splice: Rename direct_splice_read() to copy_splice_read()

Rename direct_splice_read() to copy_splice_read() to better reflect as to
what it does.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
cc: Steve French <sfrench@samba.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: linux-cifs@vger.kernel.org
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20230522135018.2742245-4-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/cifs/cifsfs.c

@@ -1416,7 +1416,7 @@ const struct file_operations cifs_file_direct_ops = {
 	.fsync = cifs_fsync,
 	.flush = cifs_flush,
 	.mmap = cifs_file_mmap,
-	.splice_read = direct_splice_read,
+	.splice_read = copy_splice_read,
 	.splice_write = iter_file_splice_write,
 	.unlocked_ioctl  = cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
@@ -1470,7 +1470,7 @@ const struct file_operations cifs_file_direct_nobrl_ops = {
 	.fsync = cifs_fsync,
 	.flush = cifs_flush,
 	.mmap = cifs_file_mmap,
-	.splice_read = direct_splice_read,
+	.splice_read = copy_splice_read,
 	.splice_write = iter_file_splice_write,
 	.unlocked_ioctl  = cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,

fs/cifs/file.c

@@ -5091,6 +5091,6 @@ ssize_t cifs_splice_read(struct file *in, loff_t *ppos,
 	if (unlikely(!len))
 		return 0;
 	if (in->f_flags & O_DIRECT)
-		return direct_splice_read(in, ppos, pipe, len, flags);
+		return copy_splice_read(in, ppos, pipe, len, flags);
 	return filemap_splice_read(in, ppos, pipe, len, flags);
 }

fs/splice.c

@@ -300,12 +300,11 @@ void splice_shrink_spd(struct splice_pipe_desc *spd)
 }
 
 /*
- * Splice data from an O_DIRECT file into pages and then add them to the output
- * pipe.
+ * Copy data from a file into pages and then splice those into the output pipe.
  */
-ssize_t direct_splice_read(struct file *in, loff_t *ppos,
-			   struct pipe_inode_info *pipe,
-			   size_t len, unsigned int flags)
+ssize_t copy_splice_read(struct file *in, loff_t *ppos,
+			 struct pipe_inode_info *pipe,
+			 size_t len, unsigned int flags)
 {
 	struct iov_iter to;
 	struct bio_vec *bv;
@@ -390,7 +389,7 @@ ssize_t direct_splice_read(struct file *in, loff_t *ppos,
 	kfree(bv);
 	return ret;
 }
-EXPORT_SYMBOL(direct_splice_read);
+EXPORT_SYMBOL(copy_splice_read);
 
 /**
  * generic_file_splice_read - splice data from file to a pipe

include/linux/fs.h

@@ -2752,9 +2752,9 @@ ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
 ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
 			    struct pipe_inode_info *pipe,
 			    size_t len, unsigned int flags);
-ssize_t direct_splice_read(struct file *in, loff_t *ppos,
-			   struct pipe_inode_info *pipe,
-			   size_t len, unsigned int flags);
+ssize_t copy_splice_read(struct file *in, loff_t *ppos,
+			 struct pipe_inode_info *pipe,
+			 size_t len, unsigned int flags);
 extern ssize_t generic_file_splice_read(struct file *, loff_t *,
 		struct pipe_inode_info *, size_t, unsigned int);
 extern ssize_t iter_file_splice_write(struct pipe_inode_info *,