Re: [git pull] vfs.git part 3

[Christoph Hellwig <hch@lst.de>]

On Thu, Jul 06, 2017 at 04:51:13PM +0100, Al Viro wrote:
> On Thu, Jul 06, 2017 at 04:46:02PM +0100, Al Viro wrote:
> 
> > That - on #work.read_write, as in vfs.git at the moment...
> 
> ... and for COMPAT_SYSCALL you need
> #define __SC_DELOUSE(t,v) ((__force t)(unsigned long)(v))
> in linux/compat.h

I'm still getting warnings with both these force casts.  This is
the current stack:


diff --git a/arch/s390/include/asm/compat.h b/arch/s390/include/asm/compat.h
index 0ddd37e6c29d..019f0de892c3 100644
--- a/arch/s390/include/asm/compat.h
+++ b/arch/s390/include/asm/compat.h
@@ -12,7 +12,7 @@
 
 #define __SC_DELOUSE(t,v) ({ \
 	BUILD_BUG_ON(sizeof(t) > 4 && !__TYPE_IS_PTR(t)); \
-	(t)(__TYPE_IS_PTR(t) ? ((v) & 0x7fffffff) : (v)); \
+	(__force t)(__TYPE_IS_PTR(t) ? ((v) & 0x7fffffff) : (v)); \
 })
 
 #define PSW32_MASK_PER		0x40000000UL
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 38d0383dc7f9..bc69d40c4e8b 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -969,7 +969,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
 	int			use_wgather;
 	loff_t			pos = offset;
 	unsigned int		pflags = current->flags;
-	int			flags = 0;
+	rwf_t			flags = 0;
 
 	if (test_bit(RQ_LOCAL, &rqstp->rq_flags))
 		/*
diff --git a/fs/read_write.c b/fs/read_write.c
index a2cbc8303dae..bc2db5e5cd19 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -633,7 +633,7 @@ unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
 EXPORT_SYMBOL(iov_shorten);
 
 static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
-		loff_t *ppos, int type, int flags)
+		loff_t *ppos, int type, rwf_t flags)
 {
 	struct kiocb kiocb;
 	ssize_t ret;
@@ -655,7 +655,7 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
 
 /* Do it by hand, with file-ops */
 static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
-		loff_t *ppos, int type, int flags)
+		loff_t *ppos, int type, rwf_t flags)
 {
 	ssize_t ret = 0;
 
@@ -871,7 +871,7 @@ ssize_t compat_rw_copy_check_uvector(int type,
 #endif
 
 static ssize_t do_iter_read(struct file *file, struct iov_iter *iter,
-		loff_t *pos, int flags)
+		loff_t *pos, rwf_t flags)
 {
 	size_t tot_len;
 	ssize_t ret = 0;
@@ -899,7 +899,7 @@ static ssize_t do_iter_read(struct file *file, struct iov_iter *iter,
 }
 
 ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
-		int flags)
+		rwf_t flags)
 {
 	if (!file->f_op->read_iter)
 		return -EINVAL;
@@ -908,7 +908,7 @@ ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
 EXPORT_SYMBOL(vfs_iter_read);
 
 static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
-		loff_t *pos, int flags)
+		loff_t *pos, rwf_t flags)
 {
 	size_t tot_len;
 	ssize_t ret = 0;
@@ -937,7 +937,7 @@ static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
 }
 
 ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
-		int flags)
+		rwf_t flags)
 {
 	if (!file->f_op->write_iter)
 		return -EINVAL;
@@ -946,7 +946,7 @@ ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
 EXPORT_SYMBOL(vfs_iter_write);
 
 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
-		  unsigned long vlen, loff_t *pos, int flags)
+		  unsigned long vlen, loff_t *pos, rwf_t flags)
 {
 	struct iovec iovstack[UIO_FASTIOV];
 	struct iovec *iov = iovstack;
@@ -964,7 +964,7 @@ ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
 EXPORT_SYMBOL(vfs_readv);
 
 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
-		   unsigned long vlen, loff_t *pos, int flags)
+		   unsigned long vlen, loff_t *pos, rwf_t flags)
 {
 	struct iovec iovstack[UIO_FASTIOV];
 	struct iovec *iov = iovstack;
@@ -981,7 +981,7 @@ ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
 EXPORT_SYMBOL(vfs_writev);
 
 static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec,
-			unsigned long vlen, int flags)
+			unsigned long vlen, rwf_t flags)
 {
 	struct fd f = fdget_pos(fd);
 	ssize_t ret = -EBADF;
@@ -1001,7 +1001,7 @@ static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec,
 }
 
 static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec,
-			 unsigned long vlen, int flags)
+			 unsigned long vlen, rwf_t flags)
 {
 	struct fd f = fdget_pos(fd);
 	ssize_t ret = -EBADF;
@@ -1027,7 +1027,7 @@ static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
 }
 
 static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec,
-			 unsigned long vlen, loff_t pos, int flags)
+			 unsigned long vlen, loff_t pos, rwf_t flags)
 {
 	struct fd f;
 	ssize_t ret = -EBADF;
@@ -1050,7 +1050,7 @@ static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec,
 }
 
 static ssize_t do_pwritev(unsigned long fd, const struct iovec __user *vec,
-			  unsigned long vlen, loff_t pos, int flags)
+			  unsigned long vlen, loff_t pos, rwf_t flags)
 {
 	struct fd f;
 	ssize_t ret = -EBADF;
@@ -1094,7 +1094,7 @@ SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
 
 SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec,
 		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
-		int, flags)
+		rwf_t, flags)
 {
 	loff_t pos = pos_from_hilo(pos_h, pos_l);
 
@@ -1114,7 +1114,7 @@ SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
 
 SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
 		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
-		int, flags)
+		rwf_t, flags)
 {
 	loff_t pos = pos_from_hilo(pos_h, pos_l);
 
@@ -1127,7 +1127,7 @@ SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
 #ifdef CONFIG_COMPAT
 static size_t compat_readv(struct file *file,
 			   const struct compat_iovec __user *vec,
-			   unsigned long vlen, loff_t *pos, int flags)
+			   unsigned long vlen, loff_t *pos, rwf_t flags)
 {
 	struct iovec iovstack[UIO_FASTIOV];
 	struct iovec *iov = iovstack;
@@ -1147,7 +1147,7 @@ static size_t compat_readv(struct file *file,
 
 static size_t do_compat_readv(compat_ulong_t fd,
 				 const struct compat_iovec __user *vec,
-				 compat_ulong_t vlen, int flags)
+				 compat_ulong_t vlen, rwf_t flags)
 {
 	struct fd f = fdget_pos(fd);
 	ssize_t ret;
@@ -1173,7 +1173,7 @@ COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
 
 static long do_compat_preadv64(unsigned long fd,
 				  const struct compat_iovec __user *vec,
-				  unsigned long vlen, loff_t pos, int flags)
+				  unsigned long vlen, loff_t pos, rwf_t flags)
 {
 	struct fd f;
 	ssize_t ret;
@@ -1211,7 +1211,7 @@ COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
 #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
 COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
 		const struct compat_iovec __user *,vec,
-		unsigned long, vlen, loff_t, pos, int, flags)
+		unsigned long, vlen, loff_t, pos, rwf_t, flags)
 {
 	return do_compat_preadv64(fd, vec, vlen, pos, flags);
 }
@@ -1220,7 +1220,7 @@ COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
 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)
+		rwf_t, flags)
 {
 	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
 
@@ -1232,7 +1232,7 @@ COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
 
 static size_t compat_writev(struct file *file,
 			    const struct compat_iovec __user *vec,
-			    unsigned long vlen, loff_t *pos, int flags)
+			    unsigned long vlen, loff_t *pos, rwf_t flags)
 {
 	struct iovec iovstack[UIO_FASTIOV];
 	struct iovec *iov = iovstack;
@@ -1252,7 +1252,7 @@ static size_t compat_writev(struct file *file,
 
 static size_t do_compat_writev(compat_ulong_t fd,
 				  const struct compat_iovec __user* vec,
-				  compat_ulong_t vlen, int flags)
+				  compat_ulong_t vlen, rwf_t flags)
 {
 	struct fd f = fdget_pos(fd);
 	ssize_t ret;
@@ -1277,7 +1277,7 @@ COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
 
 static long do_compat_pwritev64(unsigned long fd,
 				   const struct compat_iovec __user *vec,
-				   unsigned long vlen, loff_t pos, int flags)
+				   unsigned long vlen, loff_t pos, rwf_t flags)
 {
 	struct fd f;
 	ssize_t ret;
@@ -1315,7 +1315,7 @@ COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
 #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
 COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
 		const struct compat_iovec __user *,vec,
-		unsigned long, vlen, loff_t, pos, int, flags)
+		unsigned long, vlen, loff_t, pos, rwf_t, flags)
 {
 	return do_compat_pwritev64(fd, vec, vlen, pos, flags);
 }
@@ -1323,7 +1323,7 @@ COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
 
 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)
+		compat_ulong_t, vlen, u32, pos_low, u32, pos_high, rwf_t, flags)
 {
 	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
 
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 2ed54020ace0..09a975f4102f 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -27,7 +27,7 @@
 #endif
 
 #ifndef __SC_DELOUSE
-#define __SC_DELOUSE(t,v) ((t)(unsigned long)(v))
+#define __SC_DELOUSE(t,v) ((__force t)(unsigned long)(v))
 #endif
 
 #define COMPAT_SYSCALL_DEFINE0(name) \
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9380c40b498b..1f217331dae6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -70,6 +70,8 @@ extern int leases_enable, lease_break_time;
 extern int sysctl_protected_symlinks;
 extern int sysctl_protected_hardlinks;
 
