Revert "block, bfq: honor already-setup queue merges"

This reverts commit fde25220c9a54ad2df67bae8072231c2e122f4ef.

We have had several folks complain that this causes hangs for them, which
is especially problematic as the commit has also hit stable already.

As no resolution seems to be forthcoming right now, revert the patch.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=214503
Fixes: fde25220c9a5 ("block, bfq: honor already-setup queue merges")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index dd13c2bbc29c1164b6d01432b28c13545cad8a90..480e1a13485966104362f265d842887640775781 100644 (file)
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2662,15 +2662,6 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
         * are likely to increase the throughput.
         */
        bfqq->new_bfqq = new_bfqq;
-       /*
-        * The above assignment schedules the following redirections:
-        * each time some I/O for bfqq arrives, the process that
-        * generated that I/O is disassociated from bfqq and
-        * associated with new_bfqq. Here we increases new_bfqq->ref
-        * in advance, adding the number of processes that are
-        * expected to be associated with new_bfqq as they happen to
-        * issue I/O.
-        */
        new_bfqq->ref += process_refs;
        return new_bfqq;
 }
@@ -2733,10 +2724,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 {
        struct bfq_queue *in_service_bfqq, *new_bfqq;
 
-       /* if a merge has already been setup, then proceed with that first */
-       if (bfqq->new_bfqq)
-               return bfqq->new_bfqq;
-
        /*
         * Check delayed stable merge for rotational or non-queueing
         * devs. For this branch to be executed, bfqq must not be
@@ -2838,6 +2825,9 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
        if (bfq_too_late_for_merging(bfqq))
                return NULL;
 
+       if (bfqq->new_bfqq)
+               return bfqq->new_bfqq;
+
        if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
                return NULL;