Revert "block: cover another queue enter recursion via BIO_QUEUE_ENTERED"

We can't touch a bio after ->make_request_fn(), for all we know it could
already have been completed by the time this function returns.

This reverts commit 698cef173983b086977e633e46476e0f925ca01e.

Reported-by: syzbot+4df6ca820108fd248943@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-core.c b/block/blk-core.c
index 1ccec27..3c5f61c 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1083,18 +1083,7 @@ blk_qc_t generic_make_request(struct bio *bio)
                        /* 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]);
-
-                       /*
-                        * Since we're recursing into make_request here, ensure
-                        * that we mark this bio as already having entered the queue.
-                        * If not, and the queue is going away, we can get stuck
-                        * forever on waiting for the queue reference to drop. But
-                        * that will never happen, as we're already holding a
-                        * reference to it.
-                        */
-                       bio_set_flag(bio, BIO_QUEUE_ENTERED);
                        ret = q->make_request_fn(q, bio);
-                       bio_clear_flag(bio, BIO_QUEUE_ENTERED);
 
                        /* sort new bios into those for a lower level
                         * and those for the same level

diff --git a/block/blk-merge.c b/block/blk-merge.c
index d79a22f..71e9ac0 100644 (file)
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -272,6 +272,16 @@ void blk_queue_split(struct request_queue *q, struct bio **bio)
                /* there isn't chance to merge the splitted bio */
                split->bi_opf |= REQ_NOMERGE;
 
+               /*
+                * Since we're recursing into make_request here, ensure
+                * that we mark this bio as already having entered the queue.
+                * If not, and the queue is going away, we can get stuck
+                * forever on waiting for the queue reference to drop. But
+                * that will never happen, as we're already holding a
+                * reference to it.
+                */
+               bio_set_flag(*bio, BIO_QUEUE_ENTERED);
+
                bio_chain(split, *bio);
                trace_block_split(q, split, (*bio)->bi_iter.bi_sector);
                generic_make_request(*bio);