Squashfs: Make ZLIB compression support optional

Squashfs now supports XZ and LZO compression in addition to ZLIB.
As such it no longer makes sense to always include ZLIB support.
In particular embedded systems may only use LZO or XZ compression, and
the ability to exclude ZLIB support will reduce kernel size.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/squashfs/decompressor.c b/fs/squashfs/decompressor.c
index 9f1b0bb96f13..3f6271d86abc 100644
--- a/fs/squashfs/decompressor.c
+++ b/fs/squashfs/decompressor.c
@@ -52,6 +52,12 @@ static const struct squashfs_decompressor squashfs_xz_comp_ops = {
 };
 #endif
 
+#ifndef CONFIG_SQUASHFS_ZLIB
+static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
+        NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
+};
+#endif
+
 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
         NULL, NULL, NULL, 0, "unknown", 0
 };