From: "Michael Kerrisk" <mtk.manpages@googlemail.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH v2] Add preadv and pwritev system calls.
Date: Fri, 12 Dec 2008 20:18:11 -0500 [thread overview]
Message-ID: <cfd18e0f0812121718s735c492ev43b25950d9c0e3b2@mail.gmail.com> (raw)
In-Reply-To: <1229090440-32120-1-git-send-email-kraxel@redhat.com>
Gerd,
Please CC linux-api on patches that change the API!
Cheers,
Michael
On Fri, Dec 12, 2008 at 9:00 AM, Gerd Hoffmann <kraxel@redhat.com> wrote:
> This patch adds preadv and pwritev system calls. These syscalls are a
> pretty straightforward combination of pread and readv (same for write).
> They are quite useful for doing vectored I/O in threaded applications.
> Using lseek+readv instead opens race windows you'll have to plug with
> locking.
>
> Other systems have such system calls too, for example NetBSD, check
> here: http://www.daemon-systems.org/man/preadv.2.html
>
> The patch sports the actual system call implementation and the windup in
> the x86 system call tables. Other archs are TBD.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
> arch/x86/ia32/ia32entry.S | 2 +
> arch/x86/include/asm/unistd_32.h | 2 +
> arch/x86/include/asm/unistd_64.h | 4 ++
> arch/x86/kernel/syscall_table_32.S | 2 +
> fs/compat.c | 61 ++++++++++++++++++++++++++++++++++++
> fs/read_write.c | 48 ++++++++++++++++++++++++++++
> 6 files changed, 119 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
> index 256b00b..9a8501b 100644
> --- a/arch/x86/ia32/ia32entry.S
> +++ b/arch/x86/ia32/ia32entry.S
> @@ -826,4 +826,6 @@ ia32_sys_call_table:
> .quad sys_dup3 /* 330 */
> .quad sys_pipe2
> .quad sys_inotify_init1
> + .quad compat_sys_preadv
> + .quad compat_sys_pwritev
> ia32_syscall_end:
> diff --git a/arch/x86/include/asm/unistd_32.h b/arch/x86/include/asm/unistd_32.h
> index f2bba78..6e72d74 100644
> --- a/arch/x86/include/asm/unistd_32.h
> +++ b/arch/x86/include/asm/unistd_32.h
> @@ -338,6 +338,8 @@
> #define __NR_dup3 330
> #define __NR_pipe2 331
> #define __NR_inotify_init1 332
> +#define __NR_preadv 333
> +#define __NR_pwritev 334
>
> #ifdef __KERNEL__
>
> diff --git a/arch/x86/include/asm/unistd_64.h b/arch/x86/include/asm/unistd_64.h
> index d2e415e..f818294 100644
> --- a/arch/x86/include/asm/unistd_64.h
> +++ b/arch/x86/include/asm/unistd_64.h
> @@ -653,6 +653,10 @@ __SYSCALL(__NR_dup3, sys_dup3)
> __SYSCALL(__NR_pipe2, sys_pipe2)
> #define __NR_inotify_init1 294
> __SYSCALL(__NR_inotify_init1, sys_inotify_init1)
> +#define __NR_preadv 295
> +__SYSCALL(__NR_preadv, sys_preadv)
> +#define __NR_pwritev 296
> +__SYSCALL(__NR_pwritev, sys_pwritev)
>
>
> #ifndef __NO_STUBS
> diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
> index d44395f..a1a5506 100644
> --- a/arch/x86/kernel/syscall_table_32.S
> +++ b/arch/x86/kernel/syscall_table_32.S
> @@ -332,3 +332,5 @@ ENTRY(sys_call_table)
> .long sys_dup3 /* 330 */
> .long sys_pipe2
> .long sys_inotify_init1
> + .long sys_preadv
> + .long sys_pwritev
> diff --git a/fs/compat.c b/fs/compat.c
> index e5f49f5..3a25cf3 100644
> --- a/fs/compat.c
> +++ b/fs/compat.c
> @@ -1214,6 +1214,67 @@ out:
> return ret;
> }
>
> +asmlinkage ssize_t
> +compat_sys_preadv(unsigned long fd, const struct compat_iovec __user *vec,
> + unsigned long vlen, loff_t pos)
> +{
> + struct file *file;
> + ssize_t ret = -EBADF;
> +
> + if (pos < 0)
> + return -EINVAL;
> +
> + file = fget(fd);
> + if (!file)
> + return -EBADF;
> +
> + if (!(file->f_mode & FMODE_READ))
> + goto out;
> +
> + ret = -EINVAL;
> + if (!file->f_op || (!file->f_op->aio_read && !file->f_op->read))
> + goto out;
> +
> + ret = compat_do_readv_writev(READ, file, vec, vlen, &pos);
> +
> +out:
> + if (ret > 0)
> + add_rchar(current, ret);
> + inc_syscr(current);
> + fput(file);
