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From f551451a4b9975121424cb0837df67d31d2528dc Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Tue, 23 Jul 2019 14:45:45 +0100
Subject: [PATCH 07/14] block: Add bdrv_get_request_alignment()

RH-Author: Max Reitz <mreitz@redhat.com>
Message-id: <20190723144546.23701-7-mreitz@redhat.com>
Patchwork-id: 89653
O-Subject: [RHEL-8.1.0 qemu-kvm PATCH 6/7] block: Add bdrv_get_request_alignment()
Bugzilla: 1678979
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: John Snow <jsnow@redhat.com>

From: Eric Blake <eblake@redhat.com>

The next patch needs access to a device's minimum permitted
alignment, since NBD wants to advertise this to clients. Add
an accessor function, borrowing from blk_get_max_transfer()
for accessing a backend's block limits.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20190329042750.14704-6-eblake@redhat.com>
(cherry picked from commit 4841211e0d1628cd386b35835676d7f6f9a4fa9d)
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 block/block-backend.c          | 7 +++++++
 include/sysemu/block-backend.h | 1 +
 2 files changed, 8 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index 7ae5832..0d623e4 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1807,6 +1807,13 @@ int blk_get_flags(BlockBackend *blk)
     }
 }
 
+/* Returns the minimum request alignment, in bytes; guaranteed nonzero */
+uint32_t blk_get_request_alignment(BlockBackend *blk)
+{
+    BlockDriverState *bs = blk_bs(blk);
+    return bs ? bs->bl.request_alignment : BDRV_SECTOR_SIZE;
+}
+
 /* Returns the maximum transfer length, in bytes; guaranteed nonzero */
 uint32_t blk_get_max_transfer(BlockBackend *blk)
 {
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 830d873..20f8bbb 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -176,6 +176,7 @@ bool blk_is_available(BlockBackend *blk);
 void blk_lock_medium(BlockBackend *blk, bool locked);
 void blk_eject(BlockBackend *blk, bool eject_flag);
 int blk_get_flags(BlockBackend *blk);
+uint32_t blk_get_request_alignment(BlockBackend *blk);
 uint32_t blk_get_max_transfer(BlockBackend *blk);
 int blk_get_max_iov(BlockBackend *blk);
 void blk_set_guest_block_size(BlockBackend *blk, int align);
-- 
1.8.3.1