[PATCH 3/3] btrfs: Add zstd support to btrfs

[Nick Terrell <terrelln@fb.com>]

Adds zstd support to the btrfs module. I'm not sure that my changes to the
Makefiles are correct, please let me know if I need to do something
differently.

Tested on Ubuntu-18.04 with a btrfs /boot partition with and without zstd
compression. A test case was also added to the test suite that fails before
the patch, and passes after.

Signed-off-by: Nick Terrell <terrelln@fb.com>
---
 Makefile.util.def            |  8 ++++-
 grub-core/Makefile.core.def  | 10 ++++--
 grub-core/fs/btrfs.c         | 85 +++++++++++++++++++++++++++++++++++++++++++-
 tests/btrfs_test.in          |  1 +
 tests/util/grub-fs-tester.in |  4 +--
 5 files changed, 102 insertions(+), 6 deletions(-)

diff --git a/Makefile.util.def b/Makefile.util.def
index 3180ac880..b987dc637 100644
--- a/Makefile.util.def
+++ b/Makefile.util.def
@@ -54,7 +54,7 @@ library = {
 library = {
   name = libgrubmods.a;
   cflags = '-fno-builtin -Wno-undef';
-  cppflags = '-I$(top_srcdir)/grub-core/lib/minilzo -I$(srcdir)/grub-core/lib/xzembed -DMINILZO_HAVE_CONFIG_H';
+  cppflags = '-I$(top_srcdir)/grub-core/lib/minilzo -I$(srcdir)/grub-core/lib/xzembed -I$(top_srcdir)/grub-core/lib/zstd -DMINILZO_HAVE_CONFIG_H';

   common_nodist = grub_script.tab.c;
   common_nodist = grub_script.yy.c;
@@ -165,6 +165,12 @@ library = {
   common = grub-core/lib/xzembed/xz_dec_bcj.c;
   common = grub-core/lib/xzembed/xz_dec_lzma2.c;
   common = grub-core/lib/xzembed/xz_dec_stream.c;
+  common = grub-core/lib/zstd/zstd_common.c;
+  common = grub-core/lib/zstd/huf_decompress.c;
+  common = grub-core/lib/zstd/fse_decompress.c;
+  common = grub-core/lib/zstd/entropy_common.c;
+  common = grub-core/lib/zstd/decompress.c;
+  common = grub-core/lib/zstd/xxhash.c;
 };

 program = {
diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 9590e87d9..c24bf9147 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -404,7 +404,7 @@ image = {
   i386_pc = boot/i386/pc/boot.S;

   cppflags = '-DHYBRID_BOOT=1';
-
+
   i386_pc_ldflags = '$(TARGET_IMG_LDFLAGS)';
   i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT),0x7C00';

@@ -1264,8 +1264,14 @@ module = {
   name = btrfs;
   common = fs/btrfs.c;
   common = lib/crc.c;
+  common = lib/zstd/zstd_common.c;
+  common = lib/zstd/huf_decompress.c;
+  common = lib/zstd/fse_decompress.c;
+  common = lib/zstd/entropy_common.c;
+  common = lib/zstd/decompress.c;
+  common = lib/zstd/xxhash.c;
   cflags = '$(CFLAGS_POSIX) -Wno-undef';
-  cppflags = '-I$(srcdir)/lib/posix_wrap -I$(srcdir)/lib/minilzo -DMINILZO_HAVE_CONFIG_H';
+  cppflags = '-I$(srcdir)/lib/posix_wrap -I$(srcdir)/lib/minilzo -I$(srcdir)/lib/zstd -DMINILZO_HAVE_CONFIG_H';
 };

 module = {
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index be195448d..89ed4884e 100644
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -27,6 +27,7 @@
 #include <grub/lib/crc.h>
 #include <grub/deflate.h>
 #include <minilzo.h>
+#include <zstd.h>
 #include <grub/i18n.h>
 #include <grub/btrfs.h>

