[Qemu-devel] [PATCH 0/2] IDE: Do not flush empty drives

[Qemu-devel] [PATCH 0/2] IDE: Do not flush empty drives

[Stefan Hajnoczi]

John Snow is offline until Monday, QEMU 2.10-rc3 is due to be tagged on
Tuesday, and so I've taken two patches John sent for 2.10 and addressed review
comments.

Kevin Wolf (1):
  IDE: test flush on empty CDROM

Stefan Hajnoczi (1):
  IDE: Do not flush empty CDROM drives

 hw/ide/core.c    | 10 +++++++++-
 tests/ide-test.c | 19 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

-- 
2.13.3

[Qemu-devel] [PATCH 1/2] IDE: Do not flush empty CDROM drives

[Stefan Hajnoczi]

The block backend changed in a way that flushing empty CDROM drives now
crashes.  Amend IDE to avoid doing so until the root problem can be
addressed for 2.11.

Original patch by John Snow <jsnow@redhat.com>.

Reported-by: Kieron Shorrock <kshorrock@paloaltonetworks.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/ide/core.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 0b48b64d3a..bea39536b0 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1063,7 +1063,15 @@ static void ide_flush_cache(IDEState *s)
     s->status |= BUSY_STAT;
     ide_set_retry(s);
     block_acct_start(blk_get_stats(s->blk), &s->acct, 0, BLOCK_ACCT_FLUSH);
-    s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
+
+    if (blk_bs(s->blk)) {
+        s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
+    } else {
+        /* XXX blk_aio_flush() crashes when blk_bs(blk) is NULL, remove this
+         * temporary workaround when blk_aio_*() functions handle NULL blk_bs.
+         */
+        ide_flush_cb(s, 0);
+    }
 }
 
 static void ide_cfata_metadata_inquiry(IDEState *s)
-- 
2.13.3

[Qemu-devel] [PATCH 2/2] IDE: test flush on empty CDROM

[Stefan Hajnoczi]

From: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tests/ide-test.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tests/ide-test.c b/tests/ide-test.c
index bfd79ddbdc..aa9de065fc 100644
--- a/tests/ide-test.c
+++ b/tests/ide-test.c
@@ -689,6 +689,24 @@ static void test_flush_nodev(void)
     ide_test_quit();
 }
 
+static void test_flush_empty_drive(void)
+{
+    QPCIDevice *dev;
+    QPCIBar bmdma_bar, ide_bar;
+
+    ide_test_start("-device ide-cd,bus=ide.0");
+    dev = get_pci_device(&bmdma_bar, &ide_bar);
+
+    /* FLUSH CACHE command on device 0 */
+    qpci_io_writeb(dev, ide_bar, reg_device, 0);
+    qpci_io_writeb(dev, ide_bar, reg_command, CMD_FLUSH_CACHE);
+
+    /* Just testing that qemu doesn't crash... */
+
+    free_pci_device(dev);
+    ide_test_quit();
+}
+
 static void test_pci_retry_flush(void)
 {
     test_retry_flush("pc");
@@ -954,6 +972,7 @@ int main(int argc, char **argv)
 
     qtest_add_func("/ide/flush", test_flush);
     qtest_add_func("/ide/flush/nodev", test_flush_nodev);
+    qtest_add_func("/ide/flush/empty_drive", test_flush_empty_drive);
     qtest_add_func("/ide/flush/retry_pci", test_pci_retry_flush);
     qtest_add_func("/ide/flush/retry_isa", test_isa_retry_flush);
 
-- 
2.13.3

Re: [Qemu-devel] [PATCH 1/2] IDE: Do not flush empty CDROM drives

[Eric Blake]

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On 08/09/2017 11:02 AM, Stefan Hajnoczi wrote:
> The block backend changed in a way that flushing empty CDROM drives now
> crashes.  Amend IDE to avoid doing so until the root problem can be
> addressed for 2.11.
> 
> Original patch by John Snow <jsnow@redhat.com>.
> 
> Reported-by: Kieron Shorrock <kshorrock@paloaltonetworks.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  hw/ide/core.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

> 
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index 0b48b64d3a..bea39536b0 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -1063,7 +1063,15 @@ static void ide_flush_cache(IDEState *s)
>      s->status |= BUSY_STAT;
>      ide_set_retry(s);
>      block_acct_start(blk_get_stats(s->blk), &s->acct, 0, BLOCK_ACCT_FLUSH);
> -    s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
> +
> +    if (blk_bs(s->blk)) {
> +        s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
> +    } else {
> +        /* XXX blk_aio_flush() crashes when blk_bs(blk) is NULL, remove this
> +         * temporary workaround when blk_aio_*() functions handle NULL blk_bs.
> +         */
> +        ide_flush_cb(s, 0);
> +    }
>  }
>  
>  static void ide_cfata_metadata_inquiry(IDEState *s)
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH 0/2] IDE: Do not flush empty drives

[Stefan Hajnoczi]

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On Wed, Aug 09, 2017 at 05:02:10PM +0100, Stefan Hajnoczi wrote:
> John Snow is offline until Monday, QEMU 2.10-rc3 is due to be tagged on
> Tuesday, and so I've taken two patches John sent for 2.10 and addressed review
> comments.
> 
> Kevin Wolf (1):
>   IDE: test flush on empty CDROM
> 
> Stefan Hajnoczi (1):
>   IDE: Do not flush empty CDROM drives
> 
>  hw/ide/core.c    | 10 +++++++++-
>  tests/ide-test.c | 19 +++++++++++++++++++
>  2 files changed, 28 insertions(+), 1 deletion(-)

John: I am sending a pull request to get this fix into -rc3 (Aug 15th).
Feel free to send a follow-up/revert if you want to make changes when
you get back online.

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan

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