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Date:	Tue, 11 Nov 2014 16:09:11 -0500
From:	Jeff Moyer <jmoyer@...hat.com>
To:	Milosz Tanski <milosz@...in.com>
Cc:	linux-kernel@...r.kernel.org,
	Christoph Hellwig <hch@...radead.org>,
	linux-fsdevel@...r.kernel.org, linux-aio@...ck.org,
	Mel Gorman <mgorman@...e.de>,
	Volker Lendecke <Volker.Lendecke@...net.de>,
	Tejun Heo <tj@...nel.org>, "Theodore Ts'o" <tytso@....edu>,
	Al Viro <viro@...iv.linux.org.uk>, linux-api@...r.kernel.org,
	Michael Kerrisk <mtk.manpages@...il.com>,
	linux-arch@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v6 2/7] vfs: Define new syscalls preadv2,pwritev2

Milosz Tanski <milosz@...in.com> writes:

> New syscalls that take an flag argument. This change does not add any specific
> flags.

Looks good.

Reviewed-by: Jeff Moyer <jmoyer@...hat.com>

>
> Signed-off-by: Milosz Tanski <milosz@...in.com>
> Reviewed-by: Christoph Hellwig <hch@....de>
> ---
>  fs/read_write.c                   | 172 ++++++++++++++++++++++++++++++--------
>  include/linux/compat.h            |   6 ++
>  include/linux/syscalls.h          |   6 ++
>  include/uapi/asm-generic/unistd.h |   6 +-
>  mm/filemap.c                      |   5 +-
>  5 files changed, 156 insertions(+), 39 deletions(-)
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 94b2d34..b1b4bc8 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -866,6 +866,8 @@ ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
>  		return -EBADF;
>  	if (!(file->f_mode & FMODE_CAN_READ))
>  		return -EINVAL;
> +	if (flags & ~0)
> +		return -EINVAL;
>  
>  	return do_readv_writev(READ, file, vec, vlen, pos, flags);
>  }
> @@ -879,21 +881,23 @@ ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
>  		return -EBADF;
>  	if (!(file->f_mode & FMODE_CAN_WRITE))
>  		return -EINVAL;
> +	if (flags & ~0)
> +		return -EINVAL;
>  
>  	return do_readv_writev(WRITE, file, vec, vlen, pos, flags);
>  }
>  
>  EXPORT_SYMBOL(vfs_writev);
>  
> -SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
> -		unsigned long, vlen)
> +static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec,
> +			unsigned long vlen, int flags)
>  {
>  	struct fd f = fdget_pos(fd);
>  	ssize_t ret = -EBADF;
>  
>  	if (f.file) {
>  		loff_t pos = file_pos_read(f.file);
> -		ret = vfs_readv(f.file, vec, vlen, &pos, 0);
> +		ret = vfs_readv(f.file, vec, vlen, &pos, flags);
>  		if (ret >= 0)
>  			file_pos_write(f.file, pos);
>  		fdput_pos(f);
> @@ -905,15 +909,15 @@ SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
>  	return ret;
>  }
>  
> -SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
> -		unsigned long, vlen)
> +static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec,
> +			 unsigned long vlen, int flags)
>  {
>  	struct fd f = fdget_pos(fd);
>  	ssize_t ret = -EBADF;
>  
>  	if (f.file) {
>  		loff_t pos = file_pos_read(f.file);
> -		ret = vfs_writev(f.file, vec, vlen, &pos, 0);
> +		ret = vfs_writev(f.file, vec, vlen, &pos, flags);
>  		if (ret >= 0)
>  			file_pos_write(f.file, pos);
>  		fdput_pos(f);
> @@ -931,10 +935,9 @@ static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
>  	return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
>  }
>  
> -SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
> -		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
> +static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec,
> +			 unsigned long vlen, loff_t pos, int flags)
>  {
> -	loff_t pos = pos_from_hilo(pos_h, pos_l);
>  	struct fd f;
>  	ssize_t ret = -EBADF;
>  
> @@ -945,7 +948,7 @@ SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
>  	if (f.file) {
>  		ret = -ESPIPE;
>  		if (f.file->f_mode & FMODE_PREAD)
> -			ret = vfs_readv(f.file, vec, vlen, &pos, 0);
> +			ret = vfs_readv(f.file, vec, vlen, &pos, flags);
>  		fdput(f);
>  	}
>  
> @@ -955,10 +958,9 @@ SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
>  	return ret;
>  }
>  
> -SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
> -		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
> +static ssize_t do_pwritev(unsigned long fd, const struct iovec __user *vec,
> +			  unsigned long vlen, loff_t pos, int flags)
