gfs2: Variable rename

Instead of counting the number of bytes read from the filesystem,
functions gfs2_file_direct_read and gfs2_file_read_iter count the number
of bytes written into the user buffer.  Conversely, functions
gfs2_file_direct_write and gfs2_file_buffered_write count the number of
bytes read from the user buffer.  This is nothing but confusing, so
change the read functions to count how many bytes they have read, and
the write functions to count how many bytes they have written.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Author: Andreas Gruenbacher

fs/gfs2/file.c

@@ -807,7 +807,7 @@ static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to,
 	struct file *file = iocb->ki_filp;
 	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
 	size_t prev_count = 0, window_size = 0;
-	size_t written = 0;
+	size_t read = 0;
 	ssize_t ret;
 
 	/*
@@ -839,11 +839,11 @@ static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to,
 	pagefault_disable();
 	to->nofault = true;
 	ret = iomap_dio_rw(iocb, to, &gfs2_iomap_ops, NULL,
-			   IOMAP_DIO_PARTIAL, written);
+			   IOMAP_DIO_PARTIAL, read);
 	to->nofault = false;
 	pagefault_enable();
 	if (ret > 0)
-		written = ret;
+		read = ret;
 
 	if (should_fault_in_pages(ret, to, &prev_count, &window_size)) {
 		size_t leftover;
@@ -863,7 +863,7 @@ static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to,
 	gfs2_holder_uninit(gh);
 	if (ret < 0)
 		return ret;
-	return written;
+	return read;
 }
 
 static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from,
@@ -873,7 +873,7 @@ static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from,
 	struct inode *inode = file->f_mapping->host;
 	struct gfs2_inode *ip = GFS2_I(inode);
 	size_t prev_count = 0, window_size = 0;
-	size_t read = 0;
+	size_t written = 0;
 	ssize_t ret;
 
 	/*
@@ -906,13 +906,13 @@ static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from,
 
 	from->nofault = true;
 	ret = iomap_dio_rw(iocb, from, &gfs2_iomap_ops, NULL,
-			   IOMAP_DIO_PARTIAL, read);
+			   IOMAP_DIO_PARTIAL, written);
 	from->nofault = false;
 
 	if (ret == -ENOTBLK)
 		ret = 0;
 	if (ret > 0)
-		read = ret;
+		written = ret;
 
 	if (should_fault_in_pages(ret, from, &prev_count, &window_size)) {
 		size_t leftover;
@@ -933,15 +933,15 @@ static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from,
 	gfs2_holder_uninit(gh);
 	if (ret < 0)
 		return ret;
-	return read;
+	return written;
 }
 
 static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct gfs2_inode *ip;
 	struct gfs2_holder gh;
 	size_t prev_count = 0, window_size = 0;
-	size_t written = 0;
+	size_t read = 0;
 	ssize_t ret;
 
 	/*
@@ -962,7 +962,7 @@ static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	if (ret >= 0) {
 		if (!iov_iter_count(to))
 			return ret;
-		written = ret;
+		read = ret;
 	} else if (ret != -EFAULT) {
 		if (ret != -EAGAIN)
 			return ret;
@@ -980,7 +980,7 @@ static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	ret = generic_file_read_iter(iocb, to);
 	pagefault_enable();
 	if (ret > 0)
-		written += ret;
+		read += ret;
 
 	if (should_fault_in_pages(ret, to, &prev_count, &window_size)) {
 		size_t leftover;
@@ -998,7 +998,7 @@ static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 		gfs2_glock_dq(&gh);
 out_uninit:
 	gfs2_holder_uninit(&gh);
-	return written ? written : ret;
+	return read ? read : ret;
 }
 
 static ssize_t gfs2_file_buffered_write(struct kiocb *iocb,
@@ -1012,7 +1012,7 @@ static ssize_t gfs2_file_buffered_write(struct kiocb *iocb,
 	struct gfs2_holder *statfs_gh = NULL;
 	size_t prev_count = 0, window_size = 0;
 	size_t orig_count = iov_iter_count(from);
-	size_t read = 0;
+	size_t written = 0;
 	ssize_t ret;
 
 	/*
@@ -1050,13 +1050,13 @@ static ssize_t gfs2_file_buffered_write(struct kiocb *iocb,
 	current->backing_dev_info = NULL;
 	if (ret > 0) {
 		iocb->ki_pos += ret;
-		read += ret;
+		written += ret;
 	}
 
 	if (inode == sdp->sd_rindex)
 		gfs2_glock_dq_uninit(statfs_gh);
 
-	from->count = orig_count - read;
+	from->count = orig_count - written;
 	if (should_fault_in_pages(ret, from, &prev_count, &window_size)) {
 		size_t leftover;
 
@@ -1077,8 +1077,8 @@ static ssize_t gfs2_file_buffered_write(struct kiocb *iocb,
 	gfs2_holder_uninit(gh);
 	if (statfs_gh)
 		kfree(statfs_gh);
-	from->count = orig_count - read;
-	return read ? read : ret;
+	from->count = orig_count - written;
+	return written ? written : ret;
 }
 
 /**