UBUNTU: Ubuntu-4.10.0-37.41

[mirror_ubuntu-zesty-kernel.git] / block / blk-core.c

diff --git a/block/blk-core.c b/block/blk-core.c
index 61ba08c58b649b54fdfbc4e06c7e1b11b015512a..9734b5d0d932c799788109b479538f717a501c7f 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1977,7 +1977,14 @@ end_io:
  */
 blk_qc_t generic_make_request(struct bio *bio)
 {
-       struct bio_list bio_list_on_stack;
+       /*
+        * bio_list_on_stack[0] contains bios submitted by the current
+        * make_request_fn.
+        * bio_list_on_stack[1] contains bios that were submitted before
+        * the current make_request_fn, but that haven't been processed
+        * yet.
+        */
+       struct bio_list bio_list_on_stack[2];
        blk_qc_t ret = BLK_QC_T_NONE;
 
        if (!generic_make_request_checks(bio))
@@ -1994,7 +2001,7 @@ blk_qc_t generic_make_request(struct bio *bio)
         * should be added at the tail
         */
        if (current->bio_list) {
-               bio_list_add(current->bio_list, bio);
+               bio_list_add(&current->bio_list[0], bio);
                goto out;
        }
 
@@ -2013,23 +2020,39 @@ blk_qc_t generic_make_request(struct bio *bio)
         * bio_list, and call into ->make_request() again.
         */
        BUG_ON(bio->bi_next);
-       bio_list_init(&bio_list_on_stack);
-       current->bio_list = &bio_list_on_stack;
+       bio_list_init(&bio_list_on_stack[0]);
+       current->bio_list = bio_list_on_stack;
        do {
                struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 
                if (likely(blk_queue_enter(q, false) == 0)) {
+                       struct bio_list lower, same;
+
+                       /* Create a fresh bio_list for all subordinate requests */
+                       bio_list_on_stack[1] = bio_list_on_stack[0];
+                       bio_list_init(&bio_list_on_stack[0]);
                        ret = q->make_request_fn(q, bio);
 
                        blk_queue_exit(q);
 
-                       bio = bio_list_pop(current->bio_list);
+                       /* sort new bios into those for a lower level
+                        * and those for the same level
+                        */
+                       bio_list_init(&lower);
+                       bio_list_init(&same);
+                       while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
+                               if (q == bdev_get_queue(bio->bi_bdev))
+                                       bio_list_add(&same, bio);
+                               else
+                                       bio_list_add(&lower, bio);
+                       /* now assemble so we handle the lowest level first */
+                       bio_list_merge(&bio_list_on_stack[0], &lower);
+                       bio_list_merge(&bio_list_on_stack[0], &same);
+                       bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
                } else {
-                       struct bio *bio_next = bio_list_pop(current->bio_list);
-
                        bio_io_error(bio);
-                       bio = bio_next;
                }
+               bio = bio_list_pop(&bio_list_on_stack[0]);
        } while (bio);
        current->bio_list = NULL; /* deactivate */