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-rw-r--r--fs/Kconfig7
-rw-r--r--fs/jffs2/compr.c45
-rw-r--r--fs/jffs2/compr.h3
3 files changed, 50 insertions, 5 deletions
diff --git a/fs/Kconfig b/fs/Kconfig
index a2ec0b375df..42cfb7dc95b 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -1364,6 +1364,13 @@ config JFFS2_CMODE_SIZE
Tries all compressors and chooses the one which has the smallest
result.
+config JFFS2_CMODE_FAVOURLZO
+ bool "Favour LZO"
+ help
+ Tries all compressors and chooses the one which has the smallest
+ result but gives some preference to LZO (which has faster
+ decompression) at the expense of size.
+
endchoice
config CRAMFS
diff --git a/fs/jffs2/compr.c b/fs/jffs2/compr.c
index bcc28d266a1..86739ee53b3 100644
--- a/fs/jffs2/compr.c
+++ b/fs/jffs2/compr.c
@@ -24,6 +24,34 @@ 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
@@ -90,6 +118,7 @@ uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
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);
@@ -98,7 +127,7 @@ uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
if ((!this->compress)||(this->disabled))
continue;
/* Allocating memory for output buffer if necessary */
- if ((this->compr_buf_size<orig_dlen)&&(this->compr_buf)) {
+ 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);
@@ -107,15 +136,15 @@ uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
}
if (!this->compr_buf) {
spin_unlock(&jffs2_compressor_list_lock);
- tmp_buf = kmalloc(orig_dlen,GFP_KERNEL);
+ 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_dlen);
+ 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_dlen;
+ this->compr_buf_size = orig_slen;
}
}
this->usecount++;
@@ -126,7 +155,8 @@ uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
spin_lock(&jffs2_compressor_list_lock);
this->usecount--;
if (!compr_ret) {
- if ((!best_dlen)||(best_dlen>*cdatalen)) {
+ if (((!best_dlen) || jffs2_is_best_compression(this, best, *cdatalen, best_dlen))
+ && (*cdatalen < *datalen)) {
best_dlen = *cdatalen;
best_slen = *datalen;
best = this;
@@ -298,9 +328,14 @@ int __init jffs2_compressors_init(void)
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;
}
diff --git a/fs/jffs2/compr.h b/fs/jffs2/compr.h
index a54828a4e9c..e1b7efb70aa 100644
--- a/fs/jffs2/compr.h
+++ b/fs/jffs2/compr.h
@@ -38,6 +38,9 @@
#define JFFS2_COMPR_MODE_NONE 0
#define JFFS2_COMPR_MODE_PRIORITY 1
#define JFFS2_COMPR_MODE_SIZE 2
+#define JFFS2_COMPR_MODE_FAVOURLZO 3
+
+#define FAVOUR_LZO_PERCENT 80
struct jffs2_compressor {
struct list_head list;