From: NeilBrown <neilb@suse.de>
References: bnc#793954

If we get EBUSY when openning a device during ASSEMBLE,
try again a limited number of times as we could be racing with
"mdadm -I" from udev or similar.

This is fixed upstream by more intrusive locking changed.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 Assemble.c |   36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

--- mdadm-3.2.6.orig/Assemble.c
+++ mdadm-3.2.6/Assemble.c
@@ -494,7 +494,7 @@ int Assemble(struct supertype *st, char
 			tmpdev = NULL;
 			goto loop;
 		} else {
-
+			int cnt = 5;
 			content = &info;
 			tst->ss->getinfo_super(tst, content, NULL);
 
@@ -508,6 +508,13 @@ int Assemble(struct supertype *st, char
 			 * be looking at
 			 */
 			dfd = dev_open(devname, O_RDONLY | O_EXCL);
+			while (dfd < 0 && errno == EBUSY && cnt > 0) {
+				fprintf(stderr, "EBUSY - retrying dev_open of %s\n",
+					devname);
+				usleep(200000);
+				dfd = dev_open(devname, O_RDONLY | O_EXCL);
+				cnt--;
+			}
 			if (dfd < 0) {
 				if (report_missmatch)
 					fprintf(stderr, Name ": %s is busy - skipping\n", devname);
@@ -1315,13 +1322,28 @@ int Assemble(struct supertype *st, char
 				j = chosen_drive;
 
 			if (j >= 0 /* && devices[j].uptodate */) {
-				int dfd = dev_open(devices[j].devname,
-						   O_RDWR|O_EXCL);
-				if (dfd >= 0) {
-					remove_partitions(dfd);
-					close(dfd);
+				int cnt = 5;
+				while (cnt > 0) {
+					int dfd = dev_open(devices[j].devname,
+							   O_RDWR|O_EXCL);
+					cnt--;
+					if (dfd < 0 && errno == EBUSY) {
+						fprintf(stderr, "EBUSY - retrying open of %s\n",
+							devices[j].devname);
+						usleep(200000);
+						continue;
+					}
+					if (dfd >= 0) {
+						remove_partitions(dfd);
+						close(dfd);
+					}
+					rv = add_disk(mdfd, st, content, &devices[j].i);
+					if (rv == 0 || errno != EBUSY)
+						break;
+					fprintf(stderr, "EBUSY - retrying add of %s\n",
+						devices[j].devname);
+					usleep(200000);
 				}
-				rv = add_disk(mdfd, st, content, &devices[j].i);
 
 				if (rv) {
 					fprintf(stderr, Name ": failed to add "