X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Ffilesys%2Ffilesys.c;h=b77d2718e824cc73315d3083255f30a0fc34a460;hb=3c4ff7ffae2e6f05a2c78ec77814dbc5a98c4f98;hp=0b96c2723a1949bcaf1d2f2bb7a85334d1d8bdfb;hpb=2cf38a4ba2dd965c892767b0d8ee97e67f33b274;p=pintos-anon

diff --git a/src/filesys/filesys.c b/src/filesys/filesys.c
index 0b96c27..b77d271 100644
--- a/src/filesys/filesys.c
+++ b/src/filesys/filesys.c
@@ -1,187 +1,382 @@
-#include "filesys.h"
-#include "disk.h"
-#include "directory.h"
-
-static struct disk *disk;
-
-static struct file free_map_file, root_dir_file;
-
-#define FREE_MAP_SECTOR 0
-#define ROOT_DIR_SECTOR 1
-
-#define NUM_DIR_ENTRIES 10
-#define ROOT_DIR_FILE_SIZE (sizeof (struct dir_entry) * NUM_DIR_ENTRIES)
-
-static void
-do_format (void)
-{
-  struct bitmap free_map;
-  struct filehdr map_hdr, dir_hdr;
-  struct dir dir;
-
-  /* Create the initial bitmap and reserve sectors for the
-     free map and root directory file headers. */
-  bitmap_init (&free_map, disk_size (disk));
-  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 file header to disk. */
-  if (!filehdr_allocate (&map_hdr, bitmap_storage_size (&free_map)))
-    panic ("free map creation failed");
-  filehdr_write (&map_hdr, FREE_MAP_SECTOR);
-  filehdr_destroy (&map_hdr);
-
-  /* Allocate data sector(s) for the root directory file
-     and write its file header to disk. */
-  if (!filehdr_allocate (&dir_hdr, ROOT_DIR_FILE_SIZE))
-    panic ("root directory creation failed");
-  filehdr_write (&dir_hdr, FREE_MAP_SECTOR);
-  filehdr_destroy (&dir_hdr);
-
-  /* Write out the free map now that we have space reserved
-     for it. */
-  file_open (&free_map_file, FREE_MAP_SECTOR);
-  bitmapio_write (&free_map, free_map_file);
-  bitmap_destroy (&free_map);
-  file_close (&free_map_file);
-
-  /* Write out the root directory in the same way. */
-  file_open (&root_dir_file, ROOT_DIR_SECTOR);
-  if (!dir_init (&dir, NUM_DIR_ENTRIES))
-    panic ("can't initialize root directory");
-  dir_write (root_dir_file);
-  dir_destroy (&dir);
-  file_close (&free_map_file);
-}
-
+/* 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/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.
+   If FORMAT is true, reformats the filesystem. */
 void
 filesys_init (bool format) 
 {
-  disk = disk_get (1);
-  if (disk == NULL)
-    panic ("ide1:1 not present, filesystem initialization failed");
+  inode_init ();
+
+  filesys_disk = disk_get (0, 1);
+  if (filesys_disk == NULL)
+    PANIC ("hd0:1 (hdb) not present, filesystem initialization failed");
 
   if (format) 
     do_format ();
   
-  file_open (&free_map_file, FREE_MAP_SECTOR);
-  file_open (&root_dir_file, ROOT_DIR_SECTOR);
+  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");
 }
 
+/* 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. */
+void
+filesys_done (void) 
+{
+}
+
+/* Creates a file named NAME with the given INITIAL_SIZE.
+   Returns true if successful, false otherwise.
+   Fails if a file named NAME already exists,
+   or if internal memory allocation fails. */
 bool
 filesys_create (const char *name, off_t initial_size) 
 {
-  struct dir dir;
-  struct bitmap free_map;
-  disk_sector_no hdr_sector;
-  struct filehdr filehdr;
+  struct dir *dir = NULL;
+  struct bitmap *free_map = NULL;
+  disk_sector_t inode_sector;
   bool success = false;
 
   /* Read the root directory. */
-  dir_init (&dir, NUM_DIR_ENTRIES);
-  dir_read (&dir, &root_dir_file);
-  if (dir_lookup (&dir, name, NULL)) 
-    goto exit1;
-
-  /* Allocate a block for the file header. */
-  bitmap_init (&free_map, disk_size (disk));
-  bitmapio_read (&free_map, &free_map_file);
-  hdr_sector = bitmap_find_and_set (&free_map);
-  if (hdr_sector == BITMAP_ERROR)
-    goto exit2;
+  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, hdr_sector))
-    goto exit2;
+  if (!dir_add (dir, name, inode_sector))
+    goto done;
 
