[haiku-gsoc] Re: [HCD]: Bfs bug #1
- From: "Salvatore Benedetto" <emitrax@xxxxxxxxx>
- To: haiku-gsoc@xxxxxxxxxxxxx
- Date: Wed, 18 Jun 2008 22:32:09 +0000
2008/6/18 Ingo Weinhold <ingo_weinhold@xxxxxx>:
>
> On 2008-06-18 at 16:01:11 [+0200], Salvatore Benedetto <emitrax@xxxxxxxxx>
> wrote:
>> 2008/6/18 Axel Dörfler <axeld@xxxxxxxxxxxxxxxx>:
>> > The more interesting question would be why get_vnode() failed in the
>> > first place, though.
>>
>> I investigated this a bit and in the serial log I found before the crash
>> that the vnode is not becoming "unbusy"
>>
>> vnode 3:4260 is not becoming unbusy!
>> vnode 0x9149ff00
>> PANIC: ASSERT FAILED (src/system/kernel/fs/vfs.cpp:801): oldRefCount > 0
>>
>> At first, this seems the reason, but I don't know why this is
>> happening and I'll look into
>> it more.
>
> Just a hint, if you want to track this down: Turn the dprintf()s about the
> vnode not becoming unbusy into an panic()s and add ktrace_printf()s in all
> places where a node is marked busy/unbusy. When the panic is triggered it
> should be easy to find out which thread marked it busy and what it is doing.
Thanks for the hint!
>
> Anyway, we should probably use condition variables for busy vnodes, so that
> we don't run into problems with slow FSs.
Yep, I thought of that. It's better than retrying over and over to get a lock.
>
> CU, Ingo
>
>
The patch attached should prevents the kernel from crashing in this
occasion making
it more error prone. I called the boolean variable fOk. I really
didn't know how else to call
it. Can somebody review it and give me his bless so that I can commit
it please?
Regards,
--
Salvatore Benedetto (a.k.a. emitrax)
Student of Computer Engineer
University of Pisa
www.haiku-os.it
Index: src/add-ons/kernel/file_systems/bfs/Inode.h
===================================================================
--- src/add-ons/kernel/file_systems/bfs/Inode.h (revision 26005)
+++ src/add-ons/kernel/file_systems/bfs/Inode.h (working copy)
@@ -256,14 +256,16 @@
Vnode(Volume *volume, ino_t id)
:
fVolume(volume),
- fID(id)
+ fID(id),
+ fOk(true)
{
}
Vnode(Volume *volume, block_run run)
:
fVolume(volume),
- fID(volume->ToVnode(run))
+ fID(volume->ToVnode(run)),
+ fOk(true)
{
}
@@ -275,12 +277,16 @@
status_t Get(Inode **_inode)
{
// should we check inode against NULL here? it should
not be necessary
- return get_vnode(fVolume->FSVolume(), fID, (void
**)_inode);
+ status_t status
+ = get_vnode(fVolume->FSVolume(), fID, (void
**)_inode);
+ if (status < B_OK)
+ fOk = false;
+ return status;
}
void Put()
{
- if (fVolume)
+ if (fVolume && fOk)
put_vnode(fVolume->FSVolume(), fID);
fVolume = NULL;
}
@@ -293,6 +299,7 @@
private:
Volume *fVolume;
ino_t fID;
+ bool fOk;
};
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