[PATCH v6 22/24] erofs: introduce the decompression frontend

Gao Xiang
2019-08-02T12:55:00Z

This patch introduces the basic inplace fixed-sized
output decompression implementation for erofs
filesystem.

In constant to fixed-sized input compression, it has
fixed-sized capacity for each compressed cluster to
contain compressed data with the following advantages:
1) improved storage density;
2) decompression inplace support;
3) all data in a compressed physical cluster can be
decompressed and utilized.

The key point of inplace refers to one of all erofs
decompression strategies: Instead of allocating extra
compressed pages and data management structures, it
reuses the allocated file cache pages as much as
possible to store its compressed data (called inplace
I/O) and the corresponding pagevec in a time-sharing
approach, which is particularly useful for low memory
scenario.

In addition, decompression inplace technology is based
on inplace I/O, which eliminates page allocation and
all extra compressed data memcpy.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
fs/erofs/Kconfig | 1 +
fs/erofs/Makefile | 2 +-
fs/erofs/internal.h | 14 +-
fs/erofs/super.c | 11 +
fs/erofs/zdata.c | 1254 +++++++++++++++++++++++++++++++++++++++++++
fs/erofs/zdata.h | 192 +++++++
fs/erofs/zmap.c | 4 +-
7 files changed, 1474 insertions(+), 4 deletions(-)
create mode 100644 fs/erofs/zdata.c
create mode 100644 fs/erofs/zdata.h

diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig
index 5f8787c0cf89..16316d1adca3 100644
--- a/fs/erofs/Kconfig
+++ b/fs/erofs/Kconfig
@@ -76,6 +76,7 @@ config EROFS_FS_ZIP
bool "EROFS Data Compression Support"
depends on EROFS_FS
select LZ4_DECOMPRESS
+ default y
help
Enable fixed-sized output compression for EROFS.

diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile
index 5594abca6f95..46f2aa4ba46c 100644
--- a/fs/erofs/Makefile
+++ b/fs/erofs/Makefile
@@ -7,5 +7,5 @@ ccflags-y += -DEROFS_VERSION=\"$(EROFS_VERSION)\"
obj-$(CONFIG_EROFS_FS) += erofs.o
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) += decompressor.o zmap.o
+erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 1a322304560f..a492744435d4 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -69,6 +69,9 @@ struct erofs_sb_info {
/* the dedicated workstation for compression */
struct radix_tree_root workstn_tree;

+ /* threshold for decompression synchronously */
+ unsigned int max_sync_decompress_pages;
+
unsigned int shrinker_run_no;
#endif /* CONFIG_EROFS_FS_ZIP */
u32 blocks;
@@ -328,6 +331,9 @@ static inline bool is_inode_flat_inline(struct inode *inode)
extern const struct super_operations erofs_sops;

extern const struct address_space_operations erofs_raw_access_aops;
+#ifdef CONFIG_EROFS_FS_ZIP
+extern const struct address_space_operations z_erofs_vle_normalaccess_aops;
+#endif

/*
* Logical to physical block mapping, used by erofs_map_blocks()
@@ -488,7 +494,7 @@ int erofs_namei(struct inode *dir, struct qstr *name,
/* dir.c */
extern const struct file_operations erofs_dir_fops;

-/* utils.c */
+/* utils.c / zdata.c */
struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp, bool nofail);

#if (EROFS_PCPUBUF_NR_PAGES > 0)
@@ -512,16 +518,20 @@ struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
pgoff_t index, bool *tag);
int erofs_register_workgroup(struct super_block *sb,
struct erofs_workgroup *grp, bool tag);
-static inline void erofs_workgroup_free_rcu(struct erofs_workgroup *grp) {}
+void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
void erofs_shrinker_register(struct super_block *sb);
void erofs_shrinker_unregister(struct super_block *sb);
int __init erofs_init_shrinker(void);
void erofs_exit_shrinker(void);
+int __init z_erofs_init_zip_subsystem(void);
+void z_erofs_exit_zip_subsystem(void);
#else
static inline void erofs_shrinker_register(struct super_block *sb) {}
static inline void erofs_shrinker_unregister(struct super_block *sb) {}
static inline int erofs_init_shrinker(void) { return 0; }
static inline void erofs_exit_shrinker(void) {}
+static inline int z_erofs_init_zip_subsystem(void) { return 0; }
+static inline void z_erofs_exit_zip_subsystem(void) {}
#endif /* !CONFIG_EROFS_FS_ZIP */

#endif /* __EROFS_INTERNAL_H */
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index ea8d065068fa..bdac8abf3aa7 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -200,6 +200,9 @@ static unsigned int erofs_get_fault_rate(struct erofs_sb_info *sbi)
/* set up default EROFS parameters */
static void default_options(struct erofs_sb_info *sbi)
{
+#ifdef CONFIG_EROFS_FS_ZIP
+ sbi->max_sync_decompress_pages = 3;
+#endif
#ifdef CONFIG_EROFS_FS_XATTR
set_opt(sbi, XATTR_USER);
#endif
@@ -420,6 +423,11 @@ static int __init erofs_module_init(void)
err = erofs_init_shrinker();
if (err)
goto shrinker_err;
+
+ err = z_erofs_init_zip_subsystem();
+ if (err)
+ goto zip_err;
+
err = register_filesystem(&erofs_fs_type);
if (err)
goto fs_err;
@@ -428,6 +436,8 @@ static int __init erofs_module_init(void)
return 0;

