From: Christian Schoenebeck <qemu_oss@crudebyte.com>
To: qemu-devel@nongnu.org
Cc: "Greg Kurz" <groug@kaod.org>,
"Christian Schoenebeck" <qemu_oss@crudebyte.com>,
"Stefan Hajnoczi" <stefanha@gmail.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
"Antonios Motakis" <antonios.motakis@huawei.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: virtio-fs: Fix file ID collisions (was: 9p: Fix file ID collisions)
Date: Wed, 16 Oct 2019 11:42:52 +0200 [thread overview]
Message-ID: <4114483.KuMf1QML1b@silver> (raw)
In-Reply-To: <20191015112039.620997e3@bahia.lan>
On Dienstag, 15. Oktober 2019 11:20:39 CEST Greg Kurz wrote:
> On Tue, 08 Oct 2019 14:05:28 +0200
>
> Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:
> > I wonder though whether virtio-fs suffers from the same file ID collisions
> > problem when sharing multiple file systems.
>
> I gave a try and it seems that virtio-fs might expose the inode numbers from
> different devices in the host, unvirtualized AND with the same device in
> the guest:
>
> # mkdir -p /var/tmp/virtio-fs/proc
> # mount --bind /proc /var/tmp/virtio-fs/proc
> # virtiofsd -o vhost_user_socket=/tmp/vhostqemu -o source=/var/tmp/virtio-fs
> -o cache=always
>
> and then started QEMU with:
>
> -chardev socket,id=char0,path=/tmp/vhostqemu \
> -device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs \
> -m 4G -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on
> \ -numa node,memdev=mem
>
> In the host:
>
> $ stat /var/tmp/virtio-fs
> File: /var/tmp/virtio-fs
> Size: 4096 Blocks: 8 IO Block: 4096 directory
> Device: fd00h/64768d Inode: 787796 Links: 4
> Access: (0775/drwxrwxr-x) Uid: ( 1000/ greg) Gid: ( 1000/ greg)
> Context: unconfined_u:object_r:user_tmp_t:s0
> Access: 2019-10-15 11:08:52.070080922 +0200
> Modify: 2019-10-15 11:02:09.887404446 +0200
> Change: 2019-10-15 11:02:09.887404446 +0200
> Birth: 2019-10-13 19:13:04.009699354 +0200
> [greg@bahia ~]$ stat /var/tmp/virtio-fs/FOO
> File: /var/tmp/virtio-fs/FOO
> Size: 0 Blocks: 0 IO Block: 4096 regular empty
> file Device: fd00h/64768d Inode: 790740 Links: 1
> Access: (0664/-rw-rw-r--) Uid: ( 1000/ greg) Gid: ( 1000/ greg)
> Context: unconfined_u:object_r:user_tmp_t:s0
> Access: 2019-10-15 11:02:09.888404448 +0200
> Modify: 2019-10-15 11:02:09.888404448 +0200
> Change: 2019-10-15 11:02:09.888404448 +0200
> Birth: 2019-10-15 11:02:09.887404446 +0200
> [greg@bahia ~]$ stat /var/tmp/virtio-fs/proc/fs
> File: /var/tmp/virtio-fs/proc/fs
> Size: 0 Blocks: 0 IO Block: 1024 directory
> Device: 4h/4d Inode: 4026531845 Links: 5
> Access: (0555/dr-xr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
> Context: system_u:object_r:proc_t:s0
> Access: 2019-10-01 14:50:09.223233901 +0200
> Modify: 2019-10-01 14:50:09.223233901 +0200
> Change: 2019-10-01 14:50:09.223233901 +0200
> Birth: -
>
> In the guest:
>
> [greg@localhost ~]$ stat /mnt
> File: /mnt
> Size: 4096 Blocks: 8 IO Block: 4096 directory
