On Wed, 2012-02-08 at 19:01 +0800, Wu Fengguang wrote:
> Buffered write(2) is not directly tied to IO, so it's not suitable to
> handle plug in generic_file_aio_write().
>
> Also remove the redundant plug calls around ->direct_IO(), since we now
> do unplugging in the lower layer do_blockdev_direct_IO().
>
> CC: Jens Axboe <axboe@xxxxxxxxx>
> CC: Li Shaohua <shaohua.li@xxxxxxxxx>
> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> ---
> fs/direct-io.c | 4 ++++
> mm/filemap.c | 7 -------
> 2 files changed, 4 insertions(+), 7 deletions(-)
>
> --- linux-next.orig/mm/filemap.c 2012-02-08 18:51:50.000000000 +0800
> +++ linux-next/mm/filemap.c 2012-02-08 18:52:19.000000000 +0800
> @@ -1421,12 +1421,8 @@ generic_file_aio_read(struct kiocb *iocb
> retval = filemap_write_and_wait_range(mapping, pos,
> pos + iov_length(iov, nr_segs) - 1);
> if (!retval) {
> - struct blk_plug plug;
> -
> - blk_start_plug(&plug);
> retval = mapping->a_ops->direct_IO(READ, iocb,
> iov, pos, nr_segs);
> - blk_finish_plug(&plug);
> }
> if (retval > 0) {
> *ppos = pos + retval;
> @@ -2610,13 +2606,11 @@ ssize_t generic_file_aio_write(struct ki
> {
> struct file *file = iocb->ki_filp;
> struct inode *inode = file->f_mapping->host;
> - struct blk_plug plug;
> ssize_t ret;
>
> BUG_ON(iocb->ki_pos != pos);
>
> mutex_lock(&inode->i_mutex);
> - blk_start_plug(&plug);
> ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
> mutex_unlock(&inode->i_mutex);
>
> @@ -2627,7 +2621,6 @@ ssize_t generic_file_aio_write(struct ki
> if (err < 0 && ret > 0)
> ret = err;
> }
> - blk_finish_plug(&plug);
> return ret;
> }
> EXPORT_SYMBOL(generic_file_aio_write);
> --- linux-next.orig/fs/direct-io.c 2012-02-08 18:51:37.000000000 +0800
> +++ linux-next/fs/direct-io.c 2012-02-08 18:52:19.000000000 +0800
> @@ -1106,6 +1106,7 @@ do_blockdev_direct_IO(int rw, struct kio
> unsigned long user_addr;
> size_t bytes;
> struct buffer_head map_bh = { 0, };
> + struct blk_plug plug;
>
> if (rw & WRITE)
> rw = WRITE_ODIRECT;
> @@ -1221,6 +1222,8 @@ do_blockdev_direct_IO(int rw, struct kio
> PAGE_SIZE - user_addr / PAGE_SIZE);
> }
>
> + blk_start_plug(&plug);
> +
> for (seg = 0; seg < nr_segs; seg++) {
> user_addr = (unsigned long)iov[seg].iov_base;
> sdio.size += bytes = iov[seg].iov_len;
> @@ -1314,6 +1317,7 @@ do_blockdev_direct_IO(int rw, struct kio
> } else
> BUG_ON(retval != -EIOCBQUEUED);
>
> + blk_finish_plug(&plug);
This one can be moved up a little bit (before dio_cleanup)
Thanks,
Shaohua
> out:
> return retval;
> }
--
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