linux-btrfs-lz4.patch

From b33a96616ee2154dd3fdb8fd1587486e1ad9fb86 Mon Sep 17 00:00:00 2001
From: Valery Tolstov <testautomail@mail.ru>
Date: Mon, 2 Jan 2017 19:09:32 +0300
Subject: [PATCH 1/2] Apply xbian lz4/lz4hc patch

---
 fs/btrfs/Makefile      |   2 +-
 fs/btrfs/compression.c |   2 +
 fs/btrfs/compression.h |   2 +
 fs/btrfs/ctree.h       |  15 +-
 fs/btrfs/disk-io.c     |   3 +
 fs/btrfs/ioctl.c       |   4 +
 fs/btrfs/lz4_wrapper.c | 487 +++++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/super.c       |  22 ++-
 8 files changed, 526 insertions(+), 11 deletions(-)
 create mode 100644 fs/btrfs/lz4_wrapper.c

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 6d1d0b9..c4dcc60 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -9,7 +9,7 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
 	   export.o tree-log.o free-space-cache.o zlib.o lzo.o \
 	   compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
 	   reada.o backref.o ulist.o qgroup.o send.o dev-replace.o raid56.o \
-	   uuid-tree.o props.o hash.o
+	   uuid-tree.o props.o hash.o lz4_wrapper.o
 
 btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
 btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index c473c42..e974746 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -755,6 +755,8 @@ static struct {
 static const struct btrfs_compress_op * const btrfs_compress_op[] = {
 	&btrfs_zlib_compress,
 	&btrfs_lzo_compress,
+	&btrfs_lz4_compress,
+	&btrfs_lz4hc_compress,
 };
 
 void __init btrfs_init_compress(void)
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 13a4dc0..3be090a 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -79,5 +79,7 @@ struct btrfs_compress_op {
 
 extern const struct btrfs_compress_op btrfs_zlib_compress;
 extern const struct btrfs_compress_op btrfs_lzo_compress;
+extern const struct btrfs_compress_op btrfs_lz4_compress;
+extern const struct btrfs_compress_op btrfs_lz4hc_compress;
 
 #endif
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 35489e7..0410177 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -504,13 +504,7 @@ struct btrfs_super_block {
 #define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL	(1ULL << 1)
 #define BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS	(1ULL << 2)
 #define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO	(1ULL << 3)
-/*
- * some patches floated around with a second compression method
- * lets save that incompat here for when they do get in
- * Note we don't actually support it, we're just reserving the
- * number
- */
-#define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZOv2	(1ULL << 4)
+#define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZ4	(1ULL << 4)
 
 /*
  * older kernels tried to do bigger metadata blocks, but the
@@ -539,6 +533,7 @@ struct btrfs_super_block {
 	 BTRFS_FEATURE_INCOMPAT_RAID56 |		\
 	 BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF |		\
 	 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA |	\
+	 BTRFS_FEATURE_INCOMPAT_COMPRESS_LZ4 |		\
 	 BTRFS_FEATURE_INCOMPAT_NO_HOLES)
 
 #define BTRFS_FEATURE_INCOMPAT_SAFE_SET			\
@@ -709,8 +704,10 @@ enum btrfs_compression_type {
 	BTRFS_COMPRESS_NONE  = 0,
 	BTRFS_COMPRESS_ZLIB  = 1,
 	BTRFS_COMPRESS_LZO   = 2,
-	BTRFS_COMPRESS_TYPES = 2,
-	BTRFS_COMPRESS_LAST  = 3,
+	BTRFS_COMPRESS_LZ4   = 3,
+	BTRFS_COMPRESS_LZ4HC = 4,
+	BTRFS_COMPRESS_TYPES = 4,
+	BTRFS_COMPRESS_LAST  = 5,
 };
 
