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    SubjectRe: [PATCH 17/46] fs: Use rename lock and RCU for multi-step operations
    On Wed, Jan 26, 2011 at 9:18 PM, Nick Piggin <> wrote:
    > On Wed, Jan 26, 2011 at 9:10 AM, Yehuda Sadeh Weinraub
    > <> wrote:
    >> On Wed, Jan 19, 2011 at 2:32 PM, Nick Piggin <> wrote:
    >>> On Thu, Jan 20, 2011 at 9:27 AM, Yehuda Sadeh Weinraub
    >>> <> wrote:
    >>>> On Tue, Jan 18, 2011 at 2:42 PM, Nick Piggin <> wrote:
    >>>>> On Wed, Jan 19, 2011 at 9:32 AM, Yehuda Sadeh Weinraub
    >>>>>> There's an issue with ceph as it references the
    >>>>>> dentry->d_parent(->d_inode) at dentry_release(), so setting
    >>>>>> dentry->d_parent to NULL here doesn't work with ceph. Though there is
    >>>>>> some workaround for it, we would like to be sure that this one is
    >>>>>> really required so that we don't exacerbate the ugliness. The
    >>>>>> workaround is to keep a pointer to the parent inode in the private
    >>>>>> dentry structure, which will be referenced only at the .release()
    >>>>>> callback. This is clearly not ideal.
    >>>>> Hmm, I'll have to think about it. Probably we can check for
    >>>>> d_count == 0 rather than parent != NULL I think?
    >>>> That'll solve ceph's problem, don't know about how'd affect other
    >>>> stuff. We'll need to know whether this is the solution, or whether
    >>>> we'd need to introduce some other band aid fix.
    >>> No I think it will work fine. Basically we just need to know whether
    >>> we have been deleted, and if so then we restart rather than walking
    >>> back up the parent.
    >>> I'll send a patch in a few days. For the meantime, it's a rathe
    >>> small window for ceph to worry about. So we'll have something
    >>> before -rc2 which should be OK.
    >> I guess that it's a bit late for -rc2, should we assume that it'll be on -rc3?
    > Yeah, I'm sorry I've been travelling and a bit disconnected.
    > NFS folk are having a similar problem and looks like similar
    > proposed fix will do it.
    > So I think it is the best way to go to restore behaviour back to what
    > filesystems already expect, to avoid more surprises in future.

    Hi Nick,
    -rc4 is out and that issue is still broken. Do you have that patch
    ready or should we push our workaround?


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