From e829154ffe1a7f4b1e46e29bbf8ee681af959d1e Mon Sep 17 00:00:00 2001
From: Augustin Cavalier <waddlesplash@gmail.com>
Date: Wed, 20 Nov 2024 15:47:02 -0500
Subject: [PATCH] kernel/fs: Implement do_fd_io using do_iterative_fd_io.

We need to hold a reference to the file descriptor throughout
the I/O operation, which do_iterative_fd_io already takes care of.
So just modify it to handle not having the additional callbacks.

Nothing actually uses do_fd_io at present, though it will be
in the next commits.
---
 src/system/kernel/fs/vfs_request_io.cpp | 54 +++++++++++++------------
 1 file changed, 29 insertions(+), 25 deletions(-)

diff --git a/src/system/kernel/fs/vfs_request_io.cpp b/src/system/kernel/fs/vfs_request_io.cpp
index 57214cc41c..2b991c540d 100644
--- a/src/system/kernel/fs/vfs_request_io.cpp
+++ b/src/system/kernel/fs/vfs_request_io.cpp
@@ -301,8 +301,14 @@ do_synchronous_iterative_vnode_io(struct vnode* vnode, void* openCookie,
 		while (error == B_OK && vecLength > 0) {
 			file_io_vec fileVecs[8];
 			size_t fileVecCount = 8;
-			error = getVecs(cookie, request, offset, vecLength, fileVecs,
-				&fileVecCount);
+			if (getVecs != NULL) {
+				error = getVecs(cookie, request, offset, vecLength, fileVecs,
+					&fileVecCount);
+			} else {
+				fileVecs[0].offset = offset;
+				fileVecs[0].length = vecLength;
+				fileVecCount = 1;
+			}
 			if (error != B_OK || fileVecCount == 0)
 				break;
 
@@ -330,7 +336,8 @@ do_synchronous_iterative_vnode_io(struct vnode* vnode, void* openCookie,
 	bool partial = length > 0;
 	size_t bytesTransferred = request->Length() - length;
 	request->SetTransferredBytes(partial, bytesTransferred);
-	finished(cookie, request, error, partial, bytesTransferred);
+	if (finished != NULL)
+		finished(cookie, request, error, partial, bytesTransferred);
 	request->SetStatusAndNotify(error);
 	return error;
 }
@@ -469,16 +476,7 @@ vfs_asynchronous_write_pages(struct vnode* vnode, void* cookie, off_t pos,
 status_t
 do_fd_io(int fd, io_request* request)
 {
-	struct vnode* vnode;
-	file_descriptor* descriptor = get_fd_and_vnode(fd, &vnode, true);
-	if (descriptor == NULL) {
-		request->SetStatusAndNotify(B_FILE_ERROR);
-		return B_FILE_ERROR;
-	}
-
-	FileDescriptorPutter descriptorPutter(descriptor);
-
-	return vfs_vnode_io(vnode, descriptor->cookie, request);
+	return do_iterative_fd_io(fd, request, NULL, NULL, NULL);
 }
 
 
@@ -493,7 +491,8 @@ do_iterative_fd_io(int fd, io_request* request, iterative_io_get_vecs getVecs,
 	struct vnode* vnode;
 	file_descriptor* descriptor = get_fd_and_vnode(fd, &vnode, true);
 	if (descriptor == NULL) {
-		finished(cookie, request, B_FILE_ERROR, true, 0);
+		if (finished != NULL)
+			finished(cookie, request, B_FILE_ERROR, true, 0);
 		request->SetStatusAndNotify(B_FILE_ERROR);
 		return B_FILE_ERROR;
 	}
@@ -526,22 +525,27 @@ do_iterative_fd_io(int fd, io_request* request, iterative_io_get_vecs getVecs,
 		&iterationCookie->next_finished_cookie);
 
 	request->SetFinishedCallback(&do_iterative_fd_io_finish, iterationCookie);
-	request->SetIterationCallback(&do_iterative_fd_io_iterate, iterationCookie);
+	if (getVecs != NULL)
+		request->SetIterationCallback(&do_iterative_fd_io_iterate, iterationCookie);
 
 	descriptorPutter.Detach();
 		// From now on the descriptor is put by our finish callback.
 
-	bool partialTransfer = false;
-	status_t error = do_iterative_fd_io_iterate(iterationCookie, request,
-		&partialTransfer);
-	if (error != B_OK || partialTransfer) {
-		if (partialTransfer) {
-			request->SetTransferredBytes(partialTransfer,
-				request->TransferredBytes());
-		}
+	if (getVecs != NULL) {
+		bool partialTransfer = false;
+		status_t error = do_iterative_fd_io_iterate(iterationCookie, request,
+			&partialTransfer);
+		if (error != B_OK || partialTransfer) {
+			if (partialTransfer) {
+				request->SetTransferredBytes(partialTransfer,
+					request->TransferredBytes());
+			}
 
-		request->SetStatusAndNotify(error);
-		return error;
+			request->SetStatusAndNotify(error);
+			return error;
+		}
+	} else {
+		return vfs_vnode_io(vnode, descriptor->cookie, request);
 	}
 
 	return B_OK;