dm mpath: push path selector locking down to path selectors

[cascardo/linux.git] / drivers / md / dm-service-time.c

diff --git a/drivers/md/dm-service-time.c b/drivers/md/dm-service-time.c
index 9df8f6b..d09bcbe 100644 (file)
--- a/drivers/md/dm-service-time.c
+++ b/drivers/md/dm-service-time.c
@@ -19,11 +19,12 @@
 #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;
        struct list_head failed_paths;
+       spinlock_t lock;
 };
 
 struct path_info {
@@ -41,6 +42,7 @@ static struct selector *alloc_selector(void)
        if (s) {
                INIT_LIST_HEAD(&s->valid_paths);
                INIT_LIST_HEAD(&s->failed_paths);
+               spin_lock_init(&s->lock);
        }
 
        return s;
@@ -111,6 +113,7 @@ static int st_add_path(struct path_selector *ps, struct dm_path *path,
        unsigned repeat_count = ST_MIN_IO;
        unsigned relative_throughput = 1;
        char dummy;
+       unsigned long flags;
 
        /*
         * Arguments: [<repeat_count> [<relative_throughput>]]
@@ -134,6 +137,11 @@ 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)) {
@@ -155,7 +163,9 @@ static int st_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;
 }
@@ -164,16 +174,22 @@ static void st_fail_path(struct path_selector *ps, struct dm_path *path)
 {
        struct selector *s = ps->context;
        struct path_info *pi = path->pscontext;
+       unsigned long flags;
 
+       spin_lock_irqsave(&s->lock, flags);
        list_move(&pi->list, &s->failed_paths);
+       spin_unlock_irqrestore(&s->lock, flags);
 }
 
 static int st_reinstate_path(struct path_selector *ps, struct dm_path *path)
 {
        struct selector *s = ps->context;
        struct path_info *pi = path->pscontext;
+       unsigned long flags;
 
+       spin_lock_irqsave(&s->lock, flags);
        list_move_tail(&pi->list, &s->valid_paths);
+       spin_unlock_irqrestore(&s->lock, flags);
 
        return 0;
 }
@@ -260,9 +276,12 @@ static struct dm_path *st_select_path(struct path_selector *ps,
 {
        struct selector *s = ps->context;
        struct path_info *pi = NULL, *best = NULL;
+       struct dm_path *ret = NULL;
+       unsigned long flags;
 
+       spin_lock_irqsave(&s->lock, flags);
        if (list_empty(&s->valid_paths))
-               return NULL;
+               goto out;
 
        /* Change preferred (first in list) path to evenly balance. */
        list_move_tail(s->valid_paths.next, &s->valid_paths);
@@ -272,11 +291,14 @@ static struct dm_path *st_select_path(struct path_selector *ps,
                        best = pi;
 
        if (!best)
-               return NULL;
+               goto out;
 
        *repeat_count = best->repeat_count;
 
-       return best->path;
+       ret = best->path;
+out:
+       spin_unlock_irqrestore(&s->lock, flags);
+       return ret;
 }
 
 static int st_start_io(struct path_selector *ps, struct dm_path *path,