3 files changed, 50 insertions, 5 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index a2ec0b375dff..42cfb7dc95b5 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 bcc28d266a12..86739ee53b37 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 a54828a4e9c6..e1b7efb70aa4 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;