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|
/*
dblspace_alloc.c
DMSDOS CVF-FAT module: memory and sector allocation functions
******************************************************************************
DMSDOS (compressed MSDOS filesystem support) for Linux
written 1995-1998 by Frank Gockel and Pavel Pisa
(C) Copyright 1995-1998 by Frank Gockel
(C) Copyright 1996-1998 by Pavel Pisa
Some code of dmsdos has been copied from the msdos filesystem
so there are the following additional copyrights:
(C) Copyright 1992,1993 by Werner Almesberger (msdos filesystem)
(C) Copyright 1994,1995 by Jacques Gelinas (mmap code)
(C) Copyright 1992-1995 by Linus Torvalds
DMSDOS was inspired by the THS filesystem (a simple doublespace
DS-0-2 compressed read-only filesystem) written 1994 by Thomas Scheuermann.
The DMSDOS code is distributed under the Gnu General Public Licence.
See file COPYING for details.
******************************************************************************
*/
#ifdef __KERNEL__
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/msdos_fs.h>
#include <linux/string.h>
#include <linux/sched.h>
#endif
#include "dmsdos.h"
#ifdef __DMSDOS_LIB__
/* some interface hacks */
#include"lib_interface.h"
#include<malloc.h>
#include<errno.h>
#include<string.h>
#endif
extern unsigned long dmsdos_speedup;
#define NEAR_AREA 512
/* no change for doublespace, but fixes drivespace 3 problems (was 50) */
#define BIG_HOLE (dblsb->s_sectperclust*3+2)
/* experimental new memory allocation routines */
#if defined(USE_XMALLOC) && !defined(__DMSDOS_LIB__)
int told=0;
#include<linux/mm.h>
#include<linux/malloc.h>
#ifndef MAX_KMALLOC_SIZE
#define MAX_KMALLOC_SIZE 128*1024
#endif
void* xmalloc(unsigned long size)
{ void* result;
if(size<=MAX_KMALLOC_SIZE)
{ result=kmalloc(size,GFP_KERNEL);
if(result)
{ /* the xfree routine recognizes kmalloc'd memory due to that it is
usually not page-aligned -- we double-check here to be sure */
if ( ( ((unsigned long)result) & (PAGE_SIZE-1) ) ==0 )
{ /* uhhh.... the trick is broken...
tell the user and go safe using vmalloc */
kfree(result);
if(told++)printk(KERN_ERR "DMSDOS: page-aligned memory returned by kmalloc - please disable XMALLOC\n");
}
else return result;
}
}
result=vmalloc(size);
/* again check alignment to be 100% sure */
if ( ((unsigned long)result) & (PAGE_SIZE-1) )
panic("DMSDOS: vmalloc returned unaligned memory - please disable XMALLOC\n");
return result;
}
void xfree(void * data)
{ unsigned long address=(unsigned long)data;
/* we rely on the fact that kmalloc'ed memory is unaligned but
vmalloc'ed memory is page-aligned */
/* we are causing SERIOUS kernel problems if the wrong routine is called -
therefore xmalloc tests kmalloc's return address above */
if(address&(PAGE_SIZE-1))kfree(data);
else vfree(data);
}
#endif
#ifdef __DMSDOS_LIB__
/* we don't need locking in the library */
void lock_mdfat_alloc(Dblsb*dblsb) {}
