patch-1.3.60 linux/fs/msdos/fat.c

• Lines: 298
• Date: Thu Jan 1 02:00:00 1970
• Orig file: v1.3.59/linux/fs/msdos/fat.c
• Orig date: Thu Nov 9 11:23:51 1995

diff -u --recursive --new-file v1.3.59/linux/fs/msdos/fat.c linux/fs/msdos/fat.c
@@ -1,297 +0,0 @@
-/*
- *  linux/fs/msdos/fat.c
- *
- *  Written 1992,1993 by Werner Almesberger
- */
-
-#include <linux/msdos_fs.h>
-#include <linux/kernel.h>
-#include <linux/errno.h>
-#include <linux/string.h>
-#include <linux/stat.h>
-
-#include "msbuffer.h"
-
-static struct fat_cache *fat_cache,cache[FAT_CACHE];
-
-/* Returns the this'th FAT entry, -1 if it is an end-of-file entry. If
-   new_value is != -1, that FAT entry is replaced by it. */
-
-int fat_access(struct super_block *sb,int nr,int new_value)
-{
-	struct buffer_head *bh,*bh2,*c_bh,*c_bh2;
-	unsigned char *p_first,*p_last;
-	int first,last,next,copy;
-
-	if ((unsigned) (nr-2) >= MSDOS_SB(sb)->clusters) return 0;
-	if (MSDOS_SB(sb)->fat_bits == 16) first = last = nr*2;
-	else {
-		first = nr*3/2;
-		last = first+1;
-	}
-	if (!(bh = bread(sb->s_dev,MSDOS_SB(sb)->fat_start+(first >>
-	    SECTOR_BITS),SECTOR_SIZE))) {
-		printk("bread in fat_access failed\n");
-		return 0;
-	}
-	if ((first >> SECTOR_BITS) == (last >> SECTOR_BITS))
-		bh2 = bh;
-	else {
-		if (!(bh2 = bread(sb->s_dev,MSDOS_SB(sb)->fat_start+(last
-		    >> SECTOR_BITS),SECTOR_SIZE))) {
-			brelse(bh);
-			printk("bread in fat_access failed\n");
-			return 0;
-		}
-	}
-	if (MSDOS_SB(sb)->fat_bits == 16) {
-		p_first = p_last = NULL; /* GCC needs that stuff */
-		next = CF_LE_W(((unsigned short *) bh->b_data)[(first &
-		    (SECTOR_SIZE-1)) >> 1]);
-		if (next >= 0xfff7) next = -1;
-	}
-	else {
-		p_first = &((unsigned char *) bh->b_data)[first & (SECTOR_SIZE-1)];
-		p_last = &((unsigned char *) bh2->b_data)[(first+1) &
-		    (SECTOR_SIZE-1)];
-		if (nr & 1) next = ((*p_first >> 4) | (*p_last << 4)) & 0xfff;
-		else next = (*p_first+(*p_last << 8)) & 0xfff;
-		if (next >= 0xff7) next = -1;
-	}
-	if (new_value != -1) {
-		if (MSDOS_SB(sb)->fat_bits == 16)
-			((unsigned short *) bh->b_data)[(first & (SECTOR_SIZE-1)) >>
-			    1] = CT_LE_W(new_value);
-		else {
-			if (nr & 1) {
-				*p_first = (*p_first & 0xf) | (new_value << 4);
-				*p_last = new_value >> 4;
-			}
-			else {
-				*p_first = new_value & 0xff;
-				*p_last = (*p_last & 0xf0) | (new_value >> 8);
-			}
-			mark_buffer_dirty(bh2, 1);
-		}
-		mark_buffer_dirty(bh, 1);
-		for (copy = 1; copy < MSDOS_SB(sb)->fats; copy++) {
-			if (!(c_bh = bread(sb->s_dev,MSDOS_SB(sb)->
-			    fat_start+(first >> SECTOR_BITS)+MSDOS_SB(sb)->
-			    fat_length*copy,SECTOR_SIZE))) break;
-			memcpy(c_bh->b_data,bh->b_data,SECTOR_SIZE);
-			mark_buffer_dirty(c_bh, 1);
-			if (bh != bh2) {
-				if (!(c_bh2 = bread(sb->s_dev,
-				    MSDOS_SB(sb)->fat_start+(first >>
-				    SECTOR_BITS)+MSDOS_SB(sb)->fat_length*copy
-				    +1,SECTOR_SIZE))) {
-					brelse(c_bh);
-					break;
-				}
-				memcpy(c_bh2->b_data,bh2->b_data,SECTOR_SIZE);
-				brelse(c_bh2);
-			}
-			brelse(c_bh);
-		}
-	}
-	brelse(bh);
-	if (bh != bh2) brelse(bh2);
-	return next;
-}
-
-
-void cache_init(void)
-{
-	static int initialized = 0;
-	int count;
-
-	if (initialized) return;
-	fat_cache = &cache[0];
-	for (count = 0; count < FAT_CACHE; count++) {
-		cache[count].device = 0;
-		cache[count].next = count == FAT_CACHE-1 ? NULL :
-		    &cache[count+1];
-	}
-	initialized = 1;
-}
-
-
-void cache_lookup(struct inode *inode,int cluster,int *f_clu,int *d_clu)
-{
-	struct fat_cache *walk;
-
-#ifdef DEBUG
-printk("cache lookup: <%s,%d> %d (%d,%d) -> ", kdevname(inode->i_dev),
-       inode->i_ino, cluster, *f_clu, *d_clu);
-#endif
-	for (walk = fat_cache; walk; walk = walk->next)
-		if (inode->i_dev == walk->device
-		    && walk->ino == inode->i_ino
-		    && walk->file_cluster <= cluster
-		    && walk->file_cluster > *f_clu) {
-			*d_clu = walk->disk_cluster;
