diff options
| author | NeilBrown <neilb@cse.unsw.edu.au> | 2005-09-09 16:23:54 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-09 16:39:12 -0700 |
| commit | 72626685dc66d455742a7f215a0535c551628b9e (patch) | |
| tree | 91e19a61a5a3b782007132b6b2e353e8936dd656 /include/linux/raid | |
| parent | 0002b2718dd04da67c21f8a7830de8d95a9b0345 (diff) | |
[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 <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/raid')
| -rw-r--r-- | include/linux/raid/raid5.h | 14 |
1 files changed, 13 insertions, 1 deletions
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 */ |