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modify fat cache entries atomic, this was potentially unsafe

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@5534 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Jörg Hohensohn 2005-01-04 23:01:25 +00:00
parent 8be9775d53
commit 50dba1fad0
1 changed files with 24 additions and 12 deletions
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36
firmware/drivers/fat.c
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@ -27,6 +27,7 @@
#include "panic.h" #include "panic.h"
#include "system.h" #include "system.h"
#include "timefuncs.h" #include "timefuncs.h"
#include "kernel.h"
#define BYTES2INT16(array,pos) \ #define BYTES2INT16(array,pos) \
(array[pos] | (array[pos+1] << 8 )) (array[pos] | (array[pos+1] << 8 ))
@ -230,7 +231,7 @@ static struct bpb fat_bpbs[NUM_VOLUMES]; /* mounted partition info */
static int update_fsinfo(IF_MV_NONVOID(struct bpb* fat_bpb)); static int update_fsinfo(IF_MV_NONVOID(struct bpb* fat_bpb));
static int bpb_is_sane(IF_MV_NONVOID(struct bpb* fat_bpb)); static int bpb_is_sane(IF_MV_NONVOID(struct bpb* fat_bpb));
static void *cache_fat_sector(IF_MV2(struct bpb* fat_bpb,) int secnum); static void *cache_fat_sector(IF_MV2(struct bpb* fat_bpb,) int secnum, bool dirty);
static int create_dos_name(const unsigned char *name, unsigned char *newname); static int create_dos_name(const unsigned char *name, unsigned char *newname);
static unsigned int find_free_cluster(IF_MV2(struct bpb* fat_bpb,) unsigned int start); static unsigned int find_free_cluster(IF_MV2(struct bpb* fat_bpb,) unsigned int start);
static int transfer(IF_MV2(struct bpb* fat_bpb,) unsigned int start, int count, char* buf, bool write ); static int transfer(IF_MV2(struct bpb* fat_bpb,) unsigned int start, int count, char* buf, bool write );
@ -250,6 +251,7 @@ struct fat_cache_entry
static char fat_cache_sectors[FAT_CACHE_SIZE][SECTOR_SIZE]; static char fat_cache_sectors[FAT_CACHE_SIZE][SECTOR_SIZE];
static struct fat_cache_entry fat_cache[FAT_CACHE_SIZE]; static struct fat_cache_entry fat_cache[FAT_CACHE_SIZE];
static struct mutex cache_mutex;
static int cluster2sec(IF_MV2(struct bpb* fat_bpb,) int cluster) static int cluster2sec(IF_MV2(struct bpb* fat_bpb,) int cluster)
{ {
@ -299,6 +301,9 @@ void fat_size(IF_MV2(int volume,) unsigned int* size, unsigned int* free)
void fat_init(void) void fat_init(void)
{ {
unsigned int i; unsigned int i;
mutex_init(&cache_mutex);
/* mark the FAT cache as unused */ /* mark the FAT cache as unused */
for(i = 0;i < FAT_CACHE_SIZE;i++) for(i = 0;i < FAT_CACHE_SIZE;i++)
{ {
@ -488,7 +493,7 @@ void fat_recalc_free(IF_MV_NONVOID(int volume))
{ {
for (i = 0; i<fat_bpb->fatsize; i++) { for (i = 0; i<fat_bpb->fatsize; i++) {
unsigned int j; unsigned int j;
unsigned short* fat = cache_fat_sector(IF_MV2(fat_bpb,) i); unsigned short* fat = cache_fat_sector(IF_MV2(fat_bpb,) i, false);
for (j = 0; j < CLUSTERS_PER_FAT16_SECTOR; j++) { for (j = 0; j < CLUSTERS_PER_FAT16_SECTOR; j++) {
unsigned int c = i * CLUSTERS_PER_FAT16_SECTOR + j; unsigned int c = i * CLUSTERS_PER_FAT16_SECTOR + j;