-#ifdef DEBUG
-printk("cache hit: %d (%d)\n",walk->file_cluster,*d_clu);
-#endif
-			if ((*f_clu = walk->file_cluster) == cluster) return;
-		}
-#ifdef DEBUG
-printk("cache miss\n");
-#endif
-}
-
-
-#ifdef DEBUG
-static void list_cache(void)
-{
-	struct fat_cache *walk;
-
-	for (walk = fat_cache; walk; walk = walk->next) {
-		if (walk->device)
-			printk("<%s,%d>(%d,%d) ", kdevname(walk->device),
-			       walk->ino, walk->file_cluster, walk->disk_cluster);
-		else printk("-- ");
-	}
-	printk("\n");
-}
-#endif
-
-
-void cache_add(struct inode *inode,int f_clu,int d_clu)
-{
-	struct fat_cache *walk,*last;
-
-#ifdef DEBUG
-printk("cache add: <%s,%d> %d (%d)\n", kdevname(inode->i_dev),
-       inode->i_ino, f_clu, d_clu);
-#endif
-	last = NULL;
-	for (walk = fat_cache; walk->next; walk = (last = walk)->next)
-		if (inode->i_dev == walk->device
-		    && walk->ino == inode->i_ino
-		    && walk->file_cluster == f_clu) {
-			if (walk->disk_cluster != d_clu) {
-				printk("FAT cache corruption");
-				cache_inval_inode(inode);
-				return;
-			}
-			/* update LRU */
-			if (last == NULL) return;
-			last->next = walk->next;
-			walk->next = fat_cache;
-			fat_cache = walk;
-#ifdef DEBUG
-list_cache();
-#endif
-			return;
-		}
-	walk->device = inode->i_dev;
-	walk->ino = inode->i_ino;
-	walk->file_cluster = f_clu;
-	walk->disk_cluster = d_clu;
-	last->next = NULL;
-	walk->next = fat_cache;
-	fat_cache = walk;
-#ifdef DEBUG
-list_cache();
-#endif
-}
-
-
-/* Cache invalidation occurs rarely, thus the LRU chain is not updated. It
-   fixes itself after a while. */
-
-void cache_inval_inode(struct inode *inode)
-{
-	struct fat_cache *walk;
-
-	for (walk = fat_cache; walk; walk = walk->next)
-		if (walk->device == inode->i_dev
-		    && walk->ino == inode->i_ino)
-			walk->device = 0;
-}
-
-
-void cache_inval_dev(kdev_t device)
-{
-	struct fat_cache *walk;
-
-	for (walk = fat_cache; walk; walk = walk->next)
-		if (walk->device == device)
-			walk->device = 0;
-}
-
-
-int get_cluster(struct inode *inode,int cluster)
-{
-	int nr,count;
-
-	if (!(nr = MSDOS_I(inode)->i_start)) return 0;
-	if (!cluster) return nr;
-	count = 0;
-	for (cache_lookup(inode,cluster,&count,&nr); count < cluster;
-	    count++) {
-		if ((nr = fat_access(inode->i_sb,nr,-1)) == -1) return 0;
-		if (!nr) return 0;
-	}
-	cache_add(inode,cluster,nr);
-	return nr;
-}
-
-
-int msdos_smap(struct inode *inode,int sector)
-{
-	struct msdos_sb_info *sb;
-	int cluster,offset;
-
-	sb = MSDOS_SB(inode->i_sb);
-	if (inode->i_ino == MSDOS_ROOT_INO || (S_ISDIR(inode->i_mode) &&
-	    !MSDOS_I(inode)->i_start)) {
-		if (sector >= sb->dir_entries >> MSDOS_DPS_BITS) return 0;
-		return sector+sb->dir_start;
-	}
-	cluster = sector/sb->cluster_size;
-	offset = sector % sb->cluster_size;
-	if (!(cluster = get_cluster(inode,cluster))) return 0;
-	return (cluster-2)*sb->cluster_size+sb->data_start+offset;
-}
-
-
-/* Free all clusters after the skip'th cluster. Doesn't use the cache,
-   because this way we get an additional sanity check. */
-
-int fat_free(struct inode *inode,int skip)
-{
-	int nr,last;
-
-	if (!(nr = MSDOS_I(inode)->i_start)) return 0;
-	last = 0;
-	while (skip--) {
-		last = nr;
-		if ((nr = fat_access(inode->i_sb,nr,-1)) == -1) return 0;
-		if (!nr) {
-			printk("fat_free: skipped EOF\n");
-			return -EIO;
-		}
-	}
-	if (last)
-		fat_access(inode->i_sb,last,MSDOS_SB(inode->i_sb)->fat_bits ==
-		    12 ? 0xff8 : 0xfff8);
-	else {
-		MSDOS_I(inode)->i_start = 0;
-		inode->i_dirt = 1;
-	}
-	lock_fat(inode->i_sb);
-	while (nr != -1) {
-		if (!(nr = fat_access(inode->i_sb,nr,0))) {
-			fs_panic(inode->i_sb,"fat_free: deleting beyond EOF");
-			break;
-		}
-		if (MSDOS_SB(inode->i_sb)->free_clusters != -1)
-			MSDOS_SB(inode->i_sb)->free_clusters++;
-		inode->i_blocks -= MSDOS_SB(inode->i_sb)->cluster_size;
-	}
-	unlock_fat(inode->i_sb);
-	cache_inval_inode(inode);
-	return 0;
-}