2 files changed, 183 insertions, 187 deletions

diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index 967aacd20625..ea0814b51574 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -260,7 +260,7 @@ struct btree_op {
         } type:8;
 
         unsigned                csum:1;
-        unsigned                skip:1;
+        unsigned                bypass:1;
         unsigned                flush_journal:1;
 
         unsigned                insert_data_done:1;
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index a000e918b795..dbc2ef6e7a35 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -25,8 +25,6 @@
 
 struct kmem_cache *bch_search_cache;
 
-static void check_should_skip(struct cached_dev *, struct search *);
-
 /* Cgroup interface */
 
 #ifdef CONFIG_CGROUP_BCACHE
@@ -480,7 +478,7 @@ static void bch_insert_data_loop(struct closure *cl)
         struct search *s = container_of(op, struct search, op);
         struct bio *bio = op->cache_bio, *n;
 
-        if (op->skip)
+        if (op->bypass)
                 return bio_invalidate(cl);
 
         if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
@@ -557,7 +555,7 @@ err:
                  * we wait for buckets to be freed up, so just invalidate the
                  * rest of the write.
                  */
-                op->skip = true;
+                op->bypass = true;
                 return bio_invalidate(cl);
         } else {
                 /*
@@ -590,8 +588,8 @@ err:
  * It inserts the data in op->cache_bio; bi_sector is used for the key offset,
  * and op->inode is used for the key inode.
  *
- * If op->skip is true, instead of inserting the data it invalidates the region
- * of the cache represented by op->cache_bio and op->inode.
+ * If op->bypass is true, instead of inserting the data it invalidates the
+ * region of the cache represented by op->cache_bio and op->inode.
  */
 void bch_insert_data(struct closure *cl)
 {
@@ -717,7 +715,6 @@ static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
         s->orig_bio             = bio;
         s->write                = (bio->bi_rw & REQ_WRITE) != 0;
         s->op.flush_journal     = (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
-        s->op.skip              = (bio->bi_rw & REQ_DISCARD) != 0;
         s->recoverable          = 1;
         s->start_time           = jiffies;
         do_bio_hook(s);
@@ -757,6 +754,134 @@ static void cached_dev_bio_complete(struct closure *cl)
         cached_dev_put(dc);
 }
 
+unsigned bch_get_congested(struct cache_set *c)
+{
+        int i;
+        long rand;
+
+        if (!c->congested_read_threshold_us &&
+            !c->congested_write_threshold_us)
+                return 0;
+
+        i = (local_clock_us() - c->congested_last_us) / 1024;
+        if (i < 0)
+                return 0;
+
+        i += atomic_read(&c->congested);
+        if (i >= 0)
+                return 0;
+
+        i += CONGESTED_MAX;
+
+        if (i > 0)
+                i = fract_exp_two(i, 6);
+
+        rand = get_random_int();
+        i -= bitmap_weight(&rand, BITS_PER_LONG);
+
+        return i > 0 ? i : 1;
+}
+
+static void add_sequential(struct task_struct *t)
+{
+        ewma_add(t->sequential_io_avg,
+                 t->sequential_io, 8, 0);
+
+        t->sequential_io = 0;
+}
+
+static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
+{
+        return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
+}
+
+static bool check_should_bypass(struct cached_dev *dc, struct search *s)
+{
+        struct cache_set *c = s->op.c;
+        struct bio *bio = &s->bio.bio;
+        unsigned mode = cache_mode(dc, bio);
+        unsigned sectors, congested = bch_get_congested(c);
+
+        if (atomic_read(&dc->disk.detaching) ||
+            c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
+            (bio->bi_rw & REQ_DISCARD))
+                goto skip;
+
+        if (mode == CACHE_MODE_NONE ||
+            (mode == CACHE_MODE_WRITEAROUND &&
+             (bio->bi_rw & REQ_WRITE)))
+                goto skip;
+
+        if (bio->bi_sector & (c->sb.block_size - 1) ||
+            bio_sectors(bio) & (c->sb.block_size - 1)) {
+                pr_debug("skipping unaligned io");
+                goto skip;
+        }
+
+        if (!congested && !dc->sequential_cutoff)
+                goto rescale;
+
+        if (!congested &&
+            mode == CACHE_MODE_WRITEBACK &&
+            (bio->bi_rw & REQ_WRITE) &&
+            (bio->bi_rw & REQ_SYNC))
+                goto rescale;
+
+        if (dc->sequential_merge) {
+                struct io *i;
+
+                spin_lock(&dc->io_lock);
+
+                hlist_for_each_entry(i, iohash(dc, bio->bi_sector), hash)
+                        if (i->last == bio->bi_sector &&
+                            time_before(jiffies, i->jiffies))
+                                goto found;
+
+                i = list_first_entry(&dc->io_lru, struct io, lru);
+
+                add_sequential(s->task);
+                i->sequential = 0;
+found:
+                if (i->sequential + bio->bi_size > i->sequential)
+                        i->sequential   += bio->bi_size;
+
+                i->last                  = bio_end_sector(bio);
+                i->jiffies               = jiffies + msecs_to_jiffies(5000);
+                s->task->sequential_io   = i->sequential;
+
+                hlist_del(&i->hash);
+                hlist_add_head(&i->hash, iohash(dc, i->last));
+                list_move_tail(&i->lru, &dc->io_lru);
+
+                spin_unlock(&dc->io_lock);
+        } else {
+                s->task->sequential_io = bio->bi_size;
+
+                add_sequential(s->task);
+        }
+
+        sectors = max(s->task->sequential_io,
+                      s->task->sequential_io_avg) >> 9;
+
+        if (dc->sequential_cutoff &&
+            sectors >= dc->sequential_cutoff >> 9) {
+                trace_bcache_bypass_sequential(s->orig_bio);
+                goto skip;
+        }
+
+        if (congested && sectors >= congested) {
+                trace_bcache_bypass_congested(s->orig_bio);
+                goto skip;
+        }
+
+rescale:
+        bch_rescale_priorities(c, bio_sectors(bio));
+        return false;
+skip:
+        bch_mark_sectors_bypassed(s, bio_sectors(bio));
+        return true;
+}
+
 /* Process reads */
 
