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path: root/drivers/md/dm-round-robin.c
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Diffstat (limited to 'drivers/md/dm-round-robin.c')
-rw-r--r--drivers/md/dm-round-robin.c85
1 files changed, 69 insertions, 16 deletions
diff --git a/drivers/md/dm-round-robin.c b/drivers/md/dm-round-robin.c
index 6ab1192cd..4ace1da17 100644
--- a/drivers/md/dm-round-robin.c
+++ b/drivers/md/dm-round-robin.c
@@ -17,6 +17,8 @@
#include <linux/module.h>
#define DM_MSG_PREFIX "multipath round-robin"
+#define RR_MIN_IO 1000
+#define RR_VERSION "1.1.0"
/*-----------------------------------------------------------------
* Path-handling code, paths are held in lists
@@ -41,23 +43,48 @@ 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;
+ spinlock_t lock;
+ struct dm_path * __percpu *current_path;
+ struct percpu_counter repeat_count;
};
+static void set_percpu_current_path(struct selector *s, struct dm_path *path)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ *per_cpu_ptr(s->current_path, cpu) = path;
+}
+
static struct selector *alloc_selector(void)
{
struct selector *s = kmalloc(sizeof(*s), GFP_KERNEL);
- if (s) {
- INIT_LIST_HEAD(&s->valid_paths);
- INIT_LIST_HEAD(&s->invalid_paths);
- }
+ if (!s)
+ return NULL;
+
+ INIT_LIST_HEAD(&s->valid_paths);
+ INIT_LIST_HEAD(&s->invalid_paths);
+ spin_lock_init(&s->lock);
+
+ s->current_path = alloc_percpu(struct dm_path *);
+ if (!s->current_path)
+ goto out_current_path;
+ set_percpu_current_path(s, NULL);
+
+ if (percpu_counter_init(&s->repeat_count, 0, GFP_KERNEL))
+ goto out_repeat_count;
return s;
+
+out_repeat_count:
+ free_percpu(s->current_path);
+out_current_path:
+ kfree(s);
+ return NULL;;
}
static int rr_create(struct path_selector *ps, unsigned argc, char **argv)
@@ -74,10 +101,12 @@ static int rr_create(struct path_selector *ps, unsigned argc, char **argv)
static void rr_destroy(struct path_selector *ps)
{
- struct selector *s = (struct selector *) ps->context;
+ struct selector *s = ps->context;
free_paths(&s->valid_paths);
free_paths(&s->invalid_paths);
+ free_percpu(s->current_path);
+ percpu_counter_destroy(&s->repeat_count);
kfree(s);
ps->context = NULL;
}
@@ -111,10 +140,11 @@ static int rr_status(struct path_selector *ps, struct dm_path *path,
static int rr_add_path(struct path_selector *ps, struct dm_path *path,
int argc, char **argv, char **error)
{
- struct selector *s = (struct selector *) ps->context;
+ struct selector *s = ps->context;
struct path_info *pi;
unsigned repeat_count = RR_MIN_IO;
char dummy;
+ unsigned long flags;
if (argc > 1) {
*error = "round-robin ps: incorrect number of arguments";
@@ -139,42 +169,65 @@ static int rr_add_path(struct path_selector *ps, struct dm_path *path,
path->pscontext = pi;
+ spin_lock_irqsave(&s->lock, flags);
list_add_tail(&pi->list, &s->valid_paths);
+ spin_unlock_irqrestore(&s->lock, flags);
return 0;
}
static void rr_fail_path(struct path_selector *ps, struct dm_path *p)
{
- struct selector *s = (struct selector *) ps->context;
+ unsigned long flags;
+ struct selector *s = ps->context;
struct path_info *pi = p->pscontext;
+ spin_lock_irqsave(&s->lock, flags);
+ if (p == *this_cpu_ptr(s->current_path))
+ set_percpu_current_path(s, NULL);
+
list_move(&pi->list, &s->invalid_paths);
+ spin_unlock_irqrestore(&s->lock, flags);
}
static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p)
{
- struct selector *s = (struct selector *) ps->context;
+ unsigned long flags;
+ struct selector *s = ps->context;
struct path_info *pi = p->pscontext;
+ spin_lock_irqsave(&s->lock, flags);
list_move(&pi->list, &s->valid_paths);
+ spin_unlock_irqrestore(&s->lock, flags);
return 0;
}
-static struct dm_path *rr_select_path(struct path_selector *ps,
- unsigned *repeat_count, size_t nr_bytes)
+static struct dm_path *rr_select_path(struct path_selector *ps, size_t nr_bytes)
{
- struct selector *s = (struct selector *) ps->context;
+ unsigned long flags;
+ struct selector *s = ps->context;
struct path_info *pi = NULL;
+ struct dm_path *current_path = NULL;
+
+ current_path = *this_cpu_ptr(s->current_path);
+ if (current_path) {
+ percpu_counter_dec(&s->repeat_count);
+ if (percpu_counter_read_positive(&s->repeat_count) > 0)
+ return current_path;
+ }
+ spin_lock_irqsave(&s->lock, flags);
if (!list_empty(&s->valid_paths)) {
pi = list_entry(s->valid_paths.next, struct path_info, list);
list_move_tail(&pi->list, &s->valid_paths);
- *repeat_count = pi->repeat_count;
+ percpu_counter_set(&s->repeat_count, pi->repeat_count);
+ set_percpu_current_path(s, pi->path);
+ current_path = pi->path;
}
+ spin_unlock_irqrestore(&s->lock, flags);
- return pi ? pi->path : NULL;
+ return current_path;
}
static struct path_selector_type rr_ps = {
@@ -198,7 +251,7 @@ 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;
}