fs_err:
+ z_erofs_exit_zip_subsystem();
+zip_err:
erofs_exit_shrinker();
shrinker_err:
erofs_exit_inode_cache();
@@ -438,6 +448,7 @@ static int __init erofs_module_init(void)
static void __exit erofs_module_exit(void)
{
unregister_filesystem(&erofs_fs_type);
+ z_erofs_exit_zip_subsystem();
erofs_exit_shrinker();
erofs_exit_inode_cache();
infoln("successfully finalize erofs");
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
new file mode 100644
index 000000000000..ffa64b1d8908
--- /dev/null
+++ b/fs/erofs/zdata.c
@@ -0,0 +1,1254 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/erofs/zdata.c
+ *
+ * Copyright (C) 2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ */
+#include "zdata.h"
+#include "compress.h"
+#include <linux/prefetch.h>
+
+#include <trace/events/erofs.h>
+
+/*
+ * a compressed_pages[] placeholder in order to avoid
+ * being filled with file pages for in-place decompression.
+ */
+#define PAGE_UNALLOCATED ((void *)0x5F0E4B1D)
+
+/* how to allocate cached pages for a pcluster */
+enum z_erofs_cache_alloctype {
+ DONTALLOC, /* don't allocate any cached pages */
+ DELAYEDALLOC, /* delayed allocation (at the time of submitting io) */
+};
+
+/*
+ * tagged pointer with 1-bit tag for all compressed pages
+ * tag 0 - the page is just found with an extra page reference
+ */
+typedef tagptr1_t compressed_page_t;
+
+#define tag_compressed_page_justfound(page) \
+ tagptr_fold(compressed_page_t, page, 1)
+
+static struct workqueue_struct *z_erofs_workqueue __read_mostly;
+static struct kmem_cache *pcluster_cachep __read_mostly;
+
+void z_erofs_exit_zip_subsystem(void)
+{
+ destroy_workqueue(z_erofs_workqueue);
+ kmem_cache_destroy(pcluster_cachep);
+}
+
+static inline int init_unzip_workqueue(void)
+{
+ const unsigned int onlinecpus = num_possible_cpus();
+ const unsigned int flags = WQ_UNBOUND | WQ_HIGHPRI | WQ_CPU_INTENSIVE;
+
+ /*
+ * no need to spawn too many threads, limiting threads could minimum
+ * scheduling overhead, perhaps per-CPU threads should be better?
+ */
+ z_erofs_workqueue = alloc_workqueue("erofs_unzipd", flags,
+ onlinecpus + onlinecpus / 4);
+ return z_erofs_workqueue ? 0 : -ENOMEM;
+}
+
+static void init_once(void *ptr)
+{
+ struct z_erofs_pcluster *pcl = ptr;
+ struct z_erofs_collection *cl = z_erofs_primarycollection(pcl);
+ unsigned int i;
+
+ mutex_init(&cl->lock);
+ cl->nr_pages = 0;
+ cl->vcnt = 0;
+ for (i = 0; i < Z_EROFS_CLUSTER_MAX_PAGES; ++i)
+ pcl->compressed_pages[i] = NULL;
+}
+
+static void init_always(struct z_erofs_pcluster *pcl)
+{
+ struct z_erofs_collection *cl = z_erofs_primarycollection(pcl);
+
+ atomic_set(&pcl->obj.refcount, 1);
+
+ DBG_BUGON(cl->nr_pages);
+ DBG_BUGON(cl->vcnt);
+}
+
+int __init z_erofs_init_zip_subsystem(void)
+{
+ pcluster_cachep = kmem_cache_create("erofs_compress",
+ Z_EROFS_WORKGROUP_SIZE, 0,
+ SLAB_RECLAIM_ACCOUNT, init_once);
+ if (pcluster_cachep) {
+ if (!init_unzip_workqueue())
+ return 0;
+
+ kmem_cache_destroy(pcluster_cachep);
+ }
+ return -ENOMEM;
+}
+
+enum z_erofs_collectmode {
+ COLLECT_SECONDARY,
+ COLLECT_PRIMARY,
+ /*
+ * The current collection was the tail of an exist chain, in addition
+ * that the previous processed chained collections are all decided to
+ * be hooked up to it.
+ * A new chain will be created for the remaining collections which are
+ * not processed yet, therefore different from COLLECT_PRIMARY_FOLLOWED,
+ * the next collection cannot reuse the whole page safely in
+ * the following scenario:
+ * ________________________________________________________________
+ * | tail (partial) page | head (partial) page |
+ * | (belongs to the next cl) | (belongs to the current cl) |
+ * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________|
+ */
+ COLLECT_PRIMARY_HOOKED,
+ COLLECT_PRIMARY_FOLLOWED_NOINPLACE,
+ /*
+ * The current collection has been linked with the owned chain, and
+ * could also be linked with the remaining collections, which means
+ * if the processing page is the tail page of the collection, thus
+ * the current collection can safely use the whole page (since
+ * the previous collection is under control) for in-place I/O, as
+ * illustrated below:
+ * ________________________________________________________________
+ * | tail (partial) page | head (partial) page |
+ * | (of the current cl) | (of the previous collection) |
+ * | PRIMARY_FOLLOWED or | |
+ * |_____PRIMARY_HOOKED___|____________PRIMARY_FOLLOWED____________|
+ *
+ * [ (*) the above page can be used as inplace I/O. ]
+ */
+ COLLECT_PRIMARY_FOLLOWED,
+};
+
+struct z_erofs_collector {
+ struct z_erofs_pagevec_ctor vector;
+
+ struct z_erofs_pcluster *pcl;
+ struct z_erofs_collection *cl;
+ struct page **compressedpages;
+ z_erofs_next_pcluster_t owned_head;
+
+ enum z_erofs_collectmode mode;
+};
+
+struct z_erofs_decompress_frontend {
+ struct inode *const inode;
+
+ struct z_erofs_collector clt;
+ struct erofs_map_blocks map;
+
+ /* used for applying cache strategy on the fly */
+ bool backmost;
+ erofs_off_t headoffset;
+};
+
+#define COLLECTOR_INIT() { \
+ .owned_head = Z_EROFS_PCLUSTER_TAIL, \
+ .mode = COLLECT_PRIMARY_FOLLOWED }
+
+#define DECOMPRESS_FRONTEND_INIT(__i) { \
+ .inode = __i, .clt = COLLECTOR_INIT(), \
+ .backmost = true, }
+
+static struct page *z_pagemap_global[Z_EROFS_VMAP_GLOBAL_PAGES];
+static DEFINE_MUTEX(z_pagemap_global_lock);
+
+static void preload_compressed_pages(struct z_erofs_collector *clt,
+ struct address_space *mc,
+ enum z_erofs_cache_alloctype type,
+ struct list_head *pagepool)