void unlock_mdfat_alloc(Dblsb*dblsb) {}
#endif
#ifdef __KERNEL__
void lock_mdfat_alloc(Dblsb*dblsb)
{ struct semaphore*sem;
sem=dblsb->mdfat_alloc_semp;
down(sem);
}
void unlock_mdfat_alloc(Dblsb*dblsb)
{ struct semaphore*sem;
sem=dblsb->mdfat_alloc_semp;
up(sem);
}
#endif
#ifdef DMSDOS_CONFIG_DBL
void u_free_cluster_sectors(struct super_block*sb, int clusternr,
unsigned long* undo_list)
{
Mdfat_entry mde,dummy,newmde;
int newval=0;
int i;
int sectors;
int sectornr;
int undo_pnt=0;
Dblsb*dblsb=MSDOS_SB(sb)->private_data;
LOG_ALLOC("DMSDOS: free_cluster_sectors: freeing cluster %d\n",clusternr);
/* read mdfat entry and clear */
newmde.sector_minus_1=0;
newmde.size_lo_minus_1=0;
newmde.size_hi_minus_1=0;
newmde.flags=0;
dbl_mdfat_value(sb,clusternr,NULL,&mde);
dbl_mdfat_value(sb,clusternr,&newmde,&dummy);
sectors=mde.size_lo_minus_1+1;
sectornr=mde.sector_minus_1+1;
if(mde.flags&2)
{ if(mde.unknown&2)
{ /* free fragmented cluster */
struct buffer_head*bh;
int fragcount;
int fragpnt;
int sec;
int cnt;
bh=raw_bread(sb,sectornr);
if(bh==NULL)
{ printk(KERN_ERR "DMSDOS: free_cluster_sectors: fragmentation list unreadable in cluster %d\n",
clusternr);
goto nfree;
}
fragcount=bh->b_data[0];
if(fragcount<=0||fragcount>dblsb->s_sectperclust||
bh->b_data[1]!=0||bh->b_data[2]!=0||bh->b_data[3]!=0)
{ printk(KERN_ERR "DMSDOS: free_cluster_sectors: error in fragmentation list in cluster %d\n",
clusternr);
raw_brelse(sb,bh);
goto nfree;
}
for(fragpnt=1;fragpnt<=fragcount;++fragpnt)
{ cnt=bh->b_data[fragpnt*4+3];
cnt&=0xff;
cnt/=4;
cnt+=1;
sec=bh->b_data[fragpnt*4];
sec&=0xff;
sec+=bh->b_data[fragpnt*4+1]<<8;
sec&=0xffff;
sec+=bh->b_data[fragpnt*4+2]<<16;
sec&=0xffffff;
sec+=1;
if(fragpnt==1)
{ if(sec!=sectornr||cnt!=sectors)
{ printk(KERN_ERR "DMSDOS: free_cluster_sectors: first fragment wrong in cluster %d\n",
clusternr);
raw_brelse(sb,bh);
goto nfree;
}
}
for(i=0;i<cnt;++i)
{ dbl_bitfat_value(sb,sec+i,&newval);
if(undo_list)undo_list[undo_pnt++]=sec+i;
}
}
}
else
{ /* free sectors in bitfat */
nfree:
for(i=0;i<sectors;++i)
{ dbl_bitfat_value(sb,sectornr+i,&newval);
if(undo_list)undo_list[undo_pnt++]=sectornr+i;
}
}
dblsb->s_full=0;
}
else
{ LOG_CLUST("DMSDOS: stale MDFAT entry for cluster %d, zeroing.\n",
clusternr);
}
if(undo_list)undo_list[undo_pnt]=0;
}
void free_cluster_sectors(struct super_block*sb, int clusternr)
{ lock_mdfat_alloc(MSDOS_SB(sb)->private_data);
u_free_cluster_sectors(sb,clusternr,NULL);
unlock_mdfat_alloc(MSDOS_SB(sb)->private_data);
}
#endif
/* for statistics - just for interest */
int nearfound=0;
int bigfound=0;
int exactfound=0;
int anyfound=0;
int notfound=0;
int fragfound=0;
/* this function must be called locked */
int find_free_bitfat(struct super_block*sb, int sectornr, int size)
{ int testsek;
int i;
Dblsb*dblsb=MSDOS_SB(sb)->private_data;
if(dblsb->s_free_sectors<0||dblsb->s_free_sectors>0x2000000)
