From 6bfe0b499082fd3950429017cd8ebf2a6c458aa5 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Wed, 30 Apr 2008 00:52:32 -0700
Subject: md: support blocking writes to an array on device failure

Allows a userspace metadata handler to take action upon detecting a device
failure.

Based on an original patch by Neil Brown.

Changes:
-added blocked_wait waitqueue to rdev
-don't qualify Blocked with Faulty always let userspace block writes
-added md_wait_for_blocked_rdev to wait for the block device to be clear, if
 userspace misses the notification another one is sent every 5 seconds
-set MD_RECOVERY_NEEDED after clearing "blocked"
-kill DoBlock flag, just test mddev->external

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/raid/md.h   | 1 +
 include/linux/raid/md_k.h | 4 ++++
 2 files changed, 5 insertions(+)

(limited to 'include/linux/raid')

diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h
index 8ab630b..81a1a02 100644
--- a/include/linux/raid/md.h
+++ b/include/linux/raid/md.h
@@ -94,6 +94,7 @@ extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
 extern void md_do_sync(mddev_t *mddev);
 extern void md_new_event(mddev_t *mddev);
 extern void md_allow_write(mddev_t *mddev);
+extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 
 #endif /* CONFIG_MD */
 #endif 
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 7bb6d1a..812ffa5 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -84,6 +84,10 @@ struct mdk_rdev_s
 #define	AllReserved	6		/* If whole device is reserved for
 					 * one array */
 #define	AutoDetected	7		/* added by auto-detect */
+#define Blocked		8		/* An error occured on an externally
+					 * managed array, don't allow writes
+					 * until it is cleared */
+	wait_queue_head_t blocked_wait;
 
 	int desc_nr;			/* descriptor index in the superblock */
 	int raid_disk;			/* role of device in array */
-- 
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