 struct btrfs_inode_item {
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 974be09..e2f7898 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2751,6 +2751,9 @@ int open_ctree(struct super_block *sb,
 	features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
 	if (tree_root->fs_info->compress_type == BTRFS_COMPRESS_LZO)
 		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
+	else if (tree_root->fs_info->compress_type == BTRFS_COMPRESS_LZ4 ||
+	         tree_root->fs_info->compress_type == BTRFS_COMPRESS_LZ4HC)
+		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZ4;
 
 	if (features & BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)
 		printk(KERN_INFO "BTRFS: has skinny extents\n");
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index da94138..3f5fac7 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1448,6 +1448,10 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 	if (range->compress_type == BTRFS_COMPRESS_LZO) {
 		btrfs_set_fs_incompat(root->fs_info, COMPRESS_LZO);
 	}
+	if (range->compress_type == BTRFS_COMPRESS_LZ4 ||
+	    range->compress_type == BTRFS_COMPRESS_LZ4HC) {
+		btrfs_set_fs_incompat(root->fs_info, COMPRESS_LZ4);
+	}
 
 	ret = defrag_count;
 
diff --git a/fs/btrfs/lz4_wrapper.c b/fs/btrfs/lz4_wrapper.c
new file mode 100644
index 0000000..919fb10
--- /dev/null
+++ b/fs/btrfs/lz4_wrapper.c
@@ -0,0 +1,487 @@
+/*
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ * Copyright (C) 2013 SUSE.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <linux/pagemap.h>
+#include <linux/bio.h>
+#include <linux/lz4.h>
+#include "compression.h"
+
+#define LZ4_LEN		4
+#define LZ4_CHUNK_SIZE	(4096)
+#define LZ4_MAX_WORKBUF	2*LZ4_CHUNK_SIZE
+
+struct workspace {
+	void *mem;	/* work memory for compression */
+	void *buf;	/* where compressed data goes */
+	void *cbuf;	/* where decompressed data goes */
+	struct list_head list;
+};
+
+static void lz4_free_workspace(struct list_head *ws)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+
+	vfree(workspace->buf);
+	vfree(workspace->cbuf);
+	vfree(workspace->mem);
+	kfree(workspace);
+}
+
+static struct list_head *lz4_alloc_workspace_generic(int hi)
+{
+	struct workspace *workspace;
+
+	workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
+	if (!workspace)
+		return ERR_PTR(-ENOMEM);
+
+	if (hi)
+		workspace->mem = vmalloc(LZ4HC_MEM_COMPRESS);
+	else
+		workspace->mem = vmalloc(LZ4_MEM_COMPRESS);
+	workspace->buf = vmalloc(LZ4_MAX_WORKBUF);
+	workspace->cbuf = vmalloc(LZ4_MAX_WORKBUF);
+	if (!workspace->mem || !workspace->buf || !workspace->cbuf)
+		goto fail;
+
+	INIT_LIST_HEAD(&workspace->list);
+
+	return &workspace->list;
+fail:
+	lz4_free_workspace(&workspace->list);
+	return ERR_PTR(-ENOMEM);
+}
+
+static struct list_head *lz4_alloc_workspace(void)
+{
+	return lz4_alloc_workspace_generic(0);
+}
+
+static struct list_head *lz4hc_alloc_workspace(void)
+{
+	return lz4_alloc_workspace_generic(1);
+}
+
+static inline void write_compress_length(char *buf, size_t len)
+{
+	__le32 dlen;
+
+	dlen = cpu_to_le32(len);
+	memcpy(buf, &dlen, LZ4_LEN);
+}
+
+static inline size_t read_compress_length(char *buf)
+{
+	__le32 dlen;
+
+	memcpy(&dlen, buf, LZ4_LEN);
+	return le32_to_cpu(dlen);
+}
+
+static int lz4_compress_pages_generic(struct list_head *ws,
+			      struct address_space *mapping,
+			      u64 start, unsigned long len,
+			      struct page **pages,
+			      unsigned long nr_dest_pages,
+			      unsigned long *out_pages,
+			      unsigned long *total_in,
+			      unsigned long *total_out,
