[Ocfs2-devel] [DRAFT 2/2] ocfs2: fix deadlock caused by recursive cluster locking

[Eric Ren]

Hi,
> Thanks for your attention. Actually, I tried different versions of draft patch locally.
> Either of them can satisfy myself so far.

Sorry, I meat "neither of them".

Eric
> Some rules I'd like to follow:
> 1) check and avoid recursive cluster locking, rather than allow it which Junxiao had tried
> before;
> 2) Just keep track of lock resource that meets the following requirements:
>        a. normal inodes (non systemfile);
>        b. inode metadata lockres (not open, rw lockres);
> why? to avoid more special cluster locking usecases, like journal systemfile, "LOST+FOUND"
> open lockres, that lock/unlock
> operations are performed by different processes, making tracking task more tricky.
> 3) There is another problem if we follow "check + avoid" pattern, which I have mentioned in
> this thread:
> """
> This is wrong. We also depend ocfs2_inode_lock() pass out "bh" for later use.
>
> So, we may need another function something like ocfs2_inode_getbh():
>        if (!oh)
>           ocfs2_inode_lock();
>      else
>          ocfs2_inode_getbh();
> """
>
> Hope we can work out a nice solution for this tricky issue ;-)
>
> Eric
>
>
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