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Subject[PATCH 15/25] staging: erofs: add erofs_map_blocks_iter
Date
This patch introduces an iterable L2P mapping
operation 'erofs_map_blocks_iter'.
Compared with 'erofs_map_blocks', it avoids
a number of redundant 'release and regrab'
processes if they request the same meta page.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
drivers/staging/erofs/Kconfig | 10 ++
drivers/staging/erofs/Makefile | 1 +
drivers/staging/erofs/data.c | 36 +++++-
drivers/staging/erofs/internal.h | 12 ++
drivers/staging/erofs/unzip_vle.c | 243 ++++++++++++++++++++++++++++++++++++++
5 files changed, 300 insertions(+), 2 deletions(-)
create mode 100644 drivers/staging/erofs/unzip_vle.c

diff --git a/drivers/staging/erofs/Kconfig b/drivers/staging/erofs/Kconfig
index edda055..63bec70 100644
--- a/drivers/staging/erofs/Kconfig
+++ b/drivers/staging/erofs/Kconfig
@@ -77,3 +77,13 @@ config EROFS_FAULT_INJECTION
help
Test EROFS to inject faults such as ENOMEM, EIO, and so on.
If unsure, say N.
+
+config EROFS_FS_ZIP
+ bool "EROFS Data Compresssion Support"
+ depends on EROFS_FS
+ help
+ Currently we support VLE Compression only.
+ Play at your own risk.
+
+ If you don't want to use compression feature, say N.
+
diff --git a/drivers/staging/erofs/Makefile b/drivers/staging/erofs/Makefile
index 977b7e0..8558c76 100644
--- a/drivers/staging/erofs/Makefile
+++ b/drivers/staging/erofs/Makefile
@@ -9,4 +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
erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
+erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o

diff --git a/drivers/staging/erofs/data.c b/drivers/staging/erofs/data.c
index 47d1787..163bfe6 100644
--- a/drivers/staging/erofs/data.c
+++ b/drivers/staging/erofs/data.c
@@ -157,12 +157,44 @@ static int erofs_map_blocks_flatmode(struct inode *inode,
return 0;
}

+#ifdef CONFIG_EROFS_FS_ZIP
+extern int z_erofs_map_blocks_iter(struct inode *,
+ struct erofs_map_blocks *, struct page **, int);
+#endif
+
+int erofs_map_blocks_iter(struct inode *inode,
+ struct erofs_map_blocks *map,
+ struct page **mpage_ret, int flags)
+{
+ /* by default, reading raw data never use erofs_map_blocks_iter */
+ if (unlikely(!is_inode_layout_compression(inode))) {
+ if (*mpage_ret != NULL)
+ put_page(*mpage_ret);
+ *mpage_ret = NULL;
+
+ return erofs_map_blocks(inode, map, flags);
+ }
+
+#ifdef CONFIG_EROFS_FS_ZIP
+ return z_erofs_map_blocks_iter(inode, map, mpage_ret, flags);
+#else
+ /* data compression is not available */
+ return -ENOTSUPP;
+#endif
+}
+
int erofs_map_blocks(struct inode *inode,
struct erofs_map_blocks *map, int flags)
{
- if (unlikely(is_inode_layout_compression(inode)))
- return -ENOTSUPP;
+ if (unlikely(is_inode_layout_compression(inode))) {
+ struct page *mpage = NULL;
+ int err;

+ err = erofs_map_blocks_iter(inode, map, &mpage, flags);
+ if (mpage != NULL)
+ put_page(mpage);
+ return err;
+ }
return erofs_map_blocks_flatmode(inode, map, flags);
}

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index ca22486..bea5ec4 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -72,6 +72,10 @@ struct erofs_sb_info {

/* inode slot unit size in bit shift */
unsigned char islotbits;
+#ifdef CONFIG_EROFS_FS_ZIP
+ /* cluster size in bit shift */
+ unsigned char clusterbits;
+#endif

u32 build_time_nsec;
u64 build_time;
@@ -284,6 +288,14 @@ struct erofs_map_blocks {
extern struct page *erofs_get_meta_page(struct super_block *sb,
erofs_blk_t blkaddr, bool prio);
extern int erofs_map_blocks(struct inode *, struct erofs_map_blocks *, int);
+extern int erofs_map_blocks_iter(struct inode *, struct erofs_map_blocks *,
+ struct page **, int);
+
+struct erofs_map_blocks_iter {
+ struct erofs_map_blocks map;
+ struct page *mpage;
+};
+

