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-rw-r--r--fs/erofs/zdata.c1767
1 files changed, 1767 insertions, 0 deletions
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
new file mode 100644
index 000000000..cf9a2fa7f
--- /dev/null
+++ b/fs/erofs/zdata.c
@@ -0,0 +1,1767 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2018 HUAWEI, Inc.
+ * https://www.huawei.com/
+ * Copyright (C) 2022 Alibaba Cloud
+ */
+#include "compress.h"
+#include <linux/prefetch.h>
+#include <linux/psi.h>
+
+#include <trace/events/erofs.h>
+
+#define Z_EROFS_PCLUSTER_MAX_PAGES (Z_EROFS_PCLUSTER_MAX_SIZE / PAGE_SIZE)
+#define Z_EROFS_INLINE_BVECS 2
+
+/*
+ * let's leave a type here in case of introducing
+ * another tagged pointer later.
+ */
+typedef void *z_erofs_next_pcluster_t;
+
+struct z_erofs_bvec {
+ struct page *page;
+ int offset;
+ unsigned int end;
+};
+
+#define __Z_EROFS_BVSET(name, total) \
+struct name { \
+ /* point to the next page which contains the following bvecs */ \
+ struct page *nextpage; \
+ struct z_erofs_bvec bvec[total]; \
+}
+__Z_EROFS_BVSET(z_erofs_bvset,);
+__Z_EROFS_BVSET(z_erofs_bvset_inline, Z_EROFS_INLINE_BVECS);
+
+/*
+ * 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 the pcluster lock;
+ *
+ * A: Field should be accessed / updated in atomic for parallelized code.
+ */
+struct z_erofs_pcluster {
+ struct erofs_workgroup obj;
+ struct mutex lock;
+
+ /* A: point to next chained pcluster or TAILs */
+ z_erofs_next_pcluster_t next;
+
+ /* L: the maximum decompression size of this round */
+ unsigned int length;
+
+ /* L: total number of bvecs */
+ unsigned int vcnt;
+
+ /* I: page offset of start position of decompression */
+ unsigned short pageofs_out;
+
+ /* I: page offset of inline compressed data */
+ unsigned short pageofs_in;
+
+ union {
+ /* L: inline a certain number of bvec for bootstrap */
+ struct z_erofs_bvset_inline bvset;
+
+ /* I: can be used to free the pcluster by RCU. */
+ struct rcu_head rcu;
+ };
+
+ union {
+ /* I: physical cluster size in pages */
+ unsigned short pclusterpages;
+
+ /* I: tailpacking inline compressed size */
+ unsigned short tailpacking_size;
+ };
+
+ /* I: compression algorithm format */
+ unsigned char algorithmformat;
+
+ /* L: whether partial decompression or not */
+ bool partial;
+
+ /* L: indicate several pageofs_outs or not */
+ bool multibases;
+
+ /* A: compressed bvecs (can be cached or inplaced pages) */
+ struct z_erofs_bvec compressed_bvecs[];
+};
+
+/* let's avoid the valid 32-bit kernel addresses */
+
+/* the end of a chain of pclusters */
+#define Z_EROFS_PCLUSTER_TAIL ((void *)0x5F0ECAFE)
+#define Z_EROFS_PCLUSTER_NIL (NULL)
+
+struct z_erofs_decompressqueue {
+ struct super_block *sb;
+ atomic_t pending_bios;
+ z_erofs_next_pcluster_t head;
+
+ union {
+ struct completion done;
+ struct work_struct work;
+ } u;
+ bool eio, sync;
+};
+
+static inline bool z_erofs_is_inline_pcluster(struct z_erofs_pcluster *pcl)
+{
+ return !pcl->obj.index;
+}
+
+static inline unsigned int z_erofs_pclusterpages(struct z_erofs_pcluster *pcl)
+{
+ if (z_erofs_is_inline_pcluster(pcl))
+ return 1;
+ return pcl->pclusterpages;
+}
+
+/*
+ * bit 30: I/O error occurred on this page
+ * bit 0 - 29: remaining parts to complete this page
+ */
+#define Z_EROFS_PAGE_EIO (1 << 30)
+
+static inline void z_erofs_onlinepage_init(struct page *page)
+{
+ union {
+ atomic_t o;
+ unsigned long v;
+ } u = { .o = ATOMIC_INIT(1) };
+
+ set_page_private(page, u.v);
+ smp_wmb();
+ SetPagePrivate(page);
+}
+
+static inline void z_erofs_onlinepage_split(struct page *page)
+{
+ atomic_inc((atomic_t *)&page->private);
+}
+
+static inline void z_erofs_page_mark_eio(struct page *page)
+{
+ int orig;
+
+ do {
+ orig = atomic_read((atomic_t *)&page->private);
+ } while (atomic_cmpxchg((atomic_t *)&page->private, orig,
+ orig | Z_EROFS_PAGE_EIO) != orig);
+}
+
+static inline void z_erofs_onlinepage_endio(struct page *page)
+{
+ unsigned int v;
+
+ DBG_BUGON(!PagePrivate(page));
+ v = atomic_dec_return((atomic_t *)&page->private);
+ if (!(v & ~Z_EROFS_PAGE_EIO)) {
+ set_page_private(page, 0);
+ ClearPagePrivate(page);
+ if (!(v & Z_EROFS_PAGE_EIO))
+ SetPageUptodate(page);
+ unlock_page(page);
+ }
+}
+
+#define Z_EROFS_ONSTACK_PAGES 32
+
+/*
+ * since pclustersize is variable for big pcluster feature, introduce slab
+ * pools implementation for different pcluster sizes.
