-/* This file is derived from source code for the Nachos
- instructional operating system. The Nachos copyright notice
- is reproduced in full below. */
-
-/* Copyright (c) 1992-1996 The Regents of the University of California.
- All rights reserved.
-
- Permission to use, copy, modify, and distribute this software
- and its documentation for any purpose, without fee, and
- without written agreement is hereby granted, provided that the
- above copyright notice and the following two paragraphs appear
- in all copies of this software.
-
- IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO
- ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR
- CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE
- AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA
- HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
- THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY
- WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
- BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
- PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
- MODIFICATIONS.
-*/
-
#include "filesys/filesys.h"
-#include <bitmap.h>
#include <debug.h>
#include <stdio.h>
#include <string.h>
#include "filesys/file.h"
+#include "filesys/free-map.h"
#include "filesys/inode.h"
#include "filesys/directory.h"
#include "devices/disk.h"
-/* Filesystem.
-
- For the purposes of the "user processes" and "virtual memory"
- assignments (projects 2 and 3), please treat all the code in
- the filesys directory as a black box. No changes should be
- needed. For those projects, a single lock external to the
- filesystem code suffices.
-
- The filesystem consists of a set of files. Each file has a
- header called an `index node' or `inode', represented by
- struct inode, that is stored by itself in a single sector (see
- inode.h). The header contains the file's length in bytes and
- an array that lists the sector numbers for the file's
- contents.
-
- Two files are special. The first special file is the free
- map, whose inode is always stored in sector 0
- (FREE_MAP_SECTOR). The free map stores a bitmap (see
- lib/bitmap.h) that contains one bit for each sector on the
- disk. Each bit that corresponds to a sector within a file is
- set to true, and the other bits, which are not part of any
- file, are set to false.
-
- The second special file is the root directory, whose inode is
- always stored in sector 1 (ROOT_DIR_SECTOR). The root
- directory file stores an array of `struct dir_entry' (see
- directory.h), each of which, if it is in use, associates a
- filename with the sector of the file's inode.
-
- The filesystem implemented here has the following limitations:
-
- - No synchronization. Concurrent accesses will interfere
- with one another, so external synchronization is needed.
-
- - File size is fixed at creation time. Because the root
- directory is represented as a file, the number of files
- that may be created is also limited.
-
- - File data is allocated as a single extent, so that
- external fragmentation can become a serious problem as a
- file system is used over time.
-
- - No subdirectories.
-
- - Filenames limited to 14 characters.
-
- - A system crash mid-operation may corrupt the disk in a way
- that cannot be repaired automatically. No `fsck' tool is
- provided in any case.
-
- However one important feature is included:
-
- - Unix-like semantics for filesys_remove() are implemented.
- That is, if a file is open when it is removed, its blocks
- are not deallocated and it may still be accessed by the
- threads that have it open until the last one closes it. */
-
-/* Sectors of system file inodes. */
-#define FREE_MAP_SECTOR 0 /* Free map file inode sector. */
-#define ROOT_DIR_SECTOR 1 /* Root directory file inode sector. */
-
-/* Root directory. */
-#define NUM_DIR_ENTRIES 10 /* Maximum number of directory entries. */
-
/* The disk that contains the filesystem. */
struct disk *filesys_disk;
-/* The free map and root directory files.
- These files are opened by filesys_init() and never closed. */
-struct file *free_map_file, *root_dir_file;
-
static void do_format (void);
/* Initializes the filesystem module.
void
filesys_init (bool format)
{
- inode_init ();
-
filesys_disk = disk_get (0, 1);
if (filesys_disk == NULL)
PANIC ("hd0:1 (hdb) not present, filesystem initialization failed");
+ inode_init ();
+ free_map_init ();
+
if (format)
do_format ();
-
- free_map_file = file_open (FREE_MAP_SECTOR);
- if (free_map_file == NULL)
- PANIC ("can't open free map file");
- root_dir_file = file_open (ROOT_DIR_SECTOR);
- if (root_dir_file == NULL)
- PANIC ("can't open root dir file");
+
+ free_map_open ();
}
/* Shuts down the filesystem module, writing any unwritten data
- to disk.
- Currently there's nothing to do. You'll need to add code here
- when you implement write-behind caching. */
+ to disk. */
void
filesys_done (void)
{
+ free_map_close ();
}
-
+\f
/* Creates a file named NAME with the given INITIAL_SIZE.
Returns true if successful, false otherwise.
Fails if a file named NAME already exists,
bool
filesys_create (const char *name, off_t initial_size)
{
- struct dir *dir = NULL;
- struct bitmap *free_map = NULL;
- disk_sector_t inode_sector;
- bool success = false;
-
- /* Read the root directory. */
- dir = dir_create (NUM_DIR_ENTRIES);
- if (dir == NULL)
- goto done;
- dir_read (dir, root_dir_file);
- if (dir_lookup (dir, name, NULL))
- goto done;
-
- /* Allocate a block for the inode. */
- free_map = bitmap_create (disk_size (filesys_disk));
- if (free_map == NULL)
- goto done;
- bitmap_read (free_map, free_map_file);
- inode_sector = bitmap_scan_and_flip (free_map, 0, 1, false);
- if (inode_sector == BITMAP_ERROR)
- goto done;
-
- /* Add the file to the directory. */
- if (!dir_add (dir, name, inode_sector))
- goto done;
-
- /* Allocate space for the file. */
- if (!inode_create (free_map, inode_sector, initial_size))
- goto done;
-
- /* Write everything back. */
- dir_write (dir, root_dir_file);
- bitmap_write (free_map, free_map_file);
-
- success = true;
-
- /* Clean up. */
- done:
- bitmap_destroy (free_map);
- dir_destroy (dir);
+ struct dir *dir;
+ disk_sector_t inode_sector = 0;
+ bool success = (dir_open_root (&dir)
+ && free_map_allocate (1, &inode_sector)
+ && inode_create (inode_sector, initial_size)
+ && dir_add (dir, name, inode_sector));
+ if (!success && inode_sector != 0)
+ free_map_release (inode_sector, 1);
+ dir_close (dir);
return success;
}
-/* Opens a file named NAME and initializes FILE for usage with
- the file_*() functions declared in file.h.
