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linux/fs/jffs2/compr.c
Richard Purdie 3b23c1f5fa [JFFS2] Add a "favourlzo" compression mode 
Add a "favourlzo" compression mode to jffs2 which tries to
optimise by size but gives lzo an advantage when comparing sizes.
This means the faster lzo algorithm can be preferred when there
isn't much difference in compressed size (the exact threshold can
be changed).

Signed-off-by: Richard Purdie <rpurdie@openedhand.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2007-07-11 15:04:38 +01:00

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/*
* JFFS2 -- Journalling Flash File System, Version 2.
*
* Copyright © 2001-2007 Red Hat, Inc.
* Created by Arjan van de Ven <arjanv@redhat.com>
*
* Copyright © 2004 Ferenc Havasi <havasi@inf.u-szeged.hu>,
* University of Szeged, Hungary
*
* For licensing information, see the file 'LICENCE' in this directory.
*
*/
#include "compr.h"
static DEFINE_SPINLOCK(jffs2_compressor_list_lock);
/* Available compressors are on this list */
static LIST_HEAD(jffs2_compressor_list);
/* Actual compression mode */
static int jffs2_compression_mode = JFFS2_COMPR_MODE_PRIORITY;
/* Statistics for blocks stored without compression */
static uint32_t none_stat_compr_blocks=0,none_stat_decompr_blocks=0,none_stat_compr_size=0;
/*
* Return 1 to use this compression
*/
static int jffs2_is_best_compression(struct jffs2_compressor *this,
struct jffs2_compressor *best, uint32_t size, uint32_t bestsize)
{
switch (jffs2_compression_mode) {
case JFFS2_COMPR_MODE_SIZE:
if (bestsize > size)
return 1;
return 0;
case JFFS2_COMPR_MODE_FAVOURLZO:
if ((this->compr == JFFS2_COMPR_LZO) && (bestsize > size))
return 1;
if ((best->compr != JFFS2_COMPR_LZO) && (bestsize > size))
return 1;
if ((this->compr == JFFS2_COMPR_LZO) && (bestsize > (size * FAVOUR_LZO_PERCENT / 100)))
return 1;
if ((bestsize * FAVOUR_LZO_PERCENT / 100) > size)
return 1;
return 0;
}
/* Shouldn't happen */
return 0;
}
/* jffs2_compress:
* @data: Pointer to uncompressed data
* @cdata: Pointer to returned pointer to buffer for compressed data
* @datalen: On entry, holds the amount of data available for compression.
* On exit, expected to hold the amount of data actually compressed.
* @cdatalen: On entry, holds the amount of space available for compressed
* data. On exit, expected to hold the actual size of the compressed
* data.
*
* Returns: Lower byte to be stored with data indicating compression type used.
* Zero is used to show that the data could not be compressed - the
* compressed version was actually larger than the original.
* Upper byte will be used later. (soon)
*
* If the cdata buffer isn't large enough to hold all the uncompressed data,
* jffs2_compress should compress as much as will fit, and should set
* *datalen accordingly to show the amount of data which were compressed.
