From 72626685dc66d455742a7f215a0535c551628b9e Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 9 Sep 2005 16:23:54 -0700 Subject: [PATCH] md: add write-intent-bitmap support to raid5 Most awkward part of this is delaying write requests until bitmap updates have been flushed. To achieve this, we have a sequence number (seq_flush) which is incremented each time the raid5 is unplugged. If the raid thread notices that this has changed, it flushes bitmap changes, and assigned the value of seq_flush to seq_write. When a write request arrives, it is given the number from seq_write, and that write request may not complete until seq_flush is larger than the saved seq number. We have a new queue for storing stripes which are waiting for a bitmap flush and an extra flag for stripes to record if the write was 'degraded' and so should not clear the a bit in the bitmap. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/raid/raid5.h | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h index d63ddcb4afa..176fc653c28 100644 --- a/include/linux/raid/raid5.h +++ b/include/linux/raid/raid5.h @@ -134,6 +134,7 @@ struct stripe_head { unsigned long state; /* state flags */ atomic_t count; /* nr of active thread/requests */ spinlock_t lock; + int bm_seq; /* sequence number for bitmap flushes */ struct r5dev { struct bio req; struct bio_vec vec; @@ -165,12 +166,13 @@ struct stripe_head { /* * Stripe state */ -#define STRIPE_ERROR 1 #define STRIPE_HANDLE 2 #define STRIPE_SYNCING 3 #define STRIPE_INSYNC 4 #define STRIPE_PREREAD_ACTIVE 5 #define STRIPE_DELAYED 6 +#define STRIPE_DEGRADED 7 +#define STRIPE_BIT_DELAY 8 /* * Plugging: @@ -210,10 +212,20 @@ struct raid5_private_data { struct list_head handle_list; /* stripes needing handling */ struct list_head delayed_list; /* stripes that have plugged requests */ + struct list_head bitmap_list; /* stripes delaying awaiting bitmap update */ atomic_t preread_active_stripes; /* stripes with scheduled io */ char cache_name[20]; kmem_cache_t *slab_cache; /* for allocating stripes */ + + int seq_flush, seq_write; + int quiesce; + + int fullsync; /* set to 1 if a full sync is needed, + * (fresh device added). + * Cleared when a sync completes. + */ + /* * Free stripes pool */ -- cgit v1.2.3-70-g09d2