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    Subject[30/30] vfs: Fix vmtruncate() regression
    2.6.32-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

    commit cedabed49b39b4319bccc059a63344b6232b619c upstream.

    If __block_prepare_write() was failed in block_write_begin(), the
    allocated blocks can be outside of ->i_size.

    But new truncate_pagecache() in vmtuncate() does nothing if new < old.
    It means the above usage is not working anymore.

    So, this patch fixes it by removing "new < old" check. It would need
    more cleanup/change. But, now -rc and truncate working is in progress,
    so, this tried to fix it minimum change.

    Acked-by: Nick Piggin <npiggin@suse.de>
    Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    mm/truncate.c | 28 +++++++++++++---------------
    1 file changed, 13 insertions(+), 15 deletions(-)

    --- a/mm/truncate.c
    +++ b/mm/truncate.c
    @@ -516,22 +516,20 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages
    */
    void truncate_pagecache(struct inode *inode, loff_t old, loff_t new)
    {
    - if (new < old) {
    - struct address_space *mapping = inode->i_mapping;
    + struct address_space *mapping = inode->i_mapping;

    - /*
    - * unmap_mapping_range is called twice, first simply for
    - * efficiency so that truncate_inode_pages does fewer
    - * single-page unmaps. However after this first call, and
    - * before truncate_inode_pages finishes, it is possible for
    - * private pages to be COWed, which remain after
    - * truncate_inode_pages finishes, hence the second
    - * unmap_mapping_range call must be made for correctness.
    - */
    - unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
    - truncate_inode_pages(mapping, new);
    - unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
    - }
    + /*
    + * unmap_mapping_range is called twice, first simply for
    + * efficiency so that truncate_inode_pages does fewer
    + * single-page unmaps. However after this first call, and
    + * before truncate_inode_pages finishes, it is possible for
    + * private pages to be COWed, which remain after
    + * truncate_inode_pages finishes, hence the second
    + * unmap_mapping_range call must be made for correctness.
    + */
    + unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
    + truncate_inode_pages(mapping, new);
    + unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
    }
    EXPORT_SYMBOL(truncate_pagecache);




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