Re: [PATCH v5] file-posix: detect the lock using the real file

[Daniel P . Berrangé]

On Tue, Dec 15, 2020 at 06:53:56PM +0800, Li Feng wrote:
> This patch addresses this issue:
> When accessing a volume on an NFS filesystem without supporting the file lock,
> tools, like qemu-img, will complain "Failed to lock byte 100".
> 
> In the original code, the qemu_has_ofd_lock will test the lock on the
> "/dev/null" pseudo-file. Actually, the file.locking is per-drive property,
> which depends on the underlay filesystem.
> 
> In this patch, add a new 'qemu_has_file_lock' to detect whether the
> file supports the file lock. And disable the lock when the underlay file
> system doesn't support locks.
> 
> Signed-off-by: Li Feng <fengli@smartx.com>
> ---
> v5: simplify the code.
> v4: use the fd as the qemu_has_file_lock argument.
> v3: don't call the qemu_has_ofd_lock, use a new function instead.
> v2: remove the refactoring.
> ---
>  block/file-posix.c   | 61 +++++++++++++++++++++++---------------------
>  include/qemu/osdep.h |  1 +
>  util/osdep.c         | 14 ++++++++++
>  3 files changed, 47 insertions(+), 29 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


Regards,
Daniel
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