+			      unsigned long max_out, int hi)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	int ret = 0;
+	char *data_in;
+	char *cpage_out;
+	int nr_pages = 0;
+	struct page *in_page = NULL;
+	struct page *out_page = NULL;
+	unsigned long bytes_left;
+
+	size_t in_len;
+	size_t out_len;
+	char *buf;
+	unsigned long tot_in = 0;
+	unsigned long tot_out = 0;
+	unsigned long pg_bytes_left;
+	unsigned long out_offset;
+	unsigned long bytes;
+
+	*out_pages = 0;
+	*total_out = 0;
+	*total_in = 0;
+
+	in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
+	data_in = kmap(in_page);
+
+	/*
+	 * store the size of all chunks of compressed data in
+	 * the first 4 bytes
+	 */
+	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+	if (out_page == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	cpage_out = kmap(out_page);
+	out_offset = LZ4_LEN;
+	tot_out = LZ4_LEN;
+	pages[0] = out_page;
+	nr_pages = 1;
+	pg_bytes_left = PAGE_CACHE_SIZE - LZ4_LEN;
+
+	/* compress at most one page of data each time */
+	in_len = min(len, PAGE_CACHE_SIZE);
+	while (tot_in < len) {
+		if (hi)
+			ret = lz4hc_compress(data_in, in_len, workspace->cbuf,
+					&out_len, workspace->mem);
+		else
+			ret = lz4_compress(data_in, in_len, workspace->cbuf, &out_len,
+					workspace->mem);
+		if (ret < 0) {
+			printk(KERN_DEBUG
+				"btrfs: lz4 compress in loop returned %d\n",
+			       ret);
+			ret = -1;
+			goto out;
+		}
+
+		/* store the size of this chunk of compressed data */
+		write_compress_length(cpage_out + out_offset, out_len);
+		tot_out += LZ4_LEN;
+		out_offset += LZ4_LEN;
+		pg_bytes_left -= LZ4_LEN;
+
+		tot_in += in_len;
+		tot_out += out_len;
+
+		/* copy bytes from the working buffer into the pages */
+		buf = workspace->cbuf;
+		while (out_len) {
+			bytes = min_t(unsigned long, pg_bytes_left, out_len);
+
+			memcpy(cpage_out + out_offset, buf, bytes);
+
+			out_len -= bytes;
+			pg_bytes_left -= bytes;
+			buf += bytes;
+			out_offset += bytes;
+
+			/*
+			 * we need another page for writing out.
+			 *
+			 * Note if there's less than 4 bytes left, we just
+			 * skip to a new page.
+			 */
+			if ((out_len == 0 && pg_bytes_left < LZ4_LEN) ||
+			    pg_bytes_left == 0) {
+				if (pg_bytes_left) {
+					memset(cpage_out + out_offset, 0,
+					       pg_bytes_left);
+					tot_out += pg_bytes_left;
+				}
+
+				/* we're done, don't allocate new page */
+				if (out_len == 0 && tot_in >= len)
+					break;
+
+				kunmap(out_page);
+				if (nr_pages == nr_dest_pages) {
+					out_page = NULL;
+					ret = -1;
+					goto out;
+				}
+
+				out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+				if (out_page == NULL) {
+					ret = -ENOMEM;
+					goto out;
+				}
+				cpage_out = kmap(out_page);
+				pages[nr_pages++] = out_page;
+
+				pg_bytes_left = PAGE_CACHE_SIZE;
+				out_offset = 0;
+			}
+		}
+
+		/* we're making it bigger, give up */
+		if (tot_in > 8192 && tot_in < tot_out)
+			goto out;
+
+		/* we're all done */
+		if (tot_in >= len)
+			break;
+
+		if (tot_out > max_out)
+			break;
+
+		bytes_left = len - tot_in;
+		kunmap(in_page);
+		page_cache_release(in_page);
+
+		start += PAGE_CACHE_SIZE;
+		in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
+		data_in = kmap(in_page);
+		in_len = min(bytes_left, PAGE_CACHE_SIZE);
+	}
+
+	if (tot_out > tot_in)
+		goto out;
+
+	/* store the size of all chunks of compressed data */
+	cpage_out = kmap(pages[0]);
+	write_compress_length(cpage_out, tot_out);
+
+	kunmap(pages[0]);
+
+	ret = 0;
+	*total_out = tot_out;
+	*total_in = tot_in;
+out:
+	*out_pages = nr_pages;
+	if (out_page)
+		kunmap(out_page);
+
+	if (in_page) {
