md: reduce dependence on sysfs.

We will want md devices to live as dm targets where sysfs is not
visible.  So allow md to not connect to sysfs.

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

3 files changed, 62 insertions, 59 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index cb20d0b0555a..9007651ce175 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -541,14 +541,16 @@ static void mddev_unlock(mddev_t * mddev)
                 mutex_lock(&mddev->open_mutex);
                 mutex_unlock(&mddev->reconfig_mutex);
 
-                if (to_remove != &md_redundancy_group)
-                        sysfs_remove_group(&mddev->kobj, to_remove);
-                if (mddev->pers == NULL ||
-                    mddev->pers->sync_request == NULL) {
-                        sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
-                        if (mddev->sysfs_action)
-                                sysfs_put(mddev->sysfs_action);
-                        mddev->sysfs_action = NULL;
+                if (mddev->kobj.sd) {
+                        if (to_remove != &md_redundancy_group)
+                                sysfs_remove_group(&mddev->kobj, to_remove);
+                        if (mddev->pers == NULL ||
+                            mddev->pers->sync_request == NULL) {
+                                sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
+                                if (mddev->sysfs_action)
+                                        sysfs_put(mddev->sysfs_action);
+                                mddev->sysfs_action = NULL;
+                        }
                 }
                 mutex_unlock(&mddev->open_mutex);
         } else
@@ -1811,11 +1813,9 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
                 goto fail;
 
         ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
-        if ((err = sysfs_create_link(&rdev->kobj, ko, "block"))) {
-                kobject_del(&rdev->kobj);
-                goto fail;
-        }
-        rdev->sysfs_state = sysfs_get_dirent(rdev->kobj.sd, NULL, "state");
+        if (sysfs_create_link(&rdev->kobj, ko, "block"))
+                /* failure here is OK */;
+        rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
 
         list_add_rcu(&rdev->same_set, &mddev->disks);
         bd_claim_by_disk(rdev->bdev, rdev->bdev->bd_holder, mddev->gendisk);
@@ -2334,8 +2334,8 @@ state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                 set_bit(In_sync, &rdev->flags);
                 err = 0;
         }
-        if (!err && rdev->sysfs_state)
-                sysfs_notify_dirent(rdev->sysfs_state);
+        if (!err)
+                sysfs_notify_dirent_safe(rdev->sysfs_state);
         return err ? err : len;
 }
 static struct rdev_sysfs_entry rdev_state =
@@ -2430,14 +2430,10 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                         rdev->raid_disk = -1;
                         return err;
                 } else
-                        sysfs_notify_dirent(rdev->sysfs_state);
+                        sysfs_notify_dirent_safe(rdev->sysfs_state);
                 sprintf(nm, "rd%d", rdev->raid_disk);
                 if (sysfs_create_link(&rdev->mddev->kobj, &rdev->kobj, nm))
-                        printk(KERN_WARNING
-                               "md: cannot register "
-                               "%s for %s\n",
-                               nm, mdname(rdev->mddev));
-
+                        /* failure here is OK */;
                 /* don't wakeup anyone, leave that to userspace. */
         } else {
                 if (slot >= rdev->mddev->raid_disks)
@@ -2447,7 +2443,7 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                 clear_bit(Faulty, &rdev->flags);
                 clear_bit(WriteMostly, &rdev->flags);
                 set_bit(In_sync, &rdev->flags);
-                sysfs_notify_dirent(rdev->sysfs_state);
+                sysfs_notify_dirent_safe(rdev->sysfs_state);
         }
         return len;
 }
@@ -3437,7 +3433,7 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
         if (err)
                 return err;
         else {
-                sysfs_notify_dirent(mddev->sysfs_state);
+                sysfs_notify_dirent_safe(mddev->sysfs_state);
                 return len;
         }
 }
@@ -3735,7 +3731,7 @@ action_store(mddev_t *mddev, const char *page, size_t len)
         }
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
-        sysfs_notify_dirent(mddev->sysfs_action);
+        sysfs_notify_dirent_safe(mddev->sysfs_action);
         return len;
 }
 
@@ -4281,13 +4277,14 @@ static int md_alloc(dev_t dev, char *name)
                        disk->disk_name);
                 error = 0;
         }
-        if (sysfs_create_group(&mddev->kobj, &md_bitmap_group))
+        if (mddev->kobj.sd &&
+            sysfs_create_group(&mddev->kobj, &md_bitmap_group))
                 printk(KERN_DEBUG "pointless warning\n");
  abort:
         mutex_unlock(&disks_mutex);
-        if (!error) {
+        if (!error && mddev->kobj.sd) {
                 kobject_uevent(&mddev->kobj, KOBJ_ADD);
-                mddev->sysfs_state = sysfs_get_dirent(mddev->kobj.sd, NULL, "array_state");
+                mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
         }
         mddev_put(mddev);
         return error;
@@ -4325,7 +4322,7 @@ static void md_safemode_timeout(unsigned long data)
         if (!atomic_read(&mddev->writes_pending)) {
                 mddev->safemode = 1;
                 if (mddev->external)
-                        sysfs_notify_dirent(mddev->sysfs_state);
+                        sysfs_notify_dirent_safe(mddev->sysfs_state);
         }
         md_wakeup_thread(mddev->thread);
 }
@@ -4397,7 +4394,7 @@ static int md_run(mddev_t *mddev)
                                 return -EINVAL;
                         }
                 }
-                sysfs_notify_dirent(rdev->sysfs_state);
+                sysfs_notify_dirent_safe(rdev->sysfs_state);
         }
 
