- 根目录:
- fs
- jffs2
- compr.c
/*
* JFFS2 -- Journalling Flash File System, Version 2.
*
* Copyright © 2001-2007 Red Hat, Inc.
* Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
* Copyright © 2004 Ferenc Havasi <havasi@inf.u-szeged.hu>,
* University of Szeged, Hungary
*
* Created by Arjan van de Ven <arjan@infradead.org>
*
* For licensing information, see the file 'LICENCE' in this directory.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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_selected_compress:
* @compr: Explicit compression type to use (ie, JFFS2_COMPR_ZLIB).
* If 0, just take the first available compression mode.
* @data_in: Pointer to uncompressed data
* @cpage_out: 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: the compression type used. Zero is used to show that the data
* could not be compressed; probably because we couldn't find the requested
* compression mode.
*/
static int jffs2_selected_compress(u8 compr, unsigned char *data_in,
unsigned char **cpage_out, u32 *datalen, u32 *cdatalen)
{
struct jffs2_compressor *this;
int err, ret = JFFS2_COMPR_NONE;
uint32_t orig_slen, orig_dlen;
char *output_buf;
output_buf = kmalloc(*cdatalen, GFP_KERNEL);
if (!output_buf) {
pr_warn("No memory for compressor allocation. Compression failed.\n");
return ret;
}
orig_slen = *datalen;
orig_dlen = *cdatalen;
spin_lock(&jffs2_compressor_list_lock);
list_for_each_entry(this, &jffs2_compressor_list, list) {
/* Skip decompress-only and disabled modules */
if (!this->compress || this->disabled)
continue;
/* Skip if not the desired compression type */
if (compr && (compr != this->compr))
continue;
/*
* Either compression type was unspecified, or we found our
* compressor; either way, we're good to go.
*/
this->usecount++;
spin_unlock(&jffs2_compressor_list_lock);
*datalen = orig_slen;
*cdatalen = orig_dlen;
err = this->compress(data_in, output_buf, datalen, cdatalen);
spin_lock(&jffs2_compressor_list_lock);
this->usecount--;
if (!err) {
/* Success */
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);
else
*cpage_out = output_buf;
return ret;
}
/* jffs2_compress:
* @data_in: Pointer to uncompressed data
* @cpage_out: 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 mode, 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;
if (c->mount_opts.override_compr)
mode = c->mount_opts.compr;
else
mode = jffs2_compression_mode;
switch (mode) {
case JFFS2_COMPR_MODE_NONE:
break;
case JFFS2_COMPR_MODE_PRIORITY:
ret = jffs2_selected_compress(0, data_in, cpage_out, datalen,
cdatalen);
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) {
pr_warn("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);
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;
*cpage_out = output_buf;
}
spin_unlock(&jffs2_compressor_list_lock);
break;
case JFFS2_COMPR_MODE_FORCELZO:
ret = jffs2_selected_compress(JFFS2_COMPR_LZO, data_in,
cpage_out, datalen, cdatalen);
break;
case JFFS2_COMPR_MODE_FORCEZLIB:
ret = jffs2_selected_compress(JFFS2_COMPR_ZLIB, data_in,
cpage_out, datalen, cdatalen);
break;
default:
pr_err("unknown compression mode\n");
}
if (ret == JFFS2_COMPR_NONE) {
*cpage_out = data_in;
*datalen = *cdatalen;
none_stat_compr_blocks++;
none_stat_compr_size += *datalen;
}
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);
spin_lock(&jffs2_compressor_list_lock);
if (ret) {
pr_warn("Decompressor \"%s\" returned %d\n",
this->name, ret);
}
else {
this->stat_decompr_blocks++;
}
this->usecount--;
spin_unlock(&jffs2_compressor_list_lock);
return ret;
}
}
pr_warn("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) {
pr_warn("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;
jffs2_dbg(1, "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);
jffs2_dbg(1, "Unregistering JFFS2 compressor \"%s\"\n", comp->name);
spin_lock(&jffs2_compressor_list_lock);
if (comp->usecount) {
spin_unlock(&jffs2_compressor_list_lock);
pr_warn("Compressor module 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;
jffs2_dbg(1, "default compression mode: none\n");
#else
#ifdef CONFIG_JFFS2_CMODE_SIZE
jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;
jffs2_dbg(1, "default compression mode: size\n");
#else
#ifdef CONFIG_JFFS2_CMODE_FAVOURLZO
jffs2_compression_mode = JFFS2_COMPR_MODE_FAVOURLZO;
jffs2_dbg(1, "default compression mode: favourlzo\n");
#else
jffs2_dbg(1, "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;
}