Squashfs: Add XZ compression configuration option

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

4 files changed, 28 insertions, 0 deletions

diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index e5f63da64d04..50cc4edbca06 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -53,6 +53,21 @@ config SQUASHFS_LZO
 
           If unsure, say N.
 
+config SQUASHFS_XZ
+        bool "Include support for XZ compressed file systems"
+        depends on SQUASHFS
+        select XZ_DEC
+        help
+          Saying Y here includes support for reading Squashfs file systems
+          compressed with XZ compresssion.  XZ gives better compression than
+          the default zlib compression, at the expense of greater CPU and
+          memory overhead.
+
+          XZ is not the standard compression used in Squashfs and so most
+          file systems will be readable without selecting this option.
+
+          If unsure, say N.
+
 config SQUASHFS_EMBEDDED
         bool "Additional option for memory-constrained systems"
         depends on SQUASHFS
diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index 7672bac8d328..cecf2bea07af 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -7,3 +7,4 @@ squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
 squashfs-y += namei.o super.o symlink.o zlib_wrapper.o decompressor.o
 squashfs-$(CONFIG_SQUASHFS_XATTR) += xattr.o xattr_id.o
 squashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o
+squashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o
diff --git a/fs/squashfs/decompressor.c b/fs/squashfs/decompressor.c
index 24af9ce9722f..482d78197811 100644
--- a/fs/squashfs/decompressor.c
+++ b/fs/squashfs/decompressor.c
@@ -46,6 +46,12 @@ static const struct squashfs_decompressor squashfs_lzo_unsupported_comp_ops = {
 };
 #endif
 
+#ifndef CONFIG_SQUASHFS_XZ
+static const struct squashfs_decompressor squashfs_xz_comp_ops = {
+        NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
+};
+#endif
+
 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
         NULL, NULL, NULL, 0, "unknown", 0
 };
@@ -58,6 +64,7 @@ static const struct squashfs_decompressor *decompressor[] = {
 #else
         &squashfs_lzo_unsupported_comp_ops,
 #endif
+        &squashfs_xz_comp_ops,
         &squashfs_unknown_comp_ops
 };
 
diff --git a/fs/squashfs/decompressor.h b/fs/squashfs/decompressor.h
index 7425f80783f6..57e1acb4c6a9 100644
--- a/fs/squashfs/decompressor.h
+++ b/fs/squashfs/decompressor.h
@@ -52,4 +52,9 @@ static inline int squashfs_decompress(struct squashfs_sb_info *msblk,
         return msblk->decompressor->decompress(msblk, buffer, bh, b, offset,
                 length, srclength, pages);
 }
+
+#ifdef CONFIG_SQUASHFS_XZ
+extern const struct squashfs_decompressor squashfs_xz_comp_ops;
+#endif
+
 #endif