bcache: Correctly check against BIO_MAX_PAGES

bch_bio_max_sectors() was checking against BIO_MAX_PAGES as if the limit
was for the total bytes in the bio, not the number of segments.

Signed-off-by: Kent Overstreet <koverstreet@google.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c
index b4c0e28a7cd1..5304eaab6cbe 100644
--- a/drivers/md/bcache/io.c
+++ b/drivers/md/bcache/io.c
@@ -158,8 +158,10 @@ static unsigned bch_bio_max_sectors(struct bio *bio)
 {
         unsigned ret = bio_sectors(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), queue_max_segments(q));
+                min_t(int, bio_segments(bio), max_segments);
 
         struct bvec_merge_data bvm = {
                 .bi_bdev        = bio->bi_bdev,
@@ -171,7 +173,7 @@ static unsigned bch_bio_max_sectors(struct bio *bio)
         if (bio->bi_rw & REQ_DISCARD)
                 return min(ret, q->limits.max_discard_sectors);
 
-        if (bio_segments(bio) > queue_max_segments(q) ||
+        if (bio_segments(bio) > max_segments ||
             q->merge_bvec_fn) {
                 ret = 0;
 
@@ -183,9 +185,6 @@ static unsigned bch_bio_max_sectors(struct bio *bio)
                         ret             += bv->bv_len >> 9;
                         bvm.bi_size     += bv->bv_len;
                 }
-
-                if (ret >= (BIO_MAX_PAGES * PAGE_SIZE) >> 9)
-                        return (BIO_MAX_PAGES * PAGE_SIZE) >> 9;
         }
 
         ret = min(ret, queue_max_sectors(q));