>  {
> -	loff_t pos = pos_from_hilo(pos_h, pos_l);
>  	struct fd f;
>  	ssize_t ret = -EBADF;
>  
> @@ -969,7 +971,7 @@ SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
>  	if (f.file) {
>  		ret = -ESPIPE;
>  		if (f.file->f_mode & FMODE_PWRITE)
> -			ret = vfs_writev(f.file, vec, vlen, &pos, 0);
> +			ret = vfs_writev(f.file, vec, vlen, &pos, flags);
>  		fdput(f);
>  	}
>  
> @@ -979,11 +981,63 @@ SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
>  	return ret;
>  }
>  
> +SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
> +		unsigned long, vlen)
> +{
> +	return do_readv(fd, vec, vlen, 0);
> +}
> +
> +SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
> +		unsigned long, vlen)
> +{
> +	return do_writev(fd, vec, vlen, 0);
> +}
> +
> +SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
> +		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
> +{
> +	loff_t pos = pos_from_hilo(pos_h, pos_l);
> +
> +	return do_preadv(fd, vec, vlen, pos, 0);
> +}
> +
> +SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec,
> +		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
> +		int, flags)
> +{
> +	loff_t pos = pos_from_hilo(pos_h, pos_l);
> +
> +	if (pos == -1)
> +		return do_readv(fd, vec, vlen, flags);
> +
> +	return do_preadv(fd, vec, vlen, pos, flags);
> +}
> +
> +SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
> +		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
> +{
> +	loff_t pos = pos_from_hilo(pos_h, pos_l);
> +
> +	return do_pwritev(fd, vec, vlen, pos, 0);
> +}
> +
> +SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
> +		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
> +		int, flags)
> +{
> +	loff_t pos = pos_from_hilo(pos_h, pos_l);
> +
> +	if (pos == -1)
> +		return do_writev(fd, vec, vlen, flags);
> +
> +	return do_pwritev(fd, vec, vlen, pos, flags);
> +}
> +
>  #ifdef CONFIG_COMPAT
>  
>  static ssize_t compat_do_readv_writev(int type, struct file *file,
>  			       const struct compat_iovec __user *uvector,
> -			       unsigned long nr_segs, loff_t *pos)
> +			       unsigned long nr_segs, loff_t *pos, int flags)
>  {
>  	compat_ssize_t tot_len;
>  	struct iovec iovstack[UIO_FASTIOV];
> @@ -1017,7 +1071,7 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
>  
>  	if (iter_fn)
>  		ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
> -						pos, iter_fn, 0);
> +						pos, iter_fn, flags);
>  	else if (fnv)
>  		ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
>  						pos, fnv);
> @@ -1041,7 +1095,7 @@ out:
>  
>  static size_t compat_readv(struct file *file,
>  			   const struct compat_iovec __user *vec,
> -			   unsigned long vlen, loff_t *pos)
> +			   unsigned long vlen, loff_t *pos, int flags)
>  {
>  	ssize_t ret = -EBADF;
>  
> @@ -1051,8 +1105,10 @@ static size_t compat_readv(struct file *file,
>  	ret = -EINVAL;
>  	if (!(file->f_mode & FMODE_CAN_READ))
>  		goto out;
> +	if (flags & ~0)
> +		goto out;
>  
> -	ret = compat_do_readv_writev(READ, file, vec, vlen, pos);
> +	ret = compat_do_readv_writev(READ, file, vec, vlen, pos, flags);
>  
>  out:
>  	if (ret > 0)
> @@ -1061,9 +1117,9 @@ out:
>  	return ret;
>  }
>  
> -COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
> -		const struct compat_iovec __user *,vec,
> -		compat_ulong_t, vlen)
> +static size_t __compat_sys_readv(compat_ulong_t fd,
> +				 const struct compat_iovec __user *vec,
> +				 compat_ulong_t vlen, int flags)
>  {
>  	struct fd f = fdget_pos(fd);
>  	ssize_t ret;
> @@ -1072,16 +1128,24 @@ COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
>  	if (!f.file)
>  		return -EBADF;
>  	pos = f.file->f_pos;
> -	ret = compat_readv(f.file, vec, vlen, &pos);
> +	ret = compat_readv(f.file, vec, vlen, &pos, flags);
>  	if (ret >= 0)
>  		f.file->f_pos = pos;
>  	fdput_pos(f);
>  	return ret;
> +
> +}
> +
> +COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
> +		const struct compat_iovec __user *,vec,
> +		compat_ulong_t, vlen)
> +{
> +	return __compat_sys_readv(fd, vec, vlen, 0);
>  }
>  
>  static long __compat_sys_preadv64(unsigned long fd,
>  				  const struct compat_iovec __user *vec,
> -				  unsigned long vlen, loff_t pos)
