fix patch for accepting NULL qiov when padding

[pve-qemu.git] / debian / patches / pve / 0038-block-io-accept-NULL-qiov-in-bdrv_pad_request.patch

diff --git a/debian/patches/pve/0038-block-io-accept-NULL-qiov-in-bdrv_pad_request.patch b/debian/patches/pve/0038-block-io-accept-NULL-qiov-in-bdrv_pad_request.patch
index 851851ff57c9d5a472ae36883f2a9ac5fed4ae18..bb9b72cb3a380442e242ad0d4653ea990452f5e5 100644 (file)
--- a/debian/patches/pve/0038-block-io-accept-NULL-qiov-in-bdrv_pad_request.patch
+++ b/debian/patches/pve/0038-block-io-accept-NULL-qiov-in-bdrv_pad_request.patch
@@ -8,26 +8,57 @@ results (only copy-on-read matters). In this case they will pass NULL as
 the target QEMUIOVector, which will however trip bdrv_pad_request, since
 it wants to extend its passed vector.
 
-Simply check for NULL and do nothing, there's no reason to pad the
-target if it will be discarded anyway.
+If there is no qiov, no operation can be done with it, but the bytes
+and offset still need to be updated, so the subsequent aligned read
+will actually be aligned and not run into an assertion failure.
 
 Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
+[FE: do update bytes and offset in any case]
+Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
 ---
- block/io.c | 4 ++++
- 1 file changed, 4 insertions(+)
+ block/io.c | 29 ++++++++++++++++-------------
+ 1 file changed, 16 insertions(+), 13 deletions(-)
 
 diff --git a/block/io.c b/block/io.c
-index 83d1b1dfdc..24a3c84c93 100644
+index 83d1b1dfdc..e927881e40 100644
 --- a/block/io.c
 +++ b/block/io.c
-@@ -1710,6 +1710,10 @@ static int bdrv_pad_request(BlockDriverState *bs,
-     int sliced_niov;
-     size_t sliced_head, sliced_tail;
+@@ -1723,22 +1723,25 @@ static int bdrv_pad_request(BlockDriverState *bs,
+         return 0;
+     }
  
-+    if (!qiov) {
-+        return 0;
-+    }
+-    sliced_iov = qemu_iovec_slice(*qiov, *qiov_offset, *bytes,
+-                                  &sliced_head, &sliced_tail,
+-                                  &sliced_niov);
+-
+-    /* Guaranteed by bdrv_check_request32() */
+-    assert(*bytes <= SIZE_MAX);
+-    ret = bdrv_create_padded_qiov(bs, pad, sliced_iov, sliced_niov,
+-                                  sliced_head, *bytes);
+-    if (ret < 0) {
+-        bdrv_padding_finalize(pad);
+-        return ret;
++    if (qiov && *qiov) {
++        sliced_iov = qemu_iovec_slice(*qiov, *qiov_offset, *bytes,
++                                      &sliced_head, &sliced_tail,
++                                      &sliced_niov);
 +
-     /* Should have been checked by the caller already */
-     ret = bdrv_check_request32(*offset, *bytes, *qiov, *qiov_offset);
-     if (ret < 0) {
++        /* Guaranteed by bdrv_check_request32() */
++        assert(*bytes <= SIZE_MAX);
++        ret = bdrv_create_padded_qiov(bs, pad, sliced_iov, sliced_niov,
++                                      sliced_head, *bytes);
++        if (ret < 0) {
++            bdrv_padding_finalize(pad);
++            return ret;
++        }
++        *qiov = &pad->local_qiov;
++        *qiov_offset = 0;
+     }
++
+     *bytes += pad->head + pad->tail;
+     *offset -= pad->head;
+-    *qiov = &pad->local_qiov;
+-    *qiov_offset = 0;
+     if (padded) {
+         *padded = true;
+     }