> Device: 2dh/45d Inode: 787796 Links: 4
> Access: (0775/drwxrwxr-x) Uid: ( 1000/ greg) Gid: ( 1000/ greg)
> Context: system_u:object_r:unlabeled_t:s0
> Access: 2019-10-15 11:08:52.070080922 +0200
> Modify: 2019-10-15 11:02:09.887404446 +0200
> Change: 2019-10-15 11:02:09.887404446 +0200
> Birth: -
> [greg@localhost ~]$ stat /mnt/FOO
> File: /mnt/FOO
> Size: 0 Blocks: 0 IO Block: 4096 regular empty
> file Device: 2dh/45d Inode: 790740 Links: 1
> Access: (0664/-rw-rw-r--) Uid: ( 1000/ greg) Gid: ( 1000/ greg)
> Context: system_u:object_r:unlabeled_t:s0
> Access: 2019-10-15 11:02:09.888404448 +0200
> Modify: 2019-10-15 11:02:09.888404448 +0200
> Change: 2019-10-15 11:02:09.888404448 +0200
> Birth: -
> [greg@localhost ~]$ stat /mnt/proc/fs
> File: /mnt/proc/fs
> Size: 0 Blocks: 0 IO Block: 1024 directory
> Device: 2dh/45d Inode: 4026531845 Links: 5
> Access: (0555/dr-xr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
> Context: system_u:object_r:unlabeled_t:s0
> Access: 2019-10-01 14:50:09.223233901 +0200
> Modify: 2019-10-01 14:50:09.223233901 +0200
> Change: 2019-10-01 14:50:09.223233901 +0200
> Birth: -
>
> Unless I'm missing something, it seems that "virtio-fs" has the same
> issue we had on 9pfs before Christian's patches... :-\
Is a fix for this desired for virtio-fs?
Greg, did you have to update kernel version on either host or guest side to
get virtio-fs running? Or were the discussed kernel changes just for optional
acceleration purposes (i.e. DAX)?
Best regards,
Christian Schoenebeck
next prev parent reply other threads:[~2019-10-16 9:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-05 10:42 [Qemu-devel] [PATCH v7 0/3] 9p: Fix file ID collisions Christian Schoenebeck via Qemu-devel
2019-09-04 21:34 ` [Qemu-devel] [PATCH v7 1/3] 9p: Added virtfs option 'multidevs=remap|forbid|warn' Christian Schoenebeck via Qemu-devel
2019-09-04 22:05 ` [Qemu-devel] [PATCH v7 2/3] 9p: stat_to_qid: implement slow path Christian Schoenebeck via Qemu-devel
2019-09-04 22:53 ` [Qemu-devel] [PATCH v7 3/3] 9p: Use variable length suffixes for inode remapping Christian Schoenebeck via Qemu-devel
2019-09-13 17:01 ` [Qemu-devel] [PATCH v7 0/3] 9p: Fix file ID collisions Greg Kurz
2019-09-23 9:50 ` Christian Schoenebeck via
2019-09-23 12:56 ` Greg Kurz
2019-09-23 14:06 ` Christian Schoenebeck via
2019-09-23 14:46 ` Greg Kurz
2019-09-23 15:03 ` Christian Schoenebeck via
2019-09-23 16:50 ` Greg Kurz
2019-09-24 9:31 ` Christian Schoenebeck via
2019-10-08 9:14 ` Greg Kurz
2019-10-08 12:05 ` Christian Schoenebeck
2019-10-08 13:47 ` Greg Kurz
2019-10-08 14:25 ` Christian Schoenebeck
2019-10-08 14:45 ` Greg Kurz
2019-10-15 9:20 ` Greg Kurz
2019-10-16 9:42 ` Christian Schoenebeck [this message]
2019-10-16 13:44 ` virtio-fs: Fix file ID collisions (was: 9p: Fix file ID collisions) Dr. David Alan Gilbert
2019-10-18 13:15 ` Christian Schoenebeck
2019-10-16 14:00 ` Greg Kurz
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