rationalise return value for ->hot_add_disk method.

For all array types but linear, ->hot_add_disk returns 1 on
success, 0 on failure.
For linear, it returns 0 on success and -errno on failure.

This doesn't cause a functional problem because the ->hot_add_disk
function of linear is used quite differently to the others.
However it is confusing.

So convert all to return 0 for success or -errno on failure
and fix call sites to match.

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

1 files changed, 3 insertions, 4 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 5d6fac1fd39e..45e255d4916f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1977,10 +1977,8 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                         rdev->saved_raid_disk = -1;
                 err = rdev->mddev->pers->
                         hot_add_disk(rdev->mddev, rdev);
-                if (err != 1) {
+                if (err) {
                         rdev->raid_disk = -1;
-                        if (err == 0)
-                                return -EEXIST;
                         return err;
                 }
                 sprintf(nm, "rd%d", rdev->raid_disk);
@@ -5920,7 +5918,8 @@ static int remove_and_add_spares(mddev_t *mddev)
                         if (rdev->raid_disk < 0
                             && !test_bit(Faulty, &rdev->flags)) {
                                 rdev->recovery_offset = 0;
-                                if (mddev->pers->hot_add_disk(mddev,rdev)) {
+                                if (mddev->pers->
+                                    hot_add_disk(mddev, rdev) == 0) {
                                         char nm[20];
                                         sprintf(nm, "rd%d", rdev->raid_disk);
                                         if (sysfs_create_link(&mddev->kobj,