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authorMike Snitzer <snitzer@redhat.com>2010-08-12 04:14:08 +0100
committerAlasdair G Kergon <agk@redhat.com>2010-08-12 04:14:08 +0100
commit5ae89a8720c28caf35c4e53711d77df2856c404e (patch)
tree712ddc158309d7ad77e3c19e70f0ae9fafb94446 /include/linux
parent5ebaee6d290279d1df6ce45d6d54de8cfc473273 (diff)
dm: linear support discard
Allow discards to be passed through to linear mappings if at least one underlying device supports it. Discards will be forwarded only to devices that support them. A target that supports discards should set num_discard_requests to indicate how many times each discard request must be submitted to it. Verify table's underlying devices support discards prior to setting the associated DM device as capable of discards (via QUEUE_FLAG_DISCARD). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Joe Thornber <thornber@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/device-mapper.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 531a6f2635ae..751ce21dea7b 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -180,6 +180,12 @@ struct dm_target {
*/
unsigned num_flush_requests;
+ /*
+ * The number of discard requests that will be submitted to the
+ * target. map_info->request_nr is used just like num_flush_requests.
+ */
+ unsigned num_discard_requests;
+
/* target specific data */
void *private;