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    Subject[patch 2/3] fs: buffer don't PageUptodate without page locked
    Date
    __block_write_full_page is calling SetPageUptodate without the page locked.
    This is unusual, but not incorrect, as PG_writeback is still set.

    However with the previous patch, this is now a problem: so don't bother
    setting the page uptodate in this case (it is weird that the write path
    does such a thing anyway). Instead just leave it to the read side to bring
    the page uptodate when it notices that all buffers are uptodate.

    Signed-off-by: Nick Piggin <npiggin@suse.de>

    Index: linux-2.6/fs/buffer.c
    ===================================================================
    --- linux-2.6.orig/fs/buffer.c
    +++ linux-2.6/fs/buffer.c
    @@ -1679,6 +1679,7 @@ static int __block_write_full_page(struc
    */
    BUG_ON(PageWriteback(page));
    set_page_writeback(page);
    + unlock_page(page);

    do {
    struct buffer_head *next = bh->b_this_page;
    @@ -1688,7 +1689,6 @@ static int __block_write_full_page(struc
    }
    bh = next;
    } while (bh != head);
    - unlock_page(page);

    err = 0;
    done:
    @@ -1698,17 +1698,8 @@ done:
    * clean. Someone wrote them back by hand with
    * ll_rw_block/submit_bh. A rare case.
    */
    - int uptodate = 1;
    - do {
    - if (!buffer_uptodate(bh)) {
    - uptodate = 0;
    - break;
    - }
    - bh = bh->b_this_page;
    - } while (bh != head);
    - if (uptodate)
    - SetPageUptodate(page);
    end_page_writeback(page);
    +
    /*
    * The page and buffer_heads can be released at any time from
    * here on.
    -
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      Last update: 2007-02-06 09:07    [W:0.023 / U:0.788 seconds]
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