grow: don't wait forever for critical section to pass.

If an array reshape completed within 1 second, then --grow will not
notice that it has finished and will keep waiting for the critical
section to pass.

So be more cautious in the test.

Signed-off-by: NeilBrown <neilb@suse.de>

3 files changed, 29 insertions, 0 deletions

diff --git a/Grow.c b/Grow.c
index 14e48f5..fc809c6 100644
--- a/Grow.c
+++ b/Grow.c
@@ -815,6 +815,14 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
 			}
 			if (comp >= nstripe)
 				break;
+			if (comp == 0) {
+				/* Maybe it finished already */
+				char action[20];
+				if (sysfs_get_str(sra, NULL, "sync_action",
+						  action, 20) > 0 &&
+				    strncmp(action, "reshape", 7) != 0)
+					break;
+			}
 			sleep(1);
 		}
 
diff --git a/mdadm.h b/mdadm.h
index f580e3e..6770d6c 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -369,6 +369,8 @@ extern int sysfs_set_num(struct mdinfo *sra, struct mdinfo *dev,
 extern int sysfs_uevent(struct mdinfo *sra, char *event);
 extern int sysfs_get_ll(struct mdinfo *sra, struct mdinfo *dev,
 			char *name, unsigned long long *val);
+extern int sysfs_get_str(struct mdinfo *sra, struct mdinfo *dev,
+			 char *name, char *val, int size);
 extern int sysfs_set_safemode(struct mdinfo *sra, unsigned long ms);
 extern int sysfs_set_array(struct mdinfo *info, int vers);
 extern int sysfs_add_disk(struct mdinfo *sra, struct mdinfo *sd);
diff --git a/sysfs.c b/sysfs.c
index 2dad7d3..d4a1e49 100644
--- a/sysfs.c
+++ b/sysfs.c
@@ -466,6 +466,25 @@ int sysfs_get_ll(struct mdinfo *sra, struct mdinfo *dev,
 	return 0;
 }
 
+int sysfs_get_str(struct mdinfo *sra, struct mdinfo *dev,
+		       char *name, char *val, int size)
+{
+	char fname[50];
+	int n;
+	int fd;
+	sprintf(fname, "/sys/block/%s/md/%s/%s",
+		sra->sys_name, dev?dev->sys_name:"", name);
+	fd = open(fname, O_RDONLY);
+	if (fd < 0)
+		return -1;
+	n = read(fd, val, size);
+	close(fd);
+	if (n <= 0)
+		return -1;
+	val[n] = 0;
+	return n;
+}
+
 int sysfs_set_safemode(struct mdinfo *sra, unsigned long ms)
 {
 	unsigned long sec;