[PATCH 19/25] staging: erofs: add a generic z_erofs VLE decompressor

Gao Xiang
2018-07-26T12:27:44Z

Currently, this patch only simply implements LZ4
decompressor due to its development priority.

In the future, erofs will support more compression
algorithm and format other than LZ4, thus a generic
decompressor interface will be needed.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
drivers/staging/erofs/Kconfig | 14 +++
drivers/staging/erofs/Makefile | 2 +-
drivers/staging/erofs/internal.h | 5 +
drivers/staging/erofs/unzip_vle.h | 35 ++++++
drivers/staging/erofs/unzip_vle_lz4.c | 209 ++++++++++++++++++++++++++++++++++
5 files changed, 264 insertions(+), 1 deletion(-)
create mode 100644 drivers/staging/erofs/unzip_vle.h
create mode 100644 drivers/staging/erofs/unzip_vle_lz4.c

diff --git a/drivers/staging/erofs/Kconfig b/drivers/staging/erofs/Kconfig
index 63bec70..b55ce1c 100644
--- a/drivers/staging/erofs/Kconfig
+++ b/drivers/staging/erofs/Kconfig
@@ -87,3 +87,17 @@ config EROFS_FS_ZIP

If you don't want to use compression feature, say N.

+config EROFS_FS_CLUSTER_PAGE_LIMIT
+ int "EROFS Cluster Pages Hard Limit"
+ depends on EROFS_FS_ZIP
+ range 1 256
+ default "1"
+ help
+ Indicates VLE compressed pages hard limit of a
+ compressed cluster.
+
+ For example, if files of a image are compressed
+ into 8k-unit, the hard limit should not be less
+ than 2. Otherwise, the image cannot be mounted
+ correctly on this kernel.
+
diff --git a/drivers/staging/erofs/Makefile b/drivers/staging/erofs/Makefile
index e409637..9a766eb 100644
--- a/drivers/staging/erofs/Makefile
+++ b/drivers/staging/erofs/Makefile
@@ -9,5 +9,5 @@ obj-$(CONFIG_EROFS_FS) += erofs.o
ccflags-y += -I$(src)/include
erofs-objs := super.o inode.o data.o namei.o dir.o utils.o
erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
-erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o unzip_lz4.o
+erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o unzip_lz4.o unzip_vle_lz4.o

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 6a0f045..e61d417 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -161,6 +161,11 @@ static inline void *erofs_kmalloc(struct erofs_sb_info *sbi,

#define ROOT_NID(sb) ((sb)->root_nid)

+#ifdef CONFIG_EROFS_FS_ZIP
+/* hard limit of pages per compressed cluster */
+#define Z_EROFS_CLUSTER_MAX_PAGES (CONFIG_EROFS_FS_CLUSTER_PAGE_LIMIT)
+#endif
+
typedef u64 erofs_off_t;

