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