+/* Opens the file with the given NAME.
Returns the new file if successful or a null pointer
otherwise.
Fails if no file named NAME exists,
struct file *
filesys_open (const char *name)
{
- struct dir *dir = NULL;
- struct file *file = NULL;
- disk_sector_t inode_sector;
-
- dir = dir_create (NUM_DIR_ENTRIES);
- if (dir == NULL)
- goto done;
-
- dir_read (dir, root_dir_file);
- if (dir_lookup (dir, name, &inode_sector))
- file = file_open (inode_sector);
+ struct dir *dir;
+ struct inode *inode = NULL;
- done:
- dir_destroy (dir);
+ if (dir_open_root (&dir))
+ dir_lookup (dir, name, &inode);
+ dir_close (dir);
- return file;
+ return file_open (inode);
}
/* Deletes the file named NAME.
filesys_remove (const char *name)
{
struct dir *dir = NULL;
- struct inode *inode;
- disk_sector_t inode_sector;
- bool success = false;
-
- /* Read the root directory. */
- dir = dir_create (NUM_DIR_ENTRIES);
- if (dir == NULL)
- goto done;
- dir_read (dir, root_dir_file);
- if (!dir_lookup (dir, name, &inode_sector))
- goto done;
-
- /* Open the inode and delete it. */
- inode = inode_open (inode_sector);
- if (inode == NULL)
- goto done;
- inode_remove (inode);
- inode_close (inode);
-
- /* Remove file from root directory and write directory back to
- disk. */
- dir_remove (dir, name);
- dir_write (dir, root_dir_file);
-
- success = true;
-
- /* Clean up. */
- done:
- dir_destroy (dir);
+ bool success = (dir_open_root (&dir)
+ && dir_remove (dir, name));
+ dir_close (dir);
return success;
}
bool
filesys_list (void)
{
- struct dir *dir = dir_create (NUM_DIR_ENTRIES);
- if (dir == NULL)
- return false;
- dir_read (dir, root_dir_file);
- dir_list (dir);
- dir_destroy (dir);
+ struct dir *dir = NULL;
+ bool success = dir_open_root (&dir);
+ if (success)
+ dir_list (dir);
+ dir_close (dir);
- return true;
+ return success;
}
-
+\f
static void must_succeed_function (int, bool) NO_INLINE;
#define MUST_SUCCEED(EXPR) must_succeed_function (__LINE__, EXPR)
printf ("filesys: self test ok\n");
}
-\f
-/* Formats the filesystem. */
-static void
-do_format (void)
-{
- struct bitmap *free_map;
- struct dir *dir;
-
- printf ("Formatting filesystem...");
-
- /* Create the initial bitmap and reserve sectors for the
- free map and root directory inodes. */
- free_map = bitmap_create (disk_size (filesys_disk));
- if (free_map == NULL)
- PANIC ("bitmap creation failed--disk is too large");
- bitmap_mark (free_map, FREE_MAP_SECTOR);
- bitmap_mark (free_map, ROOT_DIR_SECTOR);
-
- /* Allocate free map and root dir files. */
- if (!inode_create (free_map, FREE_MAP_SECTOR, bitmap_file_size (free_map)))
- PANIC ("free map creation failed--disk is too large");
- if (!inode_create (free_map, ROOT_DIR_SECTOR, dir_size (NUM_DIR_ENTRIES)))
- PANIC ("root directory creation failed");
-
- /* Write out the free map now that we have space reserved
- for it. */
- free_map_file = file_open (FREE_MAP_SECTOR);
- if (free_map_file == NULL)
- PANIC ("can't open free map file");
- bitmap_write (free_map, free_map_file);
- bitmap_destroy (free_map);
- file_close (free_map_file);
-
- /* Write out the root directory in the same way. */
- root_dir_file = file_open (ROOT_DIR_SECTOR);
- if (root_dir_file == NULL)
- PANIC ("can't open root directory");
- dir = dir_create (NUM_DIR_ENTRIES);
- if (dir == NULL)
- PANIC ("can't initialize root directory");
- dir_write (dir, root_dir_file);
- dir_destroy (dir);
- file_close (root_dir_file);
-
- printf ("done.\n");
-}
/* If SUCCESS is false, panics with an error complaining about
LINE_NO. */
if (!success)
PANIC ("filesys_self_test: operation failed on line %d", line_no);
}
+\f
+/* Formats the filesystem. */
+static void
+do_format (void)
+{
+ printf ("Formatting filesystem...");
+ free_map_create ();
+ if (!dir_create (ROOT_DIR_SECTOR, 16))
+ PANIC ("root directory creation failed");
+ free_map_close ();
+ printf ("done.\n");
+}
projects / pintos-anon / blobdiff