debian/patches/extra/0007-block-fix-detect-zeroes-with-BDRV_REQ_REGISTERED_BUF.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Stefan Hajnoczi <stefanha@redhat.com>
   3 Date: Thu, 26 Jan 2023 15:13:58 -0500
   4 Subject: [PATCH] block: fix detect-zeroes= with BDRV_REQ_REGISTERED_BUF
   5
   6 When a write request is converted into a write zeroes request by the
   7 detect-zeroes= feature, it is no longer associated with an I/O buffer.
   8 The BDRV_REQ_REGISTERED_BUF flag doesn't make sense without an I/O
   9 buffer and must be cleared because bdrv_co_do_pwrite_zeroes() fails with
  10 -EINVAL when it's set.
  11
  12 Fiona Ebner <f.ebner@proxmox.com> bisected and diagnosed this QEMU 7.2
  13 regression where writes containing zeroes to a blockdev with
  14 discard=unmap,detect-zeroes=unmap fail.
  15
  16 Buglink: https://gitlab.com/qemu-project/qemu/-/issues/1404
  17 Fixes: e8b6535533be ("block: add BDRV_REQ_REGISTERED_BUF request flag")
  18 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
  19 ---
  20  block/io.c | 3 +++
  21  1 file changed, 3 insertions(+)
  22
  23 diff --git a/block/io.c b/block/io.c
  24 index b9424024f9..bbaa0d1b2d 100644
  25 --- a/block/io.c
  26 +++ b/block/io.c
  27 @@ -2087,6 +2087,9 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
  28          if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) {
  29              flags |= BDRV_REQ_MAY_UNMAP;
  30          }
  31 +
  32 +        /* Can't use optimization hint with bufferless zero write */
  33 +        flags &= ~BDRV_REQ_REGISTERED_BUF;
  34      }
  35
  36      if (ret < 0) {