+{
+ /* nowhere to load compressed pages from */
+}
+
+/* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
+static inline bool try_inplace_io(struct z_erofs_collector *clt,
+ struct page *page)
+{
+ struct z_erofs_pcluster *const pcl = clt->pcl;
+ const unsigned int clusterpages = BIT(pcl->clusterbits);
+
+ while (clt->compressedpages < pcl->compressed_pages + clusterpages) {
+ if (!cmpxchg(clt->compressedpages++, NULL, page))
+ return true;
+ }
+ return false;
+}
+
+/* callers must be with collection lock held */
+static int z_erofs_attach_page(struct z_erofs_collector *clt,
+ struct page *page,
+ enum z_erofs_page_type type)
+{
+ int ret;
+ bool occupied;
+
+ /* give priority for inplaceio */
+ if (clt->mode >= COLLECT_PRIMARY &&
+ type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
+ try_inplace_io(clt, page))
+ return 0;
+
+ ret = z_erofs_pagevec_enqueue(&clt->vector,
+ page, type, &occupied);
+ clt->cl->vcnt += (unsigned int)ret;
+
+ return ret ? 0 : -EAGAIN;
+}
+
+static enum z_erofs_collectmode
+try_to_claim_pcluster(struct z_erofs_pcluster *pcl,
+ z_erofs_next_pcluster_t *owned_head)
+{
+ /* let's claim these following types of pclusters */
+retry:
+ if (pcl->next == Z_EROFS_PCLUSTER_NIL) {
+ /* type 1, nil pcluster */
+ if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
+ *owned_head) != Z_EROFS_PCLUSTER_NIL)
+ goto retry;
+
+ *owned_head = &pcl->next;
+ /* lucky, I am the followee :) */
+ return COLLECT_PRIMARY_FOLLOWED;
+ } else if (pcl->next == Z_EROFS_PCLUSTER_TAIL) {
+ /*
+ * type 2, link to the end of a existing open chain,
+ * be careful that its submission itself is governed
+ * by the original owned chain.
+ */
+ if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
+ *owned_head) != Z_EROFS_PCLUSTER_TAIL)
+ goto retry;
+ *owned_head = Z_EROFS_PCLUSTER_TAIL;
+ return COLLECT_PRIMARY_HOOKED;
+ }
+ return COLLECT_PRIMARY; /* :( better luck next time */
+}
+
+static struct z_erofs_collection *cllookup(struct z_erofs_collector *clt,
+ struct inode *inode,
+ struct erofs_map_blocks *map)
+{
+ struct erofs_workgroup *grp;
+ struct z_erofs_pcluster *pcl;
+ struct z_erofs_collection *cl;
+ unsigned int length;
+ bool tag;
+
+ grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT, &tag);
+ if (!grp)
+ return NULL;
+
+ pcl = container_of(grp, struct z_erofs_pcluster, obj);
+
+ cl = z_erofs_primarycollection(pcl);
+ if (unlikely(cl->pageofs != (map->m_la & ~PAGE_MASK))) {
+ DBG_BUGON(1);
+ return ERR_PTR(-EIO);
+ }
+
+ length = READ_ONCE(pcl->length);
+ if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
+ if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
+ DBG_BUGON(1);
+ return ERR_PTR(-EIO);
+ }
+ } else {
+ unsigned int llen = map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT;
+
+ if (map->m_flags & EROFS_MAP_FULL_MAPPED)
+ llen |= Z_EROFS_PCLUSTER_FULL_LENGTH;
+
+ while (llen > length &&
+ length != cmpxchg_relaxed(&pcl->length, length, llen)) {
+ cpu_relax();
+ length = READ_ONCE(pcl->length);
+ }
+ }
+ mutex_lock(&cl->lock);
+ clt->mode = try_to_claim_pcluster(pcl, &clt->owned_head);
+ clt->pcl = pcl;
+ clt->cl = cl;
+ return cl;
+}
+
+static struct z_erofs_collection *clregister(struct z_erofs_collector *clt,
+ struct inode *inode,
+ struct erofs_map_blocks *map)
+{
+ struct z_erofs_pcluster *pcl;
+ struct z_erofs_collection *cl;
+ int err;
+
+ /* no available workgroup, let's allocate one */
+ pcl = kmem_cache_alloc(pcluster_cachep, GFP_NOFS);
+ if (unlikely(!pcl))
+ return ERR_PTR(-ENOMEM);
+
+ init_always(pcl);
+ pcl->obj.index = map->m_pa >> PAGE_SHIFT;
+
+ pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
+ (map->m_flags & EROFS_MAP_FULL_MAPPED ?
+ Z_EROFS_PCLUSTER_FULL_LENGTH : 0);
+
+ if (map->m_flags & EROFS_MAP_ZIPPED)
+ pcl->algorithmformat = Z_EROFS_COMPRESSION_LZ4;
+ else
+ pcl->algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
+
+ pcl->clusterbits = EROFS_V(inode)->z_physical_clusterbits[0];
+ pcl->clusterbits -= PAGE_SHIFT;
+
+ /* new pclusters should be claimed as type 1, primary and followed */
+ pcl->next = clt->owned_head;
+ clt->mode = COLLECT_PRIMARY_FOLLOWED;
+
+ cl = z_erofs_primarycollection(pcl);
+ cl->pageofs = map->m_la & ~PAGE_MASK;
+
+ /*
+ * lock all primary followed works before visible to others
+ * and mutex_trylock *never* fails for a new pcluster.
+ */
+ mutex_trylock(&cl->lock);
+
+ err = erofs_register_workgroup(inode->i_sb, &pcl->obj, 0);
+ if (err) {
+ mutex_unlock(&cl->lock);
+ kmem_cache_free(pcluster_cachep, pcl);
+ return ERR_PTR(-EAGAIN);
+ }
+ clt->owned_head = &pcl->next;
+ clt->pcl = pcl;
+ clt->cl = cl;
+ return cl;
+}
+
+static int z_erofs_collector_begin(struct z_erofs_collector *clt,
+ struct inode *inode,
+ struct erofs_map_blocks *map)
+{
+ struct z_erofs_collection *cl;
+
+ DBG_BUGON(clt->cl);
+
+ /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous collection */
+ DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_NIL);
+ DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
+
+ if (!PAGE_ALIGNED(map->m_pa)) {
+ DBG_BUGON(1);
+ return -EINVAL;
+ }
+
+repeat:
+ cl = cllookup(clt, inode, map);
+ if (!cl) {
+ cl = clregister(clt, inode, map);
+
+ if (unlikely(cl == ERR_PTR(-EAGAIN)))
+ goto repeat;
+ }
+
+ if (IS_ERR(cl))
+ return PTR_ERR(cl);
+
+ z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
+ cl->pagevec, cl->vcnt);
+
+ clt->compressedpages = clt->pcl->compressed_pages;
+ if (clt->mode <= COLLECT_PRIMARY) /* cannot do in-place I/O */
+ clt->compressedpages += Z_EROFS_CLUSTER_MAX_PAGES;
