block: return on congested block device

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

diff --git a/block/blk-core.c b/block/blk-core.c
index 62cf92550512241249c4bc4f05cae285e75587db..279e3c432d7be15793b54073d1cb65b6f98662ab 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -143,6 +143,7 @@ static const struct {
        [BLK_STS_MEDIUM]        = { -ENODATA,   "critical medium" },
        [BLK_STS_PROTECTION]    = { -EILSEQ,    "protection" },
        [BLK_STS_RESOURCE]      = { -ENOMEM,    "kernel resource" },
+       [BLK_STS_AGAIN]         = { -EAGAIN,    "nonblocking retry" },
 
        /* device mapper special case, should not leak out: */
        [BLK_STS_DM_REQUEUE]    = { -EREMCHG, "dm internal retry" },
@@ -1314,6 +1315,11 @@ retry:
        if (!IS_ERR(rq))
                return rq;
 
+       if (op & REQ_NOWAIT) {
+               blk_put_rl(rl);
+               return ERR_PTR(-EAGAIN);
+       }
+
        if (!gfpflags_allow_blocking(gfp_mask) || unlikely(blk_queue_dying(q))) {
                blk_put_rl(rl);
                return rq;
@@ -1961,6 +1967,14 @@ generic_make_request_checks(struct bio *bio)
                goto end_io;
        }
 
+       /*
+        * For a REQ_NOWAIT based request, return -EOPNOTSUPP
+        * if queue is not a request based queue.
+        */
+
+       if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q))
+               goto not_supported;
+
        part = bio->bi_bdev->bd_part;
        if (should_fail_request(part, bio->bi_iter.bi_size) ||
            should_fail_request(&part_to_disk(part)->part0,
@@ -2118,7 +2132,7 @@ blk_qc_t generic_make_request(struct bio *bio)
        do {
                struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 
-               if (likely(blk_queue_enter(q, false) == 0)) {
+               if (likely(blk_queue_enter(q, bio->bi_opf & REQ_NOWAIT) == 0)) {
                        struct bio_list lower, same;
 
                        /* Create a fresh bio_list for all subordinate requests */
@@ -2143,7 +2157,11 @@ blk_qc_t generic_make_request(struct bio *bio)
                        bio_list_merge(&bio_list_on_stack[0], &same);
                        bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
                } else {
-                       bio_io_error(bio);
+                       if (unlikely(!blk_queue_dying(q) &&
+                                       (bio->bi_opf & REQ_NOWAIT)))
+                               bio_wouldblock_error(bio);
+                       else
+                               bio_io_error(bio);
                }
                bio = bio_list_pop(&bio_list_on_stack[0]);
        } while (bio);