-/* 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" assignment (project
- 2), please treat all the code in the filesys directory as a
- black box. No changes should be needed. For that project, 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.
-
- - No indirect blocks. This limits maximum file size to the
- number of sector pointers that fit in a single inode
- times the size of a sector, or 126 * 512 == 63 kB given
- 32-bit sizes and 512-byte sectors.
-
- - 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;
+/* Partition that contains the file system. */
+struct block *fs_device;
static void do_format (void);
-/* Initializes the filesystem module.
- If FORMAT is true, reformats the filesystem. */
+/* Initializes the file system module.
+ If FORMAT is true, reformats the file system. */
void
filesys_init (bool format)
{
- inode_init ();
+ fs_device = block_get_role (BLOCK_FILESYS);
+ if (fs_device == NULL)
+ PANIC ("No file system device found, can't initialize file system.");
- 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. */
+/* Shuts down the file system module, writing any unwritten data
+ 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;
- struct inode *inode = 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, disk_size (filesys_disk),
- 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. */
- inode = inode_create (free_map, inode_sector, initial_size);
- if (inode == NULL)
- goto done;
-
- /* Write everything back. */
- inode_commit (inode);
- dir_write (dir, root_dir_file);
- bitmap_write (free_map, free_map_file);
-
- success = true;
-
- /* Clean up. */
- done:
- inode_close (inode);
- bitmap_destroy (free_map);
- dir_destroy (dir);
+ block_sector_t inode_sector = 0;
+ struct dir *dir = dir_open_root ();
+ bool success = (dir != NULL
+ && 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.
- Returns true if successful, false on failure.
+/* 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,
or if an internal memory allocation fails. */
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 = dir_open_root ();
+ struct inode *inode = NULL;
- done:
- dir_destroy (dir);
+ if (dir != NULL)
+ dir_lookup (dir, name, &inode);
+ dir_close (dir);
- return file;
+ return file_open (inode);
}
/* Deletes the file named NAME.
bool
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 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);
+ struct dir *dir = dir_open_root ();
+ bool success = dir != NULL && dir_remove (dir, name);
+ dir_close (dir);
return success;
}
-
-/* Prints a list of files in the filesystem to the system
- console.
- Returns true if successful, false on failure,
- which occurs only if an internal memory allocation fails. */
-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);
-
- return true;
-}
-
-/* Dumps the filesystem state to the system console,
- including the free map, the list of files, and file contents.
- Returns true if successful, false on failure,
- which occurs only if an internal memory allocation fails. */
-bool
-filesys_dump (void)
-{
- struct bitmap *free_map;
- struct dir *dir;
-
- printf ("Free map:\n");
- free_map = bitmap_create (disk_size (filesys_disk));
- if (free_map == NULL)
- return false;
- bitmap_read (free_map, free_map_file);
- bitmap_dump (free_map);
- bitmap_destroy (free_map);
- printf ("\n");
-
- dir = dir_create (NUM_DIR_ENTRIES);
- if (dir == NULL)
- return false;
- dir_read (dir, root_dir_file);
- dir_dump (dir);
- dir_destroy (dir);
-
- return true;
-}
-
-static void must_succeed_function (int, bool) NO_INLINE;
-#define MUST_SUCCEED(EXPR) must_succeed_function (__LINE__, EXPR)
-
-/* Performs basic sanity checks on the filesystem.
- The filesystem should not contain a file named `foo' when
- called. */
-void
-filesys_self_test (void)
-{
- static const char s[] = "This is a test string.";
- static const char zeros[sizeof s] = {0};
- struct file *file;
- char s2[sizeof s];
- int i;
-
- filesys_remove ("foo");
- for (i = 0; i < 2; i++)
- {
- /* Create file and check that it contains zeros
- throughout the created length. */
- MUST_SUCCEED (filesys_create ("foo", sizeof s));
- MUST_SUCCEED ((file = filesys_open ("foo")) != NULL);
- MUST_SUCCEED (file_read (file, s2, sizeof s2) == sizeof s2);
- MUST_SUCCEED (memcmp (s2, zeros, sizeof s) == 0);
- MUST_SUCCEED (file_tell (file) == sizeof s);
- MUST_SUCCEED (file_length (file) == sizeof s);
- file_close (file);
-
- /* Reopen file and write to it. */
- MUST_SUCCEED ((file = filesys_open ("foo")) != NULL);
- MUST_SUCCEED (file_write (file, s, sizeof s) == sizeof s);
- MUST_SUCCEED (file_tell (file) == sizeof s);
- MUST_SUCCEED (file_length (file) == sizeof s);
- file_close (file);
-
- /* Reopen file and verify that it reads back correctly.
- Delete file while open to check proper semantics. */
- MUST_SUCCEED ((file = filesys_open ("foo")) != NULL);
- MUST_SUCCEED (filesys_remove ("foo"));
- MUST_SUCCEED (file_read (file, s2, sizeof s) == sizeof s);
- MUST_SUCCEED (memcmp (s, s2, sizeof s) == 0);
- MUST_SUCCEED (file_tell (file) == sizeof s);
- MUST_SUCCEED (file_length (file) == sizeof s);
- file_close (file);
-
- /* Make sure file is deleted. */
- MUST_SUCCEED ((file = filesys_open ("foo")) == NULL);
- }
-
- printf ("filesys: self test ok\n");
-}
\f
-/* Formats the filesystem. */
+/* Formats the file system. */
static void
do_format (void)
{
- struct bitmap *free_map;
- struct inode *map_inode, *dir_inode;
- 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 data sector(s) for the free map file
- and write its inode to disk. */
- map_inode = inode_create (free_map, FREE_MAP_SECTOR,
- bitmap_file_size (free_map));
- if (map_inode == NULL)
- PANIC ("free map creation failed--disk is too large");
- inode_commit (map_inode);
- inode_close (map_inode);
-
- /* Allocate data sector(s) for the root directory file
- and write its inodes to disk. */
- dir_inode = inode_create (free_map, ROOT_DIR_SECTOR,
- dir_size (NUM_DIR_ENTRIES));
- if (dir_inode == NULL)
+ printf ("Formatting file system...");
+ free_map_create ();
+ if (!dir_create (ROOT_DIR_SECTOR, 16))
PANIC ("root directory creation failed");
- inode_commit (dir_inode);
- inode_close (dir_inode);
-
- /* 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);
-
+ free_map_close ();
printf ("done.\n");
}
-
-/* If SUCCESS is false, panics with an error complaining about
- LINE_NO. */
-static void
-must_succeed_function (int line_no, bool success)
-{
- if (!success)
- PANIC ("filesys_self_test: operation failed on line %d", line_no);
-}
projects / pintos-anon / blobdiff