Re: [Qemu-devel] [PATCH 1/2] Dump: introduce a Filesystem in Userspace

[Eric Blake]

On 05/07/2016 05:32 PM, Nan Li wrote:
> When running the command "dump-guest-memory", we usually need a large space
> of storage to save the dumpfile into disk. It costs not only much time to
> save a file in some of hard disks, but also costs limited storage in host.
> In order to reduce the saving time and make it convenient for users to dump
> the guest memory, we introduce a Filesystem in Userspace (FUSE) to save the
> dump file in RAM. It is selectable in the configure file, adding a compiling
> of package "fuse-devel". It doesn't change the way of dumping guest memory.

Why introduce FUSE? Can we reuse NBD instead?

> 
> qemu_fuse_main(int argc, char *argv[]) is the API for qemu code to mount
> this filesystem. And it only supports these operations just for dumping
> guest memory.
> 
> static struct fuse_operations qemu_fuse_oper = {
>       .getattr        = qemu_fuse_getattr,
>       .fgetattr       = qemu_fuse_fgetattr,
>       .readdir        = qemu_fuse_readdir,
>       .create   = qemu_fuse_create,
>       .open   = qemu_fuse_open,
>       .read   = qemu_fuse_read,
>       .write  = qemu_fuse_write,
>       .unlink = qemu_fuse_unlink,
> };
> 
> Signed-off-by: Nan Li <address@hidden>
> ---
>  Makefile.target |   1 +
>  configure       |  34 +++++
>  fuse-mem.c      | 376 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  fuse-mem.h      |   2 +
>  4 files changed, 413 insertions(+)
>  create mode 100644 fuse-mem.c
>  create mode 100644 fuse-mem.h

New files should be listed in MAINTAINERS; also, new files usually
belong better in an appropriate subdirectory rather than littering the
top directory (we're trying to reduce, not increase, the number of
top-level files).

I haven't closely reviewed the patch, because I think the meta-questions
about the feature in general should be discussed first.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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