multipath: Fix kpartx and udevd race

PATCH New Benjamin Marzinski 1 participant 1 message Jan 10, 2013 Device mapper

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Benjamin Marzinski

author maintainer

2013-01-10 20:56 UTC #0 lore raw

PATCH v2 1/1 multipath: Fix kpartx and udevd race

Sometimes when kpartx is used to view partition data on disk image files, udev still has the loop device open when kpartx is trying to tear it down. This causes the LOOP_CLR_FD ioctl to fail with EBUSY. kpartx now retries in this case.

Signed-off-by Benjamin Marzinski <[email protected]>

---
 kpartx/lopart.c |   16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

kpartx/lopart.c +12 -4

Index: multipath-tools-130107/kpartx/lopart.c
===================================================================
@@ -286,6 +286,7 @@ set_loop (const char *device, const char
 extern int 
 del_loop (const char *device)
 {
+	int retries = 3;
 	int fd;
 
 	if ((fd = open (device, O_RDONLY)) < 0) {

@@ -295,10 +296,17 @@ del_loop (const char *device)
 		return 1;
 	}
 
-	if (ioctl (fd, LOOP_CLR_FD, 0) < 0) {
-		perror ("ioctl: LOOP_CLR_FD");
-		close (fd);
-		return 1;
+	while (ioctl (fd, LOOP_CLR_FD, 0) < 0) {
+		if (errno != EBUSY || retries-- <= 0) {
+			perror ("ioctl: LOOP_CLR_FD");
+			close (fd);
+			return 1;
+		}
+		fprintf(stderr,
+			"loop: device %s still in use, retrying delete\n",
+			device);
+		sleep(1);
+		continue;
 	}
 
 	close (fd);