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authorKiyoshi Ueda <k-ueda@ct.jp.nec.com>2006-12-08 02:41:05 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-08 08:29:09 -0800
commit45cbcd798354251b99694086af9d57c99e89bb43 (patch)
treea9822364a37993b72ffecf356aa040e8fefe6cb5 /drivers/md/dm.h
parenta3d77d35be6f416a250c528c3ed5c70013a915e8 (diff)
downloadlinux-45cbcd798354251b99694086af9d57c99e89bb43.tar.bz2
[PATCH] dm: map and endio return code clarification
Tighten the use of return values from the target map and end_io functions. Values of 2 and above are now explictly reserved for future use. There are no existing targets using such values. The patch has no effect on existing behaviour. o Reserve return values of 2 and above from target map functions. Any positive value currently indicates "mapping complete", but all existing drivers use the value 1. We now make that a requirement so we can assign new meaning to higher values in future. The new definition of return values from target map functions is: < 0 : error = 0 : The target will handle the io (DM_MAPIO_SUBMITTED). = 1 : Mapping completed (DM_MAPIO_REMAPPED). > 1 : Reserved (undefined). Previously this was the same as '= 1'. o Reserve return values of 2 and above from target end_io functions for similar reasons. DM_ENDIO_INCOMPLETE is introduced for a return value of 1. Test results: I have tested by using the multipath target. I/Os succeed when valid paths exist. I/Os are queued in the multipath target when there are no valid paths and queue_if_no_path is set. I/Os fail when there are no valid paths and queue_if_no_path is not set. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/md/dm.h')
-rw-r--r--drivers/md/dm.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 81c98d6e35e9..293d5ce62a21 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -33,6 +33,17 @@
#define SECTOR_SHIFT 9
/*
+ * Definitions of return values from target end_io function.
+ */
+#define DM_ENDIO_INCOMPLETE 1
+
+/*
+ * Definitions of return values from target map function.
+ */
+#define DM_MAPIO_SUBMITTED 0
+#define DM_MAPIO_REMAPPED 1
+
+/*
* Suspend feature flags
*/
#define DM_SUSPEND_LOCKFS_FLAG (1 << 0)