md: use sysfs_notify_dirent to notify changes to md/dev-xxx/state

The 'state' file for a device reports, for example, when the device
has failed.  Changes should be reported to userspace ASAP without
the possibility of blocking on low-memory.  sysfs_notify does
have that possibility (as it takes a mutex which can be held
across a kmalloc) so use sysfs_notify_dirent instead.

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

1 files changed, 12 insertions, 9 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index feea72dc4b69..8b303477c77b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1462,6 +1462,8 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
                 kobject_del(&rdev->kobj);
                 goto fail;
         }
+        rdev->sysfs_state = sysfs_get_dirent(rdev->kobj.sd, "state");
+
         list_add_rcu(&rdev->same_set, &mddev->disks);
         bd_claim_by_disk(rdev->bdev, rdev->bdev->bd_holder, mddev->gendisk);
         return 0;
@@ -1491,7 +1493,8 @@ static void unbind_rdev_from_array(mdk_rdev_t * rdev)
         printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
         rdev->mddev = NULL;
         sysfs_remove_link(&rdev->kobj, "block");
-
+        sysfs_put(rdev->sysfs_state);
+        rdev->sysfs_state = NULL;
         /* We need to delay this, otherwise we can deadlock when
          * writing to 'remove' to "dev/state".  We also need
          * to delay it due to rcu usage.
@@ -1926,8 +1929,8 @@ state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
 
                 err = 0;
         }
-        if (!err)
-                sysfs_notify(&rdev->kobj, NULL, "state");
+        if (!err && rdev->sysfs_state)
+                sysfs_notify_dirent(rdev->sysfs_state);
         return err ? err : len;
 }
 static struct rdev_sysfs_entry rdev_state =
@@ -2022,7 +2025,7 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                         rdev->raid_disk = -1;
                         return err;
                 } else
-                        sysfs_notify(&rdev->kobj, NULL, "state");
+                        sysfs_notify_dirent(rdev->sysfs_state);
                 sprintf(nm, "rd%d", rdev->raid_disk);
                 if (sysfs_create_link(&rdev->mddev->kobj, &rdev->kobj, nm))
                         printk(KERN_WARNING
@@ -2039,7 +2042,7 @@ 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(&rdev->kobj, NULL, "state");
+                sysfs_notify_dirent(rdev->sysfs_state);
         }
         return len;
 }
@@ -3583,7 +3586,7 @@ static int do_md_run(mddev_t * mddev)
                                 return -EINVAL;
                         }
                 }
-                sysfs_notify(&rdev->kobj, NULL, "state");
+                sysfs_notify_dirent(rdev->sysfs_state);
         }
 
         md_probe(mddev->unit, NULL, NULL);
@@ -4302,7 +4305,7 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
                 if (err)
                         export_rdev(rdev);
                 else
-                        sysfs_notify(&rdev->kobj, NULL, "state");
+                        sysfs_notify_dirent(rdev->sysfs_state);
 
                 md_update_sb(mddev, 1);
                 if (mddev->degraded)
@@ -6113,7 +6116,7 @@ void md_check_recovery(mddev_t *mddev)
 
                 rdev_for_each(rdev, rtmp, mddev)
                         if (test_and_clear_bit(StateChanged, &rdev->flags))
-                                sysfs_notify(&rdev->kobj, NULL, "state");
+                                sysfs_notify_dirent(rdev->sysfs_state);
 
 
                 if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
@@ -6223,7 +6226,7 @@ void md_check_recovery(mddev_t *mddev)
 
 void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
 {
-        sysfs_notify(&rdev->kobj, NULL, "state");
+        sysfs_notify_dirent(rdev->sysfs_state);
         wait_event_timeout(rdev->blocked_wait,
                            !test_bit(Blocked, &rdev->flags),
                            msecs_to_jiffies(5000));