[RFC v2 2/5] Define new syscalls readv2,preadv2,writev2,pwritev2

[Milosz Tanski <milosz@adfin.com>]

New syscalls with an extra flag argument. For now all flags except for 0 are
not supported.

Signed-off-by: Milosz Tanski <milosz@adfin.com>
---
 fs/read_write.c                   | 80 +++++++++++++++++++++++++++++++++------
 include/linux/syscalls.h          | 12 ++++++
 include/uapi/asm-generic/unistd.h | 10 ++++-
 mm/filemap.c                      |  2 +-
 4 files changed, 90 insertions(+), 14 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 9f6d13d..3db2e87 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -864,6 +864,8 @@ 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);
 }
@@ -877,21 +879,23 @@ 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);
@@ -903,15 +907,15 @@ 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);
@@ -929,8 +933,9 @@ 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, unsigned long pos_l,
+			 unsigned long pos_h, int flags)
 {
 	loff_t pos = pos_from_hilo(pos_h, pos_l);
 	struct fd f;
@@ -943,7 +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);
 	}
 
@@ -953,8 +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, unsigned long pos_l,
+			  unsigned long pos_h, int flags)
 {
 	loff_t pos = pos_from_hilo(pos_h, pos_l);
 	struct fd f;
@@ -967,7 +973,7 @@ 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);
 	}
 
@@ -977,6 +983,56 @@ 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_DEFINE4(readv2, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen, int, flags)
+{
+	return do_readv(fd, vec, vlen, flags);
+}
+
+SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen)
+{
+	return do_writev(fd, vec, vlen, 0);
+}
+
+SYSCALL_DEFINE4(writev2, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen, int, flags)
+{
+	return do_writev(fd, vec, vlen, flags);
+}
+
+SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
+{
+	return do_preadv(fd, vec,  vlen, pos_l, pos_h, 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)
+{
+	return do_preadv(fd, vec,  vlen, pos_l, pos_h, flags);
+}
+
+SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
+{
+	return do_pwritev(fd, vec, vlen, pos_l, pos_h, 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)
+{
+	return do_pwritev(fd, vec, vlen, pos_l, pos_h, flags);
+}
+
 #ifdef CONFIG_COMPAT
 
 static ssize_t compat_do_readv_writev(int type, struct file *file,
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 0f86d85..0c49ae4 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -559,19 +559,31 @@ asmlinkage long sys_readahead(int fd, loff_t offset, size_t count);
 asmlinkage long sys_readv(unsigned long fd,
 			  const struct iovec __user *vec,
 			  unsigned long vlen);
+asmlinkage long sys_readv2(unsigned long fd,
+			  const struct iovec __user *vec,
+			  unsigned long vlen, int flags);
 asmlinkage long sys_write(unsigned int fd, const char __user *buf,
 			  size_t count);
 asmlinkage long sys_writev(unsigned long fd,
 			   const struct iovec __user *vec,
 			   unsigned long vlen);
+asmlinkage long sys_writev2(unsigned long fd,
+			    const struct iovec __user *vec,
+			    unsigned long vlen, int flags);
 asmlinkage long sys_pread64(unsigned int fd, char __user *buf,
 			    size_t count, loff_t pos);
 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 11d11bc..75ad687 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -213,6 +213,14 @@ __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_readv2 280
+__SC_COMP(__NR_readv2, sys_readv2)
+#define __NR_writev2 281
+__SC_COMP(__NR_writev2, sys_writev2)
+#define __NR_preadv2 282
+__SC_COMP(__NR_preadv2, sys_preadv2)
+#define __NR_pwritev2 283
+__SC_COMP(__NR_pwritev2, sys_pwritev2)
 
 /* fs/sendfile.c */
 #define __NR3264_sendfile 71
@@ -707,7 +715,7 @@ __SYSCALL(__NR_getrandom, sys_getrandom)
 __SYSCALL(__NR_memfd_create, sys_memfd_create)
 
 #undef __NR_syscalls
-#define __NR_syscalls 280
+#define __NR_syscalls 284
 
 /*
  * All syscalls below here should go away really,
diff --git a/mm/filemap.c b/mm/filemap.c
index 6e3ba07..e0919ba 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1726,7 +1726,7 @@ 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;
 }
-- 
2.1.0