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[1/2] dm-mpath: add a path selector interface

Message ID 49815480.2070601@ct.jp.nec.com (mailing list archive)
State Superseded, archived
Delegated to: Alasdair Kergon
Headers show

Commit Message

Kiyoshi Ueda Jan. 29, 2009, 7:02 a.m. UTC 
This patch adds a new hook for dm path selector: start_io.
Target drivers should call this hook before submitting I/O to
the selected path.
Path selectors can use it to start accounting of the I/O.
(e.g. counting the number of in-flight I/Os.)

The code is based on the patch posted by Stefan Bader:
https://www.redhat.com/archives/dm-devel/2005-October/msg00050.html


Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Vijayakumar Balasubramanian <vijayakumar@hp.com>
Cc: Alasdair G Kergon <agk@redhat.com>
---
 drivers/md/dm-mpath.c         |    3 +++
 drivers/md/dm-path-selector.h |    1 +
 2 files changed, 4 insertions(+)


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diff mbox

Patch

Index: 2.6.29-rc2/drivers/md/dm-mpath.c
===================================================================
--- 2.6.29-rc2.orig/drivers/md/dm-mpath.c
+++ 2.6.29-rc2/drivers/md/dm-mpath.c
@@ -361,6 +361,9 @@  static int map_io(struct multipath *m, s
 
 	mpio->pgpath = pgpath;
 
+	if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
+		pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path);
+
 	spin_unlock_irqrestore(&m->lock, flags);
 
 	return r;
Index: 2.6.29-rc2/drivers/md/dm-path-selector.h
===================================================================
--- 2.6.29-rc2.orig/drivers/md/dm-path-selector.h
+++ 2.6.29-rc2/drivers/md/dm-path-selector.h
@@ -75,6 +75,7 @@  struct path_selector_type {
 	int (*status) (struct path_selector *ps, struct dm_path *path,
 		       status_type_t type, char *result, unsigned int maxlen);
 
+	int (*start_io) (struct path_selector *ps, struct dm_path *path);
 	int (*end_io) (struct path_selector *ps, struct dm_path *path);
 };