 static void cached_dev_read_complete(struct closure *cl)
@@ -854,8 +979,8 @@ static void request_read_done_bh(struct closure *cl)
         struct search *s = container_of(cl, struct search, cl);
         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 
-        bch_mark_cache_accounting(s, !s->cache_miss, s->op.skip);
-        trace_bcache_read(s->orig_bio, !s->cache_miss, s->op.skip);
+        bch_mark_cache_accounting(s, !s->cache_miss, s->op.bypass);
+        trace_bcache_read(s->orig_bio, !s->cache_miss, s->op.bypass);
 
         if (s->error)
                 continue_at_nobarrier(cl, request_read_error, bcache_wq);
@@ -873,7 +998,7 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
         struct bio *miss;
 
-        if (s->cache_miss || s->op.skip) {
+        if (s->cache_miss || s->op.bypass) {
                 miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
                 if (miss == bio)
                         s->op.lookup_done = true;
@@ -940,9 +1065,7 @@ static void request_read(struct cached_dev *dc, struct search *s)
 {
         struct closure *cl = &s->cl;
 
-        check_should_skip(dc, s);
         closure_call(&s->op.cl, btree_read_async, NULL, cl);
-
         continue_at(cl, request_read_done_bh, NULL);
 }
 
@@ -961,41 +1084,48 @@ static void request_write(struct cached_dev *dc, struct search *s)
 {
         struct closure *cl = &s->cl;
         struct bio *bio = &s->bio.bio;
-        struct bkey start, end;
-        start = KEY(dc->disk.id, bio->bi_sector, 0);
-        end = KEY(dc->disk.id, bio_end_sector(bio), 0);
+        struct bkey start = KEY(dc->disk.id, bio->bi_sector, 0);
+        struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0);
 
         bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys, &start, &end);
 
-        check_should_skip(dc, s);
         down_read_non_owner(&dc->writeback_lock);
-
         if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) {
-                s->op.skip      = false;
+                /*
+                 * We overlap with some dirty data undergoing background
+                 * writeback, force this write to writeback
+                 */
+                s->op.bypass    = false;
                 s->writeback    = true;
         }
 
+        /*
+         * Discards aren't _required_ to do anything, so skipping if
+         * check_overlapping returned true is ok
+         *
+         * But check_overlapping drops dirty keys for which io hasn't started,
+         * so we still want to call it.
+         */
         if (bio->bi_rw & REQ_DISCARD)
-                goto skip;
+                s->op.bypass = true;
 
         if (should_writeback(dc, s->orig_bio,
                              cache_mode(dc, bio),
-                             s->op.skip)) {
-                s->op.skip = false;
+                             s->op.bypass)) {
+                s->op.bypass = false;
                 s->writeback = true;
         }
 