{ printk(KERN_NOTICE "DMSDOS: find_free_bitfat: free sectors=%d, cannot believe this. Counting...\n",
dblsb->s_free_sectors);
check_free_sectors(sb);
printk(KERN_NOTICE "DMSDOS: counted free sectors=%d\n",dblsb->s_free_sectors);
}
/* we needn't try in that case... */
if(dblsb->s_free_sectors<size)
{ if(dblsb->s_full<2)printk(KERN_CRIT "DMSDOS: CVF full.\n");
dblsb->s_full=2;
return -ENOSPC;
}
if(dmsdos_speedup&SP_FAST_BITFAT_ALLOC)
{ /* new strategy: find any fitting hole beginning with last result */
testsek=dblsb->s_lastnear;
if(testsek<dblsb->s_datastart||testsek>dblsb->s_dataend-size)
testsek=dblsb->s_datastart;
while(testsek<=dblsb->s_dataend-size)
{ if(dbl_bitfat_value(sb,testsek,NULL))
{ ++testsek;
continue;
}
i=1;
while(i<size&&dbl_bitfat_value(sb,testsek+i,NULL)==0)++i;
if(i==size)
{ ++nearfound;
dblsb->s_lastnear=testsek+size;
dblsb->s_full=0;
return testsek;
}
testsek+=i;
}
/* not found, continue */
goto tryany;
} /* end of new strategy */
else
{ /* old strategy: do a search in near environment first */
if(sectornr==0)sectornr=dblsb->s_lastnear;
if(sectornr>=dblsb->s_datastart&§ornr<=dblsb->s_dataend-size)
{ /* search exactly fitting hole near sectornr */
testsek=sectornr;
while(testsek<sectornr+NEAR_AREA)
{ if(dbl_bitfat_value(sb,testsek,NULL))
{ ++testsek;
continue;
}
i=1;
while(i<=size&&dbl_bitfat_value(sb,testsek+i,NULL)==0)++i;
if(i==size)
{ dblsb->s_full=0;
++nearfound;
dblsb->s_lastnear=testsek;
return testsek;
}
testsek+=i;
}
testsek=sectornr;
while(testsek>sectornr-NEAR_AREA)
{ if(dbl_bitfat_value(sb,testsek,NULL))
{ --testsek;
continue;
}
i=1;
while(i<=size&&dbl_bitfat_value(sb,testsek-i,NULL)==0)++i;
if(i==size)
{ dblsb->s_full=0;
++nearfound;
dblsb->s_lastnear=testsek-i+1;
return testsek-i+1;
}
testsek-=i;
}
}
/* not found, continue */
} /* end of old strategy */
/* search for a big hole */
if(dblsb->s_lastbig==-1)goto nobighole;
testsek=dblsb->s_lastbig;
if(testsek<dblsb->s_datastart||testsek+size>dblsb->s_dataend)
testsek=dblsb->s_datastart;
while(testsek<=dblsb->s_dataend-size)
{ if(dbl_bitfat_value(sb,testsek,NULL))
{ ++testsek;
continue;
}
i=1;
while(i<BIG_HOLE&&dbl_bitfat_value(sb,testsek+i,NULL)==0)++i;
if(i==BIG_HOLE)
{ dblsb->s_full=0;
++bigfound;
dblsb->s_lastbig=testsek;
return testsek;
}
testsek+=i;
}
if(dblsb->s_lastbig==0)
dblsb->s_lastbig=-1; /*there's no big hole any more*/
else
dblsb->s_lastbig=0; /* next time try from the beginning */
nobighole:
if((dmsdos_speedup&SP_NO_EXACT_SEARCH)==0)
{
/* search for an exactly fitting hole */
/* hmmm... now the search code becomes awfully slow */
testsek=dblsb->s_datastart;
while(testsek<=dblsb->s_dataend-size)
{ if(dbl_bitfat_value(sb,testsek,NULL))
{ ++testsek;
continue;
}
i=1;
while(i<=size&&dbl_bitfat_value(sb,testsek+i,NULL)==0)++i;
if(i==size)
{ dblsb->s_full=0;
++exactfound;
return testsek;
}
testsek+=i;
}
}
if(dblsb->s_full==0)
{ printk(KERN_CRIT "DMSDOS: CVF almost full or highly fragmented at MDFAT level.\n");
