On Mon, 16 Jul 2012 09:30:50 +0800 majianpeng <majianpeng@xxxxxxxxx> wrote:
> For regular file, write operaion used blk_plug function.But for block
> file,write operation did not use blk_plug.
>
> Signed-off-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
> ---
> fs/block_dev.c | 7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index c2bbe1f..22cd436 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -215,9 +215,14 @@ blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
> {
> struct file *file = iocb->ki_filp;
> struct inode *inode = file->f_mapping->host;
> + struct blk_plug plug;
> + ssize_t ret;
>
> - return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
> + blk_start_plug(&plug);
> + ret = __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
> nr_segs, blkdev_get_blocks, NULL, NULL, 0);
> + blk_finish_plug(&plug);
> + return ret;
> }
>
> int __sync_blockdev(struct block_device *bdev, int wait)
[cc:ing Jens Axboe]
I think we do need something like this, but I don't think this is the right
place for it.
For normal filesystem writes, the blk_{start,finish}_plug calls are in
generic_file_aio_write which is the "aio_write" function, or is called by it.
aio_write calls generic_file_aio_write, calls blk_start_plug, call
__generic_file_aio_write.
For block devices we bypass the generic_file_aio_write:
aio_write calls blkdev_aio_write calls __generic_file_aio_write - without
calling blk_start_plug.
So I think the calls to blk_start_plug and blk_finish_plug should go in
blkdev_aio_write. i.e. blkdev_aio_write should be made to look more like
generic_file_aio_write (just without the mutex_lock/unlock).
If you redo the patch like that and test it I'll happily add my Reviewed-by.
I suspect it should be merged through Jens' tree.
Thanks,
NeilBrown
Attachment:
signature.asc
Description: PGP signature
