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Date: Mon, 20 Oct 2014 14:53:45 -0700
From: josh@...htriplett.org
To: Pieter Smith <pieter@...sman.nl>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
open list <linux-kernel@...r.kernel.org>,
linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/2] fs: Moved sendfile syscall to own source file
On Mon, Oct 20, 2014 at 11:43:01PM +0200, Pieter Smith wrote:
> Part of the tinification effort. Splitting out the sendfile syscall
> allows optional compilation in the succeeding patch.
>
> Signed-off-by: Pieter Smith <pieter@...sman.nl>
Seems fine in general. One minor nit below, and with that,
Reviewed-by: Josh Triplett <josh@...htriplett.org>
> fs/Makefile | 3 +-
> fs/read_write.c | 176 -------------------------------------------------
> fs/sendfile.c | 200 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 201 insertions(+), 178 deletions(-)
> create mode 100644 fs/sendfile.c
>
> diff --git a/fs/Makefile b/fs/Makefile
> index 90c8852..1e3423f 100644
> --- a/fs/Makefile
> +++ b/fs/Makefile
> @@ -5,7 +5,7 @@
> # Rewritten to use lists instead of if-statements.
> #
>
> -obj-y := open.o read_write.o file_table.o super.o \
> +obj-y := open.o read_write.o sendfile.o file_table.o super.o \
> char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
> ioctl.o readdir.o select.o dcache.o inode.o \
> attr.o bad_inode.o file.o filesystems.o namespace.o \
> @@ -18,7 +18,6 @@ obj-y += buffer.o block_dev.o direct-io.o mpage.o
> else
> obj-y += no-block.o
> endif
> -
Unrelated whitespace change.
> obj-$(CONFIG_PROC_FS) += proc_namespace.o
>
> obj-y += notify/
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 009d854..fc27a01 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1188,179 +1188,3 @@ COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
> return __compat_sys_pwritev64(fd, vec, vlen, pos);
> }
> #endif
> -
> -static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> - size_t count, loff_t max)
> -{
> - struct fd in, out;
> - struct inode *in_inode, *out_inode;
> - loff_t pos;
> - loff_t out_pos;
> - ssize_t retval;
> - int fl;
> -
> - /*
> - * Get input file, and verify that it is ok..
> - */
> - retval = -EBADF;
> - in = fdget(in_fd);
> - if (!in.file)
> - goto out;
> - if (!(in.file->f_mode & FMODE_READ))
> - goto fput_in;
> - retval = -ESPIPE;
> - if (!ppos) {
> - pos = in.file->f_pos;
> - } else {
> - pos = *ppos;
> - if (!(in.file->f_mode & FMODE_PREAD))
> - goto fput_in;
> - }
> - retval = rw_verify_area(READ, in.file, &pos, count);
> - if (retval < 0)
> - goto fput_in;
> - count = retval;
> -
> - /*
> - * Get output file, and verify that it is ok..
> - */
> - retval = -EBADF;
> - out = fdget(out_fd);
> - if (!out.file)
> - goto fput_in;
> - if (!(out.file->f_mode & FMODE_WRITE))
> - goto fput_out;
> - retval = -EINVAL;
> - in_inode = file_inode(in.file);
> - out_inode = file_inode(out.file);
> - out_pos = out.file->f_pos;
> - retval = rw_verify_area(WRITE, out.file, &out_pos, count);
> - if (retval < 0)
> - goto fput_out;
> - count = retval;
> -
> - if (!max)
> - max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
> -
> - if (unlikely(pos + count > max)) {
> - retval = -EOVERFLOW;
> - if (pos >= max)
> - goto fput_out;
> - count = max - pos;
> - }
> -
> - fl = 0;
> -#if 0
> - /*
> - * We need to debate whether we can enable this or not. The
> - * man page documents EAGAIN return for the output at least,
> - * and the application is arguably buggy if it doesn't expect
> - * EAGAIN on a non-blocking file descriptor.
