From 643c979c2bfa0fc3c45ec8ec5f05a77e0b075356 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 16 Jul 2021 16:51:32 -0400
Subject: [PATCH 16/43] block-backend: align max_transfer to request alignment

RH-Author: Miroslav Rezanina <mrezanin@redhat.com>
RH-Bugzilla: 1957194

Block device requests must be aligned to bs->bl.request_alignment.
It makes sense for drivers to align bs->bl.max_transfer the same
way; however when there is no specified limit, blk_get_max_transfer
just returns INT_MAX.  Since the contract of the function does not
specify that INT_MAX means "no maximum", just align the outcome
of the function (whether INT_MAX or bs->bl.max_transfer) before
returning it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit b99f7fa08a3df8b8a6a907642e5851cdcf43fa9f)
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block/block-backend.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 05d8e5fb5d..136cc602c5 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1943,12 +1943,12 @@ uint32_t blk_get_request_alignment(BlockBackend *blk)
 uint32_t blk_get_max_transfer(BlockBackend *blk)
 {
     BlockDriverState *bs = blk_bs(blk);
-    uint32_t max = 0;
+    uint32_t max = INT_MAX;
 
     if (bs) {
-        max = bs->bl.max_transfer;
+        max = MIN_NON_ZERO(max, bs->bl.max_transfer);
     }
-    return MIN_NON_ZERO(max, INT_MAX);
+    return ROUND_DOWN(max, blk_get_request_alignment(blk));
 }
 
 int blk_get_max_iov(BlockBackend *blk)
-- 
2.27.0