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#include "filesys/free-map.h"
#include <bitmap.h>
#include <debug.h>
#include "filesys/file.h"
#include "filesys/filesys.h"
#include "filesys/inode.h"
#include "threads/synch.h"
static struct file *free_map_file; /* Free map file. */
static struct lock free_map_lock;
static struct bitmap *free_map; /* Free map, one bit per disk sector. */
/* Initializes the free map. */
void
free_map_init (void)
{
free_map = bitmap_create (disk_size (filesys_disk));
if (free_map == NULL)
PANIC ("bitmap creation failed--disk is too large");
lock_init (&free_map_lock);
bitmap_mark (free_map, FREE_MAP_SECTOR);
bitmap_mark (free_map, ROOT_DIR_SECTOR);
}
/* Allocates CNT consecutive sectors from the free map and stores
the first into *SECTORP.
Returns true if successful, false if all sectors were
available. */
bool
free_map_allocate (size_t cnt, disk_sector_t *sectorp)
{
lock_acquire (&free_map_lock);
disk_sector_t sector = bitmap_scan_and_flip (free_map, 0, cnt, false);
if (sector != BITMAP_ERROR
&& free_map_file != NULL
&& !bitmap_write (free_map, free_map_file))
{
bitmap_set_multiple (free_map, sector, cnt, false);
sector = BITMAP_ERROR;
}
lock_release (&free_map_lock);
if (sector != BITMAP_ERROR)
*sectorp = sector;
return sector != BITMAP_ERROR;
}
/* Makes CNT sectors starting at SECTOR available for use. */
void
free_map_release (disk_sector_t sector, size_t cnt)
{
lock_acquire (&free_map_lock);
ASSERT (bitmap_all (free_map, sector, cnt));
bitmap_set_multiple (free_map, sector, cnt, false);
bitmap_write (free_map, free_map_file);
lock_release (&free_map_lock);
}
/* Opens the free map file and reads it from disk. */
void
free_map_open (void)
{
free_map_file = file_open (inode_open (FREE_MAP_SECTOR));
if (free_map_file == NULL)
PANIC ("can't open free map");
lock_acquire (&free_map_lock);
if (!bitmap_read (free_map, free_map_file))
PANIC ("can't read free map");
lock_release (&free_map_lock);
}
/* Writes the free map to disk and closes the free map file. */
void
free_map_close (void)
{
file_close (free_map_file);
}
/* Creates a new free map file on disk and writes the free map to
it. */
void
free_map_create (void)
{
/* Create inode. */
if (!inode_create (FREE_MAP_SECTOR, bitmap_file_size (free_map)))
PANIC ("free map creation failed");
/* Write bitmap to file. */
free_map_file = file_open (inode_open (FREE_MAP_SECTOR));
if (free_map_file == NULL)
PANIC ("can't open free map");
if (!bitmap_write (free_map, free_map_file))
PANIC ("can't write free map");
}
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