dblsb->s_full=1;
}
tryany:
/* last trial: search for any hole >= size */
testsek=dblsb->s_datastart;
while(testsek<=dblsb->s_dataend-size)
{ if(dbl_bitfat_value(sb,testsek,NULL))
{ ++testsek;
continue;
}
i=1;
while(i<size&&dbl_bitfat_value(sb,testsek+i,NULL)==0)++i;
if(i==size)
{ ++anyfound;
return testsek;
}
testsek+=i;
}
/* not found, means disk full or MDFAT too fragmented */
++notfound;
if(dblsb->s_cvf_version==DRVSP3)
{ if(dblsb->s_full==0)
{ printk(KERN_CRIT "DMSDOS: CVF almost full or highly fragmented at MDFAT level.\n");
dblsb->s_full=1;
}
}
else /* this is for CVFs that cannot fragment cluster data */
{ if(dblsb->s_full<2)
printk(KERN_CRIT "DMSDOS: CVF full or too fragmented at MDFAT level.\n");
dblsb->s_full=2;
}
return 0;
}
void log_found_statistics()
{ printk(KERN_INFO "DMSDOS: free sector finding statistics:\n");
printk(KERN_INFO "nearfound=%d bigfound=%d exactfound=%d anyfound=%d fragfound=%d notfound=%d\n",
nearfound,bigfound,exactfound,anyfound,fragfound,notfound);
}
#ifdef DMSDOS_CONFIG_DRVSP3
int try_fragmented(struct super_block*sb,int anear,int nr,
unsigned char*fraglist)
{
int i;
int sector=anear;
Dblsb*dblsb=MSDOS_SB(sb)->private_data;
int again=1;
int frags;
int cnt;
/* if you never want dmsdos to write fragmented clusters as a last resort
then uncomment the next return statement */
/* return -ENOSPC; */
if(dblsb->s_free_sectors<nr)
{ if(dblsb->s_full<2)printk(KERN_CRIT "DMSDOS: CVF full.\n");
dblsb->s_full=2;
return -ENOSPC;
}
printk(KERN_DEBUG "DMSDOS: trying to allocate fragmented space...\n");
LOG_ALLOC("DMSDOS: try_fragmented: start, anear=%d nr=%d\n",anear,nr);
if(anear==0)sector=dblsb->s_lastnear;
if(sector<dblsb->s_datastart||sector>dblsb->s_dataend)
{ sector=dblsb->s_datastart;
again=0;
}
retry:
frags=0;
fraglist[0]=0;
fraglist[1]=0;
fraglist[2]=0;
fraglist[3]=0;
cnt=nr;
while(cnt>0&§or<=dblsb->s_dataend)
{ if(dbl_bitfat_value(sb,sector,NULL))
{ ++sector;
continue;
}
/* free sector found */
i=1;
while(dbl_bitfat_value(sb,sector+i,NULL)==0&&i<cnt)++i;
/* i=number of free sectors :) */
++frags;
fraglist[frags*4]=sector-1;
fraglist[frags*4+1]=(sector-1)>>8;
fraglist[frags*4+2]=(sector-1)>>16;
fraglist[frags*4+3]=(sector-1)>>24;
fraglist[frags*4+3]|=(i-1)<<2;
fraglist[0]=frags;
sector+=i+1;
cnt-=i;
}
if(cnt>0&&again!=0)
{ sector=dblsb->s_datastart;
again=0;
goto retry;
}
/* now evaluate the result, check for strange things */
if(cnt>0)
{ if(dblsb->s_full<2)
printk(KERN_CRIT "DMSDOS: CVF full (cannot even allocate fragmented space)\n");
dblsb->s_full=2;
return -ENOSPC;
}
if(cnt<0)
{ printk(KERN_ERR "DMSDOS: try_fragmented: cnt<0 ? This is a bug.\n");
return -EIO;
}
if(frags<2||frags>dblsb->s_sectperclust+1)
{ printk(KERN_ERR "DMSDOS: try_fragmented: frags=%d ? Cannot happen.\n",frags);
return -EIO;
}
/* correct statistics */
++fragfound;--notfound;
dblsb->s_lastnear=sector;