         spin_lock(&pers_lock);
@@ -4496,11 +4493,12 @@ static int md_run(mddev_t *mddev)
                 return err;
         }
         if (mddev->pers->sync_request) {
-                if (sysfs_create_group(&mddev->kobj, &md_redundancy_group))
+                if (mddev->kobj.sd &&
+                    sysfs_create_group(&mddev->kobj, &md_redundancy_group))
                         printk(KERN_WARNING
                                "md: cannot register extra attributes for %s\n",
                                mdname(mddev));
-                mddev->sysfs_action = sysfs_get_dirent(mddev->kobj.sd, NULL, "sync_action");
+                mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
         } else if (mddev->ro == 2) /* auto-readonly not meaningful */
                 mddev->ro = 0;
 
@@ -4518,8 +4516,7 @@ static int md_run(mddev_t *mddev)
                         char nm[20];
                         sprintf(nm, "rd%d", rdev->raid_disk);
                         if (sysfs_create_link(&mddev->kobj, &rdev->kobj, nm))
-                                printk("md: cannot register %s for %s\n",
-                                       nm, mdname(mddev));
+                                /* failure here is OK */;
                 }
         
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
@@ -4531,9 +4528,8 @@ static int md_run(mddev_t *mddev)
         md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
 
         md_new_event(mddev);
-        sysfs_notify_dirent(mddev->sysfs_state);
-        if (mddev->sysfs_action)
-                sysfs_notify_dirent(mddev->sysfs_action);
+        sysfs_notify_dirent_safe(mddev->sysfs_state);
+        sysfs_notify_dirent_safe(mddev->sysfs_action);
         sysfs_notify(&mddev->kobj, NULL, "degraded");
         return 0;
 }
@@ -4573,7 +4569,7 @@ static int restart_array(mddev_t *mddev)
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
         md_wakeup_thread(mddev->sync_thread);
-        sysfs_notify_dirent(mddev->sysfs_state);
+        sysfs_notify_dirent_safe(mddev->sysfs_state);
         return 0;
 }
 
@@ -4697,7 +4693,7 @@ static int md_set_readonly(mddev_t *mddev, int is_open)
                 mddev->ro = 1;
                 set_disk_ro(mddev->gendisk, 1);
                 clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
-                sysfs_notify_dirent(mddev->sysfs_state);
+                sysfs_notify_dirent_safe(mddev->sysfs_state);
                 err = 0;        
         }
 out:
@@ -4730,7 +4726,7 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
                 mddev->queue->backing_dev_info.congested_fn = NULL;
 
                 /* tell userspace to handle 'inactive' */
-                sysfs_notify_dirent(mddev->sysfs_state);
+                sysfs_notify_dirent_safe(mddev->sysfs_state);
 
                 list_for_each_entry(rdev, &mddev->disks, same_set)
                         if (rdev->raid_disk >= 0) {
@@ -4776,7 +4772,7 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
         err = 0;
         blk_integrity_unregister(disk);
         md_new_event(mddev);
-        sysfs_notify_dirent(mddev->sysfs_state);
+        sysfs_notify_dirent_safe(mddev->sysfs_state);
         return err;
 }
 
@@ -5138,7 +5134,7 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
                 if (err)
                         export_rdev(rdev);
                 else
-                        sysfs_notify_dirent(rdev->sysfs_state);
+                        sysfs_notify_dirent_safe(rdev->sysfs_state);
 
                 md_update_sb(mddev, 1);
                 if (mddev->degraded)
@@ -5813,7 +5809,7 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
         if (_IOC_TYPE(cmd) == MD_MAJOR && mddev->ro && mddev->pers) {
                 if (mddev->ro == 2) {
                         mddev->ro = 0;
-                        sysfs_notify_dirent(mddev->sysfs_state);
+                        sysfs_notify_dirent_safe(mddev->sysfs_state);
                         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                         md_wakeup_thread(mddev->thread);
                 } else {
@@ -6059,7 +6055,7 @@ void md_error(mddev_t *mddev, mdk_rdev_t *rdev)
         mddev->pers->error_handler(mddev,rdev);
         if (mddev->degraded)
                 set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
-        sysfs_notify_dirent(rdev->sysfs_state);
+        sysfs_notify_dirent_safe(rdev->sysfs_state);
         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
@@ -6520,7 +6516,7 @@ void md_write_start(mddev_t *mddev, struct bio *bi)
                 spin_unlock_irq(&mddev->write_lock);
         }
         if (did_change)
-                sysfs_notify_dirent(mddev->sysfs_state);
+                sysfs_notify_dirent_safe(mddev->sysfs_state);
         wait_event(mddev->sb_wait,
                    !test_bit(MD_CHANGE_CLEAN, &mddev->flags) &&
                    !test_bit(MD_CHANGE_PENDING, &mddev->flags));
@@ -6563,7 +6559,7 @@ int md_allow_write(mddev_t *mddev)
                         mddev->safemode = 1;
                 spin_unlock_irq(&mddev->write_lock);
                 md_update_sb(mddev, 0);
-                sysfs_notify_dirent(mddev->sysfs_state);
+                sysfs_notify_dirent_safe(mddev->sysfs_state);
         } else
                 spin_unlock_irq(&mddev->write_lock);
 
