1 #include "filesys/free-map.h"
4 #include "filesys/file.h"
5 #include "filesys/filesys.h"
6 #include "filesys/inode.h"
8 static struct file *free_map_file; /* Free map file. */
9 static struct bitmap *free_map; /* Free map, one bit per sector. */
11 /* Initializes the free map. */
15 free_map = bitmap_create (block_size (fs_device));
17 PANIC ("bitmap creation failed--file system device is too large");
18 bitmap_mark (free_map, FREE_MAP_SECTOR);
19 bitmap_mark (free_map, ROOT_DIR_SECTOR);
22 /* Allocates CNT consecutive sectors from the free map and stores
23 the first into *SECTORP.
24 Returns true if successful, false if not enough consecutive
25 sectors were available or if the free_map file could not be
28 free_map_allocate (size_t cnt, block_sector_t *sectorp)
30 block_sector_t sector = bitmap_scan_and_flip (free_map, 0, cnt, false);
31 if (sector != BITMAP_ERROR
32 && free_map_file != NULL
33 && !bitmap_write (free_map, free_map_file))
35 bitmap_set_multiple (free_map, sector, cnt, false);
36 sector = BITMAP_ERROR;
38 if (sector != BITMAP_ERROR)
40 return sector != BITMAP_ERROR;
43 /* Makes CNT sectors starting at SECTOR available for use. */
45 free_map_release (block_sector_t sector, size_t cnt)
47 ASSERT (bitmap_all (free_map, sector, cnt));
48 bitmap_set_multiple (free_map, sector, cnt, false);
49 bitmap_write (free_map, free_map_file);
52 /* Opens the free map file and reads it from disk. */
56 free_map_file = file_open (inode_open (FREE_MAP_SECTOR));
57 if (free_map_file == NULL)
58 PANIC ("can't open free map");
59 if (!bitmap_read (free_map, free_map_file))
60 PANIC ("can't read free map");
63 /* Writes the free map to disk and closes the free map file. */
67 file_close (free_map_file);
70 /* Creates a new free map file on disk and writes the free map to
73 free_map_create (void)
76 if (!inode_create (FREE_MAP_SECTOR, bitmap_file_size (free_map)))
77 PANIC ("free map creation failed");
79 /* Write bitmap to file. */
80 free_map_file = file_open (inode_open (FREE_MAP_SECTOR));
81 if (free_map_file == NULL)
82 PANIC ("can't open free map");
83 if (!bitmap_write (free_map, free_map_file))
84 PANIC ("can't write free map");