static inline struct page *erofs_get_inline_page(struct inode *inode,
erofs_blk_t blkaddr)
diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
new file mode 100644
index 0000000..329cbe4
--- /dev/null
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/drivers/staging/erofs/unzip_vle.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 "internal.h"
+
+#define __vle_cluster_advise(x, bit, bits) \
+ ((le16_to_cpu(x) >> (bit)) & ((1 << (bits)) - 1))
+
+#define __vle_cluster_type(advise) __vle_cluster_advise(advise, \
+ Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT, Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS)
+
+enum {
+ Z_EROFS_VLE_CLUSTER_TYPE_PLAIN,
+ Z_EROFS_VLE_CLUSTER_TYPE_HEAD,
+ Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD,
+ Z_EROFS_VLE_CLUSTER_TYPE_RESERVED,
+ Z_EROFS_VLE_CLUSTER_TYPE_MAX
+};
+
+#define vle_cluster_type(di) \
+ __vle_cluster_type((di)->di_advise)
+
+static inline unsigned
+vle_compressed_index_clusterofs(unsigned clustersize,
+ struct z_erofs_vle_decompressed_index *di)
+{
+ debugln("%s, vle=%pK, advise=%x (type %u), clusterofs=%x blkaddr=%x",
+ __func__, di, di->di_advise, vle_cluster_type(di),
+ di->di_clusterofs, di->di_u.blkaddr);
+
+ switch (vle_cluster_type(di)) {
+ case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+ break;
+ case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+ case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+ return di->di_clusterofs;
+ default:
+ BUG_ON(1);
+ }
+ return clustersize;
+}
+
+static inline erofs_blk_t
+vle_extent_blkaddr(struct inode *inode, pgoff_t index)
+{
+ struct erofs_sb_info *sbi = EROFS_I_SB(inode);
+ struct erofs_vnode *vi = EROFS_V(inode);
+
+ unsigned ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
+ vi->xattr_isize) + sizeof(struct erofs_extent_header) +
+ index * sizeof(struct z_erofs_vle_decompressed_index);
+
+ return erofs_blknr(iloc(sbi, vi->nid) + ofs);
+}
+
+static inline unsigned int
+vle_extent_blkoff(struct inode *inode, pgoff_t index)
+{
+ struct erofs_sb_info *sbi = EROFS_I_SB(inode);
+ struct erofs_vnode *vi = EROFS_V(inode);
+
+ unsigned ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
+ vi->xattr_isize) + sizeof(struct erofs_extent_header) +
+ index * sizeof(struct z_erofs_vle_decompressed_index);
+
+ return erofs_blkoff(iloc(sbi, vi->nid) + ofs);
+}
+
+/*
+ * Variable-sized Logical Extent (Fixed Physical Cluster) Compression Mode
+ * ---
+ * VLE compression mode attempts to compress a number of logical data into
+ * a physical cluster with a fixed size.
+ * VLE compression mode uses "struct z_erofs_vle_decompressed_index".
+ */
+static erofs_off_t vle_get_logical_extent_head(
+ struct inode *inode,
+ struct page **page_iter,
+ void **kaddr_iter,
+ unsigned lcn, /* logical cluster number */
+ erofs_blk_t *pcn,
+ unsigned *flags)
+{
+ /* for extent meta */
+ struct page *page = *page_iter;
+ erofs_blk_t blkaddr = vle_extent_blkaddr(inode, lcn);
+ struct z_erofs_vle_decompressed_index *di;
+ unsigned long long ofs;
+ const unsigned int clusterbits = EROFS_SB(inode->i_sb)->clusterbits;
+ const unsigned int clustersize = 1 << clusterbits;
+
+ if (page->index != blkaddr) {
+ kunmap_atomic(*kaddr_iter);
+ unlock_page(page);
+ put_page(page);
+
+ *page_iter = page = erofs_get_meta_page(inode->i_sb,
+ blkaddr, false);
+ *kaddr_iter = kmap_atomic(page);
+ }
+
+ di = *kaddr_iter + vle_extent_blkoff(inode, lcn);
+ switch (vle_cluster_type(di)) {
+ case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+ BUG_ON(!di->di_u.delta[0]);
+ BUG_ON(lcn < di->di_u.delta[0]);
+
+ ofs = vle_get_logical_extent_head(inode,
