Squashfs: add a decompressor framework

This adds a decompressor framework which allows multiple compression
algorithms to be cleanly supported.

Also update zlib wrapper and other code to use the new framework.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>

1 files changed, 26 insertions, 19 deletions

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index b9f8c6a92d6a..3550aec2f655 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -41,27 +41,35 @@
 #include "squashfs_fs_sb.h"
 #include "squashfs_fs_i.h"
 #include "squashfs.h"
+#include "decompressor.h"
 
 static struct file_system_type squashfs_fs_type;
 static const struct super_operations squashfs_super_ops;
 
-static int supported_squashfs_filesystem(short major, short minor, short comp)
+static const struct squashfs_decompressor *supported_squashfs_filesystem(short
+        major, short minor, short id)
 {
+        const struct squashfs_decompressor *decompressor;
+
         if (major < SQUASHFS_MAJOR) {
                 ERROR("Major/Minor mismatch, older Squashfs %d.%d "
                         "filesystems are unsupported\n", major, minor);
-                return -EINVAL;
+                return NULL;
         } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
                 ERROR("Major/Minor mismatch, trying to mount newer "
                         "%d.%d filesystem\n", major, minor);
                 ERROR("Please update your kernel\n");
-                return -EINVAL;
+                return NULL;
         }
 
-        if (comp != ZLIB_COMPRESSION)
-                return -EINVAL;
+        decompressor = squashfs_lookup_decompressor(id);
+        if (!decompressor->supported) {
+                ERROR("Filesystem uses \"%s\" compression. This is not "
+                        "supported\n", decompressor->name);
+                return NULL;
+        }
 
-        return 0;
+        return decompressor;
 }
 
 
@@ -86,10 +94,6 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
         }
         msblk = sb->s_fs_info;
 
-        msblk->stream = squashfs_zlib_init();
-        if (msblk->stream == NULL)
-                goto failure;
-
         sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
         if (sblk == NULL) {
                 ERROR("Failed to allocate squashfs_super_block\n");
@@ -116,25 +120,25 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
                 goto failed_mount;
         }
 
+        err = -EINVAL;
+
         /* Check it is a SQUASHFS superblock */
         sb->s_magic = le32_to_cpu(sblk->s_magic);
         if (sb->s_magic != SQUASHFS_MAGIC) {
                 if (!silent)
                         ERROR("Can't find a SQUASHFS superblock on %s\n",
                                                 bdevname(sb->s_bdev, b));
-                err = -EINVAL;
                 goto failed_mount;
         }
 
-        /* Check the MAJOR & MINOR versions and compression type */
-        err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major),
+        /* Check the MAJOR & MINOR versions and lookup compression type */
+        msblk->decompressor = supported_squashfs_filesystem(
+                        le16_to_cpu(sblk->s_major),
                         le16_to_cpu(sblk->s_minor),
                         le16_to_cpu(sblk->compression));
-        if (err < 0)
+        if (msblk->decompressor == NULL)
                 goto failed_mount;
 
-        err = -EINVAL;
-
         /*
          * Check if there's xattrs in the filesystem.  These are not
          * supported in this version, so warn that they will be ignored.
@@ -201,6 +205,10 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
 
         err = -ENOMEM;
 
+        msblk->stream = squashfs_decompressor_init(msblk);
+        if (msblk->stream == NULL)
+                goto failed_mount;
+
         msblk->block_cache = squashfs_cache_init("metadata",
                         SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
         if (msblk->block_cache == NULL)
@@ -288,7 +296,7 @@ failed_mount:
         squashfs_cache_delete(msblk->block_cache);
         squashfs_cache_delete(msblk->fragment_cache);
         squashfs_cache_delete(msblk->read_page);
-        squashfs_zlib_free(msblk->stream);
+        squashfs_decompressor_free(msblk, msblk->stream);
         kfree(msblk->inode_lookup_table);
         kfree(msblk->fragment_index);
         kfree(msblk->id_table);
@@ -298,7 +306,6 @@ failed_mount:
         return err;
 
 failure:
-        squashfs_zlib_free(msblk->stream);
         kfree(sb->s_fs_info);
         sb->s_fs_info = NULL;
         return -ENOMEM;
@@ -342,7 +349,7 @@ static void squashfs_put_super(struct super_block *sb)
                 squashfs_cache_delete(sbi->block_cache);
                 squashfs_cache_delete(sbi->fragment_cache);
                 squashfs_cache_delete(sbi->read_page);
-                squashfs_zlib_free(sbi->stream);
+                squashfs_decompressor_free(sbi, sbi->stream);
                 kfree(sbi->id_table);
                 kfree(sbi->fragment_index);
                 kfree(sbi->meta_index);