*/
uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
unsigned char *data_in, unsigned char **cpage_out,
uint32_t *datalen, uint32_t *cdatalen)
{
int ret = JFFS2_COMPR_NONE;
int compr_ret;
struct jffs2_compressor *this, *best=NULL;
unsigned char *output_buf = NULL, *tmp_buf;
uint32_t orig_slen, orig_dlen;
uint32_t best_slen=0, best_dlen=0;
switch (jffs2_compression_mode) {
case JFFS2_COMPR_MODE_NONE:
break;
case JFFS2_COMPR_MODE_PRIORITY:
output_buf = kmalloc(*cdatalen,GFP_KERNEL);
if (!output_buf) {
printk(KERN_WARNING "JFFS2: No memory for compressor allocation. Compression failed.\n");
goto out;
}
orig_slen = *datalen;
orig_dlen = *cdatalen;
spin_lock(&jffs2_compressor_list_lock);
list_for_each_entry(this, &jffs2_compressor_list, list) {
/* Skip decompress-only backwards-compatibility and disabled modules */
if ((!this->compress)||(this->disabled))
continue;
this->usecount++;
spin_unlock(&jffs2_compressor_list_lock);
*datalen = orig_slen;
*cdatalen = orig_dlen;
compr_ret = this->compress(data_in, output_buf, datalen, cdatalen, NULL);
spin_lock(&jffs2_compressor_list_lock);
this->usecount--;
if (!compr_ret) {
ret = this->compr;
this->stat_compr_blocks++;
this->stat_compr_orig_size += *datalen;
this->stat_compr_new_size += *cdatalen;
break;
}
}
spin_unlock(&jffs2_compressor_list_lock);
if (ret == JFFS2_COMPR_NONE)
kfree(output_buf);
break;
case JFFS2_COMPR_MODE_SIZE:
case JFFS2_COMPR_MODE_FAVOURLZO:
orig_slen = *datalen;
orig_dlen = *cdatalen;
spin_lock(&jffs2_compressor_list_lock);
list_for_each_entry(this, &jffs2_compressor_list, list) {
/* Skip decompress-only backwards-compatibility and disabled modules */
if ((!this->compress)||(this->disabled))
continue;
/* Allocating memory for output buffer if necessary */
if ((this->compr_buf_size < orig_slen) && (this->compr_buf)) {
spin_unlock(&jffs2_compressor_list_lock);
kfree(this->compr_buf);
spin_lock(&jffs2_compressor_list_lock);
this->compr_buf_size=0;
this->compr_buf=NULL;
}
if (!this->compr_buf) {
spin_unlock(&jffs2_compressor_list_lock);
tmp_buf = kmalloc(orig_slen, GFP_KERNEL);
spin_lock(&jffs2_compressor_list_lock);
if (!tmp_buf) {
printk(KERN_WARNING "JFFS2: No memory for compressor allocation. (%d bytes)\n", orig_slen);
continue;
}
else {
this->compr_buf = tmp_buf;
this->compr_buf_size = orig_slen;
}
}
this->usecount++;
spin_unlock(&jffs2_compressor_list_lock);
*datalen = orig_slen;
*cdatalen = orig_dlen;
compr_ret = this->compress(data_in, this->compr_buf, datalen, cdatalen, NULL);
spin_lock(&jffs2_compressor_list_lock);
this->usecount--;
if (!compr_ret) {
if (((!best_dlen) || jffs2_is_best_compression(this, best, *cdatalen, best_dlen))
&& (*cdatalen < *datalen)) {
best_dlen = *cdatalen;
best_slen = *datalen;
best = this;
}
}
}
if (best_dlen) {
*cdatalen = best_dlen;
*datalen = best_slen;
output_buf = best->compr_buf;
best->compr_buf = NULL;
best->compr_buf_size = 0;
best->stat_compr_blocks++;
best->stat_compr_orig_size += best_slen;
best->stat_compr_new_size += best_dlen;
ret = best->compr;
}
spin_unlock(&jffs2_compressor_list_lock);
break;
default:
printk(KERN_ERR "JFFS2: unknow compression mode.\n");
}
out:
if (ret == JFFS2_COMPR_NONE) {
*cpage_out = data_in;
*datalen = *cdatalen;
none_stat_compr_blocks++;
none_stat_compr_size += *datalen;
}
else {
*cpage_out = output_buf;
}
return ret;
}
int jffs2_decompress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
uint16_t comprtype, unsigned char *cdata_in,
unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)
{
struct jffs2_compressor *this;
int ret;
/* Older code had a bug where it would write non-zero 'usercompr'
fields. Deal with it. */
if ((comprtype & 0xff) <= JFFS2_COMPR_ZLIB)
