jffs2: add compr=lzo and compr=zlib options

..to allow forcing of either compression scheme.  This will override
compiled-in defaults.  jffs2_compress is reworked a bit, as the lzo/zlib
override shares lots of code w/ the PRIORITY mode.

v2: update show_options accordingly.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>

3 files changed, 110 insertions, 37 deletions

diff --git a/fs/jffs2/compr.c b/fs/jffs2/compr.c
index 97bc74db2c96..5b6c9d1a2fb9 100644
--- a/fs/jffs2/compr.c
+++ b/fs/jffs2/compr.c
@@ -53,6 +53,78 @@ static int jffs2_is_best_compression(struct jffs2_compressor *this,
         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) {
+                printk(KERN_WARNING "JFFS2: 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
@@ -91,37 +163,8 @@ uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
         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);
-                        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);
+                ret = jffs2_selected_compress(0, data_in, cpage_out, datalen,
+                                cdatalen);
                 break;
         case JFFS2_COMPR_MODE_SIZE:
         case JFFS2_COMPR_MODE_FAVOURLZO:
@@ -179,22 +222,28 @@ uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
                         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:
                 printk(KERN_ERR "JFFS2: unknown 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;
 }
 
diff --git a/fs/jffs2/compr.h b/fs/jffs2/compr.h
index 13bb7597ab39..5e91d578f4ed 100644
--- a/fs/jffs2/compr.h
+++ b/fs/jffs2/compr.h
@@ -40,6 +40,8 @@
 #define JFFS2_COMPR_MODE_PRIORITY   1
 #define JFFS2_COMPR_MODE_SIZE       2
 #define JFFS2_COMPR_MODE_FAVOURLZO  3
+#define JFFS2_COMPR_MODE_FORCELZO   4
+#define JFFS2_COMPR_MODE_FORCEZLIB  5
 
 #define FAVOUR_LZO_PERCENT 80
 
diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index 40f6e6385fd1..e7e974454115 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c
@@ -82,6 +82,14 @@ static const char *jffs2_compr_name(unsigned int compr)
         switch (compr) {
         case JFFS2_COMPR_MODE_NONE:
                 return "none";
+#ifdef CONFIG_JFFS2_LZO
+        case JFFS2_COMPR_MODE_FORCELZO:
+                return "lzo";
+#endif
+#ifdef CONFIG_JFFS2_ZLIB
+        case JFFS2_COMPR_MODE_FORCEZLIB:
+                return "zlib";
+#endif
         default:
                 /* should never happen; programmer error */
                 WARN_ON(1);
@@ -195,11 +203,25 @@ static int jffs2_parse_options(struct jffs2_sb_info *c, char *data)
 
                         if (!name)
                                 return -ENOMEM;
-                        if (!strcmp(name, "none")) {
+                        if (!strcmp(name, "none"))
                                 c->mount_opts.compr = JFFS2_COMPR_MODE_NONE;
-                                c->mount_opts.override_compr = true;
+#ifdef CONFIG_JFFS2_LZO
+                        else if (!strcmp(name, "lzo"))
+                                c->mount_opts.compr = JFFS2_COMPR_MODE_FORCELZO;
+#endif
+#ifdef CONFIG_JFFS2_ZLIB
+                        else if (!strcmp(name, "zlib"))
+                                c->mount_opts.compr =
+                                                JFFS2_COMPR_MODE_FORCEZLIB;
+#endif
+                        else {
+                                printk(KERN_ERR "JFFS2 Error: unknown compressor \"%s\"",
+                                                name);
+                                kfree(name);
+                                return -EINVAL;
                         }
                         kfree(name);
+                        c->mount_opts.override_compr = true;
                         break;
                 default:
                         printk(KERN_ERR "JFFS2 Error: unrecognized mount option '%s' or missing value\n",