/* data type for filesystem-wide blocks number */
diff --git a/drivers/staging/erofs/unzip_vle.h b/drivers/staging/erofs/unzip_vle.h
new file mode 100644
index 0000000..b34f5bc
--- /dev/null
+++ b/drivers/staging/erofs/unzip_vle.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * linux/drivers/staging/erofs/unzip_vle.h
+ *
+ * Copyright (C) 2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+#ifndef __EROFS_FS_UNZIP_VLE_H
+#define __EROFS_FS_UNZIP_VLE_H
+
+#include "internal.h"
+
+#define Z_EROFS_VLE_INLINE_PAGEVECS 3
+
+/* unzip_vle_lz4.c */
+extern int z_erofs_vle_plain_copy(struct page **compressed_pages,
+ unsigned clusterpages, struct page **pages,
+ unsigned nr_pages, unsigned short pageofs);
+
+extern int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
+ unsigned clusterpages, struct page **pages,
+ unsigned outlen, unsigned short pageofs,
+ void (*endio)(struct page *));
+
+extern int z_erofs_vle_unzip_vmap(struct page **compressed_pages,
+ unsigned clusterpages, void *vaddr, unsigned llen,
+ unsigned short pageofs, bool overlapped);
+
+#endif
+
diff --git a/drivers/staging/erofs/unzip_vle_lz4.c b/drivers/staging/erofs/unzip_vle_lz4.c
new file mode 100644
index 0000000..f5b665f
--- /dev/null
+++ b/drivers/staging/erofs/unzip_vle_lz4.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/drivers/staging/erofs/unzip_vle_lz4.c
+ *
+ * Copyright (C) 2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+#include "unzip_vle.h"
+
+#if Z_EROFS_CLUSTER_MAX_PAGES > Z_EROFS_VLE_INLINE_PAGEVECS
+#define EROFS_PERCPU_NR_PAGES Z_EROFS_CLUSTER_MAX_PAGES
+#else
+#define EROFS_PERCPU_NR_PAGES Z_EROFS_VLE_INLINE_PAGEVECS
+#endif
+
+static struct {
+ char data[PAGE_SIZE * EROFS_PERCPU_NR_PAGES];
+} erofs_pcpubuf[NR_CPUS];
+
+int z_erofs_vle_plain_copy(struct page **compressed_pages,
+ unsigned clusterpages,
+ struct page **pages,
+ unsigned nr_pages,
+ unsigned short pageofs)
+{
+ unsigned i, j;
+ void *src = NULL;
+ const unsigned righthalf = PAGE_SIZE - pageofs;
+ char *percpu_data;
+ bool mirrored[Z_EROFS_CLUSTER_MAX_PAGES] = { 0 };
+
+ preempt_disable();
+ percpu_data = erofs_pcpubuf[smp_processor_id()].data;
+
+ j = 0;
+ for (i = 0; i < nr_pages; j = i++) {
+ struct page *page = pages[i];
+ void *dst;
+
+ if (page == NULL) {
+ if (src != NULL) {
+ if (!mirrored[j])
+ kunmap_atomic(src);
+ src = NULL;
+ }
+ continue;
+ }
+
+ dst = kmap_atomic(page);
+
+ for (; j < clusterpages; ++j) {
+ if (compressed_pages[j] != page)
+ continue;
+
+ BUG_ON(mirrored[j]);
+ memcpy(percpu_data + j * PAGE_SIZE, dst, PAGE_SIZE);
+ mirrored[j] = true;
+ break;
+ }
+
+ if (i) {
+ if (src == NULL)
+ src = mirrored[i-1] ?
+ percpu_data + (i-1) * PAGE_SIZE :
+ kmap_atomic(compressed_pages[i-1]);
+
+ memcpy(dst, src + righthalf, pageofs);
+
+ if (!mirrored[i-1])
+ kunmap_atomic(src);
+
+ if (unlikely(i >= clusterpages)) {
+ kunmap_atomic(dst);
+ break;
+ }
+ }
+
+ if (!righthalf)
+ src = NULL;
+ else {
+ src = mirrored[i] ? percpu_data + i * PAGE_SIZE :
+ kmap_atomic(compressed_pages[i]);
+
+ memcpy(dst + pageofs, src, righthalf);
+ }
+
+ kunmap_atomic(dst);
+ }
+
+ if (src != NULL && !mirrored[j])
+ kunmap_atomic(src);
+
+ preempt_enable();
+ return 0;
+}
+
+extern int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen);
+
+int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
+ unsigned clusterpages,
+ struct page **pages,
+ unsigned outlen,
+ unsigned short pageofs,
+ void (*endio)(struct page *))
+{
+ void *vin, *vout;
+ unsigned nr_pages, i, j;
+ int ret;
+
+ if (outlen + pageofs > EROFS_PERCPU_NR_PAGES * PAGE_SIZE)
+ return -ENOTSUPP;
+
+ nr_pages = DIV_ROUND_UP(outlen + pageofs, PAGE_SIZE);
+
+ if (clusterpages == 1)
+ vin = kmap_atomic(compressed_pages[0]);
+ else
+ vin = erofs_vmap(compressed_pages, clusterpages);
+
+ preempt_disable();
+ vout = erofs_pcpubuf[smp_processor_id()].data;
+
+ ret = z_erofs_unzip_lz4(vin, vout + pageofs,
+ clusterpages * PAGE_SIZE, outlen);
+
+ if (ret >= 0) {
+ outlen = ret;
+ ret = 0;
+ }
+
+ for (i = 0; i < nr_pages; ++i) {
+ j = min((unsigned)PAGE_SIZE - pageofs, outlen);
+
+ if (pages[i] != NULL) {
+ if (ret < 0)
+ SetPageError(pages[i]);
+ else if (clusterpages == 1 && pages[i] == compressed_pages[0])
+ memcpy(vin + pageofs, vout + pageofs, j);
+ else {
+ void *dst = kmap_atomic(pages[i]);
+
+ memcpy(dst + pageofs, vout + pageofs, j);
+ kunmap_atomic(dst);
+ }
+ endio(pages[i]);
+ }
+ vout += PAGE_SIZE;
+ outlen -= j;
+ pageofs = 0;
+ }
+ preempt_enable();
+
+ if (clusterpages == 1)
+ kunmap_atomic(vin);
+ else
+ erofs_vunmap(vin, clusterpages);
+
+ return ret;
+}
+
+int z_erofs_vle_unzip_vmap(struct page **compressed_pages,
+ unsigned clusterpages,
+ void *vout,
+ unsigned llen,
+ unsigned short pageofs,
+ bool overlapped)
+{
+ void *vin;
+ unsigned i;
+ int ret;
+
+ if (overlapped) {
+ preempt_disable();
+ vin = erofs_pcpubuf[smp_processor_id()].data;
+
+ for (i = 0; i < clusterpages; ++i) {
+ void *t = kmap_atomic(compressed_pages[i]);
+
+ memcpy(vin + PAGE_SIZE *i, t, PAGE_SIZE);
+ kunmap_atomic(t);
+ }
+ } else if (clusterpages == 1)
+ vin = kmap_atomic(compressed_pages[0]);
+ else {
+ vin = erofs_vmap(compressed_pages, clusterpages);
+ }
+
+ ret = z_erofs_unzip_lz4(vin, vout + pageofs,
+ clusterpages * PAGE_SIZE, llen);
+ if (ret > 0)
+ ret = 0;
+
+ if (!overlapped) {
+ if (clusterpages == 1)
+ kunmap_atomic(vin);
+ else {
+ erofs_vunmap(vin, clusterpages);
+ }
+ } else
+ preempt_enable();
+
+ return ret;
+}
+
--
1.9.1