Re: [Qemu-devel] [PATCH 0/5] ide: avoid main-loop hang on CDROM/NFS failure

[John Snow <jsnow@redhat.com>]

On 09/21/2015 08:25 AM, Peter Lieven wrote:
> This series aims at avoiding a hanging main-loop if a vserver has a
> CDROM image mounted from a NFS share and that NFS share goes down.
> Typical situation is that users mount an CDROM ISO to install something
> and then forget to eject that CDROM afterwards.
> As a consequence this mounted CD is able to bring down the
> whole vserver if the backend NFS share is unreachable. This is bad
> especially if the CDROM itself is not needed anymore at this point.
> 
> This series aims at fixing 3 blocking I/O operations that would
> hang if the NFS server is unavailable:
>  - ATAPI PIO read requests used sync calls to blk_read, convert
>    them to an async variant.
>  - If a busmaster DMA request is cancelled all requests are drained.
>    Convert the drain to an async request canceling.
>  - query-block in the HMP or QMP hangs because it indirectly calls
>    bdrv_get_allocated_file_size.
> 
> Note that Patch 5 is only included for completeness.
> 
> Peter
> 
> Peter Lieven (5):
>   ide/atapi: make PIO read requests async
>   ide/atapi: blk_aio_readv may return NULL
>   ide: add support for cancelable read requests
>   ide/atapi: enable cancelable requests
>   block/nfs: cache allocated filesize for read-only files
> 
>  block/nfs.c       | 36 ++++++++++++++++++++++++++
>  hw/ide/atapi.c    | 75 +++++++++++++++++++++++++++++++++++--------------------
>  hw/ide/core.c     | 55 ++++++++++++++++++++++++++++++++++++++++
>  hw/ide/internal.h | 16 ++++++++++++
>  hw/ide/pci.c      | 42 ++++++++++++++++++++-----------
>  5 files changed, 183 insertions(+), 41 deletions(-)
> 

I assume this supersedes both:

[Qemu-devel] [PATCH 0/2] ide/atapi: partially avoid deadlock if the
storage backend is dead

and

[Qemu-devel] [PATCH] ide/atapi: make PIO read requests async

right?

--js