dblsb->s_full=1; /* uhh... 0 might be dangerous... */
/* fraglist must be written to disk in *any* case in order to
still represent a correct filesystem
this is handled by dbl_write_cluster to prevent too much overhead */
LOG_ALLOC("DMSDOS: try_fragmented: success, frags=%d\n",frags);
return 0;
}
#endif /* DMSDOS_CONFIG_DRVSP3 */
#ifdef DMSDOS_CONFIG_DBL
/* replaces an existing cluster;
this unusual function must be called before rewriting any file cluster;
*** size must be known (encoded in mde) ***
if fraglist!=NULL fragmented clusters are allowed for drivespace 3
returns first sector nr
changes mde and fraglist
*/
#define MAX_UNDO_LIST 70
int dbl_replace_existing_cluster(struct super_block*sb, int cluster,
int near_sector,
Mdfat_entry*mde,
unsigned char*fraglist)
{ Mdfat_entry old_mde,dummy;
int i;
int newval;
int sector;
int old_sector;
int old_size;
int new_size;
unsigned long undo_list[MAX_UNDO_LIST];
Dblsb*dblsb=MSDOS_SB(sb)->private_data;
lock_mdfat_alloc(dblsb);
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster cluster=%d near_sector=%d\n",
cluster,near_sector);
dbl_mdfat_value(sb,cluster,NULL,&old_mde);
old_size=old_mde.size_lo_minus_1+1;
old_sector=old_mde.sector_minus_1+1;
new_size=mde->size_lo_minus_1+1;
mde->unknown=0; /* ensure fragmented bit is clear */
if(old_mde.flags&2)
{
/* test whether same length (and not fragmented in drivespace 3) */
if(old_size==new_size&&
(dblsb->s_cvf_version!=DRVSP3||(old_mde.unknown&2)==0)
)
{ LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: same length, ok\n");
sector=old_sector;
goto mdfat_update;
}
if(dblsb->s_cvf_version==DRVSP3&&(old_mde.unknown&2)!=0&&fraglist!=NULL)
{ /*old cluster is fragmented and new *is allowed* to be fragmentd */
struct buffer_head*bh=raw_bread(sb,old_sector);
if(bh)
{ int fragcount;
int cnt;
int sec;
int fragpnt;
int sects;
int m_cnt=0;
int m_sec=0;
fragcount=bh->b_data[0];
sects=0;
if(fragcount<2||fragcount>dblsb->s_sectperclust+1||
bh->b_data[1]!=0||bh->b_data[2]!=0||bh->b_data[3]!=0
)
{ raw_brelse(sb,bh);
goto check_failed;
}
for(fragpnt=1;fragpnt<=fragcount;++fragpnt)
{ cnt=bh->b_data[fragpnt*4+3];
cnt&=0xff;
cnt/=4;
cnt+=1;
sec=bh->b_data[fragpnt*4];
sec&=0xff;
sec+=bh->b_data[fragpnt*4+1]<<8;
sec&=0xffff;
sec+=bh->b_data[fragpnt*4+2]<<16;
sec&=0xffffff;
sec+=1;
if(fragpnt==1)
{ m_cnt=cnt;
m_sec=sec;
if(sec!=old_mde.sector_minus_1+1||cnt!=old_mde.size_lo_minus_1+1)
{ printk(KERN_ERR "DMSDOS: dbl_replace_existing_cluster: checking old fraglist: first fragment wrong in cluster %d\n",
cluster);
raw_brelse(sb,bh);
goto check_failed;
}
}
sects+=cnt;
}
raw_brelse(sb,bh);
if(sects-1/*subtract space for fraglist*/==new_size)
{ /* we can reuse it */
memcpy(fraglist,bh->b_data,4*(fragcount+1));
mde->unknown|=2;
mde->size_lo_minus_1=m_cnt-1;
sector=m_sec;
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: same fragmented size, ok.\n");
goto mdfat_update;
}
