1 files changed, 26 insertions, 42 deletions

diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c
index 48efd4dea645..9056632995b1 100644
--- a/drivers/md/bcache/io.c
+++ b/drivers/md/bcache/io.c
@@ -9,6 +9,8 @@
 #include "bset.h"
 #include "debug.h"
 
+#include <linux/blkdev.h>
+
 static void bch_bi_idx_hack_endio(struct bio *bio, int error)
 {
         struct bio *p = bio->bi_private;
@@ -66,13 +68,6 @@ static void bch_generic_make_request_hack(struct bio *bio)
  * The newly allocated bio will point to @bio's bi_io_vec, if the split was on a
  * bvec boundry; it is the caller's responsibility to ensure that @bio is not
  * freed before the split.
- *
- * If bch_bio_split() is running under generic_make_request(), it's not safe to
- * allocate more than one bio from the same bio set. Therefore, if it is running
- * under generic_make_request() it masks out __GFP_WAIT when doing the
- * allocation. The caller must check for failure if there's any possibility of
- * it being called from under generic_make_request(); it is then the caller's
- * responsibility to retry from a safe context (by e.g. punting to workqueue).
  */
 struct bio *bch_bio_split(struct bio *bio, int sectors,
                           gfp_t gfp, struct bio_set *bs)
@@ -83,20 +78,13 @@ struct bio *bch_bio_split(struct bio *bio, int sectors,
 
         BUG_ON(sectors <= 0);
 
-        /*
-         * If we're being called from underneath generic_make_request() and we
-         * already allocated any bios from this bio set, we risk deadlock if we
-         * use the mempool. So instead, we possibly fail and let the caller punt
-         * to workqueue or somesuch and retry in a safe context.
-         */
-        if (current->bio_list)
-                gfp &= ~__GFP_WAIT;
-
         if (sectors >= bio_sectors(bio))
                 return bio;
 
         if (bio->bi_rw & REQ_DISCARD) {
                 ret = bio_alloc_bioset(gfp, 1, bs);
+                if (!ret)
+                        return NULL;
                 idx = 0;
                 goto out;
         }
@@ -160,17 +148,18 @@ static unsigned bch_bio_max_sectors(struct bio *bio)
         struct request_queue *q = bdev_get_queue(bio->bi_bdev);
         unsigned max_segments = min_t(unsigned, BIO_MAX_PAGES,
                                       queue_max_segments(q));
-        struct bio_vec *bv, *end = bio_iovec(bio) +
-                min_t(int, bio_segments(bio), max_segments);
 
         if (bio->bi_rw & REQ_DISCARD)
                 return min(ret, q->limits.max_discard_sectors);
 
         if (bio_segments(bio) > max_segments ||
             q->merge_bvec_fn) {
+                struct bio_vec *bv;
+                int i, seg = 0;
+
                 ret = 0;
 
-                for (bv = bio_iovec(bio); bv < end; bv++) {
+                bio_for_each_segment(bv, bio, i) {
                         struct bvec_merge_data bvm = {
                                 .bi_bdev        = bio->bi_bdev,
                                 .bi_sector      = bio->bi_sector,
@@ -178,10 +167,14 @@ static unsigned bch_bio_max_sectors(struct bio *bio)
                                 .bi_rw          = bio->bi_rw,
                         };
 
+                        if (seg == max_segments)
+                                break;
+
                         if (q->merge_bvec_fn &&
                             q->merge_bvec_fn(q, &bvm, bv) < (int) bv->bv_len)
                                 break;
 
+                        seg++;
                         ret += bv->bv_len >> 9;
                 }
         }
@@ -218,30 +211,10 @@ static void bch_bio_submit_split_endio(struct bio *bio, int error)
         closure_put(cl);
 }
 
-static void __bch_bio_submit_split(struct closure *cl)
-{
-        struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
-        struct bio *bio = s->bio, *n;
-
-        do {
-                n = bch_bio_split(bio, bch_bio_max_sectors(bio),
-                                  GFP_NOIO, s->p->bio_split);
-                if (!n)
-                        continue_at(cl, __bch_bio_submit_split, system_wq);
-
-                n->bi_end_io    = bch_bio_submit_split_endio;
-                n->bi_private   = cl;
-
-                closure_get(cl);
-                bch_generic_make_request_hack(n);
-        } while (n != bio);
-
-        continue_at(cl, bch_bio_submit_split_done, NULL);
-}
-
 void bch_generic_make_request(struct bio *bio, struct bio_split_pool *p)
 {
         struct bio_split_hook *s;
+        struct bio *n;
 
         if (!bio_has_data(bio) && !(bio->bi_rw & REQ_DISCARD))
                 goto submit;
@@ -250,6 +223,7 @@ void bch_generic_make_request(struct bio *bio, struct bio_split_pool *p)
                 goto submit;
 
         s = mempool_alloc(p->bio_split_hook, GFP_NOIO);
+        closure_init(&s->cl, NULL);
 
         s->bio          = bio;
         s->p            = p;
@@ -257,8 +231,18 @@ void bch_generic_make_request(struct bio *bio, struct bio_split_pool *p)
         s->bi_private   = bio->bi_private;
         bio_get(bio);
 
-        closure_call(&s->cl, __bch_bio_submit_split, NULL, NULL);
-        return;
+        do {
+                n = bch_bio_split(bio, bch_bio_max_sectors(bio),
+                                  GFP_NOIO, s->p->bio_split);
+
+                n->bi_end_io    = bch_bio_submit_split_endio;
+                n->bi_private   = &s->cl;
+
+                closure_get(&s->cl);
+                bch_generic_make_request_hack(n);
+        } while (n != bio);
+
+        continue_at(&s->cl, bch_bio_submit_split_done, NULL);
 submit:
         bch_generic_make_request_hack(bio);
 }