-        if (s->op.skip)
-                goto skip;
-
-        trace_bcache_write(s->orig_bio, s->writeback, s->op.skip);
+        trace_bcache_write(s->orig_bio, s->writeback, s->op.bypass);
 
-        if (!s->writeback) {
-                s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
-                                                   dc->disk.bio_split);
+        if (s->op.bypass) {
+                s->op.cache_bio = s->orig_bio;
+                bio_get(s->op.cache_bio);
 
-                closure_bio_submit(bio, cl, s->d);
-        } else {
+                if (!(bio->bi_rw & REQ_DISCARD) ||
+                    blk_queue_discard(bdev_get_queue(dc->bdev)))
+                        closure_bio_submit(bio, cl, s->d);
+        } else if (s->writeback) {
                 bch_writeback_add(dc);
                 s->op.cache_bio = bio;
 
@@ -1011,21 +1141,15 @@ static void request_write(struct cached_dev *dc, struct search *s)
 
                         closure_bio_submit(flush, cl, s->d);
                 }
+        } else {
+                s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
+                                                   dc->disk.bio_split);
+
+                closure_bio_submit(bio, cl, s->d);
         }
-out:
+
         closure_call(&s->op.cl, bch_insert_data, NULL, cl);
         continue_at(cl, cached_dev_write_complete, NULL);
-skip:
-        s->op.skip = true;
-        s->op.cache_bio = s->orig_bio;
-        bio_get(s->op.cache_bio);
-
-        if ((bio->bi_rw & REQ_DISCARD) &&
-            !blk_queue_discard(bdev_get_queue(dc->bdev)))
-                goto out;
-
-        closure_bio_submit(bio, cl, s->d);
-        goto out;
 }
 
 static void request_nodata(struct cached_dev *dc, struct search *s)
@@ -1033,14 +1157,10 @@ static void request_nodata(struct cached_dev *dc, struct search *s)
         struct closure *cl = &s->cl;
         struct bio *bio = &s->bio.bio;
 
-        if (bio->bi_rw & REQ_DISCARD) {
-                request_write(dc, s);
-                return;
-        }
-
         if (s->op.flush_journal)
                 bch_journal_meta(s->op.c, cl);
 
+        /* If it's a flush, we send the flush to the backing device too */
         closure_bio_submit(bio, cl, s->d);
 
         continue_at(cl, cached_dev_bio_complete, NULL);
@@ -1048,134 +1168,6 @@ static void request_nodata(struct cached_dev *dc, struct search *s)
 
