From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
"Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>,
Shuah Khan <shuah@kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-man@vger.kernel.org,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH 1/3] readfile: implement readfile syscall
Date: Sat, 4 Jul 2020 20:35:36 +0200 [thread overview]
Message-ID: <CAMuHMdWeuzVjZMpR+d20X0mDCpVpNzEU0qpZO4LiMVGCgJBy3A@mail.gmail.com> (raw)
In-Reply-To: <20200704140250.423345-2-gregkh@linuxfoundation.org>
Hi Greg,
On Sat, Jul 4, 2020 at 4:05 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> It's a tiny syscall, meant to allow a user to do a single "open this
> file, read into this buffer, and close the file" all in a single shot.
>
> Should be good for reading "tiny" files like sysfs, procfs, and other
> "small" files.
>
> There is no restarting the syscall, this is a "simple" syscall, with the
> attempt to make reading "simple" files easier with less syscall
> overhead.
>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Thanks for your patch!
> --- a/fs/open.c
> +++ b/fs/open.c
> +SYSCALL_DEFINE5(readfile, int, dfd, const char __user *, filename,
> + char __user *, buffer, size_t, bufsize, int, flags)
> +{
> + struct open_flags op;
> + struct open_how how;
> + struct file *file;
> + loff_t pos = 0;
> + int retval;
> +
> + /* only accept a small subset of O_ flags that make sense */
> + if ((flags & (O_NOFOLLOW | O_NOATIME)) != flags)
> + return -EINVAL;
> +
> + /* add some needed flags to be able to open the file properly */
> + flags |= O_RDONLY | O_LARGEFILE;
> +
> + how = build_open_how(flags, 0000);
> + retval = build_open_flags(&how, &op);
> + if (retval)
> + return retval;
> +
> + file = readfile_open(dfd, filename, &op);
> + if (IS_ERR(file))
> + return PTR_ERR(file);
> +
> + retval = vfs_read(file, buffer, bufsize, &pos);
Should there be a way for the user to be informed that the file doesn't
fit in the provided buffer (.e.g. -EFBIG)?
> +
> + filp_close(file, NULL);
> +
> + return retval;
> +}
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2020-07-04 18:35 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-04 14:02 [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster Greg Kroah-Hartman
2020-07-04 14:02 ` [PATCH 1/3] readfile: implement readfile syscall Greg Kroah-Hartman
2020-07-04 18:35 ` Geert Uytterhoeven [this message]
2020-07-04 19:14 ` Matthew Wilcox
2020-07-04 19:41 ` Miklos Szeredi
2020-07-04 20:12 ` Al Viro
2020-07-04 20:16 ` Al Viro
2020-07-04 14:02 ` [PATCH 2/3] arch: wire up the " Greg Kroah-Hartman
2020-07-04 18:36 ` Geert Uytterhoeven
2020-07-04 14:02 ` [PATCH 3/3] selftests: add readfile(2) selftests Greg Kroah-Hartman
2020-07-04 18:38 ` Geert Uytterhoeven
2020-07-05 6:55 ` Greg Kroah-Hartman
2020-07-05 11:24 ` Geert Uytterhoeven
2020-07-05 11:36 ` Greg Kroah-Hartman
2020-07-05 1:41 ` Heinrich Schuchardt
2020-07-05 7:34 ` Greg Kroah-Hartman
2020-07-05 9:46 ` Heinrich Schuchardt
2020-07-04 14:02 ` [PATCH] readfile.2: new page describing readfile(2) Greg Kroah-Hartman
2020-07-05 2:54 ` Heinrich Schuchardt
2020-07-04 19:30 ` [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster Al Viro
2020-07-05 11:47 ` Greg Kroah-Hartman
2020-07-06 17:25 ` Dave Martin
2020-07-04 20:50 [PATCH 1/3] readfile: implement readfile syscall Alexey Dobriyan
2020-07-04 21:15 ` Miklos Szeredi
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