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    SubjectRe: [RFC] block integrity: Fix write after checksum calculation problem
    On Mon, Apr 11, 2011 at 05:46:52PM -0700, Mingming Cao wrote:
    > Oh, right. Currently ext4_page_mkwrite drops the page lock before
    > calling it's dirty the page (by write_begin() and write_end(). I
    > suspect regrab the lock() after write_end() (with your proposed change)
    > and returning with locked still leave the dirty by ext4_page_mkwrite
    > unlocked. We probably should to keep the page locked the page during
    > the entire ext4_page_mkwrite() call. Any reason to drop the page lock()
    > before calling aops->write_begin()?

    write_begin takes the page lock by itself. That's one of the reasons why
    block_page_mkwrite doesn't use plain ->write_begin / write_end, the
    other beeing that we already get a page passed to use, so there's no
    need to do the pagecache lookup or allocation done by

    The best thing would be to completely drop ext4's current version
    of page_mkwrite and start out with a copy of block_page_mkwrite which
    has the journalling calls added back into it.

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