kernel/vfs: split vfs_backend_refdown into two functions

5 files changed, 51 insertions, 28 deletions

diff --git a/src/kernel/handle.c b/src/kernel/handle.c
index 882a4fa..f216c13 100644
--- a/src/kernel/handle.c
+++ b/src/kernel/handle.c
@@ -39,8 +39,9 @@ void handle_close(Handle *h) {
 		if (h->req) vfsreq_finish_short(h->req, -1);
 	}
 
-	if (h->backend)
-		vfs_backend_refdown(h->backend, true);
+	if (h->backend) {
+		vfsback_userdown(h->backend);
+	}
 
 	// TODO sanity check to check if refcount is true. handle_sanity?
 
diff --git a/src/kernel/proc.c b/src/kernel/proc.c
index 194353a..fcb51c6 100644
--- a/src/kernel/proc.c
+++ b/src/kernel/proc.c
@@ -217,7 +217,7 @@ void proc_kill(Proc *p, int ret) {
 				assert(p->state == PS_WAITS4REQUEST);
 				p->controlled->user.handler = NULL;
 			}
-			vfs_backend_refdown(p->controlled, false);
+			vfsback_provdown(p->controlled);
 			p->controlled = NULL;
 		}
 
diff --git a/src/kernel/vfs/mount.c b/src/kernel/vfs/mount.c
index adf9b8c..15d1382 100644
--- a/src/kernel/vfs/mount.c
+++ b/src/kernel/vfs/mount.c
@@ -61,7 +61,7 @@ void vfs_mount_remref(VfsMount *mnt) {
 
 	VfsMount *prev = mnt->prev;
 	if (mnt->backend) {
-		vfs_backend_refdown(mnt->backend, true);
+		vfsback_userdown(mnt->backend);
 	}
 	if (mnt->prefix_owned) {
 		kfree((void*)mnt->prefix);
diff --git a/src/kernel/vfs/request.c b/src/kernel/vfs/request.c
index e3f0316..8fe0114 100644
--- a/src/kernel/vfs/request.c
+++ b/src/kernel/vfs/request.c
@@ -80,11 +80,13 @@ void vfsreq_finish(VfsReq *req, char __user *stored, long ret,
 		assert((size_t)ret <= req->output.len);
 	}
 
-	if (req->input.kern)
+	if (req->input.kern) {
 		kfree(req->input.buf_kern);
+	}
 
-	if (req->backend)
-		vfs_backend_refdown(req->backend, true);
+	if (req->backend) {
+		vfsback_userdown(req->backend);
+	}
 
 	if (req->caller) {
 		assert(req->caller->state == PS_WAITS4FS);
@@ -159,26 +161,28 @@ static void vfs_backend_user_accept(VfsReq *req) {
 	return;
 }
 
-void vfs_backend_refdown(VfsBackend *b, bool use) {
-	size_t *field = use ? &b->usehcnt : &b->provhcnt;
-	assert(b);
-	assert(0 < *field);
-	*field -= 1;
-
-	if (b->provhcnt == 0 && use == false) {
-		VfsReq *q = b->queue;
-		while (q) {
-			VfsReq *q2 = q->queue_next;
-			vfsreq_finish_short(q, -1);
-			q = q2;
-		}
-		b->queue = NULL;
+static void
+vfsback_checkfree(VfsBackend *b)
+{
+	if (b->usehcnt == 0 && b->provhcnt == 0) {
+		assert(!b->queue);
+		kfree(b);
 	}
-	if (b->usehcnt == 0 && use == true) {
+}
+
+void
+vfsback_userdown(VfsBackend *b)
+{
+	assert(b);
+	assert(0 < b->usehcnt);
+	b->usehcnt--;
+	if (b->usehcnt == 0) {
 		if (!b->is_user && b->kern.cleanup) {
 			b->kern.cleanup(b);
 		}
 		if (b->is_user && b->user.handler) {
+			/* tell the process that the filesystem won't receive any more
+			 * requests */
 			Proc *p = b->user.handler;
 			b->user.handler = NULL;
 			assert(p->state == PS_WAITS4REQUEST);
@@ -186,8 +190,24 @@ void vfs_backend_refdown(VfsBackend *b, bool use) {
 			proc_setstate(p, PS_RUNNING);
 		}
 	}
-	if (b->usehcnt == 0 && b->provhcnt == 0) {
-		assert(!b->queue);
-		kfree(b);
+	vfsback_checkfree(b);
+}
+
+void
+vfsback_provdown(VfsBackend *b)
+{
+	assert(b);
+	assert(0 < b->provhcnt);
+	b->provhcnt--;
+	if (b->provhcnt == 0) {
+		/* discard everything in the queue */
+		VfsReq *q = b->queue;
+		while (q) {
+			VfsReq *q2 = q->queue_next;
+			vfsreq_finish_short(q, -1);
+			q = q2;
+		}
+		b->queue = NULL;
 	}
+	vfsback_checkfree(b);
 }
diff --git a/src/kernel/vfs/request.h b/src/kernel/vfs/request.h
index 182202c..2bd8c61 100644
--- a/src/kernel/vfs/request.h
+++ b/src/kernel/vfs/request.h
@@ -74,6 +74,8 @@ static inline void vfsreq_finish_short(VfsReq *req, long ret) {
 /** Try to accept an enqueued request */
 void vfs_backend_tryaccept(VfsBackend *);
 
-// TODO the bool arg is confusing. maybe this should just be a function
-// that verified the refcount and potentially frees the backend
-void vfs_backend_refdown(VfsBackend *, bool use);
+/** Decrements the "user" reference count. */
+void vfsback_userdown(VfsBackend *);
+
+/** Decrements the "provider" reference count. */
+void vfsback_provdown(VfsBackend *);