+ return 0;
+}
+
+/*
+ * keep in mind that no referenced pclusters will be freed
+ * only after a RCU grace period.
+ */
+static void z_erofs_rcu_callback(struct rcu_head *head)
+{
+ struct z_erofs_collection *const cl =
+ container_of(head, struct z_erofs_collection, rcu);
+
+ kmem_cache_free(pcluster_cachep,
+ container_of(cl, struct z_erofs_pcluster,
+ primary_collection));
+}
+
+void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
+{
+ struct z_erofs_pcluster *const pcl =
+ container_of(grp, struct z_erofs_pcluster, obj);
+ struct z_erofs_collection *const cl = z_erofs_primarycollection(pcl);
+
+ call_rcu(&cl->rcu, z_erofs_rcu_callback);
+}
+
+static void z_erofs_collection_put(struct z_erofs_collection *cl)
+{
+ struct z_erofs_pcluster *const pcl =
+ container_of(cl, struct z_erofs_pcluster, primary_collection);
+
+ erofs_workgroup_put(&pcl->obj);
+}
+
+static bool z_erofs_collector_end(struct z_erofs_collector *clt)
+{
+ struct z_erofs_collection *cl = clt->cl;
+
+ if (!cl)
+ return false;
+
+ z_erofs_pagevec_ctor_exit(&clt->vector, false);
+ mutex_unlock(&cl->lock);
+
+ /*
+ * if all pending pages are added, don't hold its reference
+ * any longer if the pcluster isn't hosted by ourselves.
+ */
+ if (clt->mode < COLLECT_PRIMARY_FOLLOWED_NOINPLACE)
+ z_erofs_collection_put(cl);
+
+ clt->cl = NULL;
+ return true;
+}
+
+static inline struct page *__stagingpage_alloc(struct list_head *pagepool,
+ gfp_t gfp)
+{
+ struct page *page = erofs_allocpage(pagepool, gfp, true);
+
+ page->mapping = Z_EROFS_MAPPING_STAGING;
+ return page;
+}
+
+static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
+ struct page *page,
+ struct list_head *pagepool)
+{
+ struct inode *const inode = fe->inode;
+ struct erofs_sb_info *const sbi __maybe_unused = EROFS_I_SB(inode);
+ struct erofs_map_blocks *const map = &fe->map;
+ struct z_erofs_collector *const clt = &fe->clt;
+ const loff_t offset = page_offset(page);
+ bool tight = (clt->mode >= COLLECT_PRIMARY_HOOKED);
+
+ enum z_erofs_cache_alloctype cache_strategy;
+ enum z_erofs_page_type page_type;
+ unsigned int cur, end, spiltted, index;
+ int err = 0;
+
+ /* register locked file pages as online pages in pack */
+ z_erofs_onlinepage_init(page);
+
+ spiltted = 0;
+ end = PAGE_SIZE;
+repeat:
+ cur = end - 1;
+
+ /* lucky, within the range of the current map_blocks */
+ if (offset + cur >= map->m_la &&
+ offset + cur < map->m_la + map->m_llen) {
+ /* didn't get a valid collection previously (very rare) */
+ if (!clt->cl)
+ goto restart_now;
+ goto hitted;
+ }
+
+ /* go ahead the next map_blocks */
+ debugln("%s: [out-of-range] pos %llu", __func__, offset + cur);
+
+ if (z_erofs_collector_end(clt))
+ fe->backmost = false;
+
+ map->m_la = offset + cur;
+ map->m_llen = 0;
+ err = z_erofs_map_blocks_iter(inode, map, 0);
+ if (unlikely(err))
+ goto err_out;
+
+restart_now:
+ if (unlikely(!(map->m_flags & EROFS_MAP_MAPPED)))
+ goto hitted;
+
+ err = z_erofs_collector_begin(clt, inode, map);
+ if (unlikely(err))
+ goto err_out;
+
+ /* preload all compressed pages (maybe downgrade role if necessary) */
+ preload_compressed_pages(clt, MNGD_MAPPING(sbi), DONTALLOC, pagepool);
+
+ tight &= (clt->mode >= COLLECT_PRIMARY_HOOKED);
+hitted:
+ cur = end - min_t(unsigned int, offset + end - map->m_la, end);
+ if (unlikely(!(map->m_flags & EROFS_MAP_MAPPED))) {
+ zero_user_segment(page, cur, end);
+ goto next_part;
+ }
+
+ /* let's derive page type */
+ page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
+ (!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
+ (tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
+ Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
+
+ if (cur)
+ tight &= (clt->mode >= COLLECT_PRIMARY_FOLLOWED);
+
+retry:
+ err = z_erofs_attach_page(clt, page, page_type);
+ /* should allocate an additional staging page for pagevec */
+ if (err == -EAGAIN) {
+ struct page *const newpage =
+ __stagingpage_alloc(pagepool, GFP_NOFS);
+
+ err = z_erofs_attach_page(clt, newpage,
+ Z_EROFS_PAGE_TYPE_EXCLUSIVE);
+ if (likely(!err))
+ goto retry;
+ }
+
+ if (unlikely(err))
+ goto err_out;
+
+ index = page->index - (map->m_la >> PAGE_SHIFT);
+
+ z_erofs_onlinepage_fixup(page, index, true);
+
+ /* bump up the number of spiltted parts of a page */
+ ++spiltted;
+ /* also update nr_pages */
+ clt->cl->nr_pages = max_t(pgoff_t, clt->cl->nr_pages, index + 1);
+next_part:
+ /* can be used for verification */
+ map->m_llen = offset + cur - map->m_la;
+
+ end = cur;
+ if (end > 0)
+ goto repeat;
+
+out:
+ z_erofs_onlinepage_endio(page);
+
+ debugln("%s, finish page: %pK spiltted: %u map->m_llen %llu",
+ __func__, page, spiltted, map->m_llen);
+ return err;
+
+ /* if some error occurred while processing this page */
+err_out:
+ SetPageError(page);
+ goto out;
+}
+
+static void z_erofs_vle_unzip_kickoff(void *ptr, int bios)
+{
+ tagptr1_t t = tagptr_init(tagptr1_t, ptr);
+ struct z_erofs_unzip_io *io = tagptr_unfold_ptr(t);
+ bool background = tagptr_unfold_tags(t);
+
+ if (!background) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&io->u.wait.lock, flags);
+ if (!atomic_add_return(bios, &io->pending_bios))
+ wake_up_locked(&io->u.wait);
+ spin_unlock_irqrestore(&io->u.wait.lock, flags);
+ return;
+ }
+
+ if (!atomic_add_return(bios, &io->pending_bios))
+ queue_work(z_erofs_workqueue, &io->u.work);
+}
+
+static inline void z_erofs_vle_read_endio(struct bio *bio)
+{
+ struct erofs_sb_info *sbi = NULL;
+ blk_status_t err = bio->bi_status;
+ struct bio_vec *bvec;
