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dm mpath: remove repeat_count support from multipath core 

Preparation for making __multipath_map() avoid taking the m->lock
spinlock -- in favor of using RCU locking.

repeat_count was primarily for bio-based DM multipath's benefit.  There
is really no need for it anymore now that DM multipath is request-based.
As such, repeat_count > 1 is no longer honored and a warning is
displayed if the user attempts to use a value > 1.  This is a temporary
change for the round-robin path-selector (as a later commit will restore
its support for repeat_count > 1).

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer 2016-02-10 11:58:45 -05:00
parent 7943bd6dd3
commit 21136f89d7
4 changed files with 24 additions and 10 deletions
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7
drivers/md/dm-mpath.c
View File

@ -83,7 +83,6 @@ struct multipath {
struct pgpath *current_pgpath;
struct priority_group *current_pg;
struct priority_group *next_pg; /* Switch to this PG if set */
unsigned repeat_count; /* I/Os left before calling PS again */
unsigned queue_io:1; /* Must we queue all I/O? */
unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */
@ -319,8 +318,9 @@ static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
size_t nr_bytes)
{
struct dm_path *path;
unsigned repeat_count;
path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
path = pg->ps.type->select_path(&pg->ps, &repeat_count, nr_bytes);
if (!path)
return -ENXIO;
@ -412,8 +412,7 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
spin_lock_irq(&m->lock);
/* Do we need to select a new pgpath? */
if (!m->current_pgpath ||
(!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
if (!m->current_pgpath || !m->queue_io)
__choose_pgpath(m, nr_bytes);
pgpath = m->current_pgpath;

9
drivers/md/dm-queue-length.c
View File

@ -23,8 +23,8 @@
#include <linux/atomic.h>
#define DM_MSG_PREFIX "multipath queue-length"
#define QL_MIN_IO 128
#define QL_VERSION "0.1.0"
#define QL_MIN_IO 1
#define QL_VERSION "0.2.0"
struct selector {
struct list_head valid_paths;
@ -129,6 +129,11 @@ static int ql_add_path(struct path_selector *ps, struct dm_path *path,
return -EINVAL;
}
if (repeat_count > 1) {
DMWARN_LIMIT("repeat_count > 1 is deprecated, using 1 instead");
repeat_count = 1;
}
/* Allocate the path information structure */
pi = kmalloc(sizeof(*pi), GFP_KERNEL);
if (!pi) {

11
drivers/md/dm-round-robin.c
View File

@ -17,6 +17,8 @@
#include <linux/module.h>
#define DM_MSG_PREFIX "multipath round-robin"
#define RR_MIN_IO 1
#define RR_VERSION "1.1.0"
/*-----------------------------------------------------------------
* Path-handling code, paths are held in lists
@ -41,8 +43,6 @@ static void free_paths(struct list_head *paths)
* Round-robin selector
*---------------------------------------------------------------*/
#define RR_MIN_IO 1000
struct selector {
struct list_head valid_paths;
struct list_head invalid_paths;
@ -127,6 +127,11 @@ static int rr_add_path(struct path_selector *ps, struct dm_path *path,
return -EINVAL;
}
if (repeat_count > 1) {
DMWARN_LIMIT("repeat_count > 1 is deprecated, using 1 instead");
repeat_count = 1;
}
/* allocate the path */
pi = kmalloc(sizeof(*pi), GFP_KERNEL);
if (!pi) {
@ -198,7 +203,7 @@ static int __init dm_rr_init(void)
if (r < 0)
DMERR("register failed %d", r);
DMINFO("version 1.0.0 loaded");
DMINFO("version " RR_VERSION " loaded");
return r;
}

7
drivers/md/dm-service-time.c
View File

@ -19,7 +19,7 @@
#define ST_MAX_RELATIVE_THROUGHPUT 100
#define ST_MAX_RELATIVE_THROUGHPUT_SHIFT 7
#define ST_MAX_INFLIGHT_SIZE ((size_t)-1 >> ST_MAX_RELATIVE_THROUGHPUT_SHIFT)
#define ST_VERSION "0.2.0"
#define ST_VERSION "0.3.0"
struct selector {
struct list_head valid_paths;
@ -134,6 +134,11 @@ static int st_add_path(struct path_selector *ps, struct dm_path *path,
return -EINVAL;
}
if (repeat_count > 1) {
DMWARN_LIMIT("repeat_count > 1 is deprecated, using 1 instead");
repeat_count = 1;
}
if ((argc == 2) &&
(sscanf(argv[1], "%u%c", &relative_throughput, &dummy) != 1 ||
relative_throughput > ST_MAX_RELATIVE_THROUGHPUT)) {