> +				  unsigned long vlen, loff_t pos, int flags)
>  {
>  	struct fd f;
>  	ssize_t ret;
> @@ -1093,7 +1157,7 @@ static long __compat_sys_preadv64(unsigned long fd,
>  		return -EBADF;
>  	ret = -ESPIPE;
>  	if (f.file->f_mode & FMODE_PREAD)
> -		ret = compat_readv(f.file, vec, vlen, &pos);
> +		ret = compat_readv(f.file, vec, vlen, &pos, flags);
>  	fdput(f);
>  	return ret;
>  }
> @@ -1103,7 +1167,7 @@ COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
>  		const struct compat_iovec __user *,vec,
>  		unsigned long, vlen, loff_t, pos)
>  {
> -	return __compat_sys_preadv64(fd, vec, vlen, pos);
> +	return __compat_sys_preadv64(fd, vec, vlen, pos, 0);
>  }
>  #endif
>  
> @@ -1113,12 +1177,25 @@ COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
>  {
>  	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
>  
> -	return __compat_sys_preadv64(fd, vec, vlen, pos);
> +	return __compat_sys_preadv64(fd, vec, vlen, pos, 0);
> +}
> +
> +COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
> +		const struct compat_iovec __user *,vec,
> +		compat_ulong_t, vlen, u32, pos_low, u32, pos_high,
> +		int, flags)
> +{
> +	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
> +
> +	if (pos == -1)
> +		return __compat_sys_readv(fd, vec, vlen, flags);
> +
> +	return __compat_sys_preadv64(fd, vec, vlen, pos, flags);
>  }
>  
>  static size_t compat_writev(struct file *file,
>  			    const struct compat_iovec __user *vec,
> -			    unsigned long vlen, loff_t *pos)
> +			    unsigned long vlen, loff_t *pos, int flags)
>  {
>  	ssize_t ret = -EBADF;
>  
> @@ -1128,8 +1205,10 @@ static size_t compat_writev(struct file *file,
>  	ret = -EINVAL;
>  	if (!(file->f_mode & FMODE_CAN_WRITE))
>  		goto out;
> +	if (flags & ~0)
> +		goto out;
>  
> -	ret = compat_do_readv_writev(WRITE, file, vec, vlen, pos);
> +	ret = compat_do_readv_writev(WRITE, file, vec, vlen, pos, flags);
>  
>  out:
>  	if (ret > 0)
> @@ -1138,9 +1217,9 @@ out:
>  	return ret;
>  }
>  
> -COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
> -		const struct compat_iovec __user *, vec,
> -		compat_ulong_t, vlen)
> +static size_t __compat_sys_writev(compat_ulong_t fd,
> +				  const struct compat_iovec __user* vec,
> +				  compat_ulong_t vlen, int flags)
>  {
>  	struct fd f = fdget_pos(fd);
>  	ssize_t ret;
> @@ -1149,28 +1228,36 @@ COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
>  	if (!f.file)
>  		return -EBADF;
>  	pos = f.file->f_pos;
> -	ret = compat_writev(f.file, vec, vlen, &pos);
> +	ret = compat_writev(f.file, vec, vlen, &pos, flags);
>  	if (ret >= 0)
>  		f.file->f_pos = pos;
>  	fdput_pos(f);
>  	return ret;
>  }
>  
> +COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
> +		const struct compat_iovec __user *, vec,
> +		compat_ulong_t, vlen)
> +{
> +	return __compat_sys_writev(fd, vec, vlen, 0);
> +}
> +
>  static long __compat_sys_pwritev64(unsigned long fd,
>  				   const struct compat_iovec __user *vec,
> -				   unsigned long vlen, loff_t pos)
> +				   unsigned long vlen, loff_t pos, int flags)
>  {
>  	struct fd f;
>  	ssize_t ret;
>  
>  	if (pos < 0)
>  		return -EINVAL;
> +
>  	f = fdget(fd);
>  	if (!f.file)
>  		return -EBADF;
>  	ret = -ESPIPE;
>  	if (f.file->f_mode & FMODE_PWRITE)
> -		ret = compat_writev(f.file, vec, vlen, &pos);
> +		ret = compat_writev(f.file, vec, vlen, &pos, flags);
>  	fdput(f);
>  	return ret;
>  }
> @@ -1180,7 +1267,7 @@ COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd,
>  		const struct compat_iovec __user *,vec,
>  		unsigned long, vlen, loff_t, pos)
>  {
> -	return __compat_sys_pwritev64(fd, vec, vlen, pos);
> +	return __compat_sys_pwritev64(fd, vec, vlen, pos, 0);
>  }
>  #endif
>  
> @@ -1190,8 +1277,21 @@ COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
>  {
>  	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
>  
> -	return __compat_sys_pwritev64(fd, vec, vlen, pos);
> +	return __compat_sys_pwritev64(fd, vec, vlen, pos, 0);
> +}
> +
> +COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
> +		const struct compat_iovec __user *,vec,
> +		compat_ulong_t, vlen, u32, pos_low, u32, pos_high, int, flags)
> +{
> +	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