+ struct bvec_iter_all iter_all;
+
+ bio_for_each_segment_all(bvec, bio, iter_all) {
+ struct page *page = bvec->bv_page;
+ bool cachemngd = false;
+
+ DBG_BUGON(PageUptodate(page));
+ DBG_BUGON(!page->mapping);
+
+ if (unlikely(!sbi && !z_erofs_page_is_staging(page))) {
+ sbi = EROFS_SB(page->mapping->host->i_sb);
+
+ if (time_to_inject(sbi, FAULT_READ_IO)) {
+ erofs_show_injection_info(FAULT_READ_IO);
+ err = BLK_STS_IOERR;
+ }
+ }
+
+ /* sbi should already be gotten if the page is managed */
+ if (sbi)
+ cachemngd = erofs_page_is_managed(sbi, page);
+
+ if (unlikely(err))
+ SetPageError(page);
+ else if (cachemngd)
+ SetPageUptodate(page);
+
+ if (cachemngd)
+ unlock_page(page);
+ }
+
+ z_erofs_vle_unzip_kickoff(bio->bi_private, -1);
+ bio_put(bio);
+}
+
+static int z_erofs_decompress_pcluster(struct super_block *sb,
+ struct z_erofs_pcluster *pcl,
+ struct list_head *pagepool)
+{
+ struct erofs_sb_info *const sbi = EROFS_SB(sb);
+ const unsigned int clusterpages = BIT(pcl->clusterbits);
+ struct z_erofs_pagevec_ctor ctor;
+ unsigned int i, outputsize, llen, nr_pages;
+ struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
+ struct page **pages, **compressed_pages, *page;
+
+ enum z_erofs_page_type page_type;
+ bool overlapped, partial;
+ struct z_erofs_collection *cl;
+ int err;
+
+ might_sleep();
+ cl = z_erofs_primarycollection(pcl);
+ DBG_BUGON(!READ_ONCE(cl->nr_pages));
+
+ mutex_lock(&cl->lock);
+ nr_pages = cl->nr_pages;
+
+ if (likely(nr_pages <= Z_EROFS_VMAP_ONSTACK_PAGES)) {
+ pages = pages_onstack;
+ } else if (nr_pages <= Z_EROFS_VMAP_GLOBAL_PAGES &&
+ mutex_trylock(&z_pagemap_global_lock)) {
+ pages = z_pagemap_global;
+ } else {
+ gfp_t gfp_flags = GFP_KERNEL;
+
+ if (nr_pages > Z_EROFS_VMAP_GLOBAL_PAGES)
+ gfp_flags |= __GFP_NOFAIL;
+
+ pages = kvmalloc_array(nr_pages, sizeof(struct page *),
+ gfp_flags);
+
+ /* fallback to global pagemap for the lowmem scenario */
+ if (unlikely(!pages)) {
+ mutex_lock(&z_pagemap_global_lock);
+ pages = z_pagemap_global;
+ }
+ }
+
+ for (i = 0; i < nr_pages; ++i)
+ pages[i] = NULL;
+
+ z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
+ cl->pagevec, 0);
+
+ for (i = 0; i < cl->vcnt; ++i) {
+ unsigned int pagenr;
+
+ page = z_erofs_pagevec_dequeue(&ctor, &page_type);
+
+ /* all pages in pagevec ought to be valid */
+ DBG_BUGON(!page);
+ DBG_BUGON(!page->mapping);
+
+ if (z_erofs_put_stagingpage(pagepool, page))
+ continue;
+
+ if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
+ pagenr = 0;
+ else
+ pagenr = z_erofs_onlinepage_index(page);
+
+ DBG_BUGON(pagenr >= nr_pages);
+ DBG_BUGON(pages[pagenr]);
+
+ pages[pagenr] = page;
+ }
+ z_erofs_pagevec_ctor_exit(&ctor, true);
+
+ overlapped = false;
+ compressed_pages = pcl->compressed_pages;
+
+ err = 0;
+ for (i = 0; i < clusterpages; ++i) {
+ unsigned int pagenr;
+
+ page = compressed_pages[i];
+
+ /* all compressed pages ought to be valid */
+ DBG_BUGON(!page);
+ DBG_BUGON(!page->mapping);
+
+ if (!z_erofs_page_is_staging(page)) {
+ if (erofs_page_is_managed(sbi, page)) {
+ if (unlikely(!PageUptodate(page)))
+ err = -EIO;
+ continue;
+ }
+
+ /*
+ * only if non-head page can be selected
+ * for inplace decompression
+ */
+ pagenr = z_erofs_onlinepage_index(page);
+
+ DBG_BUGON(pagenr >= nr_pages);
+ DBG_BUGON(pages[pagenr]);
+ pages[pagenr] = page;
+
+ overlapped = true;
+ }
+
+ /* PG_error needs checking for inplaced and staging pages */
+ if (unlikely(PageError(page))) {
+ DBG_BUGON(PageUptodate(page));
+ err = -EIO;
+ }
+ }
+
+ if (unlikely(err))
+ goto out;
+
+ llen = pcl->length >> Z_EROFS_PCLUSTER_LENGTH_BIT;
+ if (nr_pages << PAGE_SHIFT >= cl->pageofs + llen) {
+ outputsize = llen;
+ partial = !(pcl->length & Z_EROFS_PCLUSTER_FULL_LENGTH);
+ } else {
+ outputsize = (nr_pages << PAGE_SHIFT) - cl->pageofs;
+ partial = true;
+ }
+
+ err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
+ .sb = sb,
+ .in = compressed_pages,
+ .out = pages,
+ .pageofs_out = cl->pageofs,
+ .inputsize = PAGE_SIZE,
+ .outputsize = outputsize,
+ .alg = pcl->algorithmformat,
+ .inplace_io = overlapped,
+ .partial_decoding = partial
+ }, pagepool);
+
+out:
+ /* must handle all compressed pages before endding pages */
+ for (i = 0; i < clusterpages; ++i) {
+ page = compressed_pages[i];
+
+ if (erofs_page_is_managed(sbi, page))
+ continue;
+
+ /* recycle all individual staging pages */
+ (void)z_erofs_put_stagingpage(pagepool, page);
+
+ WRITE_ONCE(compressed_pages[i], NULL);
+ }
+
+ for (i = 0; i < nr_pages; ++i) {
+ page = pages[i];
+ if (!page)
+ continue;
+
+ DBG_BUGON(!page->mapping);
+
+ /* recycle all individual staging pages */
+ if (z_erofs_put_stagingpage(pagepool, page))
+ continue;
+
+ if (unlikely(err < 0))
+ SetPageError(page);
+
+ z_erofs_onlinepage_endio(page);
+ }
+
+ if (pages == z_pagemap_global)
+ mutex_unlock(&z_pagemap_global_lock);
+ else if (unlikely(pages != pages_onstack))
+ kvfree(pages);
+
+ cl->nr_pages = 0;
+ cl->vcnt = 0;
+
+ /* all cl locks MUST be taken before the following line */
+ WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
+
+ /* all cl locks SHOULD be released right now */
+ mutex_unlock(&cl->lock);
+
+ z_erofs_collection_put(cl);
+ return err;
+}
+
+static void z_erofs_vle_unzip_all(struct super_block *sb,
+ struct z_erofs_unzip_io *io,
+ struct list_head *pagepool)
+{
+ z_erofs_next_pcluster_t owned = io->head;
+
+ while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
+ struct z_erofs_pcluster *pcl;
+
+ /* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
+ DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
+
+ /* no possible that 'owned' equals NULL */
+ DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
+
+ pcl = container_of(owned, struct z_erofs_pcluster, next);
+ owned = READ_ONCE(pcl->next);
+
+ z_erofs_decompress_pcluster(sb, pcl, pagepool);
+ }
+}
+
+static void z_erofs_vle_unzip_wq(struct work_struct *work)
+{
+ struct z_erofs_unzip_io_sb *iosb =
+ container_of(work, struct z_erofs_unzip_io_sb, io.u.work);
+ LIST_HEAD(pagepool);
+
+ DBG_BUGON(iosb->io.head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
+ z_erofs_vle_unzip_all(iosb->sb, &iosb->io, &pagepool);
+
+ put_pages_list(&pagepool);
+ kvfree(iosb);
+}
+
+static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
+ unsigned int nr,
+ struct list_head *pagepool,
+ struct address_space *mc,
+ gfp_t gfp)
+{
+ /* determined at compile time to avoid too many #ifdefs */
+ const bool nocache = __builtin_constant_p(mc) ? !mc : false;
+ const pgoff_t index = pcl->obj.index;
+ bool tocache = false;
+
+ struct address_space *mapping;
+ struct page *oldpage, *page;
+
+ compressed_page_t t;
+ int justfound;
+
+repeat:
+ page = READ_ONCE(pcl->compressed_pages[nr]);
+ oldpage = page;
+
+ if (!page)
+ goto out_allocpage;
+
+ /*
+ * the cached page has not been allocated and
+ * an placeholder is out there, prepare it now.
+ */
+ if (!nocache && page == PAGE_UNALLOCATED) {
+ tocache = true;
+ goto out_allocpage;
+ }
+
+ /* process the target tagged pointer */
+ t = tagptr_init(compressed_page_t, page);
+ justfound = tagptr_unfold_tags(t);
+ page = tagptr_unfold_ptr(t);
+
+ mapping = READ_ONCE(page->mapping);
+
+ /*
+ * if managed cache is disabled, it's no way to
+ * get such a cached-like page.
+ */
+ if (nocache) {
+ /* if managed cache is disabled, it is impossible `justfound' */
+ DBG_BUGON(justfound);
+
+ /* and it should be locked, not uptodate, and not truncated */
+ DBG_BUGON(!PageLocked(page));
+ DBG_BUGON(PageUptodate(page));
+ DBG_BUGON(!mapping);
+ goto out;
+ }
+
+ /*
+ * unmanaged (file) pages are all locked solidly,
+ * therefore it is impossible for `mapping' to be NULL.
+ */
+ if (mapping && mapping != mc)
+ /* ought to be unmanaged pages */
+ goto out;
+
+ lock_page(page);
+
+ /* only true if page reclaim goes wrong, should never happen */
+ DBG_BUGON(justfound && PagePrivate(page));
+
+ /* the page is still in manage cache */
+ if (page->mapping == mc) {
+ WRITE_ONCE(pcl->compressed_pages[nr], page);
+
+ ClearPageError(page);
+ if (!PagePrivate(page)) {
+ /*
+ * impossible to be !PagePrivate(page) for
+ * the current restriction as well if
+ * the page is already in compressed_pages[].
+ */
+ DBG_BUGON(!justfound);
+
+ justfound = 0;
+ set_page_private(page, (unsigned long)pcl);
+ SetPagePrivate(page);
+ }
+
+ /* no need to submit io if it is already up-to-date */
+ if (PageUptodate(page)) {
+ unlock_page(page);
+ page = NULL;
+ }
+ goto out;
+ }
+
+ /*
+ * the managed page has been truncated, it's unsafe to
+ * reuse this one, let's allocate a new cache-managed page.
+ */
+ DBG_BUGON(page->mapping);
+ DBG_BUGON(!justfound);
+
+ tocache = true;
+ unlock_page(page);
+ put_page(page);
+out_allocpage:
+ page = __stagingpage_alloc(pagepool, gfp);
+ if (oldpage != cmpxchg(&pcl->compressed_pages[nr], oldpage, page)) {
+ list_add(&page->lru, pagepool);
+ cpu_relax();
+ goto repeat;
+ }
+ if (nocache || !tocache)
+ goto out;
+ if (add_to_page_cache_lru(page, mc, index + nr, gfp)) {
+ page->mapping = Z_EROFS_MAPPING_STAGING;
+ goto out;
+ }
+
+ set_page_private(page, (unsigned long)pcl);
+ SetPagePrivate(page);
+out: /* the only exit (for tracing and debugging) */
+ return page;
+}
+
+static struct z_erofs_unzip_io *jobqueue_init(struct super_block *sb,
+ struct z_erofs_unzip_io *io,
+ bool foreground)
+{
+ struct z_erofs_unzip_io_sb *iosb;
+
+ if (foreground) {
+ /* waitqueue available for foreground io */
+ DBG_BUGON(!io);
+
+ init_waitqueue_head(&io->u.wait);
+ atomic_set(&io->pending_bios, 0);
+ goto out;
+ }
+
+ iosb = kvzalloc(sizeof(*iosb), GFP_KERNEL | __GFP_NOFAIL);
+ DBG_BUGON(!iosb);
+
+ /* initialize fields in the allocated descriptor */
+ io = &iosb->io;
+ iosb->sb = sb;
+ INIT_WORK(&io->u.work, z_erofs_vle_unzip_wq);
+out:
+ io->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
+ return io;
+}
+
+/* define decompression jobqueue types */
+enum {
+ JQ_SUBMIT,
+ NR_JOBQUEUES,
+};
+
+static void *jobqueueset_init(struct super_block *sb,
+ z_erofs_next_pcluster_t qtail[],
+ struct z_erofs_unzip_io *q[],
+ struct z_erofs_unzip_io *fgq,
+ bool forcefg)
+{
+ q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, forcefg);
+ qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
+
+ return tagptr_cast_ptr(tagptr_fold(tagptr1_t, q[JQ_SUBMIT], !forcefg));
+}
+
+static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
+ z_erofs_next_pcluster_t qtail[],
+ z_erofs_next_pcluster_t owned_head)
+{
+ /* impossible to bypass submission for managed cache disabled */
+ DBG_BUGON(1);
+}
+
+static bool postsubmit_is_all_bypassed(struct z_erofs_unzip_io *q[],
+ unsigned int nr_bios,
+ bool force_fg)
+{
+ /* bios should be >0 if managed cache is disabled */
+ DBG_BUGON(!nr_bios);
+ return false;
+}
+
+static bool z_erofs_vle_submit_all(struct super_block *sb,
+ z_erofs_next_pcluster_t owned_head,
+ struct list_head *pagepool,
+ struct z_erofs_unzip_io *fgq,
+ bool force_fg)
+{
+ struct erofs_sb_info *const sbi __maybe_unused = EROFS_SB(sb);
+ z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
