f2fs: compress: support zstd compress algorithm

Add zstd compress algorithm support, use "compress_algorithm=zstd"
mountoption to enable it.

Signed-off-by: Chao Yu <[e-mail]>
Signed-off-by: Jaegeuk Kim <[e-mail]>

Documentation/filesystems/f2fs.txt

···
                        hide up to all remaining free space. The actual space that
                        would be unusable can be viewed at /sys/fs/f2fs/<disk>/unusable
                        This space is reclaimed once checkpoint=enable.
-compress_algorithm=%s  Control compress algorithm, currently f2fs supports "lzo"
-                       and "lz4" algorithm.
+compress_algorithm=%s  Control compress algorithm, currently f2fs supports "lzo",
+                       "lz4" and "zstd" algorithm.
 compress_log_size=%u   Support configuring compress cluster size, the size will
                        be 4KB * (1 << %u), 16KB is minimum size, also it's
                        default size.

fs/f2fs/Kconfig

···
 	default y
 	help
 	  Support LZ4 compress algorithm, if unsure, say Y.
+
+config F2FS_FS_ZSTD
+	bool "ZSTD compression support"
+	depends on F2FS_FS_COMPRESSION
+	select ZSTD_COMPRESS
+	select ZSTD_DECOMPRESS
+	default y
+	help
+	  Support ZSTD compress algorithm, if unsure, say Y.

fs/f2fs/compress.c

···
 #include <linux/backing-dev.h>
 #include <linux/lzo.h>
 #include <linux/lz4.h>
+#include <linux/zstd.h>
 
 #include "f2fs.h"
 #include "node.h"
···
 };
 #endif
 
+#ifdef CONFIG_F2FS_FS_ZSTD
+#define F2FS_ZSTD_DEFAULT_CLEVEL	1
+
+static int zstd_init_compress_ctx(struct compress_ctx *cc)
+{
+	ZSTD_parameters params;
+	ZSTD_CStream *stream;
+	void *workspace;
+	unsigned int workspace_size;
+
+	params = ZSTD_getParams(F2FS_ZSTD_DEFAULT_CLEVEL, cc->rlen, 0);
+	workspace_size = ZSTD_CStreamWorkspaceBound(params.cParams);
+
+	workspace = f2fs_kvmalloc(F2FS_I_SB(cc->inode),
+					workspace_size, GFP_NOFS);
+	if (!workspace)
+		return -ENOMEM;
+
+	stream = ZSTD_initCStream(params, 0, workspace, workspace_size);
+	if (!stream) {
+		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_initCStream failed\n",
+				KERN_ERR, F2FS_I_SB(cc->inode)->sb->s_id,
+				__func__);
+		kvfree(workspace);
+		return -EIO;
+	}
+
+	cc->private = workspace;
+	cc->private2 = stream;
+
+	cc->clen = cc->rlen - PAGE_SIZE - COMPRESS_HEADER_SIZE;
+	return 0;
+}
+
+static void zstd_destroy_compress_ctx(struct compress_ctx *cc)
+{
+	kvfree(cc->private);
+	cc->private = NULL;
+	cc->private2 = NULL;
+}
+
+static int zstd_compress_pages(struct compress_ctx *cc)
+{
+	ZSTD_CStream *stream = cc->private2;
+	ZSTD_inBuffer inbuf;
+	ZSTD_outBuffer outbuf;
+	int src_size = cc->rlen;
+	int dst_size = src_size - PAGE_SIZE - COMPRESS_HEADER_SIZE;
+	int ret;
+
+	inbuf.pos = 0;
+	inbuf.src = cc->rbuf;
+	inbuf.size = src_size;
+
+	outbuf.pos = 0;
+	outbuf.dst = cc->cbuf->cdata;
+	outbuf.size = dst_size;
+
+	ret = ZSTD_compressStream(stream, &outbuf, &inbuf);
+	if (ZSTD_isError(ret)) {
+		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_compressStream failed, ret: %d\n",
+				KERN_ERR, F2FS_I_SB(cc->inode)->sb->s_id,
+				__func__, ZSTD_getErrorCode(ret));
+		return -EIO;
+	}
+
+	ret = ZSTD_endStream(stream, &outbuf);
+	if (ZSTD_isError(ret)) {
+		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_endStream returned %d\n",
+				KERN_ERR, F2FS_I_SB(cc->inode)->sb->s_id,
+				__func__, ZSTD_getErrorCode(ret));
+		return -EIO;
+	}
+
+	cc->clen = outbuf.pos;
+	return 0;
+}
+
+static int zstd_init_decompress_ctx(struct decompress_io_ctx *dic)
+{
+	ZSTD_DStream *stream;
+	void *workspace;
+	unsigned int workspace_size;
+
+	workspace_size = ZSTD_DStreamWorkspaceBound(MAX_COMPRESS_WINDOW_SIZE);
+
+	workspace = f2fs_kvmalloc(F2FS_I_SB(dic->inode),
+					workspace_size, GFP_NOFS);
+	if (!workspace)
+		return -ENOMEM;
+
+	stream = ZSTD_initDStream(MAX_COMPRESS_WINDOW_SIZE,
+					workspace, workspace_size);
+	if (!stream) {
+		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_initDStream failed\n",
+				KERN_ERR, F2FS_I_SB(dic->inode)->sb->s_id,
+				__func__);
+		kvfree(workspace);
+		return -EIO;
+	}
+
+	dic->private = workspace;
+	dic->private2 = stream;
+
+	return 0;
+}
+
+static void zstd_destroy_decompress_ctx(struct decompress_io_ctx *dic)
+{
+	kvfree(dic->private);
+	dic->private = NULL;
+	dic->private2 = NULL;
+}
+
+static int zstd_decompress_pages(struct decompress_io_ctx *dic)
+{
+	ZSTD_DStream *stream = dic->private2;
+	ZSTD_inBuffer inbuf;
+	ZSTD_outBuffer outbuf;
+	int ret;
+
+	inbuf.pos = 0;
+	inbuf.src = dic->cbuf->cdata;
+	inbuf.size = dic->clen;
+
+	outbuf.pos = 0;
+	outbuf.dst = dic->rbuf;
+	outbuf.size = dic->rlen;
+
+	ret = ZSTD_decompressStream(stream, &outbuf, &inbuf);
+	if (ZSTD_isError(ret)) {
+		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_compressStream failed, ret: %d\n",
+				KERN_ERR, F2FS_I_SB(dic->inode)->sb->s_id,
+				__func__, ZSTD_getErrorCode(ret));
+		return -EIO;
+	}
+
+	if (dic->rlen != outbuf.pos) {
+		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD invalid rlen:%zu, "
+				"expected:%lu\n", KERN_ERR,
+				F2FS_I_SB(dic->inode)->sb->s_id,
+				__func__, dic->rlen,
+				PAGE_SIZE << dic->log_cluster_size);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static const struct f2fs_compress_ops f2fs_zstd_ops = {
+	.init_compress_ctx	= zstd_init_compress_ctx,
+	.destroy_compress_ctx	= zstd_destroy_compress_ctx,
+	.compress_pages		= zstd_compress_pages,
+	.init_decompress_ctx	= zstd_init_decompress_ctx,
+	.destroy_decompress_ctx	= zstd_destroy_decompress_ctx,
+	.decompress_pages	= zstd_decompress_pages,
+};
+#endif
+
 static const struct f2fs_compress_ops *f2fs_cops[COMPRESS_MAX] = {
 #ifdef CONFIG_F2FS_FS_LZO
 	&f2fs_lzo_ops,
···
 #endif
 #ifdef CONFIG_F2FS_FS_LZ4
 	&f2fs_lz4_ops,
+#else
+	NULL,
+#endif
+#ifdef CONFIG_F2FS_FS_ZSTD
+	&f2fs_zstd_ops,
 #else
 	NULL,
 #endif