@@ -45,6 +46,9 @@ GRUB_MOD_LICENSE ("GPLv3+");
 #define GRUB_BTRFS_LZO_BLOCK_MAX_CSIZE (GRUB_BTRFS_LZO_BLOCK_SIZE + \
 				     (GRUB_BTRFS_LZO_BLOCK_SIZE / 16) + 64 + 3)

+#define ZSTD_BTRFS_MAX_WINDOWLOG 17
+#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
+
 typedef grub_uint8_t grub_btrfs_checksum_t[0x20];
 typedef grub_uint16_t grub_btrfs_uuid_t[8];

@@ -212,6 +216,7 @@ struct grub_btrfs_extent_data
 #define GRUB_BTRFS_COMPRESSION_NONE 0
 #define GRUB_BTRFS_COMPRESSION_ZLIB 1
 #define GRUB_BTRFS_COMPRESSION_LZO  2
+#define GRUB_BTRFS_COMPRESSION_ZSTD  3

 #define GRUB_BTRFS_OBJECT_ID_CHUNK 0x100

@@ -912,6 +917,70 @@ grub_btrfs_read_inode (struct grub_btrfs_data *data,
   return grub_btrfs_read_logical (data, elemaddr, inode, sizeof (*inode), 0);
 }

+static grub_ssize_t
+grub_btrfs_zstd_decompress(char *ibuf, grub_size_t isize, grub_off_t off,
+			  char *obuf, grub_size_t osize)
+{
+	void *allocated = NULL;
+	char *otmpbuf = obuf;
+	grub_size_t otmpsize = osize;
+	void *wmem = NULL;
+	const grub_size_t wmem_size = ZSTD_DCtxWorkspaceBound ();
+	ZSTD_DCtx *dctx;
+	grub_size_t zstd_ret;
+	grub_ssize_t ret = -1;
+
+	/* Zstd will fail if it can't fit the entire output in the destination
+	 * buffer, so if osize isn't large enough, allocate a temporary buffer.
+	 */
+	if (otmpsize < ZSTD_BTRFS_MAX_INPUT) {
+		allocated = grub_malloc (ZSTD_BTRFS_MAX_INPUT);
+		if (!allocated) {
+			grub_dprintf ("zstd", "outtmpbuf allocation failed\n");
+			goto out;
+		}
+		otmpbuf = (char*)allocated;
+		otmpsize = ZSTD_BTRFS_MAX_INPUT;
+	}
+
+	/* Allocate space for, and initialize, the ZSTD_DCtx. */
+	wmem = grub_malloc (wmem_size);
+	if (!wmem) {
+		grub_dprintf ("zstd", "wmem allocation failed\n");
+		goto out;
+	}
+	dctx = ZSTD_initDCtx (wmem, wmem_size);
+
+	/* Get the real input size, there may be junk at the
+	 * end of the frame.
+	 */
+	isize = ZSTD_findFrameCompressedSize (ibuf, isize);
+	if (ZSTD_isError (isize)) {
+		grub_dprintf ("zstd", "first frame is invalid %d\n",
+				(int)ZSTD_getErrorCode (isize));
+		goto out;
+	}
+
+	/* Decompress and check for errors */
+	zstd_ret = ZSTD_decompressDCtx (dctx, otmpbuf, otmpsize, ibuf, isize);
+	if (ZSTD_isError (zstd_ret)) {
+		grub_dprintf ("zstd", "zstd failed with  code %d\n",
+				(int)ZSTD_getErrorCode (zstd_ret));
+		goto out;
+	}
+
+	/* Move the requested data into the obuf.
+	 * obuf may be equal to otmpbuf, which is why grub_memmove() is required.
+	 */
+	grub_memmove (obuf, otmpbuf + off, osize);
+	ret = osize;
+
+out:
+	grub_free (allocated);
+	grub_free (wmem);
+	return ret;
+}
+
 static grub_ssize_t
 grub_btrfs_lzo_decompress(char *ibuf, grub_size_t isize, grub_off_t off,
 			  char *obuf, grub_size_t osize)
@@ -1087,7 +1156,8 @@ grub_btrfs_extent_read (struct grub_btrfs_data *data,

