1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
9pfs does not honor open file handles on unlinked files
This was originally filed over here: https://bugzilla.redhat.com/show_bug.cgi?id=1114221
The open-unlink-fstat idiom used in some places to create an anonymous private temporary file does not work in a QEMU guest over a virtio-9p filesystem.
Version-Release number of selected component (if applicable):
qemu-kvm-1.6.2-6.fc20.x86_64
qemu-system-x86-1.6.2-6.fc20.x86_64
(those are fedora RPMs)
How reproducible:
Always. See this example C program:
https://bugzilla.redhat.com/attachment.cgi?id=913069
Steps to Reproduce:
1. Export a filesystem with virt-manager for the guest.
(type: mount, driver: default, mode: passthrough)
2. Start guest and mount that filesystem
(mount -t 9p -o trans=virtio,version=9p2000.L ...)
3. Run a program that uses open-unlink-fstat
(in my case it was trying to compile Perl 5.20)
Actual results:
fstat fails:
open("/home/tst/filename", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
unlink("/home/tst/filename") = 0
fstat(3, 0x23aa1a8) = -1 ENOENT (No such file or directory)
close(3)
Expected results:
open("/home/tst/filename", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
unlink("/home/tst/filename") = 0
fstat(3, {st_mode=S_IFREG|0600, st_size=0, ...}) = 0
fcntl(3, F_SETFD, FD_CLOEXEC) = 0
close(3)
Additional info:
There was a patch put into the kernel back in '07 to handle this very problem for other filesystems; maybe its helpful:
http://lwn.net/Articles/251228/
There is also a thread on LKML from last December specifically about this very problem:
https://lkml.org/lkml/2013/12/31/163
There was a discussion on the QEMU list back in '11 that doesn't seem to have come to a conclusion, but did provide the test program that i've attached to this report:
http://marc.info/?l=qemu-devel&m=130443605720648&w=2
|