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>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index feea72d..8b30347 100644 (file)
--- 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));

diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index b16ad86..8fc909e 100644 (file)
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -115,6 +115,9 @@ struct mdk_rdev_s
                                           * in superblock.
                                           */
        struct work_struct del_work;    /* used for delayed sysfs removal */
+
+       struct sysfs_dirent *sysfs_state; /* handle for 'state'
+                                          * sysfs entry */
 };
 
 struct mddev_s