -44,7 +44,7 @@ int Kill(char *dev, int force)
 	mdp_super_t super;
 	int fd, rv = 0;
 		
-	fd = open(dev, O_RDWR);
+	fd = open(dev, O_RDWR|O_EXCL);
 	if (fd < 0) {
 		fprintf(stderr, Name ": Couldn't open %s for write - not zeroing\n",
 			dev);
diff --git a/Manage.c b/Manage.c
index 8835095..b323fd3 100644
--- a/Manage.c
+++ b/Manage.c
@@ -194,6 +194,14 @@ int Manage_subdevs(char *devname, int fd,
 			return 1;
 		case 'a':
 			/* add the device - hot or cold */
+			/* Make sure it isn' in use (in 2.6 or later) */
+			fd = open(dv->devname, O_RDONLY|O_EXCL);
+			if (fd < 0) {
+				fprintf(stderr, Name ": Cannot open %s: %s\n",
+					dv->devname, strerror(errno));
+				return 1;
+			}
+			close(fd);
 			if (ioctl(fd, HOT_ADD_DISK, (unsigned long)stb.st_rdev)==0) {
 				fprintf(stderr, Name ": hot added %s\n",
 					dv->devname);