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Go Back   Linux Archive > Redhat > Device-mapper Development

 
 
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Old 05-08-2012, 03:19 AM
Mike Snitzer
 
Default dm mpath: add support for using previously attached scsi_dh

Use the previously attached scsi_dh if "default" is provided as the
hardware handler name (the new 'use_default_hw_handler' flag is set in
the multipath structure).

Leverage scsi_dh_attach's ability to increment the scsi_dh's reference
count if the same scsi_dh name is provided when attaching -- currently
attached scsi_dh name is determined with scsi_dh_attached_handler_name.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
drivers/md/dm-mpath.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)

Index: linux-2.6/drivers/md/dm-mpath.c
================================================== =================
--- linux-2.6.orig/drivers/md/dm-mpath.c
+++ linux-2.6/drivers/md/dm-mpath.c
@@ -63,6 +63,7 @@ struct multipath {

spinlock_t lock;

+ unsigned use_default_hw_handler:1;
const char *hw_handler_name;
char *hw_handler_params;

@@ -566,6 +567,7 @@ static struct pgpath *parse_path(struct
int r;
struct pgpath *p;
struct multipath *m = ti->private;
+ struct request_queue *q = NULL;

/* we need at least a path arg */
if (as->argc < 1) {
@@ -584,9 +586,16 @@ static struct pgpath *parse_path(struct
goto bad;
}

- if (m->hw_handler_name) {
- struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
+ if (m->use_default_hw_handler || m->hw_handler_name)
+ q = bdev_get_queue(p->path.dev->bdev);
+
+ if (m->use_default_hw_handler) {
+ const char *attached_handler_name = scsi_dh_attached_handler_name(q);
+ if (attached_handler_name)
+ m->hw_handler_name = kstrdup(attached_handler_name, GFP_KERNEL);
+ }

+ if (m->hw_handler_name) {
r = scsi_dh_attach(q, m->hw_handler_name);
if (r == -EBUSY) {
/*
@@ -706,6 +715,7 @@ static int parse_hw_handler(struct dm_ar
unsigned hw_argc;
int ret;
struct dm_target *ti = m->ti;
+ const char *hw_handler_name;

static struct dm_arg _args[] = {
{0, 1024, "invalid number of hardware handler args"},
@@ -717,7 +727,13 @@ static int parse_hw_handler(struct dm_ar
if (!hw_argc)
return 0;

- m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
+ hw_handler_name = dm_shift_arg(as);
+ if (!strncmp(hw_handler_name, "default", 8)) {
+ m->use_default_hw_handler = 1;
+ goto parse_hw_handler_params;
+ }
+
+ m->hw_handler_name = kstrdup(hw_handler_name, GFP_KERNEL);
if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name),
"scsi_dh_%s", m->hw_handler_name)) {
ti->error = "unknown hardware handler type";
@@ -725,6 +741,7 @@ static int parse_hw_handler(struct dm_ar
goto fail;
}

+parse_hw_handler_params:
if (hw_argc > 1) {
char *p;
int i, j, len = 4;

--
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