dm path selector: remove 'repeat_count' return from .select_path hook

[cascardo/linux.git] / drivers / md / dm-queue-length.c

diff --git a/drivers/md/dm-queue-length.c b/drivers/md/dm-queue-length.c
index 3941fae..23f1786 100644 (file)
--- a/drivers/md/dm-queue-length.c
+++ b/drivers/md/dm-queue-length.c
@@ -23,12 +23,13 @@
 #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;
        struct list_head        failed_paths;
+       spinlock_t lock;
 };
 
 struct path_info {
@@ -45,6 +46,7 @@ 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;
@@ -113,6 +115,7 @@ static int ql_add_path(struct path_selector *ps, struct dm_path *path,
        struct path_info *pi;
        unsigned repeat_count = QL_MIN_IO;
        char dummy;
+       unsigned long flags;
 
        /*
         * Arguments: [<repeat_count>]
@@ -129,6 +132,11 @@ 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) {
@@ -142,7 +150,9 @@ static int ql_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;
 }
@@ -151,16 +161,22 @@ static void ql_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 ql_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;
 }
@@ -168,14 +184,16 @@ static int ql_reinstate_path(struct path_selector *ps, struct dm_path *path)
 /*
  * Select a path having the minimum number of in-flight I/Os
  */
-static struct dm_path *ql_select_path(struct path_selector *ps,
-                                     unsigned *repeat_count, size_t nr_bytes)
+static struct dm_path *ql_select_path(struct path_selector *ps, size_t nr_bytes)
 {
        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);
@@ -190,11 +208,12 @@ static struct dm_path *ql_select_path(struct path_selector *ps,
        }
 
        if (!best)
-               return NULL;
-
-       *repeat_count = best->repeat_count;
+               goto out;
 
-       return best->path;
+       ret = best->path;
+out:
+       spin_unlock_irqrestore(&s->lock, flags);
+       return ret;
 }
 
 static int ql_start_io(struct path_selector *ps, struct dm_path *path,