> +
> +	if (pos == -1)
> +		return __compat_sys_writev(fd, vec, vlen, flags);
> +
> +	return __compat_sys_pwritev64(fd, vec, vlen, pos, flags);
>  }
> +
>  #endif
>  
>  static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index e649426..63a94e2 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -340,6 +340,12 @@ asmlinkage ssize_t compat_sys_preadv(compat_ulong_t fd,
>  asmlinkage ssize_t compat_sys_pwritev(compat_ulong_t fd,
>  		const struct compat_iovec __user *vec,
>  		compat_ulong_t vlen, u32 pos_low, u32 pos_high);
> +asmlinkage ssize_t compat_sys_preadv2(compat_ulong_t fd,
> +		const struct compat_iovec __user *vec,
> +		compat_ulong_t vlen, u32 pos_low, u32 pos_high, int flags);
> +asmlinkage ssize_t compat_sys_pwritev2(compat_ulong_t fd,
> +		const struct compat_iovec __user *vec,
> +		compat_ulong_t vlen, u32 pos_low, u32 pos_high, int flags);
>  
>  #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
>  asmlinkage long compat_sys_preadv64(unsigned long fd,
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index bda9b81..cedc22e 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -571,8 +571,14 @@ asmlinkage long sys_pwrite64(unsigned int fd, const char __user *buf,
>  			     size_t count, loff_t pos);
>  asmlinkage long sys_preadv(unsigned long fd, const struct iovec __user *vec,
>  			   unsigned long vlen, unsigned long pos_l, unsigned long pos_h);
> +asmlinkage long sys_preadv2(unsigned long fd, const struct iovec __user *vec,
> +			    unsigned long vlen, unsigned long pos_l, unsigned long pos_h,
> +			    int flags);
>  asmlinkage long sys_pwritev(unsigned long fd, const struct iovec __user *vec,
>  			    unsigned long vlen, unsigned long pos_l, unsigned long pos_h);
> +asmlinkage long sys_pwritev2(unsigned long fd, const struct iovec __user *vec,
> +			    unsigned long vlen, unsigned long pos_l, unsigned long pos_h,
> +			    int flags);
>  asmlinkage long sys_getcwd(char __user *buf, unsigned long size);
>  asmlinkage long sys_mkdir(const char __user *pathname, umode_t mode);
>  asmlinkage long sys_chdir(const char __user *filename);
> diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> index 22749c1..9406018 100644
> --- a/include/uapi/asm-generic/unistd.h
> +++ b/include/uapi/asm-generic/unistd.h
> @@ -213,6 +213,10 @@ __SC_COMP(__NR_pwrite64, sys_pwrite64, compat_sys_pwrite64)
>  __SC_COMP(__NR_preadv, sys_preadv, compat_sys_preadv)
>  #define __NR_pwritev 70
>  __SC_COMP(__NR_pwritev, sys_pwritev, compat_sys_pwritev)
> +#define __NR_preadv2 281
> +__SC_COMP(__NR_preadv2, sys_preadv2, compat_sys_preadv2)
> +#define __NR_pwritev2 282
> +__SC_COMP(__NR_pwritev2, sys_pwritev2, compat_sys_pwritev2)
>  
>  /* fs/sendfile.c */
>  #define __NR3264_sendfile 71
> @@ -709,7 +713,7 @@ __SYSCALL(__NR_memfd_create, sys_memfd_create)
>  __SYSCALL(__NR_bpf, sys_bpf)
>  
>  #undef __NR_syscalls
> -#define __NR_syscalls 281
> +#define __NR_syscalls 283
>  
>  /*
>   * All syscalls below here should go away really,
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 14b4642..530c263 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1457,6 +1457,7 @@ static void shrink_readahead_size_eio(struct file *filp,
>   * @ppos:	current file position
>   * @iter:	data destination
>   * @written:	already copied
> + * @flags:	optional flags
>   *
>   * This is a generic file read routine, and uses the
>   * mapping->a_ops->readpage() function for the actual low-level stuff.
> @@ -1465,7 +1466,7 @@ static void shrink_readahead_size_eio(struct file *filp,
>   * of the logic when it comes to error handling etc.
>   */
>  static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
> -		struct iov_iter *iter, ssize_t written)
> +		struct iov_iter *iter, ssize_t written, int flags)
>  {
>  	struct address_space *mapping = filp->f_mapping;
>  	struct inode *inode = mapping->host;
> @@ -1735,7 +1736,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
>  		}
>  	}
>  
> -	retval = do_generic_file_read(file, ppos, iter, retval);
> +	retval = do_generic_file_read(file, ppos, iter, retval, iocb->ki_rwflags);
>  out:
>  	return retval;
>  }
--
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