 /* Cached devices - read & write stuff */
 
-unsigned bch_get_congested(struct cache_set *c)
-{
-        int i;
-        long rand;
-
-        if (!c->congested_read_threshold_us &&
-            !c->congested_write_threshold_us)
-                return 0;
-
-        i = (local_clock_us() - c->congested_last_us) / 1024;
-        if (i < 0)
-                return 0;
-
-        i += atomic_read(&c->congested);
-        if (i >= 0)
-                return 0;
-
-        i += CONGESTED_MAX;
-
-        if (i > 0)
-                i = fract_exp_two(i, 6);
-
-        rand = get_random_int();
-        i -= bitmap_weight(&rand, BITS_PER_LONG);
-
-        return i > 0 ? i : 1;
-}
-
-static void add_sequential(struct task_struct *t)
-{
-        ewma_add(t->sequential_io_avg,
-                 t->sequential_io, 8, 0);
-
-        t->sequential_io = 0;
-}
-
-static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
-{
-        return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
-}
-
-static void check_should_skip(struct cached_dev *dc, struct search *s)
-{
-        struct cache_set *c = s->op.c;
-        struct bio *bio = &s->bio.bio;
-        unsigned mode = cache_mode(dc, bio);
-        unsigned sectors, congested = bch_get_congested(c);
-
-        if (atomic_read(&dc->disk.detaching) ||
-            c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
-            (bio->bi_rw & REQ_DISCARD))
-                goto skip;
-
-        if (mode == CACHE_MODE_NONE ||
-            (mode == CACHE_MODE_WRITEAROUND &&
-             (bio->bi_rw & REQ_WRITE)))
-                goto skip;
-
-        if (bio->bi_sector   & (c->sb.block_size - 1) ||
-            bio_sectors(bio) & (c->sb.block_size - 1)) {
-                pr_debug("skipping unaligned io");
-                goto skip;
-        }
-
-        if (!congested && !dc->sequential_cutoff)
-                goto rescale;
-
-        if (!congested &&
-            mode == CACHE_MODE_WRITEBACK &&
-            (bio->bi_rw & REQ_WRITE) &&
-            (bio->bi_rw & REQ_SYNC))
-                goto rescale;
-
-        if (dc->sequential_merge) {
-                struct io *i;
-
-                spin_lock(&dc->io_lock);
-
-                hlist_for_each_entry(i, iohash(dc, bio->bi_sector), hash)
-                        if (i->last == bio->bi_sector &&
-                            time_before(jiffies, i->jiffies))
-                                goto found;
-
-                i = list_first_entry(&dc->io_lru, struct io, lru);
-
-                add_sequential(s->task);
-                i->sequential = 0;
-found:
-                if (i->sequential + bio->bi_size > i->sequential)
-                        i->sequential   += bio->bi_size;
-
-                i->last                  = bio_end_sector(bio);
-                i->jiffies               = jiffies + msecs_to_jiffies(5000);
-                s->task->sequential_io   = i->sequential;
-
-                hlist_del(&i->hash);
-                hlist_add_head(&i->hash, iohash(dc, i->last));
-                list_move_tail(&i->lru, &dc->io_lru);
-
-                spin_unlock(&dc->io_lock);
-        } else {
-                s->task->sequential_io = bio->bi_size;
-
-                add_sequential(s->task);
-        }
-
-        sectors = max(s->task->sequential_io,
-                      s->task->sequential_io_avg) >> 9;
-
-        if (dc->sequential_cutoff &&
-            sectors >= dc->sequential_cutoff >> 9) {
-                trace_bcache_bypass_sequential(s->orig_bio);
-                goto skip;
-        }
-
-        if (congested && sectors >= congested) {
-                trace_bcache_bypass_congested(s->orig_bio);
-                goto skip;
-        }
-
-rescale:
-        bch_rescale_priorities(c, bio_sectors(bio));
-        return;
-skip:
-        bch_mark_sectors_bypassed(s, bio_sectors(bio));
-        s->op.skip = true;
-}
-
 static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
 {
         struct search *s;
@@ -1195,12 +1187,16 @@ static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
                 s = search_alloc(bio, d);
                 trace_bcache_request_start(s, bio);
 
-                if (!bio_has_data(bio))
+                if (!bio->bi_size)
                         request_nodata(dc, s);
-                else if (rw)
-                        request_write(dc, s);
-                else
-                        request_read(dc, s);
+                else {
+                        s->op.bypass = check_should_bypass(dc, s);
+
+                        if (rw)
+                                request_write(dc, s);
+                        else
+                                request_read(dc, s);
+                }
         } else {
                 if ((bio->bi_rw & REQ_DISCARD) &&
                     !blk_queue_discard(bdev_get_queue(dc->bdev)))
@@ -1298,21 +1294,21 @@ static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
 
         trace_bcache_request_start(s, bio);
 
-        if (bio_has_data(bio) && !rw) {
-                closure_call(&s->op.cl, btree_read_async, NULL, cl);
-        } else if (bio_has_data(bio) || s->op.skip) {
+        if (!bio->bi_size) {
+                if (s->op.flush_journal)
+                        bch_journal_meta(s->op.c, cl);
+        } else if (rw) {
                 bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys,
                                         &KEY(d->id, bio->bi_sector, 0),
                                         &KEY(d->id, bio_end_sector(bio), 0));
 
+                s->op.bypass    = (bio->bi_rw & REQ_DISCARD) != 0;
                 s->writeback    = true;
                 s->op.cache_bio = bio;
 
                 closure_call(&s->op.cl, bch_insert_data, NULL, cl);
         } else {
-                /* No data - probably a cache flush */
-                if (s->op.flush_journal)
-                        bch_journal_meta(s->op.c, cl);
+                closure_call(&s->op.cl, btree_read_async, NULL, cl);
         }
 
         continue_at(cl, search_free, NULL);