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    Subject[PATCH] rd: Mark ramdisk buffers heads dirty
    Date

    I have not observed this case but it is possible to get a dirty page
    cache with clean buffer heads if we get a clean ramdisk page with
    buffer heads generated by a filesystem calling __getblk and then write
    to that page from user space through the block device. Then we just
    need to hit the proper window and try_to_free_buffers() will mark that
    page clean and eventually drop it. Ouch!

    To fix this use the generic __set_page_dirty_buffers in the ramdisk
    code so that when we mark a page dirty we also mark it's buffer heads
    dirty.

    Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    ---
    drivers/block/rd.c | 13 +------------
    1 files changed, 1 insertions(+), 12 deletions(-)

    diff --git a/drivers/block/rd.c b/drivers/block/rd.c
    index 701ea77..84163da 100644
    --- a/drivers/block/rd.c
    +++ b/drivers/block/rd.c
    @@ -178,23 +178,12 @@ static int ramdisk_writepages(struct address_space *mapping,
    return 0;
    }

    -/*
    - * ramdisk blockdev pages have their own ->set_page_dirty() because we don't
    - * want them to contribute to dirty memory accounting.
    - */
    -static int ramdisk_set_page_dirty(struct page *page)
    -{
    - if (!TestSetPageDirty(page))
    - return 1;
    - return 0;
    -}
    -
    static const struct address_space_operations ramdisk_aops = {
    .readpage = ramdisk_readpage,
    .prepare_write = ramdisk_prepare_write,
    .commit_write = ramdisk_commit_write,
    .writepage = ramdisk_writepage,
    - .set_page_dirty = ramdisk_set_page_dirty,
    + .set_page_dirty = __set_page_dirty_buffers,
    .writepages = ramdisk_writepages,
    };

    --
    1.5.3.rc6.17.g1911
    -
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