[linux-cifs-client] [PATCH] non-direct reading

[Jeff Layton]

On Wed, 1 Apr 2009 00:09:17 +0400
Pavel Shilovsky <piastry at etersoft.ru> wrote:

> I found bug in my patch, Here is right variant.
> 
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 3ae62fb..6525661 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -622,6 +622,23 @@ static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
>         return written;
>  }
> 
> +static ssize_t cifs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
> +                                 unsigned long nr_segs, loff_t pos)
> +{
> +       struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
> +       ssize_t read;
> +
> +       if (CIFS_I(inode)->clientCanCacheRead)
> +               read = generic_file_aio_read(iocb, iov, nr_segs, pos);
> +       else {
> +               read = cifs_user_read(iocb->ki_filp, iov->iov_base,
> +                               iov->iov_len, &pos);
> +               iocb->ki_pos = pos;
> +       }
> +       return read;
> +}
> +

I don't think this is what you want at all. Won't this make it so that
all reads will hit the server unless we have an oplock?

If you're having problems with cache consistency, then what you really
want to do is to fix it so that the inode is properly revalidated and
then invalidate the cache only if it looks like the file has changed.

> +
>  static loff_t cifs_llseek(struct file *file, loff_t offset, int origin)
>  {
>         /* origin == SEEK_END => we must revalidate the cached file length */
> @@ -733,7 +750,7 @@ const struct inode_operations cifs_symlink_inode_ops = {
>  const struct file_operations cifs_file_ops = {
>         .read = do_sync_read,
>         .write = do_sync_write,
> -       .aio_read = generic_file_aio_read,
> +       .aio_read = cifs_file_aio_read,
>         .aio_write = cifs_file_aio_write,
>         .open = cifs_open,
>         .release = cifs_close,
> 


-- 
Jeff Layton <jlayton at redhat.com>