   /* Allocate space for the file. */
-  if (!filehdr_allocate (&filehdr, initial_size))
-    goto exit2;
+  if (!inode_create (free_map, inode_sector, initial_size))
+    goto done;
 
   /* Write everything back. */
-  filehdr_write (&filehdr, hdr_sector);
-  dir_write (&dir, &root_dir_file);
-  bitmapio_write (&free_map, &free_map_file);
+  dir_write (dir, root_dir_file);
+  bitmap_write (free_map, free_map_file);
 
   success = true;
 
   /* Clean up. */
-  filehdr_destroy (&filehdr);
- exit2:
-  bitmap_destroy (&free_map);
- exit1:
-  dir_destroy (&dir);
+ done:
+  bitmap_destroy (free_map);
+  dir_destroy (dir);
 
   return success;
 }
 
-bool
-filesys_remove (const char *name) 
+/* Opens a file named NAME and initializes FILE for usage with
+   the file_*() functions declared in file.h.
+   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;
-  disk_sector_no hdr_sector;
-  struct filehdr filehdr;
-  struct bitmap free_map;
-  bool success = false;
+  struct dir *dir = NULL;
+  struct file *file = NULL;
+  disk_sector_t inode_sector;
 
-  /* Read the root directory. */
-  dir_init (&dir, NUM_DIR_ENTRIES);
-  dir_read (&dir, &root_dir_file);
-  if (!dir_lookup (&dir, name, &hdr_sector))
-    goto exit;
+  dir = dir_create (NUM_DIR_ENTRIES);
+  if (dir == NULL)
+    goto done;
 
-  /* Read the file header. */
-  filehdr_read (&filehdr, hdr_sector);
+  dir_read (dir, root_dir_file);
+  if (dir_lookup (dir, name, &inode_sector))
+    file = file_open (inode_sector);
 
-  /* Allocate a block for the file header. */
-  bitmap_init (&free_map, disk_size (disk));
-  bitmapio_read (&free_map, &free_map_file);
+ done:
+  dir_destroy (dir); 
 
-  /* Deallocate. */
-  filehdr_deallocate (&filehdr, &free_map);
-  bitmap_reset (&free_map, hdr_sector);
-  dir_remove (&dir, name);
+  return file;
+}
 
-  /* Write everything back. */
-  bitmapio_write (&free_map, &free_map_file);
-  dir_write (&dir, &root_dir_file);
+/* Deletes the file named NAME.
+   Returns true if successful, false on failure.
+   Fails if no file named NAME exists,
+   or if an internal memory allocation fails. */
+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. */
+  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. */
-  filehdr_destroy (&filehdr);
-  bitmap_destroy (&free_map);
- exit:
-  dir_destroy (&dir);
+ done:
+  dir_destroy (dir);
 
   return success;
 }
 
-#undef NDEBUG
-#include "debug.h"
-#include "file.h"
+/* 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;
+}
 
+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 (filesys_open ("foo") == NULL);
+      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);
+    }
+  
+  printf ("filesys: self test ok\n");
+}
+
+/* Formats the filesystem. */
+static void
+do_format (void)
+{
+  struct bitmap *free_map;
+  struct dir *dir;
+
+  printf ("Formatting filesystem...");
 
-  ASSERT (filesys_create ("foo"));
-  ASSERT ((file = filesys_open ("foo")) != NULL);
-  ASSERT (file_write (file, s, sizeof s) == sizeof s);
-  ASSERT (file_tell (file) == sizeof s);
-  ASSERT (file_length (file) == sizeof s);
-  file_close (file);
-
-  ASSERT ((file = filesys_open ("foo")) != NULL);
-  ASSERT (file_read (file, s2, sizeof s2) == sizeof s2);
-  ASSERT (memcmp (s, s2, sizeof s) == 0);
-  ASSERT (file_tell (file) == sizeof s2);
-  ASSERT (file_length (file) == sizeof s2);
-  file_close (file);
-
-  ASSERT (filesys_remove ("foo"));
+  /* 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. */
+static void 
+must_succeed_function (int line_no, bool success) 
+{
+  if (!success)
+    PANIC ("filesys_self_test: operation failed on line %d", line_no);
 }