       if (data->extent->compression != GRUB_BTRFS_COMPRESSION_NONE
 	  && data->extent->compression != GRUB_BTRFS_COMPRESSION_ZLIB
-	  && data->extent->compression != GRUB_BTRFS_COMPRESSION_LZO)
+	  && data->extent->compression != GRUB_BTRFS_COMPRESSION_LZO
+	  && data->extent->compression != GRUB_BTRFS_COMPRESSION_ZSTD)
 	{
 	  grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
 		      "compression type 0x%x not supported",
@@ -1127,6 +1197,15 @@ grub_btrfs_extent_read (struct grub_btrfs_data *data,
 		  != (grub_ssize_t) csize)
 		return -1;
 	    }
+	  else if (data->extent->compression == GRUB_BTRFS_COMPRESSION_ZSTD)
+	    {
+	      if (grub_btrfs_zstd_decompress(data->extent->inl, data->extsize -
+					   ((grub_uint8_t *) data->extent->inl
+					    - (grub_uint8_t *) data->extent),
+					   extoff, buf, csize)
+		  != (grub_ssize_t) csize)
+		return -1;
+	    }
 	  else
 	    grub_memcpy (buf, data->extent->inl + extoff, csize);
 	  break;
@@ -1164,6 +1243,10 @@ grub_btrfs_extent_read (struct grub_btrfs_data *data,
 		ret = grub_btrfs_lzo_decompress (tmp, zsize, extoff
 				    + grub_le_to_cpu64 (data->extent->offset),
 				    buf, csize);
+	      else if (data->extent->compression == GRUB_BTRFS_COMPRESSION_ZSTD)
+		ret = grub_btrfs_zstd_decompress (tmp, zsize, extoff
+				    + grub_le_to_cpu64 (data->extent->offset),
+				    buf, csize);
 	      else
 		ret = -1;

diff --git a/tests/btrfs_test.in b/tests/btrfs_test.in
index 2b37ddd33..0c9bf3a68 100644
--- a/tests/btrfs_test.in
+++ b/tests/btrfs_test.in
@@ -18,6 +18,7 @@ fi
 "@builddir@/grub-fs-tester" btrfs
 "@builddir@/grub-fs-tester" btrfs_zlib
 "@builddir@/grub-fs-tester" btrfs_lzo
+"@builddir@/grub-fs-tester" btrfs_zstd
 "@builddir@/grub-fs-tester" btrfs_raid0
 "@builddir@/grub-fs-tester" btrfs_raid1
 "@builddir@/grub-fs-tester" btrfs_single
diff --git a/tests/util/grub-fs-tester.in b/tests/util/grub-fs-tester.in
index ef65fbc93..147d946d2 100644
--- a/tests/util/grub-fs-tester.in
+++ b/tests/util/grub-fs-tester.in
@@ -600,7 +600,7 @@ for LOGSECSIZE in $(range "$MINLOGSECSIZE" "$MAXLOGSECSIZE" 1); do
 	    GENERATED=n
 	    LODEVICES=
 	    MOUNTDEVICE=
-
+
 	    case x"$fs" in
 		x"tarfs" | x"cpio_"*| x"ziso9660" | x"romfs" | x"squash4_"*\
                     | x"iso9660" | xjoliet | xrockridge | xrockridge_joliet \
@@ -629,7 +629,7 @@ for LOGSECSIZE in $(range "$MINLOGSECSIZE" "$MAXLOGSECSIZE" 1); do
 		    ;;
 		x"btrfs")
 		    "mkfs.btrfs" -s $SECSIZE -L "$FSLABEL" "${MOUNTDEVICE}" ;;
-		x"btrfs_zlib" | x"btrfs_lzo")
+		x"btrfs_zlib" | x"btrfs_lzo" | x"btrfs_zstd")
 		    "mkfs.btrfs" -s $SECSIZE -L "$FSLABEL" "${MOUNTDEVICE}"
 		    MOUNTOPTS="compress=${fs/btrfs_/},"
 		    MOUNTFS="btrfs"
--
2.16.2