check_failed: ; /*Win32 compiler wants a semicolon here */
/* fall through */
}
}
/* different length, replace mdfat entry */
newval=0;
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: freeing old sectors...\n");
u_free_cluster_sectors(sb,cluster,undo_list);
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: freeing finished\n");
}
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: call find_free_bitfat...\n");
sector=find_free_bitfat(sb,near_sector,new_size);
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: find_free_bitfat returned %d\n",
sector);
if(sector<=0)
{
#ifdef DMSDOS_CONFIG_DRVSP3
if(dblsb->s_cvf_version==DRVSP3&&fraglist!=NULL
&&(dmsdos_speedup&SP_NO_FRAG_WRITE)==0)
{ i=try_fragmented(sb,near_sector,new_size+1,fraglist);/*yes one sector more*/
if(i==0) /* success */
{ /* scan fraglist */
int frags;
int seccount;
int usector;
int j;
frags=fraglist[0];
for(i=1;i<=frags;++i)
{ seccount=fraglist[i*4+3];
seccount&=0xff;
seccount/=4;
seccount+=1;
usector=fraglist[i*4];
usector&=0xff;
usector+=fraglist[i*4+1]<<8;
usector&=0xffff;
usector+=fraglist[i*4+2]<<16;
usector&=0xffffff;
usector+=1;
if(i==1) /* note values for mdfat */
{ mde->size_lo_minus_1=seccount-1;
sector=usector;
}
/* allocate in bitfat */
newval=1;
for(j=0;j<seccount;++j)
{ /* check whether sectors are really free */
if(dbl_bitfat_value(sb,usector+j,NULL))
{ printk(KERN_EMERG "DMSDOS: try_fragmented returned non-free sectors!\n");
/* WARNING: bitfat is corrupt now */
unlock_mdfat_alloc(dblsb);
panic("DMSDOS: dbl_replace_existing_cluster: This is a bug - reboot and check filesystem\n");
return -EIO;
}
dbl_bitfat_value(sb,usector+j,&newval);
}
}
mde->unknown|=2; /* set fragmented bit */
goto mdfat_update;
}
/* try_fragmented failed: fall through */
}
#endif /* DMSDOS_CONFIG_DRVSP3 */
if(old_mde.flags&2)
{ /* undo bitfat free */
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: undoing bitfat free...\n");
newval=1;
for(i=0;undo_list[i]!=0;++i)
dbl_bitfat_value(sb,undo_list[i],&newval);
}
unlock_mdfat_alloc(dblsb);
return -ENOSPC; /* disk full */
}
/* check whether really free (bug supposed in find_free_bitfat) */
for(i=0;i<new_size;++i)
{ if(dbl_bitfat_value(sb,sector+i,NULL))
{ printk(KERN_EMERG "DMSDOS: find_free_bitfat returned sector %d size %d but they are not all free!\n",
sector,new_size);
unlock_mdfat_alloc(dblsb);
panic("DMSDOS: dbl_replace_existing_cluster: This is a bug - reboot and check filesystem\n");
return -EIO;
}
}
newval=1;
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: allocating in bitfat...\n");
for(i=0;i<new_size;++i)dbl_bitfat_value(sb,sector+i,&newval);
mdfat_update:
mde->sector_minus_1=sector-1;
mde->flags|=2;
LOG_ALLOC("DMSDOS: dbl_replace_existing_cluster: writing mdfat...\n");
dbl_mdfat_value(sb,cluster,mde,&dummy);
unlock_mdfat_alloc(dblsb);
return sector; /* okay */
}
#endif
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