Re: [PATCH v6 2/7] vfs: Define new syscalls preadv2,pwritev2

From: Jeff Moyer
Date: Tue Nov 11 2014 - 16:10:07 EST

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In reply to: Milosz Tanski: "[PATCH v6 2/7] vfs: Define new syscalls preadv2,pwritev2"
Next in thread: Milosz Tanski: "[PATCH v6 7/7] fs: add a flag for per-operation O_DSYNC semantics"
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Milosz Tanski <milosz@xxxxxxxxx> writes:

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

Looks good.

Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx>

>
> Signed-off-by: Milosz Tanski <milosz@xxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> ---
> 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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