fs/f2fs/f2fs.h

···
 enum compress_algorithm_type {
 	COMPRESS_LZO,
 	COMPRESS_LZ4,
+	COMPRESS_ZSTD,
 	COMPRESS_MAX,
 };
 
···
 	size_t rlen;			/* valid data length in rbuf */
 	size_t clen;			/* valid data length in cbuf */
 	void *private;			/* payload buffer for specified compression algorithm */
+	void *private2;			/* extra payload buffer */
 };
 
 /* compress context for write IO path */
···
 	size_t clen;			/* valid data length in cbuf */
 	refcount_t ref;			/* referrence count of compressed page */
 	bool failed;			/* indicate IO error during decompression */
+	void *private;			/* payload buffer for specified decompression algorithm */
+	void *private2;			/* extra payload buffer */
 };
 
 #define NULL_CLUSTER			((unsigned int)(~0))
 #define MIN_COMPRESS_LOG_SIZE		2
 #define MAX_COMPRESS_LOG_SIZE		8
+#define MAX_COMPRESS_WINDOW_SIZE	((PAGE_SIZE) << MAX_COMPRESS_LOG_SIZE)
 
 struct f2fs_sb_info {
 	struct super_block *sb;			/* pointer to VFS super block */

fs/f2fs/super.c

···
 					!strcmp(name, "lz4")) {
 				F2FS_OPTION(sbi).compress_algorithm =
 								COMPRESS_LZ4;
+			} else if (strlen(name) == 4 &&
+					!strcmp(name, "zstd")) {
+				F2FS_OPTION(sbi).compress_algorithm =
+								COMPRESS_ZSTD;
 			} else {
 				kfree(name);
 				return -EINVAL;
···
 		break;
 	case COMPRESS_LZ4:
 		algtype = "lz4";
+		break;
+	case COMPRESS_ZSTD:
+		algtype = "zstd";
 		break;
 	}
 	seq_printf(seq, ",compress_algorithm=%s", algtype);

include/trace/events/f2fs.h

···
 #define show_compress_algorithm(type)					\
 	__print_symbolic(type,						\
 		{ COMPRESS_LZO,		"LZO" },			\
-		{ COMPRESS_LZ4,		"LZ4" })
+		{ COMPRESS_LZ4,		"LZ4" },			\
+		{ COMPRESS_ZSTD,	"ZSTD" })
 
 struct f2fs_sb_info;
 struct f2fs_io_info;