+		kunmap(in_page);
+		page_cache_release(in_page);
+	}
+
+	return ret;
+}
+
+static int lz4_compress_pages(struct list_head *ws,
+			      struct address_space *mapping,
+			      u64 start, unsigned long len,
+			      struct page **pages,
+			      unsigned long nr_dest_pages,
+			      unsigned long *out_pages,
+			      unsigned long *total_in,
+			      unsigned long *total_out,
+			      unsigned long max_out)
+{
+	return lz4_compress_pages_generic(ws, mapping, start, len, pages,
+				nr_dest_pages, out_pages, total_in, total_out,
+				max_out, 0);
+}
+
+static int lz4hc_compress_pages(struct list_head *ws,
+			      struct address_space *mapping,
+			      u64 start, unsigned long len,
+			      struct page **pages,
+			      unsigned long nr_dest_pages,
+			      unsigned long *out_pages,
+			      unsigned long *total_in,
+			      unsigned long *total_out,
+			      unsigned long max_out)
+{
+	return lz4_compress_pages_generic(ws, mapping, start, len, pages,
+				nr_dest_pages, out_pages, total_in, total_out,
+				max_out, 1);
+}
+
+static int lz4_decompress_biovec(struct list_head *ws,
+				 struct page **pages_in,
+				 u64 disk_start,
+				 struct bio_vec *bvec,
+				 int vcnt,
+				 size_t srclen)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	int ret = 0, ret2;
+	char *data_in;
+	unsigned long page_in_index = 0;
+	unsigned long page_out_index = 0;
+	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
+					PAGE_CACHE_SIZE;
+	unsigned long buf_start;
+	unsigned long buf_offset = 0;
+	unsigned long bytes;
+	unsigned long working_bytes;
+	unsigned long pg_offset;
+
+	size_t in_len;
+	size_t out_len;
+	unsigned long in_offset;
+	unsigned long in_page_bytes_left;
+	unsigned long tot_in;
+	unsigned long tot_out;
+	unsigned long tot_len;
+	char *buf;
+	bool may_late_unmap, need_unmap;
+
+	data_in = kmap(pages_in[0]);
+	tot_len = read_compress_length(data_in);
+
+	tot_in = LZ4_LEN;
+	in_offset = LZ4_LEN;
+	tot_len = min_t(size_t, srclen, tot_len);
+	in_page_bytes_left = PAGE_CACHE_SIZE - LZ4_LEN;
+
+	tot_out = 0;
+	pg_offset = 0;
+
+	while (tot_in < tot_len) {
+		in_len = read_compress_length(data_in + in_offset);
+		in_page_bytes_left -= LZ4_LEN;
+		in_offset += LZ4_LEN;
+		tot_in += LZ4_LEN;
+
+		tot_in += in_len;
+		working_bytes = in_len;
+		may_late_unmap = need_unmap = false;
+
+		/* fast path: avoid using the working buffer */
+		if (in_page_bytes_left >= in_len) {
+			buf = data_in + in_offset;
+			bytes = in_len;
+			may_late_unmap = true;
+			goto cont;
+		}
+
+		/* copy bytes from the pages into the working buffer */
+		buf = workspace->cbuf;
+		buf_offset = 0;
+		while (working_bytes) {
+			bytes = min(working_bytes, in_page_bytes_left);
+
+			memcpy(buf + buf_offset, data_in + in_offset, bytes);
+			buf_offset += bytes;
+cont:
+			working_bytes -= bytes;
+			in_page_bytes_left -= bytes;
+			in_offset += bytes;
+
+			/* check if we need to pick another page */
+			if ((working_bytes == 0 && in_page_bytes_left < LZ4_LEN)
+			    || in_page_bytes_left == 0) {
+				tot_in += in_page_bytes_left;
+
+				if (working_bytes == 0 && tot_in >= tot_len)
+					break;
+
+				if (page_in_index + 1 >= total_pages_in) {
+					ret = -1;
+					goto done;
+				}
+
+				if (may_late_unmap)
+					need_unmap = true;
+				else
+					kunmap(pages_in[page_in_index]);
+
+				data_in = kmap(pages_in[++page_in_index]);
+
+				in_page_bytes_left = PAGE_CACHE_SIZE;
+				in_offset = 0;
+			}
+		}
+
+		out_len = LZ4_CHUNK_SIZE;
+		ret = lz4_decompress_unknownoutputsize(buf, in_len, workspace->buf,
+				&out_len);
+		if (need_unmap)
