[PATCH 1/3] fs: add vfs_bvec_{read,write} helpers

[Christoph Hellwig <hch@lst.de>]

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/read_write.c    | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/splice.c        | 23 +++------------------
 include/linux/fs.h |  5 +++++
 3 files changed, 68 insertions(+), 20 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index c0805c9..299e262 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -333,6 +333,66 @@ out_putf:
 }
 #endif
 
+ssize_t vfs_bvec_read(struct file *file, struct bio_vec *vec,
+		unsigned long nr_segs, size_t count, loff_t *ppos)
+{
+	struct iov_iter iter;
+	struct kiocb kiocb;
+	ssize_t ret;
+
+	if (!file->f_op->read_iter)
+		return -EBADFD;
+
+	iter.type = ITER_BVEC | READ;
+	iter.bvec = vec;
+	iter.nr_segs = nr_segs;
+	iter.count = count;
+	iter.iov_offset = 0;
+
+	init_sync_kiocb(&kiocb, file);
+	kiocb.ki_pos = *ppos;
+	kiocb.ki_nbytes = count;
+
+	ret = file->f_op->read_iter(&kiocb, &iter);
+	if (ret == -EIOCBQUEUED)
+		ret = wait_on_sync_kiocb(&kiocb);
+
+	if (ret > 0)
+		*ppos = kiocb.ki_pos;
+	return ret;
+}
+EXPORT_SYMBOL(vfs_bvec_read);
+
+ssize_t vfs_bvec_write(struct file *file, struct bio_vec *vec,
+		unsigned long nr_segs, size_t count, loff_t *ppos)
+{
+	struct iov_iter iter;
+	struct kiocb kiocb;
+	ssize_t ret;
+
+	if (!file->f_op->write_iter)
+		return -EBADFD;
+
+	iter.type = ITER_BVEC | WRITE;
+	iter.bvec = vec;
+	iter.nr_segs = nr_segs;
+	iter.count = count;
+	iter.iov_offset = 0;
+
+	init_sync_kiocb(&kiocb, file);
+	kiocb.ki_pos = *ppos;
+	kiocb.ki_nbytes = count;
+
+	ret = file->f_op->write_iter(&kiocb, &iter);
+	if (ret == -EIOCBQUEUED)
+		ret = wait_on_sync_kiocb(&kiocb);
+
+	if (ret > 0)
+		*ppos = kiocb.ki_pos;
+	return ret;
+}
+EXPORT_SYMBOL(vfs_bvec_write);
+
 /*
  * rw_verify_area doesn't like huge counts. We limit
  * them to something that fits in "int" so that others
diff --git a/fs/splice.c b/fs/splice.c
index 75c6058..370e6c3 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -960,8 +960,6 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 
 	splice_from_pipe_begin(&sd);
 	while (sd.total_len) {
-		struct iov_iter from;
-		struct kiocb kiocb;
 		size_t left;
 		int n, idx;
 
@@ -1005,29 +1003,14 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 			left -= this_len;
 		}
 
-		/* ... iov_iter */
-		from.type = ITER_BVEC | WRITE;
-		from.bvec = array;
-		from.nr_segs = n;
-		from.count = sd.total_len - left;
-		from.iov_offset = 0;
-
-		/* ... and iocb */
-		init_sync_kiocb(&kiocb, out);
-		kiocb.ki_pos = sd.pos;
-		kiocb.ki_nbytes = sd.total_len - left;
-
-		/* now, send it */
-		ret = out->f_op->write_iter(&kiocb, &from);
-		if (-EIOCBQUEUED == ret)
-			ret = wait_on_sync_kiocb(&kiocb);
-
+		ret = vfs_bvec_write(out, array, n, sd.total_len - left,
+					&sd.pos);
 		if (ret <= 0)
 			break;
 
 		sd.num_spliced += ret;
 		sd.total_len -= ret;
-		*ppos = sd.pos = kiocb.ki_pos;
+		*ppos = sd.pos;
 
 		/* dismiss the fully eaten buffers, adjust the partial one */
 		while (ret) {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 42efe13..6423bdc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2494,6 +2494,11 @@ extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t l
 extern ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
 extern ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
 
+ssize_t vfs_bvec_read(struct file *file, struct bio_vec *vec,
+		unsigned long nr_segs, size_t count, loff_t *ppos);
+ssize_t vfs_bvec_write(struct file *file, struct bio_vec *vec,
+		unsigned long nr_segs, size_t count, loff_t *ppos);
+
 /* fs/block_dev.c */
 extern ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to);
 extern ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from);
-- 
1.9.1