> - */
> - if (in.file->f_flags & O_NONBLOCK)
> - fl = SPLICE_F_NONBLOCK;
> -#endif
> - file_start_write(out.file);
> - retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl);
> - file_end_write(out.file);
> -
> - if (retval > 0) {
> - add_rchar(current, retval);
> - add_wchar(current, retval);
> - fsnotify_access(in.file);
> - fsnotify_modify(out.file);
> - out.file->f_pos = out_pos;
> - if (ppos)
> - *ppos = pos;
> - else
> - in.file->f_pos = pos;
> - }
> -
> - inc_syscr(current);
> - inc_syscw(current);
> - if (pos > max)
> - retval = -EOVERFLOW;
> -
> -fput_out:
> - fdput(out);
> -fput_in:
> - fdput(in);
> -out:
> - return retval;
> -}
> -
> -SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
> -{
> - loff_t pos;
> - off_t off;
> - ssize_t ret;
> -
> - if (offset) {
> - if (unlikely(get_user(off, offset)))
> - return -EFAULT;
> - pos = off;
> - ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
> - if (unlikely(put_user(pos, offset)))
> - return -EFAULT;
> - return ret;
> - }
> -
> - return do_sendfile(out_fd, in_fd, NULL, count, 0);
> -}
> -
> -SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
> -{
> - loff_t pos;
> - ssize_t ret;
> -
> - if (offset) {
> - if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
> - return -EFAULT;
> - ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
> - if (unlikely(put_user(pos, offset)))
> - return -EFAULT;
> - return ret;
> - }
> -
> - return do_sendfile(out_fd, in_fd, NULL, count, 0);
> -}
> -
> -#ifdef CONFIG_COMPAT
> -COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd,
> - compat_off_t __user *, offset, compat_size_t, count)
> -{
> - loff_t pos;
> - off_t off;
> - ssize_t ret;
> -
> - if (offset) {
> - if (unlikely(get_user(off, offset)))
> - return -EFAULT;
> - pos = off;
> - ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
> - if (unlikely(put_user(pos, offset)))
> - return -EFAULT;
> - return ret;
> - }
> -
> - return do_sendfile(out_fd, in_fd, NULL, count, 0);
> -}
> -
> -COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
> - compat_loff_t __user *, offset, compat_size_t, count)
> -{
> - loff_t pos;
> - ssize_t ret;
> -
> - if (offset) {
> - if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
> - return -EFAULT;
> - ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
> - if (unlikely(put_user(pos, offset)))
> - return -EFAULT;
> - return ret;
> - }
> -
> - return do_sendfile(out_fd, in_fd, NULL, count, 0);
> -}
> -#endif
> diff --git a/fs/sendfile.c b/fs/sendfile.c
> new file mode 100644
> index 0000000..4ceccd4
> --- /dev/null
> +++ b/fs/sendfile.c
> @@ -0,0 +1,200 @@
> +/*
> + * linux/fs/sendfile.c
> + *
> + * Copyright (C) 1991, 1992 Linus Torvalds
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/stat.h>
> +#include <linux/fcntl.h>
> +#include <linux/file.h>
> +#include <linux/uio.h>
> +#include <linux/aio.h>
> +#include <linux/fsnotify.h>
> +#include <linux/security.h>
> +#include <linux/export.h>
> +#include <linux/syscalls.h>
> +#include <linux/pagemap.h>
> +#include <linux/splice.h>
> +#include <linux/compat.h>
> +#include "internal.h"
> +
> +#include <linux/uaccess.h>
> +#include <asm/unistd.h>
> +
> +
> +static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> + size_t count, loff_t max)
> +{
> + struct fd in, out;
> + struct inode *in_inode, *out_inode;
> + loff_t pos;
> + loff_t out_pos;
> + ssize_t retval;
> + int fl;
> +
> + /*
> + * Get input file, and verify that it is ok..