comprtype &= 0xff;
switch (comprtype & 0xff) {
case JFFS2_COMPR_NONE:
/* This should be special-cased elsewhere, but we might as well deal with it */
memcpy(data_out, cdata_in, datalen);
none_stat_decompr_blocks++;
break;
case JFFS2_COMPR_ZERO:
memset(data_out, 0, datalen);
break;
default:
spin_lock(&jffs2_compressor_list_lock);
list_for_each_entry(this, &jffs2_compressor_list, list) {
if (comprtype == this->compr) {
this->usecount++;
spin_unlock(&jffs2_compressor_list_lock);
ret = this->decompress(cdata_in, data_out, cdatalen, datalen, NULL);
spin_lock(&jffs2_compressor_list_lock);
if (ret) {
printk(KERN_WARNING "Decompressor \"%s\" returned %d\n", this->name, ret);
}
else {
this->stat_decompr_blocks++;
}
this->usecount--;
spin_unlock(&jffs2_compressor_list_lock);
return ret;
}
}
printk(KERN_WARNING "JFFS2 compression type 0x%02x not available.\n", comprtype);
spin_unlock(&jffs2_compressor_list_lock);
return -EIO;
}
return 0;
}
int jffs2_register_compressor(struct jffs2_compressor *comp)
{
struct jffs2_compressor *this;
if (!comp->name) {
printk(KERN_WARNING "NULL compressor name at registering JFFS2 compressor. Failed.\n");
return -1;
}
comp->compr_buf_size=0;
comp->compr_buf=NULL;
comp->usecount=0;
comp->stat_compr_orig_size=0;
comp->stat_compr_new_size=0;
comp->stat_compr_blocks=0;
comp->stat_decompr_blocks=0;
D1(printk(KERN_DEBUG "Registering JFFS2 compressor \"%s\"\n", comp->name));
spin_lock(&jffs2_compressor_list_lock);
list_for_each_entry(this, &jffs2_compressor_list, list) {
if (this->priority < comp->priority) {
list_add(&comp->list, this->list.prev);
goto out;
}
}
list_add_tail(&comp->list, &jffs2_compressor_list);
out:
D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
})
spin_unlock(&jffs2_compressor_list_lock);
return 0;
}
int jffs2_unregister_compressor(struct jffs2_compressor *comp)
{
D2(struct jffs2_compressor *this;)
D1(printk(KERN_DEBUG "Unregistering JFFS2 compressor \"%s\"\n", comp->name));
spin_lock(&jffs2_compressor_list_lock);
if (comp->usecount) {
spin_unlock(&jffs2_compressor_list_lock);
printk(KERN_WARNING "JFFS2: Compressor modul is in use. Unregister failed.\n");
return -1;
}
list_del(&comp->list);
D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
})
spin_unlock(&jffs2_compressor_list_lock);
return 0;
}
void jffs2_free_comprbuf(unsigned char *comprbuf, unsigned char *orig)
{
if (orig != comprbuf)
kfree(comprbuf);
}
int __init jffs2_compressors_init(void)
{
/* Registering compressors */
#ifdef CONFIG_JFFS2_ZLIB
jffs2_zlib_init();
#endif
#ifdef CONFIG_JFFS2_RTIME
jffs2_rtime_init();
#endif
#ifdef CONFIG_JFFS2_RUBIN
jffs2_rubinmips_init();
jffs2_dynrubin_init();
#endif
#ifdef CONFIG_JFFS2_LZO
jffs2_lzo_init();
#endif
/* Setting default compression mode */
#ifdef CONFIG_JFFS2_CMODE_NONE
jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;
D1(printk(KERN_INFO "JFFS2: default compression mode: none\n");)
#else
#ifdef CONFIG_JFFS2_CMODE_SIZE
jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;
D1(printk(KERN_INFO "JFFS2: default compression mode: size\n");)
#else
#ifdef CONFIG_JFFS2_CMODE_FAVOURLZO
jffs2_compression_mode = JFFS2_COMPR_MODE_FAVOURLZO;
D1(printk(KERN_INFO "JFFS2: default compression mode: favourlzo\n");)
#else
D1(printk(KERN_INFO "JFFS2: default compression mode: priority\n");)
#endif
#endif
#endif
return 0;
}
int jffs2_compressors_exit(void)
{
/* Unregistering compressors */
#ifdef CONFIG_JFFS2_LZO
jffs2_lzo_exit();
#endif
#ifdef CONFIG_JFFS2_RUBIN
jffs2_dynrubin_exit();
jffs2_rubinmips_exit();
#endif
#ifdef CONFIG_JFFS2_RTIME
jffs2_rtime_exit();
#endif
#ifdef CONFIG_JFFS2_ZLIB
jffs2_zlib_exit();
#endif
return 0;
}
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