+			kunmap(pages_in[page_in_index - 1]);
+		if (ret < 0) {
+			printk(KERN_WARNING "btrfs: lz4 decompress failed\n");
+			ret = -1;
+			break;
+		}
+
+		buf_start = tot_out;
+		tot_out += out_len;
+
+		ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
+						 tot_out, disk_start,
+						 bvec, vcnt,
+						 &page_out_index, &pg_offset);
+		if (ret2 == 0)
+			break;
+	}
+done:
+	kunmap(pages_in[page_in_index]);
+	return ret;
+}
+
+static int lz4_decompress_wrapper(struct list_head *ws, unsigned char *data_in,
+			  struct page *dest_page,
+			  unsigned long start_byte,
+			  size_t srclen, size_t destlen)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	size_t in_len;
+	size_t out_len;
+	size_t tot_len;
+	int ret = 0;
+	char *kaddr;
+	unsigned long bytes;
+
+	BUG_ON(srclen < LZ4_LEN);
+
+	tot_len = read_compress_length(data_in);
+	data_in += LZ4_LEN;
+
+	in_len = read_compress_length(data_in);
+	data_in += LZ4_LEN;
+
+	out_len = LZ4_CHUNK_SIZE;
+	ret = lz4_decompress_unknownoutputsize(data_in, in_len, workspace->buf,
+			&out_len);
+	if (ret < 0) {
+		printk(KERN_WARNING "btrfs: lz4 decompress failed\n");
+		ret = -1;
+		goto out;
+	}
+
+	if (out_len < start_byte) {
+		ret = -1;
+		goto out;
+	}
+
+	bytes = min_t(unsigned long, destlen, out_len - start_byte);
+
+	kaddr = kmap_atomic(dest_page);
+	memcpy(kaddr, workspace->buf + start_byte, bytes);
+	kunmap_atomic(kaddr);
+out:
+	return ret;
+}
+
+struct btrfs_compress_op btrfs_lz4_compress = {
+	.alloc_workspace	= lz4_alloc_workspace,
+	.free_workspace		= lz4_free_workspace,
+	.compress_pages		= lz4_compress_pages,
+	.decompress_biovec	= lz4_decompress_biovec,
+	.decompress		= lz4_decompress_wrapper,
+};
+
+struct btrfs_compress_op btrfs_lz4hc_compress = {
+	.alloc_workspace	= lz4hc_alloc_workspace,
+	.free_workspace		= lz4_free_workspace,
+	.compress_pages		= lz4hc_compress_pages,
+	.decompress_biovec	= lz4_decompress_biovec,
+	.decompress		= lz4_decompress_wrapper,
+};
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 24154e4..8c83f9b 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -478,6 +478,20 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 				btrfs_clear_opt(info->mount_opt, COMPRESS);
 				btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 				compress_force = false;
+			} else if (strcmp(args[0].from, "lz4") == 0) {
+				compress_type = "lz4";
+				info->compress_type = BTRFS_COMPRESS_LZ4;
+				btrfs_set_opt(info->mount_opt, COMPRESS);
+				btrfs_clear_opt(info->mount_opt, NODATACOW);
+				btrfs_clear_opt(info->mount_opt, NODATASUM);
+				btrfs_set_fs_incompat(info, COMPRESS_LZ4);
+			} else if (strcmp(args[0].from, "lz4hc") == 0) {
+				compress_type = "lz4hc";
+				info->compress_type = BTRFS_COMPRESS_LZ4HC;
+				btrfs_set_opt(info->mount_opt, COMPRESS);
+				btrfs_clear_opt(info->mount_opt, NODATACOW);
+				btrfs_clear_opt(info->mount_opt, NODATASUM);
+				btrfs_set_fs_incompat(info, COMPRESS_LZ4);
 			} else {
 				ret = -EINVAL;
 				goto out;
@@ -1139,8 +1153,14 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 	if (btrfs_test_opt(root, COMPRESS)) {
 		if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 			compress_type = "zlib";
-		else
+		else if (info->compress_type == BTRFS_COMPRESS_LZ4)
+			compress_type = "lz4";
+		else if (info->compress_type == BTRFS_COMPRESS_LZ4HC)
+			compress_type = "lz4hc";
+		else if (info->compress_type == BTRFS_COMPRESS_LZO)
 			compress_type = "lzo";
+		else
+			compress_type = "none";
 		if (btrfs_test_opt(root, FORCE_COMPRESS))
 			seq_printf(seq, ",compress-force=%s", compress_type);
 		else
-- 
2.10.2