> + */
> + retval = -EBADF;
> + in = fdget(in_fd);
> + if (!in.file)
> + goto out;
> + if (!(in.file->f_mode & FMODE_READ))
> + goto fput_in;
> + retval = -ESPIPE;
> + if (!ppos) {
> + pos = in.file->f_pos;
> + } else {
> + pos = *ppos;
> + if (!(in.file->f_mode & FMODE_PREAD))
> + goto fput_in;
> + }
> + retval = rw_verify_area(READ, in.file, &pos, count);
> + if (retval < 0)
> + goto fput_in;
> + count = retval;
> +
> + /*
> + * Get output file, and verify that it is ok..
> + */
> + retval = -EBADF;
> + out = fdget(out_fd);
> + if (!out.file)
> + goto fput_in;
> + if (!(out.file->f_mode & FMODE_WRITE))
> + goto fput_out;
> + retval = -EINVAL;
> + in_inode = file_inode(in.file);
> + out_inode = file_inode(out.file);
> + out_pos = out.file->f_pos;
> + retval = rw_verify_area(WRITE, out.file, &out_pos, count);
> + if (retval < 0)
> + goto fput_out;
> + count = retval;
> +
> + if (!max)
> + max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
> +
> + if (unlikely(pos + count > max)) {
> + retval = -EOVERFLOW;
> + if (pos >= max)
> + goto fput_out;
> + count = max - pos;
> + }
> +
> + fl = 0;
> +#if 0
> + /*
> + * We need to debate whether we can enable this or not. The
> + * man page documents EAGAIN return for the output at least,
> + * and the application is arguably buggy if it doesn't expect
> + * EAGAIN on a non-blocking file descriptor.
> + */
> + if (in.file->f_flags & O_NONBLOCK)
> + fl = SPLICE_F_NONBLOCK;
> +#endif
> + file_start_write(out.file);
> + retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl);
> + file_end_write(out.file);
> +
> + if (retval > 0) {
> + add_rchar(current, retval);
> + add_wchar(current, retval);
> + fsnotify_access(in.file);
> + fsnotify_modify(out.file);
> + out.file->f_pos = out_pos;
> + if (ppos)
> + *ppos = pos;
> + else
> + in.file->f_pos = pos;
> + }
> +
> + inc_syscr(current);
> + inc_syscw(current);
> + if (pos > max)
> + retval = -EOVERFLOW;
> +
> +fput_out:
> + fdput(out);
> +fput_in:
> + fdput(in);
> +out:
> + return retval;
> +}
> +
> +SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
> +{
> + loff_t pos;
> + off_t off;
> + ssize_t ret;
> +
> + if (offset) {
> + if (unlikely(get_user(off, offset)))
> + return -EFAULT;
> + pos = off;
> + ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
> + if (unlikely(put_user(pos, offset)))
> + return -EFAULT;
> + return ret;
> + }
> +
> + return do_sendfile(out_fd, in_fd, NULL, count, 0);
> +}
> +
> +SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
> +{
> + loff_t pos;
> + ssize_t ret;
> +
> + if (offset) {
> + if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
> + return -EFAULT;
> + ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
> + if (unlikely(put_user(pos, offset)))
> + return -EFAULT;
> + return ret;
> + }
> +
> + return do_sendfile(out_fd, in_fd, NULL, count, 0);
> +}
> +
> +#ifdef CONFIG_COMPAT
> +COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd,
> + compat_off_t __user *, offset, compat_size_t, count)
> +{
> + loff_t pos;
> + off_t off;
> + ssize_t ret;
> +
> + if (offset) {
> + if (unlikely(get_user(off, offset)))
> + return -EFAULT;
> + pos = off;
> + ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
> + if (unlikely(put_user(pos, offset)))
> + return -EFAULT;
> + return ret;
> + }
> +
> + return do_sendfile(out_fd, in_fd, NULL, count, 0);
> +}
> +
> +COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
> + compat_loff_t __user *, offset, compat_size_t, count)
> +{
> + loff_t pos;
> + ssize_t ret;
> +
> + if (offset) {
> + if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
> + return -EFAULT;
> + ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
> + if (unlikely(put_user(pos, offset)))
> + return -EFAULT;
> + return ret;
> + }
> +
> + return do_sendfile(out_fd, in_fd, NULL, count, 0);
> +}
> +#endif
> --
> 1.9.1
>
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