@@ -6950,10 +6946,7 @@ static int remove_and_add_spares(mddev_t *mddev)
                                         sprintf(nm, "rd%d", rdev->raid_disk);
                                         if (sysfs_create_link(&mddev->kobj,
                                                               &rdev->kobj, nm))
-                                                printk(KERN_WARNING
-                                                       "md: cannot register "
-                                                       "%s for %s\n",
-                                                       nm, mdname(mddev));
+                                                /* failure here is OK */;
                                         spares++;
                                         md_new_event(mddev);
                                         set_bit(MD_CHANGE_DEVS, &mddev->flags);
@@ -7046,7 +7039,7 @@ void md_check_recovery(mddev_t *mddev)
                                 mddev->safemode = 0;
                         spin_unlock_irq(&mddev->write_lock);
                         if (did_change)
-                                sysfs_notify_dirent(mddev->sysfs_state);
+                                sysfs_notify_dirent_safe(mddev->sysfs_state);
                 }
 
                 if (mddev->flags)
@@ -7085,7 +7078,7 @@ void md_check_recovery(mddev_t *mddev)
                         mddev->recovery = 0;
                         /* flag recovery needed just to double check */
                         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-                        sysfs_notify_dirent(mddev->sysfs_action);
+                        sysfs_notify_dirent_safe(mddev->sysfs_action);
                         md_new_event(mddev);
                         goto unlock;
                 }
@@ -7147,7 +7140,7 @@ void md_check_recovery(mddev_t *mddev)
                                 mddev->recovery = 0;
                         } else
                                 md_wakeup_thread(mddev->sync_thread);
-                        sysfs_notify_dirent(mddev->sysfs_action);
+                        sysfs_notify_dirent_safe(mddev->sysfs_action);
                         md_new_event(mddev);
                 }
         unlock:
@@ -7156,7 +7149,7 @@ void md_check_recovery(mddev_t *mddev)
                         if (test_and_clear_bit(MD_RECOVERY_RECOVER,
                                                &mddev->recovery))
                                 if (mddev->sysfs_action)
-                                        sysfs_notify_dirent(mddev->sysfs_action);
+                                        sysfs_notify_dirent_safe(mddev->sysfs_action);
                 }
                 mddev_unlock(mddev);
         }
@@ -7164,7 +7157,7 @@ void md_check_recovery(mddev_t *mddev)
 
 void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
 {
-        sysfs_notify_dirent(rdev->sysfs_state);
+        sysfs_notify_dirent_safe(rdev->sysfs_state);
         wait_event_timeout(rdev->blocked_wait,
                            !test_bit(Blocked, &rdev->flags),
                            msecs_to_jiffies(5000));
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 10597bfec000..1e6405918eec 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -382,6 +382,18 @@ struct md_sysfs_entry {
 };
 extern struct attribute_group md_bitmap_group;
 
+static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
+{
+        if (sd)
+                return sysfs_get_dirent(sd, NULL, name);
+        return sd;
+}
+static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
+{
+        if (sd)
+                sysfs_notify_dirent(sd);
+}
+
 static inline char * mdname (mddev_t * mddev)
 {
         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 96c690279fc6..6a7a30113161 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5158,7 +5158,8 @@ static int run(mddev_t *mddev)
         /* Ok, everything is just fine now */
         if (mddev->to_remove == &raid5_attrs_group)
                 mddev->to_remove = NULL;
-        else if (sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
+        else if (mddev->kobj.sd &&
+            sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
                 printk(KERN_WARNING
                        "md/raid:%s: failed to create sysfs attributes.\n",
                        mdname(mddev));
@@ -5545,10 +5546,7 @@ static int raid5_start_reshape(mddev_t *mddev)
                                 sprintf(nm, "rd%d", rdev->raid_disk);
                                 if (sysfs_create_link(&mddev->kobj,
                                                       &rdev->kobj, nm))
-                                        printk(KERN_WARNING
-                                               "md/raid:%s: failed to create "
-                                               " link %s\n",
-                                               mdname(mddev), nm);
+                                        /* Failure here is OK */;
                         } else
                                 break;
                 }