Enhance incremental removal.

When asked to incrementally-remove a device, try marking the array
read-auto first.  That will delay recording the failure in the
metadata until it is really relevant.
This way, if the device are just unplugged when the array is not
really in use, the metadata will remain clean.

If marking the default as faulty fails because it is EBUSY, that
implies that the array would be failed without the device.  As the
device has (presumably gone) - that means the array is dead.  So try
to stop it.  If that fails because it is in use, send a uevent to
report that it is gone.  Hopefully whoever mounted it will now let go.

This means that if  you plug in some devices and they are
auto-assembled, then unplugging them will auto-deassemble relatively
cleanly.

To be complete, we really need the kernel to disassemble the array
after the last close somehow.  Maybe if a REMOVE has failed and a STOP
has failed and nothing else much has happened, it could safely stop
the array on last close.

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

1 files changed, 30 insertions, 7 deletions

diff --git a/Incremental.c b/Incremental.c
index 36f79ef..1b7ebfa 100644
--- a/Incremental.c
+++ b/Incremental.c
@@ -1578,9 +1578,11 @@ static int Incremental_container(struct supertype *st, char *devname,
 int IncrementalRemove(char *devname, char *id_path, int verbose)
 {
 	int mdfd;
-	int rv;
+	int rv = 0;
 	struct mdstat_ent *ent;
 	struct mddev_dev devlist;
+	struct mdinfo mdi;
+	char buf[32];
 
 	if (!id_path)
 		dprintf(Name ": incremental removal without --path <id_path> "
@@ -1598,6 +1600,14 @@ int IncrementalRemove(char *devname, char *id_path, int verbose)
 			"of any array\n", devname);
 		return 1;
 	}
+	sysfs_init(&mdi, -1, ent->devnm);
+	if (sysfs_get_str(&mdi, NULL, "array_state",
+			  buf, sizeof(buf)) > 0) {
+		if (strncmp(buf, "active", 6) == 0 ||
+		    strncmp(buf, "clean", 5) == 0)
+			sysfs_set_str(&mdi, NULL,
+				      "array_state", "read-auto");
+	}
 	mdfd = open_dev(ent->devnm);
 	if (mdfd < 0) {
 		pr_err("Cannot open array %s!!\n", ent->dev);
@@ -1625,17 +1635,30 @@ int IncrementalRemove(char *devname, char *id_path, int verbose)
 			if (is_container_member(memb, ent->dev)) {
 				int subfd = open_dev(memb->devnm);
 				if (subfd >= 0) {
-					Manage_subdevs(memb->dev, subfd,
-						       &devlist, verbose, 0,
-						       NULL, 0);
+					rv |= Manage_subdevs(
+						memb->dev, subfd,
+						&devlist, verbose, 0,
+						NULL, 0);
 					close(subfd);
 				}
 			}
 		free_mdstat(mdstat);
 	} else
-		Manage_subdevs(ent->dev, mdfd, &devlist, verbose, 0, NULL, 0);
-	devlist.disposition = 'r';
-	rv = Manage_subdevs(ent->dev, mdfd, &devlist, verbose, 0, NULL, 0);
+		rv |= Manage_subdevs(ent->dev, mdfd, &devlist,
+				    verbose, 0, NULL, 0);
+	if (rv & 2) {
+		/* Failed due to EBUSY, try to stop the array
+		 */
+		rv = Manage_runstop(ent->dev, mdfd, -1,
+				    verbose, 1);
+		if (rv)
+			/* At least we can try to trigger a 'remove' */
+			sysfs_uevent(&mdi, "remove");
+	} else {
+		devlist.disposition = 'r';
+		rv = Manage_subdevs(ent->dev, mdfd, &devlist,
+				    verbose, 0, NULL, 0);
+	}
 	close(mdfd);
 	free_mdstat(ent);
 	return rv;