if ( c > fat_bpb->dataclusters+1 ) /* nr 0 is unused */ if ( c > fat_bpb->dataclusters+1 ) /* nr 0 is unused */
@ -507,7 +512,7 @@ void fat_recalc_free(IF_MV_NONVOID(int volume))
{ {
for (i = 0; i<fat_bpb->fatsize; i++) { for (i = 0; i<fat_bpb->fatsize; i++) {
unsigned int j; unsigned int j;
unsigned int* fat = cache_fat_sector(IF_MV2(fat_bpb,) i); unsigned int* fat = cache_fat_sector(IF_MV2(fat_bpb,) i, false);
for (j = 0; j < CLUSTERS_PER_FAT_SECTOR; j++) { for (j = 0; j < CLUSTERS_PER_FAT_SECTOR; j++) {
unsigned int c = i * CLUSTERS_PER_FAT_SECTOR + j; unsigned int c = i * CLUSTERS_PER_FAT_SECTOR + j;
if ( c > fat_bpb->dataclusters+1 ) /* nr 0 is unused */ if ( c > fat_bpb->dataclusters+1 ) /* nr 0 is unused */
@ -621,7 +626,10 @@ static void flush_fat_sector(struct fat_cache_entry *fce,
fce->dirty = false; fce->dirty = false;
} }
static void *cache_fat_sector(IF_MV2(struct bpb* fat_bpb,) int fatsector) /* Note: The returned pointer is only safely valid until the next
task switch! (Any subsequent ata read/write may yield.) */
static void *cache_fat_sector(IF_MV2(struct bpb* fat_bpb,)
int fatsector, bool dirty)
{ {
#ifndef HAVE_MULTIVOLUME #ifndef HAVE_MULTIVOLUME
struct bpb* fat_bpb = &fat_bpbs[0]; struct bpb* fat_bpb = &fat_bpbs[0];
@ -632,6 +640,8 @@ static void *cache_fat_sector(IF_MV2(struct bpb* fat_bpb,) int fatsector)
unsigned char *sectorbuf = &fat_cache_sectors[cache_index][0]; unsigned char *sectorbuf = &fat_cache_sectors[cache_index][0];
int rc; int rc;
mutex_lock(&cache_mutex); /* make changes atomic */
/* Delete the cache entry if it isn't the sector we want */ /* Delete the cache entry if it isn't the sector we want */
if(fce->inuse && (fce->secnum != secnum if(fce->inuse && (fce->secnum != secnum
#ifdef HAVE_MULTIVOLUME #ifdef HAVE_MULTIVOLUME
@ -657,6 +667,7 @@ static void *cache_fat_sector(IF_MV2(struct bpb* fat_bpb,) int fatsector)
{ {
DEBUGF( "cache_fat_sector() - Could not read sector %d" DEBUGF( "cache_fat_sector() - Could not read sector %d"
" (error %d)\n", secnum, rc); " (error %d)\n", secnum, rc);
mutex_unlock(&cache_mutex);
return NULL; return NULL;
} }
fce->inuse = true; fce->inuse = true;
@ -665,6 +676,9 @@ static void *cache_fat_sector(IF_MV2(struct bpb* fat_bpb,) int fatsector)
fce->fat_vol = fat_bpb; fce->fat_vol = fat_bpb;
#endif #endif
} }
if (dirty)
fce->dirty = true; /* dirt remains, sticky until flushed */
mutex_unlock(&cache_mutex);
return sectorbuf; return sectorbuf;
} }
@ -686,7 +700,7 @@ static unsigned int find_free_cluster(IF_MV2(struct bpb* fat_bpb,) unsigned int
for (i = 0; i<fat_bpb->fatsize; i++) { for (i = 0; i<fat_bpb->fatsize; i++) {
unsigned int j; unsigned int j;
unsigned int nr = (i + sector) % fat_bpb->fatsize; unsigned int nr = (i + sector) % fat_bpb->fatsize;
unsigned short* fat = cache_fat_sector(IF_MV2(fat_bpb,) nr); unsigned short* fat = cache_fat_sector(IF_MV2(fat_bpb,) nr, false);
if ( !fat ) if ( !fat )
break; break;
for (j = 0; j < CLUSTERS_PER_FAT16_SECTOR; j++) { for (j = 0; j < CLUSTERS_PER_FAT16_SECTOR; j++) {
