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dm raid1: add is_remote_recovering hook for clusters

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The logging API needs an extra function to make cluster mirroring
possible.  This new function allows us to check whether a mirror
region is being recovered on another machine in the cluster.  This
helps us prevent simultaneous recovery I/O and process I/O to the
same locations on disk.

Cluster-aware log modules will implement this function.  Single
machine log modules will not.  So, there is no performance
penalty for single machine mirrors.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Acked-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Jonathan Brassow 2009-04-02 19:55:30 +01:00 committed by Alasdair G Kergon
parent b2a1146529
commit 7513c2a761
2 changed files with 33 additions and 2 deletions
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25
drivers/md/dm-raid1.c
View file

@ -588,6 +588,9 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
int state;
struct bio *bio;
struct bio_list sync, nosync, recover, *this_list = NULL;
struct bio_list requeue;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
region_t region;
if (!writes->head)
return;
@ -598,10 +601,18 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
bio_list_init(&sync);
bio_list_init(&nosync);
bio_list_init(&recover);
bio_list_init(&requeue);
while ((bio = bio_list_pop(writes))) {
state = dm_rh_get_state(ms->rh,
dm_rh_bio_to_region(ms->rh, bio), 1);
region = dm_rh_bio_to_region(ms->rh, bio);
if (log->type->is_remote_recovering &&
log->type->is_remote_recovering(log, region)) {
bio_list_add(&requeue, bio);
continue;
}
state = dm_rh_get_state(ms->rh, region, 1);
switch (state) {
case DM_RH_CLEAN:
case DM_RH_DIRTY:
@ -620,6 +631,16 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
bio_list_add(this_list, bio);
}
/*
* Add bios that are delayed due to remote recovery
* back on to the write queue
*/
if (unlikely(requeue.head)) {
spin_lock_irq(&ms->lock);
bio_list_merge(&ms->writes, &requeue);
spin_unlock_irq(&ms->lock);
}
/*
* Increment the pending counts for any regions that will
* be written to (writes to recover regions are going to

10
include/linux/dm-dirty-log.h
View file

@ -116,6 +116,16 @@ struct dm_dirty_log_type {
*/
int (*status)(struct dm_dirty_log *log, status_type_t status_type,
char *result, unsigned maxlen);
/*
* is_remote_recovering is necessary for cluster mirroring. It provides
* a way to detect recovery on another node, so we aren't writing
* concurrently. This function is likely to block (when a cluster log
* is used).
*
* Returns: 0, 1
*/
int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
};
int dm_dirty_log_type_register(struct dm_dirty_log_type *type);