Support --auto-update-homehost

This can be used to bootstrape homehost tagging.

If no arrays are found that are tagged, we look for any array
and tag it.

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

Assemble.c

@@ -134,7 +134,7 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 	int chosen_drive;
 	int change = 0;
 	int inargv = 0;
-	int start_partial_ok = (runstop >= 0) && (force || devlist==NULL);
+	int start_partial_ok = (runstop >= 0) && (force || devlist==NULL || mdfd < 0);
 	unsigned int num_devs;
 	mddev_dev_t tmpdev;
 	struct mdinfo info;
@@ -293,11 +293,14 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 		if (mdfd < 0) {
 			if (tst == NULL || super == NULL)
 				continue;
-			if (tst->ss->match_home(super, homehost)==0) {
+			if (update == NULL &&
+			    tst->ss->match_home(super, homehost)==0) {
 				if ((inargv && verbose >= 0) || verbose > 0)
 					fprintf(stderr, Name ": %s is not built for host %s.\n",
 						devname, homehost);
 				/* Auto-assemble, and this is not a usable host */
+				/* if update != NULL, we are updating the host
+				 * name... */
 				continue;
 			}
 		}
@@ -846,7 +849,32 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 						fprintf(stderr, " and %d spare%s", sparecnt, sparecnt==1?"":"s");
 					fprintf(stderr, ".\n");
 				}
-				if (must_close) close(mdfd);
+				if (must_close) {
+					int usecs = 1;
+					close(mdfd);
+					/* There is a nasty race with 'mdadm --monitor'.
+					 * If it opens this device before we close it,
+					 * it gets an incomplete open on which IO
+					 * doesn't work and the capacity if wrong.
+					 * If we reopen (to check for layered devices)
+					 * before --monitor closes, we loose.
+					 *
+					 * So: wait upto 1 second for there to be
+					 * a non-zero capacity.
+					 */
+					while (usecs < 1000) {
+						mdfd = open(mddev, O_RDONLY);
+						if (mdfd >= 0) {
+							unsigned long size;
+							if (ioctl(mdfd, BLKGETSIZE, &size) == 0 &&
+							    size > 0)
+								break;
+							close(mdfd);
+						}
+						usleep(usecs);
+						usecs <<= 1;
+					}
+				}
 				return 0;
 			}
 			fprintf(stderr, Name ": failed to RUN_ARRAY %s: %s\n",

ReadMe.c

@@ -138,6 +138,7 @@ struct option long_options[] = {
     {"write-mostly",0, 0, 'W'},
     {"re-add",    0, 0,  ReAdd},
     {"homehost",  1, 0,  HomeHost},
+    {"auto-update-homehost", 0, 0, AutoHomeHost},
 
     /* For assemble */
     {"uuid",      1, 0, 'u'},

mdadm.c

@@ -100,6 +100,7 @@ int main(int argc, char *argv[])
 	int re_add = 0;
 	char *shortopt = short_options;
 	int dosyslog = 0;
+	int auto_update_home = 0;
 
 	int copies;
 	int print_help = 0;
@@ -315,6 +316,9 @@ int main(int argc, char *argv[])
 			}
 			continue;
 
+		case O(ASSEMBLE,AutoHomeHost):
+			auto_update_home = 1;
+			continue;
 		case O(CREATE,'e'):
 		case O(ASSEMBLE,'e'):
 		case O(MISC,'e'): /* set metadata (superblock) information */
@@ -1037,10 +1041,33 @@ int main(int argc, char *argv[])
 							cnt++;
 							acnt++;
 						}
+						if (rv2 == 1)
+							/* found something so even though assembly failed  we
+							 * want to avoid auto-updates
+							 */
+							auto_update_home = 0;
 					} while (rv2!=2);
 					/* Incase there are stacked devices, we need to go around again */
 					devlist = conf_get_devs(configfile);
 				} while (acnt);
+				if (cnt == 0 && auto_update_home && homehost) {
+					/* Nothing found, maybe we need to bootstrap homehost info */
+					do {
+						acnt = 0;
+						do {
+							rv2 = Assemble(ss, NULL, -1,
+								       &ident, configfile,
+								       devlist, NULL,
+								       readonly, runstop, "homehost", homehost, verbose-quiet, force);
+							if (rv2==0) {
+								cnt++;
+								acnt++;
+							}
+						} while (rv2!=2);
+						/* Incase there are stacked devices, we need to go around again */
+						devlist = conf_get_devs(configfile);
+					} while (acnt);
+				}
 				if (cnt == 0 && rv == 0) {
 					fprintf(stderr, Name ": No arrays found in config file or automatically\n");
 					rv = 1;

mdadm.h

@@ -137,6 +137,7 @@ enum special_options {
 	Sparc22,
 	BackupFile,
 	HomeHost,
+	AutoHomeHost,
 };
 
 /* structures read from config file */