[PATCH] md: improve locking on 'safemode' and move superblock writes
When md marks the superblock dirty before a write, it calls
generic_make_request (to write the superblock) from within
generic_make_request (to write the first dirty block), which could cause
problems later.
With this patch, the superblock write is always done by the helper thread, and
write request are delayed until that write completes.
Also, the locking around marking the array dirty and writing the superblock is
improved to avoid possible races.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h
index a6a67d1..cfde8f4 100644
--- a/include/linux/raid/md.h
+++ b/include/linux/raid/md.h
@@ -69,7 +69,7 @@
extern void md_unregister_thread (mdk_thread_t *thread);
extern void md_wakeup_thread(mdk_thread_t *thread);
extern void md_check_recovery(mddev_t *mddev);
-extern void md_write_start(mddev_t *mddev);
+extern int md_write_start(mddev_t *mddev, struct bio *bi);
extern void md_write_end(mddev_t *mddev);
extern void md_handle_safemode(mddev_t *mddev);
extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index c9a0d40..d92db54 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -15,6 +15,9 @@
#ifndef _MD_K_H
#define _MD_K_H
+/* and dm-bio-list.h is not under include/linux because.... ??? */
+#include "../../../drivers/md/dm-bio-list.h"
+
#define MD_RESERVED 0UL
#define LINEAR 1UL
#define RAID0 2UL
@@ -252,6 +255,10 @@
atomic_t recovery_active; /* blocks scheduled, but not written */
wait_queue_head_t recovery_wait;
sector_t recovery_cp;
+
+ spinlock_t write_lock;
+ struct bio_list write_list;
+
unsigned int safemode; /* if set, update "clean" superblock
* when no writes pending.
*/