bcache: Use blkdev_issue_discard()

The old asynchronous discard code was really a relic from when all the
allocation code was asynchronous - now that allocation runs out of a
dedicated thread there's no point in keeping around all that complicated
machinery.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c
index e45f557..e033b02 100644 (file)
--- a/drivers/md/bcache/alloc.c
+++ b/drivers/md/bcache/alloc.c
@@ -63,13 +63,12 @@
 #include "bcache.h"
 #include "btree.h"
 
+#include <linux/blkdev.h>
 #include <linux/freezer.h>
 #include <linux/kthread.h>
 #include <linux/random.h>
 #include <trace/events/bcache.h>
 
-#define MAX_IN_FLIGHT_DISCARDS         8U
-
 /* Bucket heap / gen */
 
 uint8_t bch_inc_gen(struct cache *ca, struct bucket *b)
@@ -121,75 +120,6 @@ void bch_rescale_priorities(struct cache_set *c, int sectors)
        mutex_unlock(&c->bucket_lock);
 }
 
-/* Discard/TRIM */
-
-struct discard {
-       struct list_head        list;
-       struct work_struct      work;
-       struct cache            *ca;
-       long                    bucket;
-
-       struct bio              bio;
-       struct bio_vec          bv;
-};
-
-static void discard_finish(struct work_struct *w)
-{
-       struct discard *d = container_of(w, struct discard, work);
-       struct cache *ca = d->ca;
-       char buf[BDEVNAME_SIZE];
-
-       if (!test_bit(BIO_UPTODATE, &d->bio.bi_flags)) {
-               pr_notice("discard error on %s, disabling",
-                        bdevname(ca->bdev, buf));
-               d->ca->discard = 0;
-       }
-
-       mutex_lock(&ca->set->bucket_lock);
-
-       fifo_push(&ca->free, d->bucket);
-       list_add(&d->list, &ca->discards);
-       atomic_dec(&ca->discards_in_flight);
-
-       mutex_unlock(&ca->set->bucket_lock);
-
-       closure_wake_up(&ca->set->bucket_wait);
-       wake_up_process(ca->alloc_thread);
-
-       closure_put(&ca->set->cl);
-}
-
-static void discard_endio(struct bio *bio, int error)
-{
-       struct discard *d = container_of(bio, struct discard, bio);
-       schedule_work(&d->work);
-}
-
-static void do_discard(struct cache *ca, long bucket)
-{
-       struct discard *d = list_first_entry(&ca->discards,
-                                            struct discard, list);
-
-       list_del(&d->list);
-       d->bucket = bucket;
-
-       atomic_inc(&ca->discards_in_flight);
-       closure_get(&ca->set->cl);
-
-       bio_init(&d->bio);
-
-       d->bio.bi_sector        = bucket_to_sector(ca->set, d->bucket);
-       d->bio.bi_bdev          = ca->bdev;
-       d->bio.bi_rw            = REQ_WRITE|REQ_DISCARD;
-       d->bio.bi_max_vecs      = 1;
-       d->bio.bi_io_vec        = d->bio.bi_inline_vecs;
-       d->bio.bi_size          = bucket_bytes(ca);
-       d->bio.bi_end_io        = discard_endio;
-       bio_set_prio(&d->bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
-
-       submit_bio(0, &d->bio);
-}
-
 /* Allocation */
 
 static inline bool can_inc_bucket_gen(struct bucket *b)
@@ -398,16 +328,18 @@ static int bch_allocator_thread(void *arg)
                        else
                                break;
 
-                       allocator_wait(ca, (int) fifo_free(&ca->free) >
-                                      atomic_read(&ca->discards_in_flight));
-
                        if (ca->discard) {
-                               allocator_wait(ca, !list_empty(&ca->discards));
-                               do_discard(ca, bucket);
-                       } else {
-                               fifo_push(&ca->free, bucket);
-                               closure_wake_up(&ca->set->bucket_wait);
+                               mutex_unlock(&ca->set->bucket_lock);
+                               blkdev_issue_discard(ca->bdev,
+                                       bucket_to_sector(ca->set, bucket),
+                                       ca->sb.block_size, GFP_KERNEL, 0);
+                               mutex_lock(&ca->set->bucket_lock);
                        }
+
+                       allocator_wait(ca, !fifo_full(&ca->free));
+
+                       fifo_push(&ca->free, bucket);
+                       closure_wake_up(&ca->set->bucket_wait);
                }
 
                /*
@@ -556,22 +488,8 @@ int bch_cache_allocator_start(struct cache *ca)
        return 0;
 }
 
-void bch_cache_allocator_exit(struct cache *ca)
-{
-       struct discard *d;
-
-       while (!list_empty(&ca->discards)) {
-               d = list_first_entry(&ca->discards, struct discard, list);
-               cancel_work_sync(&d->work);
-               list_del(&d->list);
-               kfree(d);
-       }
-}
-
 int bch_cache_allocator_init(struct cache *ca)
 {
-       unsigned i;
-
        /*
         * Reserve:
         * Prio/gen writes first
@@ -589,15 +507,5 @@ int bch_cache_allocator_init(struct cache *ca)
        ca->watermark[WATERMARK_NONE] = ca->free.size / 2 +
                ca->watermark[WATERMARK_MOVINGGC];
 
-       for (i = 0; i < MAX_IN_FLIGHT_DISCARDS; i++) {
-               struct discard *d = kzalloc(sizeof(*d), GFP_KERNEL);
-               if (!d)
-                       return -ENOMEM;
-
-               d->ca = ca;
-               INIT_WORK(&d->work, discard_finish);
-               list_add(&d->list, &ca->discards);
-       }
-
        return 0;
 }

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 0f12382..bf37474 100644 (file)
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -620,15 +620,6 @@ struct cache {
 
        bool                    discard; /* Get rid of? */
 
-       /*
-        * We preallocate structs for issuing discards to buckets, and keep them
-        * on this list when they're not in use; do_discard() issues discards
-        * whenever there's work to do and is called by free_some_buckets() and
-        * when a discard finishes.
-        */
-       atomic_t                discards_in_flight;
-       struct list_head        discards;
-
        struct journal_device   journal;
 
        /* The rest of this all shows up in sysfs */
@@ -1222,7 +1213,6 @@ int bch_btree_cache_alloc(struct cache_set *);
 void bch_moving_init_cache_set(struct cache_set *);
 
 int bch_cache_allocator_start(struct cache *ca);
-void bch_cache_allocator_exit(struct cache *ca);
 int bch_cache_allocator_init(struct cache *ca);
 
 void bch_debug_exit(void);

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 547c4c5..fd37342 100644 (file)
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1725,8 +1725,6 @@ void bch_cache_release(struct kobject *kobj)
        if (ca->set)
                ca->set->cache[ca->sb.nr_this_dev] = NULL;
 
-       bch_cache_allocator_exit(ca);
-
        bio_split_pool_free(&ca->bio_split_hook);
 
        free_pages((unsigned long) ca->disk_buckets, ilog2(bucket_pages(ca)));
@@ -1758,8 +1756,6 @@ static int cache_alloc(struct cache_sb *sb, struct cache *ca)
        __module_get(THIS_MODULE);
        kobject_init(&ca->kobj, &bch_cache_ktype);
 
-       INIT_LIST_HEAD(&ca->discards);
-
        bio_init(&ca->journal.bio);
        ca->journal.bio.bi_max_vecs = 8;
        ca->journal.bio.bi_io_vec = ca->journal.bio.bi_inline_vecs;