+ struct z_erofs_unzip_io *q[NR_JOBQUEUES];
+ struct bio *bio;
+ void *bi_private;
+ /* since bio will be NULL, no need to initialize last_index */
+ pgoff_t uninitialized_var(last_index);
+ bool force_submit = false;
+ unsigned int nr_bios;
+
+ if (unlikely(owned_head == Z_EROFS_PCLUSTER_TAIL))
+ return false;
+
+ force_submit = false;
+ bio = NULL;
+ nr_bios = 0;
+ bi_private = jobqueueset_init(sb, qtail, q, fgq, force_fg);
+
+ /* by default, all need io submission */
+ q[JQ_SUBMIT]->head = owned_head;
+
+ do {
+ struct z_erofs_pcluster *pcl;
+ unsigned int clusterpages;
+ pgoff_t first_index;
+ struct page *page;
+ unsigned int i = 0, bypass = 0;
+ int err;
+
+ /* no possible 'owned_head' equals the following */
+ DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
+ DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
+
+ pcl = container_of(owned_head, struct z_erofs_pcluster, next);
+
+ clusterpages = BIT(pcl->clusterbits);
+
+ /* close the main owned chain at first */
+ owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
+ Z_EROFS_PCLUSTER_TAIL_CLOSED);
+
+ first_index = pcl->obj.index;
+ force_submit |= (first_index != last_index + 1);
+
+repeat:
+ page = pickup_page_for_submission(pcl, i, pagepool,
+ MNGD_MAPPING(sbi),
+ GFP_NOFS);
+ if (!page) {
+ force_submit = true;
+ ++bypass;
+ goto skippage;
+ }
+
+ if (bio && force_submit) {
+submit_bio_retry:
+ __submit_bio(bio, REQ_OP_READ, 0);
+ bio = NULL;
+ }
+
+ if (!bio) {
+ bio = erofs_grab_bio(sb, first_index + i,
+ BIO_MAX_PAGES, bi_private,
+ z_erofs_vle_read_endio, true);
+ ++nr_bios;
+ }
+
+ err = bio_add_page(bio, page, PAGE_SIZE, 0);
+ if (err < PAGE_SIZE)
+ goto submit_bio_retry;
+
+ force_submit = false;
+ last_index = first_index + i;
+skippage:
+ if (++i < clusterpages)
+ goto repeat;
+
+ if (bypass < clusterpages)
+ qtail[JQ_SUBMIT] = &pcl->next;
+ else
+ move_to_bypass_jobqueue(pcl, qtail, owned_head);
+ } while (owned_head != Z_EROFS_PCLUSTER_TAIL);
+
+ if (bio)
+ __submit_bio(bio, REQ_OP_READ, 0);
+
+ if (postsubmit_is_all_bypassed(q, nr_bios, force_fg))
+ return true;
+
+ z_erofs_vle_unzip_kickoff(bi_private, nr_bios);
+ return true;
+}
+
+static void z_erofs_submit_and_unzip(struct super_block *sb,
+ struct z_erofs_collector *clt,
+ struct list_head *pagepool,
+ bool force_fg)
+{
+ struct z_erofs_unzip_io io[NR_JOBQUEUES];
+
+ if (!z_erofs_vle_submit_all(sb, clt->owned_head,
+ pagepool, io, force_fg))
+ return;
+
+ if (!force_fg)
+ return;
+
+ /* wait until all bios are completed */
+ wait_event(io[JQ_SUBMIT].u.wait,
+ !atomic_read(&io[JQ_SUBMIT].pending_bios));
+
+ /* let's synchronous decompression */
+ z_erofs_vle_unzip_all(sb, &io[JQ_SUBMIT], pagepool);
+}
+
+static int z_erofs_vle_normalaccess_readpage(struct file *file,
+ struct page *page)
+{
+ struct inode *const inode = page->mapping->host;
+ struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
+ int err;
+ LIST_HEAD(pagepool);
+
+ trace_erofs_readpage(page, false);
+
+ f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
+
+ err = z_erofs_do_read_page(&f, page, &pagepool);
+ (void)z_erofs_collector_end(&f.clt);
+
+ if (err) {
+ errln("%s, failed to read, err [%d]", __func__, err);
+ goto out;
+ }
+
+ z_erofs_submit_and_unzip(inode->i_sb, &f.clt, &pagepool, true);
+out:
+ if (f.map.mpage)
+ put_page(f.map.mpage);
+
+ /* clean up the remaining free pages */
+ put_pages_list(&pagepool);
+ return 0;
+}
+
+static bool should_decompress_synchronously(struct erofs_sb_info *sbi,
+ unsigned int nr)
+{
+ return nr <= sbi->max_sync_decompress_pages;
+}
+
+static int z_erofs_vle_normalaccess_readpages(struct file *filp,
+ struct address_space *mapping,
+ struct list_head *pages,
+ unsigned int nr_pages)
+{
+ struct inode *const inode = mapping->host;
+ struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
+
+ bool sync = should_decompress_synchronously(sbi, nr_pages);
+ struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
+ gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
+ struct page *head = NULL;
+ LIST_HEAD(pagepool);
+
+ trace_erofs_readpages(mapping->host, lru_to_page(pages),
+ nr_pages, false);
+
+ f.headoffset = (erofs_off_t)lru_to_page(pages)->index << PAGE_SHIFT;
+
+ for (; nr_pages; --nr_pages) {
+ struct page *page = lru_to_page(pages);
+
+ prefetchw(&page->flags);
+ list_del(&page->lru);
+
+ /*
+ * A pure asynchronous readahead is indicated if
+ * a PG_readahead marked page is hitted at first.
+ * Let's also do asynchronous decompression for this case.
+ */
+ sync &= !(PageReadahead(page) && !head);
+
+ if (add_to_page_cache_lru(page, mapping, page->index, gfp)) {
+ list_add(&page->lru, &pagepool);
+ continue;
+ }
+
+ set_page_private(page, (unsigned long)head);
+ head = page;
+ }
+
+ while (head) {
+ struct page *page = head;
+ int err;
+
+ /* traversal in reverse order */
+ head = (void *)page_private(page);
+
+ err = z_erofs_do_read_page(&f, page, &pagepool);
+ if (err) {
+ struct erofs_vnode *vi = EROFS_V(inode);
+
+ errln("%s, readahead error at page %lu of nid %llu",
+ __func__, page->index, vi->nid);
+ }
+ put_page(page);
+ }
+
+ (void)z_erofs_collector_end(&f.clt);
+
+ z_erofs_submit_and_unzip(inode->i_sb, &f.clt, &pagepool, sync);
+
+ if (f.map.mpage)
+ put_page(f.map.mpage);
+
+ /* clean up the remaining free pages */
+ put_pages_list(&pagepool);
+ return 0;
+}
+
+const struct address_space_operations z_erofs_vle_normalaccess_aops = {
+ .readpage = z_erofs_vle_normalaccess_readpage,
+ .readpages = z_erofs_vle_normalaccess_readpages,
