/*
 * 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;
}