+typedef __kernel_rwf_t rwf_t;
+
 struct buffer_head;
 typedef int (get_block_t)(struct inode *inode, sector_t iblock,
 			struct buffer_head *bh_result, int create);
@@ -1764,9 +1766,9 @@ extern ssize_t __vfs_write(struct file *, const char __user *, size_t, loff_t *)
 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
 extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
-		unsigned long, loff_t *, int);
+		unsigned long, loff_t *, rwf_t);
 extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
-		unsigned long, loff_t *, int);
+		unsigned long, loff_t *, rwf_t);
 extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
 				   loff_t, size_t, unsigned int);
 extern int vfs_clone_file_prep_inodes(struct inode *inode_in, loff_t pos_in,
@@ -2820,9 +2822,9 @@ extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_perform_write(struct file *, struct iov_iter *, loff_t);
 
 ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
-		int flags);
+		rwf_t flags);
 ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
-		int flags);
+		rwf_t flags);
 
 /* fs/block_dev.c */
 extern ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to);
@@ -3088,7 +3090,7 @@ static inline int iocb_flags(struct file *file)
 	return res;
 }
 
-static inline int kiocb_set_rw_flags(struct kiocb *ki, int flags)
+static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags)
 {
 	if (unlikely(flags & ~RWF_SUPPORTED))
 		return -EOPNOTSUPP;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 980c3c9b06f8..1a78dbc6c900 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -104,7 +104,7 @@ union bpf_attr;
 #define __TYPE_IS_UL(t)	(__same_type((t)0, 0UL))
 #define __TYPE_IS_LL(t) (__same_type((t)0, 0LL) || __same_type((t)0, 0ULL))
 #define __SC_LONG(t, a) __typeof(__builtin_choose_expr(__TYPE_IS_LL(t), 0LL, 0L)) a
-#define __SC_CAST(t, a)	(t) a
+#define __SC_CAST(t, a)	(__force t) a
 #define __SC_ARGS(t, a)	a
 #define __SC_TEST(t, a) (void)BUILD_BUG_ON_ZERO(!__TYPE_IS_LL(t) && sizeof(t) > sizeof(long))
 
diff --git a/include/uapi/linux/aio_abi.h b/include/uapi/linux/aio_abi.h
index a2d4a8ac94ca..a04adbc70ddf 100644
--- a/include/uapi/linux/aio_abi.h
+++ b/include/uapi/linux/aio_abi.h
@@ -28,6 +28,7 @@
 #define __LINUX__AIO_ABI_H
 
 #include <linux/types.h>
+#include <linux/fs.h>
 #include <asm/byteorder.h>
 
 typedef __kernel_ulong_t aio_context_t;
@@ -62,14 +63,6 @@ struct io_event {
 	__s64		res2;		/* secondary result */
 };
 
-#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
-#define PADDED(x,y)	x, y
-#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
-#define PADDED(x,y)	y, x
-#else
-#error edit for your odd byteorder.
-#endif
-
 /*
  * we always use a 64bit off_t when communicating
  * with userland.  its up to libraries to do the
@@ -79,8 +72,16 @@ struct io_event {
 struct iocb {
 	/* these are internal to the kernel/libc. */
 	__u64	aio_data;	/* data to be returned in event's data */
-	__u32	PADDED(aio_key, aio_rw_flags);
-				/* the kernel sets aio_key to the req # */
+
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
+	__u32	aio_key;	/* the kernel sets aio_key to the req # */
+	__kernel_rwf_t aio_rw_flags;	/* RWF_* flags */
+#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
+	__kernel_rwf_t aio_rw_flags;	/* RWF_* flags */
+	__u32	aio_key;	/* the kernel sets aio_key to the req # */
+#else
+#error edit for your odd byteorder.
+#endif
 
 	/* common fields */
 	__u16	aio_lio_opcode;	/* see IOCB_CMD_ above */
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 27d8c36c04af..e8ebc18aa9c9 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -356,13 +356,25 @@ struct fscrypt_key {
 #define SYNC_FILE_RANGE_WRITE		2
 #define SYNC_FILE_RANGE_WAIT_AFTER	4
 
-/* flags for preadv2/pwritev2: */
-#define RWF_HIPRI			0x00000001 /* high priority request, poll if possible */
-#define RWF_DSYNC			0x00000002 /* per-IO O_DSYNC */
-#define RWF_SYNC			0x00000004 /* per-IO O_SYNC */
-#define RWF_NOWAIT			0x00000008 /* per-IO, return -EAGAIN if operation would block */
-
-#define RWF_SUPPORTED			(RWF_HIPRI | RWF_DSYNC | RWF_SYNC |\
-					 RWF_NOWAIT)
+/*
+ * Flags for preadv2/pwritev2:
+ */
+
+typedef int __bitwise __kernel_rwf_t;
+
+/* high priority request, poll if possible */
+#define RWF_HIPRI	((__force __kernel_rwf_t)0x00000001)
+
+/* per-IO O_DSYNC */
+#define RWF_DSYNC	((__force __kernel_rwf_t)0x00000002)
+
+/* per-IO O_SYNC */
+#define RWF_SYNC	((__force __kernel_rwf_t)0x00000004)
+
+/* per-IO, return -EAGAIN if operation would block */
+#define RWF_NOWAIT	((__force __kernel_rwf_t)0x00000008)
+
+/* mask of flags supported by the kernel */
+#define RWF_SUPPORTED	(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT)
 
 #endif /* _UAPI_LINUX_FS_H */