+};
+
diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h
new file mode 100644
index 000000000000..3a82ae933015
--- /dev/null
+++ b/fs/erofs/zdata.h
@@ -0,0 +1,192 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * linux/fs/erofs/zdata.h
+ *
+ * Copyright (C) 2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ */
+#ifndef __EROFS_FS_ZDATA_H
+#define __EROFS_FS_ZDATA_H
+
+#include "internal.h"
+#include "zpvec.h"
+
+#define Z_EROFS_NR_INLINE_PAGEVECS 3
+
+/*
+ * Structure fields follow one of the following exclusion rules.
+ *
+ * I: Modifiable by initialization/destruction paths and read-only
+ * for everyone else;
+ *
+ * L: Field should be protected by pageset lock;
+ *
+ * A: Field should be accessed / updated in atomic for parallelized code.
+ */
+struct z_erofs_collection {
+ struct mutex lock;
+
+ /* I: page offset of start position of decompression */
+ unsigned short pageofs;
+
+ /* L: maximum relative page index in pagevec[] */
+ unsigned short nr_pages;
+
+ /* L: total number of pages in pagevec[] */
+ unsigned int vcnt;
+
+ union {
+ /* L: inline a certain number of pagevecs for bootstrap */
+ erofs_vtptr_t pagevec[Z_EROFS_NR_INLINE_PAGEVECS];
+
+ /* I: can be used to free the pcluster by RCU. */
+ struct rcu_head rcu;
+ };
+};
+
+#define Z_EROFS_PCLUSTER_FULL_LENGTH 0x00000001
+#define Z_EROFS_PCLUSTER_LENGTH_BIT 1
+
+/*
+ * let's leave a type here in case of introducing
+ * another tagged pointer later.
+ */
+typedef void *z_erofs_next_pcluster_t;
+
+struct z_erofs_pcluster {
+ struct erofs_workgroup obj;
+ struct z_erofs_collection primary_collection;
+
+ /* A: point to next chained pcluster or TAILs */
+ z_erofs_next_pcluster_t next;
+
+ /* A: compressed pages (including multi-usage pages) */
+ struct page *compressed_pages[Z_EROFS_CLUSTER_MAX_PAGES];
+
+ /* A: lower limit of decompressed length and if full length or not */
+ unsigned int length;
+
+ /* I: compression algorithm format */
+ unsigned char algorithmformat;
+ /* I: bit shift of physical cluster size */
+ unsigned char clusterbits;
+};
+
+#define z_erofs_primarycollection(pcluster) (&(pcluster)->primary_collection)
+
+/* let's avoid the valid 32-bit kernel addresses */
+
+/* the chained workgroup has't submitted io (still open) */
+#define Z_EROFS_PCLUSTER_TAIL ((void *)0x5F0ECAFE)
+/* the chained workgroup has already submitted io */
+#define Z_EROFS_PCLUSTER_TAIL_CLOSED ((void *)0x5F0EDEAD)
+
+#define Z_EROFS_PCLUSTER_NIL (NULL)
+
+#define Z_EROFS_WORKGROUP_SIZE sizeof(struct z_erofs_pcluster)
+
+struct z_erofs_unzip_io {
+ atomic_t pending_bios;
+ z_erofs_next_pcluster_t head;
+
+ union {
+ wait_queue_head_t wait;
+ struct work_struct work;
+ } u;
+};
+
+struct z_erofs_unzip_io_sb {
+ struct z_erofs_unzip_io io;
+ struct super_block *sb;
+};
+
+#define MNGD_MAPPING(sbi) (NULL)
+static inline bool erofs_page_is_managed(const struct erofs_sb_info *sbi,
+ struct page *page) { return false; }
+
+#define Z_EROFS_ONLINEPAGE_COUNT_BITS 2
+#define Z_EROFS_ONLINEPAGE_COUNT_MASK ((1 << Z_EROFS_ONLINEPAGE_COUNT_BITS) - 1)
+#define Z_EROFS_ONLINEPAGE_INDEX_SHIFT (Z_EROFS_ONLINEPAGE_COUNT_BITS)
+
+/*
+ * waiters (aka. ongoing_packs): # to unlock the page
+ * sub-index: 0 - for partial page, >= 1 full page sub-index
+ */
+typedef atomic_t z_erofs_onlinepage_t;
+
+/* type punning */
+union z_erofs_onlinepage_converter {
+ z_erofs_onlinepage_t *o;
+ unsigned long *v;
+};
+
+static inline unsigned int z_erofs_onlinepage_index(struct page *page)
+{
+ union z_erofs_onlinepage_converter u;
+
+ DBG_BUGON(!PagePrivate(page));
+ u.v = &page_private(page);
+
+ return atomic_read(u.o) >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
+}
+
+static inline void z_erofs_onlinepage_init(struct page *page)
+{
+ union {
+ z_erofs_onlinepage_t o;
+ unsigned long v;
+ /* keep from being unlocked in advance */
+ } u = { .o = ATOMIC_INIT(1) };
+
+ set_page_private(page, u.v);
+ smp_wmb();
+ SetPagePrivate(page);
+}
+
+static inline void z_erofs_onlinepage_fixup(struct page *page,
+ uintptr_t index, bool down)
+{
+ unsigned long *p, o, v, id;
+repeat:
+ p = &page_private(page);
+ o = READ_ONCE(*p);
+
+ id = o >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
+ if (id) {
+ if (!index)
+ return;
+
+ DBG_BUGON(id != index);
+ }
+
+ v = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) |
+ ((o & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down);
+ if (cmpxchg(p, o, v) != o)
+ goto repeat;
+}
+
+static inline void z_erofs_onlinepage_endio(struct page *page)
+{
+ union z_erofs_onlinepage_converter u;
+ unsigned int v;
+
+ DBG_BUGON(!PagePrivate(page));
+ u.v = &page_private(page);
+
+ v = atomic_dec_return(u.o);
+ if (!(v & Z_EROFS_ONLINEPAGE_COUNT_MASK)) {
+ ClearPagePrivate(page);
+ if (!PageError(page))
+ SetPageUptodate(page);
+ unlock_page(page);
+ }
+ debugln("%s, page %p value %x", __func__, page, atomic_read(u.o));
+}
+
+#define Z_EROFS_VMAP_ONSTACK_PAGES \
+ min_t(unsigned int, THREAD_SIZE / 8 / sizeof(struct page *), 96U)
+#define Z_EROFS_VMAP_GLOBAL_PAGES 2048
+
+#endif
+
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 8cd55c33f50b..d887ea6d4fd5 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -23,7 +23,9 @@ int z_erofs_fill_inode(struct inode *inode)
vi->z_physical_clusterbits[1] = vi->z_logical_clusterbits;
set_bit(EROFS_V_Z_INITED_BIT, &vi->flags);
}
- return -ENOTSUPP;
+
+ inode->i_mapping->a_ops = &z_erofs_vle_normalaccess_aops;
+ return 0;
}

static int fill_inode_lazy(struct inode *inode)
--
2.17.1