> + return ret;
> +}
> +
> +asmlinkage ssize_t
> +compat_sys_pwritev(unsigned long fd, const struct compat_iovec __user *vec,
> + unsigned long vlen, loff_t pos)
> +{
> + struct file *file;
> + ssize_t ret = -EBADF;
> +
> + if (pos < 0)
> + return -EINVAL;
> +
> + file = fget(fd);
> + if (!file)
> + return -EBADF;
> + if (!(file->f_mode & FMODE_WRITE))
> + goto out;
> +
> + ret = -EINVAL;
> + if (!file->f_op || (!file->f_op->aio_write && !file->f_op->write))
> + goto out;
> +
> + ret = compat_do_readv_writev(WRITE, file, vec, vlen, &pos);
> +
> +out:
> + if (ret > 0)
> + add_wchar(current, ret);
> + inc_syscw(current);
> + fput(file);
> + return ret;
> +}
> +
> asmlinkage long
> compat_sys_vmsplice(int fd, const struct compat_iovec __user *iov32,
> unsigned int nr_segs, unsigned int flags)
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 969a6d9..89f273d 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -701,6 +701,54 @@ sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
> return ret;
> }
>
> +asmlinkage ssize_t sys_preadv(unsigned long fd, const struct iovec __user *vec,
> + unsigned long vlen, loff_t pos)
> +{
> + struct file *file;
> + ssize_t ret = -EBADF;
> + int fput_needed;
> +
> + if (pos < 0)
> + return -EINVAL;
> +
> + file = fget_light(fd, &fput_needed);
> + if (file) {
> + ret = -ESPIPE;
> + if (file->f_mode & FMODE_PREAD)
> + ret = vfs_readv(file, vec, vlen, &pos);
> + fput_light(file, fput_needed);
> + }
> +
> + if (ret > 0)
> + add_rchar(current, ret);
> + inc_syscr(current);
> + return ret;
> +}
> +
> +asmlinkage ssize_t sys_pwritev(unsigned long fd, const struct iovec __user *vec,
> + unsigned long vlen, loff_t pos)
> +{
> + struct file *file;
> + ssize_t ret = -EBADF;
> + int fput_needed;
> +
> + if (pos < 0)
> + return -EINVAL;
> +
> + file = fget_light(fd, &fput_needed);
> + if (file) {
> + ret = -ESPIPE;
> + if (file->f_mode & FMODE_PWRITE)
> + ret = vfs_writev(file, vec, vlen, &pos);
> + fput_light(file, fput_needed);
> + }
> +
> + if (ret > 0)
> + add_wchar(current, ret);
> + inc_syscw(current);
> + return ret;
> +}
> +
> static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> size_t count, loff_t max)
> {
> --
> 1.5.6.5
>
> --
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--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git
man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html
Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html
prev parent reply other threads:[~2008-12-13 1:18 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-12 14:00 [PATCH v2] Add preadv and pwritev system calls Gerd Hoffmann
2008-12-12 15:29 ` Matthew Wilcox
2008-12-12 15:48 ` Gerd Hoffmann
2008-12-12 15:51 ` Matthew Wilcox
2008-12-12 16:02 ` Gerd Hoffmann
2008-12-12 17:03 ` Matthew Wilcox
2008-12-12 17:03 ` Matthew Wilcox
2008-12-12 18:21 ` Alan Cox
2008-12-12 19:02 ` Russell King
2008-12-12 18:29 ` Scott Lurndal
2008-12-12 19:07 ` Russell King
2008-12-12 19:56 ` Gerd Hoffmann
2008-12-12 19:56 ` Gerd Hoffmann
2008-12-12 20:12 ` Russell King
2008-12-12 20:12 ` Russell King
2008-12-12 20:39 ` Gerd Hoffmann
2008-12-12 20:39 ` Gerd Hoffmann
2008-12-14 18:19 ` Pavel Machek
2008-12-14 18:19 ` Pavel Machek
2008-12-15 16:37 ` Jennifer Pioch
2008-12-15 20:43 ` Gerd Hoffmann
2008-12-16 9:57 ` Arnd Bergmann
[not found] ` <200812161057.03025.arnd-r2nGTMty4D4@public.gmane.org>
2008-12-17 1:45 ` Dan Mick
2008-12-17 1:45 ` [osol-code] " Dan Mick
2008-12-12 19:47 ` Arnd Bergmann
2008-12-12 20:02 ` Gerd Hoffmann
2008-12-14 11:49 ` Heiko Carstens
2008-12-15 4:14 ` Paul Mackerras
2008-12-15 6:20 ` David Miller
2008-12-12 15:40 ` Ralf Baechle
2008-12-12 16:59 ` Russell King
2008-12-13 1:18 ` Michael Kerrisk [this message]
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