+ page_iter, kaddr_iter,
+ lcn - di->di_u.delta[0], pcn, flags);
+ break;
+ case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+ *flags ^= EROFS_MAP_ZIPPED;
+ case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+ /* clustersize should be a power of two */
+ ofs = ((unsigned long long)lcn << clusterbits) +
+ (le16_to_cpu(di->di_clusterofs) & (clustersize - 1));
+ *pcn = le32_to_cpu(di->di_u.blkaddr);
+ break;
+ default:
+ BUG_ON(1);
+ }
+ return ofs;
+}
+
+int z_erofs_map_blocks_iter(struct inode *inode,
+ struct erofs_map_blocks *map,
+ struct page **mpage_ret, int flags)
+{
+ /* logicial extent (start, end) offset */
+ unsigned long long ofs, end;
+ struct z_erofs_vle_decompressed_index *di;
+ erofs_blk_t e_blkaddr, pcn;
+ unsigned lcn, logical_cluster_ofs;
+ u32 ofs_rem;
+ struct page *mpage = *mpage_ret;
+ void *kaddr;
+ bool initial;
+ const unsigned int clusterbits = EROFS_SB(inode->i_sb)->clusterbits;
+ const unsigned int clustersize = 1 << clusterbits;
+
+ /* if both m_(l,p)len are 0, regularize l_lblk, l_lofs, etc... */
+ initial = !map->m_llen;
+
+ /* when trying to read beyond EOF, leave it unmapped */
+ if (unlikely(map->m_la >= inode->i_size)) {
+ BUG_ON(!initial);
+ map->m_llen = map->m_la + 1 - inode->i_size;
+ map->m_la = inode->i_size - 1;
+ map->m_flags = 0;
+ goto out;
+ }
+
+ debugln("%s, m_la %llu m_llen %llu --- start", __func__,
+ map->m_la, map->m_llen);
+
+ ofs = map->m_la + map->m_llen;
+
+ /* clustersize should be power of two */
+ lcn = ofs >> clusterbits;
+ ofs_rem = ofs & (clustersize - 1);
+
+ e_blkaddr = vle_extent_blkaddr(inode, lcn);
+
+ if (mpage == NULL || mpage->index != e_blkaddr) {
+ if (mpage != NULL)
+ put_page(mpage);
+
+ mpage = erofs_get_meta_page(inode->i_sb, e_blkaddr, false);
+ *mpage_ret = mpage;
+ } else {
+ lock_page(mpage);
+ DBG_BUGON(!PageUptodate(mpage));
+ }
+
+ kaddr = kmap_atomic(mpage);
+ di = kaddr + vle_extent_blkoff(inode, lcn);
+
+ debugln("%s, lcn %u e_blkaddr %u e_blkoff %u", __func__, lcn,
+ e_blkaddr, vle_extent_blkoff(inode, lcn));
+
+ logical_cluster_ofs = vle_compressed_index_clusterofs(clustersize, di);
+ if (!initial) {
+ /* [walking mode] 'map' has been already initialized */
+ map->m_llen += logical_cluster_ofs;
+ goto unmap_out;
+ }
+
+ /* by default, compressed */
+ map->m_flags |= EROFS_MAP_ZIPPED;
+
+ end = (u64)(lcn + 1) * clustersize;
+
+ switch (vle_cluster_type(di)) {
+ case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+ if (ofs_rem >= logical_cluster_ofs)
+ map->m_flags ^= EROFS_MAP_ZIPPED;
+ case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+ if (ofs_rem == logical_cluster_ofs) {
+ pcn = le32_to_cpu(di->di_u.blkaddr);
+ goto exact_hitted;
+ }
+
+ if (ofs_rem > logical_cluster_ofs) {
+ ofs = lcn * clustersize | logical_cluster_ofs;
+ pcn = le32_to_cpu(di->di_u.blkaddr);
+ break;
+ }
+
+ BUG_ON(!lcn); /* logical cluster number >= 1 */
+ end = (lcn-- * clustersize) | logical_cluster_ofs;
+ case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+ /* get the correspoinding first chunk */
+ ofs = vle_get_logical_extent_head(inode, mpage_ret,
+ &kaddr, lcn, &pcn, &map->m_flags);
+ mpage = *mpage_ret;
+ }
+
+ map->m_la = ofs;
+exact_hitted:
+ map->m_llen = end - ofs;
+ map->m_plen = clustersize;
+ map->m_pa = blknr_to_addr(pcn);
+ map->m_flags |= EROFS_MAP_MAPPED;
+unmap_out:
+ kunmap_atomic(kaddr);
+ unlock_page(mpage);
+out:
+ debugln("%s, m_la %llu m_pa %llu m_llen %llu m_plen %llu m_flags 0%o",
+ __func__, map->m_la, map->m_pa,
+ map->m_llen, map->m_plen, map->m_flags);
+ return 0;
+}
+
--
1.9.1
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