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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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10
include/linux/dm-dirty-log.h
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@ -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);