On 2010-11-25, at 02:54, Morten Hustveit wrote:
> +static int f_readahead(struct file *filp, unsigned long arg)
> +{
> + if (arg) {
> + filp->f_ra.ra_pages = (arg + PAGE_SIZE - 1) >> PAGE_SHIFT;
Functionality itself is fine, but it would be clearer if you used a better variable name than "arg" here. Something like "readahead_bytes" or similar would make it immediately clear what the parameter is.
> + spin_lock(&filp->f_lock);
> + filp->f_mode &= ~FMODE_RANDOM;
> + spin_unlock(&filp->f_lock);
> + } else {
> + spin_lock(&filp->f_lock);
> + filp->f_mode |= FMODE_RANDOM;
> + spin_unlock(&filp->f_lock);
> + }
> +
> + return 0;
> +}
> +
> static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
> struct file *filp)
> {
> @@ -420,6 +445,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
> case F_GETPIPE_SZ:
> err = pipe_fcntl(filp, cmd, arg);
> break;
> + case F_READAHEAD:
> + err = f_readahead(filp, arg);
> + break;
> default:
> break;
> }
> diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
> index afc00af..69d8e4d 100644
> --- a/include/linux/fcntl.h
> +++ b/include/linux/fcntl.h
> @@ -28,6 +28,11 @@
> #define F_GETPIPE_SZ (F_LINUX_SPECIFIC_BASE + 8)
>
> /*
> + * Set read-ahead buffer size
> + */
> +#define F_READAHEAD (F_LINUX_SPECIFIC_BASE + 9)
> +
> +/*
> * Types of directory notifications that may be requested.
> */
> #define DN_ACCESS 0x00000001 /* File accessed */
> --
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Cheers, Andreas
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