Re: [Gluster-devel] Recent dict changes affecting QEMU-GlusterFS patches

[John Mark Walker]

Greetings,

I just wanted to pop in and say thank you for doing this. This is exactly the 
type of integration activity we want to encourage. If you need anything from 
us, please feel free to send me a note. I'll make sure someone on our team gets 
back to you, although it seems that there's already a dialogue.

In any case, welcome to Gluster-land. If you have other ideas about features we 
should implement or that you are interested in implementing yourself, please do 
send a message to this list or to me personally. We would love to hear from you.

Thanks,
John Mark Walker
Gluster Community Guy



----- Original Message -----
> Hi,
> 
> I recently posted patches to integrate GlusterFS with QEMU.
> (http://lists.nongnu.org/archive/html/qemu-devel/2012-06/msg01745.html).
> While updating those patches to latest gluster git, I am seeing a
> problem and I tracked that down to this commit:
> 
> e8eb0a9cb6539a7607d4c134daf331400a93d136 (Optimize for small dicts,
> and avoid an overrun).
> 
> With this commit, I see an invalid memory reference in
> _dict_lookup().
> Some details from gdb are shown below:
> 
> address@hidden qemu]# gdb ./x86_64-softmmu/qemu-system-x86_64
> (gdb) set args --enable-kvm --nographic -m 1024 -smp 4 -drive
> file=gluster:/home/bharata/c-qemu-rpcbypass.vol:/dir1/F16,format=gluster,cache=none
> -net nic,model=virtio -net user -redir tcp:2000::22
> (gdb) r
> Starting program: x86_64-softmmu/qemu-system-x86_64 --enable-kvm
> --nographic -m 1024 -smp 4 -drive
> file=gluster:/home/bharata/c-qemu-rpcbypass.vol:/dir1/F16,format=gluster,cache=none
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x00007ffff66e8ff6 in __strcmp_sse42 () from /lib64/libc.so.6
> Missing separate debuginfos, use: debuginfo-install
> glib2-2.30.3-1.fc16.x86_64 glibc-2.14.90-24.fc16.7.x86_64
> libuuid-2.20.1-2.3.fc16.x86_64 openssl-1.0.0j-1.fc16.x86_64
> zlib-1.2.5-6.fc16.x86_64
> (gdb) bt
> #0  0x00007ffff66e8ff6 in __strcmp_sse42 () from /lib64/libc.so.6
> #1  0x00007ffff7241ab1 in _dict_lookup (key=0x5555564e11b0
> "directory",
>     this=<optimized out>) at dict.c:204
> #2  _dict_lookup (this=<optimized out>, key=0x5555564e11b0
> "directory") at dict.c:192
> #3  0x00007ffff72427ae in _dict_set (value=0x7ffff534302c, key=
>     0x5555564e11b0 "directory", this=0x5555564c6c6c) at dict.c:254
> #4  dict_set (value=0x7ffff534302c, key=<optimized out>,
> this=0x5555564c6c6c)
>     at dict.c:327
> #5  dict_set (this=0x5555564c6c6c, key=<optimized out>,
> value=0x7ffff534302c)
>     at dict.c:313
> #6  0x00007ffff728c2a8 in volume_option (value=0x5555564e2470 "/vm",
> key=
>     0x5555564e11b0 "directory") at ./graph.y:249
> #7  yyparse () at ./graph.y:76
> #8  0x00007ffff728cbbc in glusterfs_graph_construct
> (fp=0x5555564dcbe0) at ./graph.y:597
> <snipped>
> 
> (gdb) up
> #1  0x00007ffff7241ab1 in _dict_lookup (key=0x5555564e11b0
> "directory",
>     this=<optimized out>) at dict.c:204
> 204                     if (pair->key && !strcmp (pair->key, key))
> (gdb) p *pair
> $1 = {hash_next = 0x5555564c6ca4, prev = 0x5555564dbbfc, next =
> 0x3ff00000001, value =
>     0x1, key = 0x54 <Address 0x54 out of bounds>}
> 
> You can see that pair->key has invalid address.
> 
> I am using QEMU in RPC-bypass  mode and the volume file looks like
> this:
> # cat c-qemu-rpcbypass.vol
> volume vm
>   type storage/posix
>   option directory /vm
> end-volume
> 
> I am not familiar with this part of the code and hence will need time
> to debug this. Meanwhile if anyone else familiar with this part of
> the
> code could give some pointers, it will be useful.
> 
> Regards,
> Bharata.
> --
> http://bharata.sulekha.com/blog/posts.htm,
> http://raobharata.wordpress.com/
> 
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