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    SubjectRe: [PATCH 2/4] AFS: Add a function to excise a rejected write from the pagecache
    Date
    Andrew Morton <akpm@linux-foundation.org> wrote:

    > hm. I don't see why that race window would be a problem in practice: the
    > page-exciser does a lock_page();wait_on_page_writeback() as normal, then
    > proceeds with its business?

    No. The page-exciser ends (cancels) PG_writeback, not waits for it (something
    has to clear the flag). The problem is that the truncation routines may be
    sat there holding a lock on the page whilst waiting for PG_writeback to go
    away - so we have to clear PG_writeback before we can think about getting
    PG_lock:-(

    > But given that this doesn't work right for some reason, can we use PG_error
    > and then handle that appropriately in the filesystem's ->prepare_write() and
    > ->page_mkwrite()?

    Possibly, though I'd rather they didn't see such a page.

    David
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