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    SubjectRe: [PATCH] UBI: flush wl before clearing update marker
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    On Fri, 2009-12-04 at 02:58 +0100, ext Greg KH wrote:
    > On Thu, Dec 03, 2009 at 09:01:45AM +0200, Artem Bityutskiy wrote:
    > > On Wed, 2009-12-02 at 16:42 +0100, ext Greg KH wrote:
    > > > On Wed, Dec 02, 2009 at 08:48:43AM +0200, Artem Bityutskiy wrote:
    > > > > From: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
    > > > >
    > > > > ubiupdatevol -t does the following:
    > > > > - ubi_start_update()
    > > > > - set_update_marker()
    > > > > - for all LEBs ubi_eba_unmap_leb()
    > > > > - clear_update_marker()
    > > > > - ubi_wl_flush()
    > > > >
    > > > > ubi_wl_flush() physically erases all PEB, once it returns all PEBs are
    > > > > empty. clear_update_marker() has the update marker written after return.
    > > > > If there is a power cut between the last two functions then the UBI
    > > > > volume has no longer the "update" marker set and may have some valid
    > > > > LEBs while some of them may be gone.
    > > > > If that volume in question happens to be a UBIFS volume, then mount
    > > > > will fail with
    > > > >
    > > > > |UBIFS error (pid 1361): ubifs_read_node: bad node type (255 but expected 6)
    > > > > |UBIFS error (pid 1361): ubifs_read_node: bad node at LEB 0:0
    > > > > |Not a node, first 24 bytes:
    > > > > |00000000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
    > > > >
    > > > > if there is at least one valid LEB and the wear-leveling worker managed
    > > > > to clear LEB 0.
    > > > >
    > > > > The patch waits for the wl worker to finish prior clearing the "update"
    > > > > marker on flash. The two new LEB which are scheduled for erasing after
    > > > > clear_update_marker() should not matter because they are only visible to
    > > > > UBI.
    > > > >
    > > > > Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
    > > > > Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
    > > > > Cc: stable@kernel.org
    > > > > Cc: linux-kernel@vger.kernel.org
    > > > > ---
    > > > > drivers/mtd/ubi/upd.c | 20 +++++++++++---------
    > > >
    > > >
    > > > I'm not the mtd or ubi maintainer, so why did you send this to me?
    > >
    > > Sorry, I thought the protocol to get to -stable is to send to you and CC
    > > stable. I maintain UBI and just wanted to send this patch to -stable. I
    > > googled a bit and could not find the right way.
    >
    > Look in the Documentation/stable_kernel_rules.txt that shows all you
    > need is the Cc: stable@kernel.org section in the Signed-off-by area like
    > you did.
    >
    > So when this goes into Linus's tree, I'll automatically get it in the
    > right inbox and know to apply it to the -stable tree.

    Oh, thanks a lot!

    --
    Best Regards,
    Artem Bityutskiy (Артём Битюцкий)

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