From 89160ba488b0ba534d3631a101b8c781c69e0651 Mon Sep 17 00:00:00 2001
From: Valery Tolstov <testautomail@mail.ru>
Date: Mon, 2 Jan 2017 21:19:16 +0300
Subject: [PATCH 2/2] Little update

---
 fs/btrfs/Kconfig       | 3 +++
 fs/btrfs/lz4_wrapper.c | 4 ++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 80e9c18..4b843c6 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -6,6 +6,9 @@ config BTRFS_FS
 	select ZLIB_DEFLATE
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
+	select LZ4_COMPRESS
+	select LZ4_DECOMPRESS
+	select LZ4HC_COMPRESS
 	select RAID6_PQ
 	select XOR_BLOCKS
 	select SRCU
diff --git a/fs/btrfs/lz4_wrapper.c b/fs/btrfs/lz4_wrapper.c
index 919fb10..a3c9a06 100644
--- a/fs/btrfs/lz4_wrapper.c
+++ b/fs/btrfs/lz4_wrapper.c
@@ -470,7 +470,7 @@ out:
 	return ret;
 }
 
-struct btrfs_compress_op btrfs_lz4_compress = {
+const struct btrfs_compress_op btrfs_lz4_compress = {
 	.alloc_workspace	= lz4_alloc_workspace,
 	.free_workspace		= lz4_free_workspace,
 	.compress_pages		= lz4_compress_pages,
@@ -478,7 +478,7 @@ struct btrfs_compress_op btrfs_lz4_compress = {
 	.decompress		= lz4_decompress_wrapper,
 };
 
-struct btrfs_compress_op btrfs_lz4hc_compress = {
+const struct btrfs_compress_op btrfs_lz4hc_compress = {
 	.alloc_workspace	= lz4hc_alloc_workspace,
 	.free_workspace		= lz4_free_workspace,
 	.compress_pages		= lz4hc_compress_pages,
-- 
2.10.2