[Patch] write and wait on range before direct io read

This adds filemap_write_and_wait_range(mapping, lstart, lend) which starts writeback and waits on a range of pages. We call this from __blkdev_direct_IO with just the range that is going to be read by the direct_IO read. It was lightly tested with fsx and ext3 and passed. Signed-off-by: Zach

[Patch] write and wait on range before direct io read

This adds filemap_write_and_wait_range(mapping, lstart, lend) which starts writeback and waits on a range of pages. We call this from __blkdev_direct_IO with just the range that is going to be read by the direct_IO read. It was lightly tested with fsx and ext3 and passed. Signed-off-by: Zach