@ -714,7 +728,7 @@ static unsigned int find_free_cluster(IF_MV2(struct bpb* fat_bpb,) unsigned int
for (i = 0; i<fat_bpb->fatsize; i++) { for (i = 0; i<fat_bpb->fatsize; i++) {
unsigned int j; unsigned int j;
unsigned int nr = (i + sector) % fat_bpb->fatsize; unsigned int nr = (i + sector) % fat_bpb->fatsize;
unsigned int* fat = cache_fat_sector(IF_MV2(fat_bpb,) nr); unsigned int* fat = cache_fat_sector(IF_MV2(fat_bpb,) nr, false);
if ( !fat ) if ( !fat )
break; break;
for (j = 0; j < CLUSTERS_PER_FAT_SECTOR; j++) { for (j = 0; j < CLUSTERS_PER_FAT_SECTOR; j++) {
@ -760,13 +774,12 @@ static int update_fat_entry(IF_MV2(struct bpb* fat_bpb,) unsigned int entry, uns
if ( entry < 2 ) if ( entry < 2 )
panicf("Updating reserved FAT entry %d.\n",entry); panicf("Updating reserved FAT entry %d.\n",entry);
sec = cache_fat_sector(IF_MV2(fat_bpb,) sector); sec = cache_fat_sector(IF_MV2(fat_bpb,) sector, true);
if (!sec) if (!sec)
{ {
DEBUGF( "update_fat_entry() - Could not cache sector %d\n", sector); DEBUGF( "update_fat_entry() - Could not cache sector %d\n", sector);
return -1; return -1;
} }
fat_cache[(sector + fat_bpb->bpb_rsvdseccnt) & FAT_CACHE_MASK].dirty = true;
if ( val ) { if ( val ) {
if (SWAB16(sec[offset]) == 0x0000 && fat_bpb->fsinfo.freecount > 0) if (SWAB16(sec[offset]) == 0x0000 && fat_bpb->fsinfo.freecount > 0)
@ -796,13 +809,12 @@ static int update_fat_entry(IF_MV2(struct bpb* fat_bpb,) unsigned int entry, uns
if ( entry < 2 ) if ( entry < 2 )
panicf("Updating reserved FAT entry %d.\n",entry); panicf("Updating reserved FAT entry %d.\n",entry);
sec = cache_fat_sector(IF_MV2(fat_bpb,) sector); sec = cache_fat_sector(IF_MV2(fat_bpb,) sector, true);
if (!sec) if (!sec)
{ {
DEBUGF( "update_fat_entry() - Could not cache sector %d\n", sector); DEBUGF( "update_fat_entry() - Could not cache sector %d\n", sector);
return -1; return -1;
} }
fat_cache[(sector + fat_bpb->bpb_rsvdseccnt) & FAT_CACHE_MASK].dirty = true;
if ( val ) { if ( val ) {
if (!(SWAB32(sec[offset]) & 0x0fffffff) && if (!(SWAB32(sec[offset]) & 0x0fffffff) &&
@ -836,7 +848,7 @@ static int read_fat_entry(IF_MV2(struct bpb* fat_bpb,) unsigned int entry)
int offset = entry % CLUSTERS_PER_FAT16_SECTOR; int offset = entry % CLUSTERS_PER_FAT16_SECTOR;
unsigned short* sec; unsigned short* sec;
sec = cache_fat_sector(IF_MV2(fat_bpb,) sector); sec = cache_fat_sector(IF_MV2(fat_bpb,) sector, false);
if (!sec) if (!sec)
{ {
DEBUGF( "read_fat_entry() - Could not cache sector %d\n", sector); DEBUGF( "read_fat_entry() - Could not cache sector %d\n", sector);
@ -852,7 +864,7 @@ static int read_fat_entry(IF_MV2(struct bpb* fat_bpb,) unsigned int entry)
int offset = entry % CLUSTERS_PER_FAT_SECTOR; int offset = entry % CLUSTERS_PER_FAT_SECTOR;
unsigned int* sec; unsigned int* sec;
sec = cache_fat_sector(IF_MV2(fat_bpb,) sector); sec = cache_fat_sector(IF_MV2(fat_bpb,) sector, false);
if (!sec) if (!sec)
{ {
DEBUGF( "read_fat_entry() - Could not cache sector %d\n", sector); DEBUGF( "read_fat_entry() - Could not cache sector %d\n", sector);