block: don't check for required features in elevator_match

Checking for the required features in the callers simplifies the code
quite a bit, so do that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221030100714.876891-7-hch@lst.de
[axboe: adjust for dropping patch 1, use __elevator_find()]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/elevator.c b/block/elevator.c
index 9a13d1959b768bf2819aae5d65d0a12b57559551..5781f5d50bb8e741623332156b49cf6c2958ef84 100644 (file)
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -83,10 +83,11 @@ bool elv_bio_merge_ok(struct request *rq, struct bio *bio)
 }
 EXPORT_SYMBOL(elv_bio_merge_ok);
 
-static inline bool elv_support_features(unsigned int elv_features,
-                                       unsigned int required_features)
+static inline bool elv_support_features(struct request_queue *q,
+               const struct elevator_type *e)
 {
-       return (required_features & elv_features) == required_features;
+       return (q->required_elevator_features & e->elevator_features) ==
+               q->required_elevator_features;
 }
 
 /**
@@ -98,37 +99,19 @@ static inline bool elv_support_features(unsigned int elv_features,
  * Return true if the elevator @e name matches @name and if @e provides all
  * the features specified by @required_features.
  */
-static bool elevator_match(const struct elevator_type *e, const char *name,
-                          unsigned int required_features)
+static bool elevator_match(const struct elevator_type *e, const char *name)
 {
-       if (!elv_support_features(e->elevator_features, required_features))
-               return false;
-       if (!strcmp(e->elevator_name, name))
-               return true;
-       if (e->elevator_alias && !strcmp(e->elevator_alias, name))
-               return true;
-
-       return false;
+       return !strcmp(e->elevator_name, name) ||
+               (e->elevator_alias && !strcmp(e->elevator_alias, name));
 }
 
-/**
- * elevator_find - Find an elevator
- * @name: Name of the elevator to find
- * @required_features: Features that the elevator must provide
- *
- * Return the first registered scheduler with name @name and supporting the
- * features @required_features and NULL otherwise.
- */
-static struct elevator_type *elevator_find(const char *name,
-                                          unsigned int required_features)
+static struct elevator_type *__elevator_find(const char *name)
 {
        struct elevator_type *e;
 
-       list_for_each_entry(e, &elv_list, list) {
-               if (elevator_match(e, name, required_features))
+       list_for_each_entry(e, &elv_list, list)
+               if (elevator_match(e, name))
                        return e;
-       }
-
        return NULL;
 }
 
@@ -138,8 +121,8 @@ static struct elevator_type *elevator_find_get(struct request_queue *q,
        struct elevator_type *e;
 
        spin_lock(&elv_list_lock);
-       e = elevator_find(name, q->required_elevator_features);
-       if (e && !elevator_tryget(e))
+       e = __elevator_find(name);
+       if (e && (!elv_support_features(q, e) || !elevator_tryget(e)))
                e = NULL;
        spin_unlock(&elv_list_lock);
        return e;
@@ -538,7 +521,7 @@ int elv_register(struct elevator_type *e)
 
        /* register, don't allow duplicate names */
        spin_lock(&elv_list_lock);
-       if (elevator_find(e->elevator_name, 0)) {
+       if (__elevator_find(e->elevator_name)) {
                spin_unlock(&elv_list_lock);
                kmem_cache_destroy(e->icq_cache);
                return -EBUSY;
@@ -639,8 +622,7 @@ static struct elevator_type *elevator_get_by_features(struct request_queue *q)
        spin_lock(&elv_list_lock);
 
        list_for_each_entry(e, &elv_list, list) {
-               if (elv_support_features(e->elevator_features,
-                                        q->required_elevator_features)) {
+               if (elv_support_features(q, e)) {
                        found = e;
                        break;
                }
@@ -745,7 +727,7 @@ static int elevator_change(struct request_queue *q, const char *elevator_name)
                return elevator_switch(q, NULL);
        }
 
-       if (q->elevator && elevator_match(q->elevator->type, elevator_name, 0))
+       if (q->elevator && elevator_match(q->elevator->type, elevator_name))
                return 0;
 
        e = elevator_find_get(q, elevator_name);
@@ -796,8 +778,7 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name)
                        len += sprintf(name+len, "[%s] ", cur->elevator_name);
                        continue;
                }
-               if (elevator_match(e, e->elevator_name,
-                                  q->required_elevator_features))
+               if (elv_support_features(q, e))
                        len += sprintf(name+len, "%s ", e->elevator_name);
        }
        spin_unlock(&elv_list_lock);