Re: [PATCH 0/3] virtiofsd: Fix lo_flush() and inode->posix_lock init

[Laszlo Ersek]

Hi Vivek,

On 12/07/20 19:30, Vivek Goyal wrote:
> Laszlo is writing a virtiofs client for OVMF and noticed that if he
> sends fuse FLUSH command for directory object, virtiofsd crashes.
> virtiofsd does not expect a FLUSH arriving for a directory object.
> 
> This patch series has one of the patches which fixes that. It also
> has couple of posix lock fixes as a result of lo_flush() related debugging.
> 
> Vivek Goyal (3):
>   virtiofsd: Set up posix_lock hash table for root inode
>   virtiofsd: Disable posix_lock hash table if remote locks are not
>     enabled
>   virtiofsd: Check file type in lo_flush()
> 
>  tools/virtiofsd/passthrough_ll.c | 54 +++++++++++++++++++++++---------
>  1 file changed, 39 insertions(+), 15 deletions(-)
> 

I put back the (wrong) FLUSH for the root dir into my code temporarily, to 
reproduce the crash (it does, with v5.2.0-rc4).

Then I applied your series [*], and retested.

[*] I'm unsure about the email you sent in response to 1/3, namely 
<https://lists.gnu.org/archive/html/qemu-devel/2020-12/msg01504.html>; I 
ignored that when applying the patches.

Indeed now I get a graceful -EBADF:

[13316825985314] [ID: 00000004] unique: 60, opcode: FLUSH (25), nodeid: 1, 
insize: 64, pid: 1
[13316825993517] [ID: 00000004]    unique: 60, error: -9 (Bad file descriptor), 
outsize: 16

For whichever patch in the series my testing is relevant:

Tested-by: Laszlo Ersek <lersek@redhat.com>

(I'm having some difficulty figuring out which patch(es) should carry my T-b.

- I think I didn't really test patch#2 with the above, so that one should 
likely not get the T-b

- I think patch#3 is what I really tested.

- But, if that's the case, doesn't patch#3 make the fix in patch#1 untestable, 
in my scenario? I believe the code is no longer reached in lo_flush(), due to 
patch#3, where the change from patch#1 would matter. Patch#1 seems correct, and 
the last paragraph of its commit message relevant, but I think my testing 
currently only covered patch#3.

I'll let you decide where to apply my T-b.)

Thanks!
Laszlo