Wiring between mm0 page cache and vfs almost what it should look like.

This implements the infrastructure for read/write system calls where
file content is first searched in mm0's page cache and then read-in
or written via the vfs read/write functions.
	modified:   tasks/fs0/src/syscalls.c
	modified:   tasks/mm0/include/lib/bit.h
	modified:   tasks/mm0/include/lib/idpool.h
	modified:   tasks/mm0/include/task.h
	modified:   tasks/mm0/include/vm_area.h
	modified:   tasks/mm0/main.c
	modified:   tasks/mm0/src/devzero.c
	modified:   tasks/mm0/src/fault.c
	new file:   tasks/mm0/src/file.c
	modified:   tasks/mm0/src/init.c
	modified:   tasks/mm0/src/lib/bit.c
	modified:   tasks/mm0/src/lib/idpool.c
	modified:   tasks/mm0/src/task.c

tasks/mm0/include/lib/bit.h

@@ -9,6 +9,7 @@ int find_and_set_first_free_contig_bits(u32 *word,  unsigned int limit,
 					int nbits);
 int check_and_clear_bit(u32 *word, int bit);
 int check_and_clear_contig_bits(u32 *word, int first, int nbits);
+int check_and_set_bit(u32 *word, int bit);
 
 
 /* Set */

tasks/mm0/include/lib/idpool.h

@@ -2,8 +2,10 @@
 #define __MM0_IDPOOL_H__
 
 #include <lib/bit.h>
+#include <lib/spinlock.h>
 
 struct id_pool {
+	struct spinlock lock;
 	int nwords;
 	u32 bitmap[];
 };
@@ -11,6 +13,7 @@ struct id_pool {
 struct id_pool *id_pool_new_init(int mapsize);
 int id_new(struct id_pool *pool);
 int id_del(struct id_pool *pool, int id);
+int id_get(struct id_pool *pool, int id);
 int ids_new_contiguous(struct id_pool *pool, int numids);
 int ids_del_contiguous(struct id_pool *pool, int first, int numids);
 

tasks/mm0/include/task.h

@@ -13,13 +13,21 @@
 #include <l4lib/types.h>
 #include <l4lib/utcb.h>
 
-#define __TASKNAME__		"mm0"
+#define __TASKNAME__		__PAGERNAME__
+
+#define TASK_OFILES_MAX			32
 
 /* Allow per-task anonymous memory to grow as much as 1 MB for now. */
 #define TASK_SWAPFILE_MAXSIZE				SZ_1MB
 
 struct vm_file;
 
+struct file_descriptor {
+	unsigned long vnum;
+	unsigned long cursor;
+	struct vm_file *vmfile;
+};
+
 /* Stores all task information that can be kept in userspace. */
 struct tcb {
 	/* Task list */
@@ -53,6 +61,9 @@ struct tcb {
 	/* Per-task swap file for now */
 	struct vm_file *swap_file;
 
+	/* File descriptors for this task */
+	struct file_descriptor fd[TASK_OFILES_MAX];
+
 	/* Pool to generate swap file offsets for fileless anonymous regions */
 	struct id_pool *swap_file_offset_pool;
 };

tasks/mm0/include/vm_area.h

@@ -59,8 +59,8 @@ struct fault_data {
 };
 
 struct vm_pager_ops {
-	void (*read_page)(struct fault_data *f, void *);
-	void (*write_page)(struct fault_data *f, void *);
+	int (*read_page)(struct vm_file *f, unsigned long f_offset, void *pagebuf);
+	int (*write_page)(struct vm_file *f, unsigned long f_offset, void *pagebuf);
 };
 
 /* Describes the pager task that handles a vm_area. */
@@ -68,27 +68,22 @@ struct vm_pager {
 	struct vm_pager_ops ops;	/* The ops the pager does on area */
 };
 
-/*
- * TODO: Since there's no vfs yet, an inode's i_addr field is the
- * virtual memory address of a file which uniquely identifies that file.
- */
-struct inode {
-	unsigned long i_addr;	/* The unique, global resource id. */
-};
-
 /*
  * Describes the in-memory representation of a file. This could
  * point at a file or another resource, e.g. a device area or swapper space.
  */
 struct vm_file {
-	struct inode inode;
+	int refcnt;
+	unsigned long vnum;	/* Vnode number */
 	unsigned long length;
 	struct list_head list; /* List of all vm files in memory */
+
 	/* This is the cache of physical pages that this file has in memory. */
 	struct list_head page_cache_list;
 	struct vm_pager *pager;
 };
 
+
 /*
  * Describes a virtually contiguous chunk of memory region in a task. It covers
  * a unique virtual address area within its task, meaning that it does not
@@ -119,6 +114,7 @@ static inline struct vm_area *find_vma(unsigned long addr,
 
 /* Pagers */
 extern struct vm_pager default_file_pager;
+extern struct vm_pager boot_file_pager;
 extern struct vm_pager swap_pager;