kernel: reuse a single allocation for all vfs_requests of a process

$ iostress 32 512 0 > /vtty # before
512 calls, 0 bytes. avg 121133
$ iostress 32 512 0 > /vtty # after
512 calls, 0 bytes. avg 103540

103540/121133 = ~85%

I think the tiny bit of added complexity is worth it here.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/kernel/vfs/request.h b/src/kernel/vfs/request.h
index cb560c9..ee33623 100644
--- a/src/kernel/vfs/request.h
+++ b/src/kernel/vfs/request.h
@@ -51,6 +51,8 @@ struct vfs_request {
 	long offset;
 	int flags;
 
+	/* if caller != NULL, owned by it - don't free, the allocation will be reused
+	 * if caller == NULL, free on finish */
 	struct process *caller;
 	struct vfs_backend *backend;