[PULL for-8.1 0/2] Block patches

[PULL for-8.1 0/2] Block patches

[Stefan Hajnoczi]

The following changes since commit 9ba37026fcf6b7f3f096c0cca3e1e7307802486b:

  Update version for v8.1.0-rc2 release (2023-08-02 08:22:45 -0700)

are available in the Git repository at:

  https://gitlab.com/stefanha/qemu.git tags/block-pull-request

for you to fetch changes up to 9b06d0d076271d76e5384d767ef94a676f0a9efd:

  block/blkio: add more comments on the fd passing handling (2023-08-03 11:28:43 -0400)

----------------------------------------------------------------
Pull request

Fix for an fd leak in the blkio block driver.

----------------------------------------------------------------

Stefano Garzarella (2):
  block/blkio: close the fd when blkio_connect() fails
  block/blkio: add more comments on the fd passing handling

 block/blkio.c | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

-- 
2.41.0

[PULL for-8.1 1/2] block/blkio: close the fd when blkio_connect() fails

[Stefan Hajnoczi]

From: Stefano Garzarella <sgarzare@redhat.com>

libblkio drivers take ownership of `fd` only after a successful
blkio_connect(), so if it fails, we are still the owners.

Fixes: cad2ccc395 ("block/blkio: use qemu_open() to support fd passing for virtio-blk")
Suggested-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Message-id: 20230803082825.25293-2-sgarzare@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/blkio.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/block/blkio.c b/block/blkio.c
index 8e7ce42c79..baba2f0b67 100644
--- a/block/blkio.c
+++ b/block/blkio.c
@@ -678,7 +678,7 @@ static int blkio_virtio_blk_connect(BlockDriverState *bs, QDict *options,
     const char *path = qdict_get_try_str(options, "path");
     BDRVBlkioState *s = bs->opaque;
     bool fd_supported = false;
-    int fd, ret;
+    int fd = -1, ret;
 
     if (!path) {
         error_setg(errp, "missing 'path' option");
@@ -719,6 +719,7 @@ static int blkio_virtio_blk_connect(BlockDriverState *bs, QDict *options,
             if (ret < 0) {
                 fd_supported = false;
                 qemu_close(fd);
+                fd = -1;
             }
         }
     }
@@ -733,14 +734,18 @@ static int blkio_virtio_blk_connect(BlockDriverState *bs, QDict *options,
     }
 
     ret = blkio_connect(s->blkio);
+    if (ret < 0 && fd >= 0) {
+        /* Failed to give the FD to libblkio, close it */
+        qemu_close(fd);
+        fd = -1;
+    }
+
     /*
      * If the libblkio driver doesn't support the `fd` property, blkio_connect()
      * will fail with -EINVAL. So let's try calling blkio_connect() again by
      * directly setting `path`.
      */
     if (fd_supported && ret == -EINVAL) {
-        qemu_close(fd);
-
         /*
          * We need to clear the `fd` property we set previously by setting
          * it to -1.
-- 
2.41.0

[PULL for-8.1 2/2] block/blkio: add more comments on the fd passing handling

[Stefan Hajnoczi]

From: Stefano Garzarella <sgarzare@redhat.com>

As Hanna pointed out, it is not clear in the code why qemu_open()
can fail, and why blkio_set_int("fd") is not enough to discover
the `fd` property support.

Let's fix them by adding more details in the code comments.

Suggested-by: Hanna Czenczek <hreitz@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20230803082825.25293-3-sgarzare@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/blkio.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/block/blkio.c b/block/blkio.c
index baba2f0b67..1dd495617c 100644
--- a/block/blkio.c
+++ b/block/blkio.c
@@ -713,6 +713,12 @@ static int blkio_virtio_blk_connect(BlockDriverState *bs, QDict *options,
          */
         fd = qemu_open(path, O_RDWR, NULL);
         if (fd < 0) {
+            /*
+             * qemu_open() can fail if the user specifies a path that is not
+             * a file or device, for example in the case of Unix Domain Socket
+             * for the virtio-blk-vhost-user driver. In such cases let's have
+             * libblkio open the path directly.
+             */
             fd_supported = false;
         } else {
             ret = blkio_set_int(s->blkio, "fd", fd);
@@ -741,9 +747,12 @@ static int blkio_virtio_blk_connect(BlockDriverState *bs, QDict *options,
     }
 
     /*
-     * If the libblkio driver doesn't support the `fd` property, blkio_connect()
-     * will fail with -EINVAL. So let's try calling blkio_connect() again by
-     * directly setting `path`.
+     * Before https://gitlab.com/libblkio/libblkio/-/merge_requests/208
+     * (libblkio <= v1.3.0), setting the `fd` property is not enough to check
+     * whether the driver supports the `fd` property or not. In that case,
+     * blkio_connect() will fail with -EINVAL.
+     * So let's try calling blkio_connect() again by directly setting `path`
+     * to cover this scenario.
      */
     if (fd_supported && ret == -EINVAL) {
         /*
-- 
2.41.0

Re: [PULL for-8.1 0/2] Block patches

[Richard Henderson]

On 8/3/23 08:55, Stefan Hajnoczi wrote:
> The following changes since commit 9ba37026fcf6b7f3f096c0cca3e1e7307802486b:
> 
>    Update version for v8.1.0-rc2 release (2023-08-02 08:22:45 -0700)
> 
> are available in the Git repository at:
> 
>    https://gitlab.com/stefanha/qemu.git  tags/block-pull-request
> 
> for you to fetch changes up to 9b06d0d076271d76e5384d767ef94a676f0a9efd:
> 
>    block/blkio: add more comments on the fd passing handling (2023-08-03 11:28:43 -0400)
> 
> ----------------------------------------------------------------
> Pull request
> 
> Fix for an fd leak in the blkio block driver.

Applied, thanks.  Please update https://wiki.qemu.org/ChangeLog/8.1 as appropriate.


r~