+ */
+struct z_erofs_pcluster_slab {
+ struct kmem_cache *slab;
+ unsigned int maxpages;
+ char name[48];
+};
+
+#define _PCLP(n) { .maxpages = n }
+
+static struct z_erofs_pcluster_slab pcluster_pool[] __read_mostly = {
+ _PCLP(1), _PCLP(4), _PCLP(16), _PCLP(64), _PCLP(128),
+ _PCLP(Z_EROFS_PCLUSTER_MAX_PAGES)
+};
+
+struct z_erofs_bvec_iter {
+ struct page *bvpage;
+ struct z_erofs_bvset *bvset;
+ unsigned int nr, cur;
+};
+
+static struct page *z_erofs_bvec_iter_end(struct z_erofs_bvec_iter *iter)
+{
+ if (iter->bvpage)
+ kunmap_local(iter->bvset);
+ return iter->bvpage;
+}
+
+static struct page *z_erofs_bvset_flip(struct z_erofs_bvec_iter *iter)
+{
+ unsigned long base = (unsigned long)((struct z_erofs_bvset *)0)->bvec;
+ /* have to access nextpage in advance, otherwise it will be unmapped */
+ struct page *nextpage = iter->bvset->nextpage;
+ struct page *oldpage;
+
+ DBG_BUGON(!nextpage);
+ oldpage = z_erofs_bvec_iter_end(iter);
+ iter->bvpage = nextpage;
+ iter->bvset = kmap_local_page(nextpage);
+ iter->nr = (PAGE_SIZE - base) / sizeof(struct z_erofs_bvec);
+ iter->cur = 0;
+ return oldpage;
+}
+
+static void z_erofs_bvec_iter_begin(struct z_erofs_bvec_iter *iter,
+ struct z_erofs_bvset_inline *bvset,
+ unsigned int bootstrap_nr,
+ unsigned int cur)
+{
+ *iter = (struct z_erofs_bvec_iter) {
+ .nr = bootstrap_nr,
+ .bvset = (struct z_erofs_bvset *)bvset,
+ };
+
+ while (cur > iter->nr) {
+ cur -= iter->nr;
+ z_erofs_bvset_flip(iter);
+ }
+ iter->cur = cur;
+}
+
+static int z_erofs_bvec_enqueue(struct z_erofs_bvec_iter *iter,
+ struct z_erofs_bvec *bvec,
+ struct page **candidate_bvpage)
+{
+ if (iter->cur == iter->nr) {
+ if (!*candidate_bvpage)
+ return -EAGAIN;
+
+ DBG_BUGON(iter->bvset->nextpage);
+ iter->bvset->nextpage = *candidate_bvpage;
+ z_erofs_bvset_flip(iter);
+
+ iter->bvset->nextpage = NULL;
+ *candidate_bvpage = NULL;
+ }
+ iter->bvset->bvec[iter->cur++] = *bvec;
+ return 0;
+}
+
+static void z_erofs_bvec_dequeue(struct z_erofs_bvec_iter *iter,
+ struct z_erofs_bvec *bvec,
+ struct page **old_bvpage)
+{
+ if (iter->cur == iter->nr)
+ *old_bvpage = z_erofs_bvset_flip(iter);
+ else
+ *old_bvpage = NULL;
+ *bvec = iter->bvset->bvec[iter->cur++];
+}
+
+static void z_erofs_destroy_pcluster_pool(void)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
+ if (!pcluster_pool[i].slab)
+ continue;
+ kmem_cache_destroy(pcluster_pool[i].slab);
+ pcluster_pool[i].slab = NULL;
+ }
+}
+
+static int z_erofs_create_pcluster_pool(void)
+{
+ struct z_erofs_pcluster_slab *pcs;
+ struct z_erofs_pcluster *a;
+ unsigned int size;
+
+ for (pcs = pcluster_pool;
+ pcs < pcluster_pool + ARRAY_SIZE(pcluster_pool); ++pcs) {
+ size = struct_size(a, compressed_bvecs, pcs->maxpages);
+
+ sprintf(pcs->name, "erofs_pcluster-%u", pcs->maxpages);
+ pcs->slab = kmem_cache_create(pcs->name, size, 0,
+ SLAB_RECLAIM_ACCOUNT, NULL);
+ if (pcs->slab)
+ continue;
+
+ z_erofs_destroy_pcluster_pool();
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+static struct z_erofs_pcluster *z_erofs_alloc_pcluster(unsigned int nrpages)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
+ struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
+ struct z_erofs_pcluster *pcl;
+
+ if (nrpages > pcs->maxpages)
+ continue;
+
+ pcl = kmem_cache_zalloc(pcs->slab, GFP_NOFS);
+ if (!pcl)
+ return ERR_PTR(-ENOMEM);
+ pcl->pclusterpages = nrpages;
+ return pcl;
+ }
+ return ERR_PTR(-EINVAL);
+}
+
+static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
+{
+ unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
+ struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
+
+ if (pclusterpages > pcs->maxpages)
+ continue;
+
+ kmem_cache_free(pcs->slab, pcl);
+ return;
+ }
+ DBG_BUGON(1);
+}
+
+static struct workqueue_struct *z_erofs_workqueue __read_mostly;
+
+void z_erofs_exit_zip_subsystem(void)
+{
+ destroy_workqueue(z_erofs_workqueue);
+ z_erofs_destroy_pcluster_pool();
+}
+
+static inline int z_erofs_init_workqueue(void)
+{
+ const unsigned int onlinecpus = num_possible_cpus();
+
+ /*
+ * 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",
+ WQ_UNBOUND | WQ_HIGHPRI,
+ onlinecpus + onlinecpus / 4);
+ return z_erofs_workqueue ? 0 : -ENOMEM;
+}
+
+int __init z_erofs_init_zip_subsystem(void)
+{
+ int err = z_erofs_create_pcluster_pool();
+
+ if (err)
+ return err;
+ err = z_erofs_init_workqueue();
+ if (err)
+ z_erofs_destroy_pcluster_pool();
+ return err;
+}
+
+enum z_erofs_pclustermode {
+ Z_EROFS_PCLUSTER_INFLIGHT,
+ /*
+ * a weak form of Z_EROFS_PCLUSTER_FOLLOWED, the difference is that it
+ * could be dispatched into bypass queue later due to uptodated managed
+ * pages. All related online pages cannot be reused for inplace I/O (or
+ * bvpage) since it can be directly decoded without I/O submission.
+ */
+ Z_EROFS_PCLUSTER_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) |
+ * | | |
+ * |__PCLUSTER_FOLLOWED___|___________PCLUSTER_FOLLOWED____________|
+ *
+ * [ (*) the above page can be used as inplace I/O. ]
+ */
+ Z_EROFS_PCLUSTER_FOLLOWED,
+};
+
+struct z_erofs_decompress_frontend {
+ struct inode *const inode;
+ struct erofs_map_blocks map;
+ struct z_erofs_bvec_iter biter;
+
+ struct page *candidate_bvpage;
+ struct z_erofs_pcluster *pcl;
+ z_erofs_next_pcluster_t owned_head;
+ enum z_erofs_pclustermode mode;
+
+ bool readahead;
+ /* used for applying cache strategy on the fly */
+ bool backmost;
+ erofs_off_t headoffset;
+
+ /* a pointer used to pick up inplace I/O pages */
+ unsigned int icur;
+};
+
+#define DECOMPRESS_FRONTEND_INIT(__i) { \
+ .inode = __i, .owned_head = Z_EROFS_PCLUSTER_TAIL, \
+ .mode = Z_EROFS_PCLUSTER_FOLLOWED, .backmost = true }
+
+static bool z_erofs_should_alloc_cache(struct z_erofs_decompress_frontend *fe)
+{
+ unsigned int cachestrategy = EROFS_I_SB(fe->inode)->opt.cache_strategy;
+
+ if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
+ return false;
+
+ if (fe->backmost)
+ return true;
+
+ if (cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
+ fe->map.m_la < fe->headoffset)
+ return true;
+
+ return false;
+}
+
+static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,
+ struct page **pagepool)
+{
+ struct address_space *mc = MNGD_MAPPING(EROFS_I_SB(fe->inode));
+ struct z_erofs_pcluster *pcl = fe->pcl;
+ bool shouldalloc = z_erofs_should_alloc_cache(fe);
+ bool standalone = true;
+ /*
+ * optimistic allocation without direct reclaim since inplace I/O
+ * can be used if low memory otherwise.
+ */
+ gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) |
+ __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
+ unsigned int i;
+
+ if (fe->mode < Z_EROFS_PCLUSTER_FOLLOWED)
+ return;
+
+ for (i = 0; i < pcl->pclusterpages; ++i) {
+ struct page *page;
+ void *t; /* mark pages just found for debugging */
+ struct page *newpage = NULL;
+
+ /* the compressed page was loaded before */
+ if (READ_ONCE(pcl->compressed_bvecs[i].page))
+ continue;
+
+ page = find_get_page(mc, pcl->obj.index + i);
+
+ if (page) {
+ t = (void *)((unsigned long)page | 1);
+ } else {
+ /* I/O is needed, no possible to decompress directly */
+ standalone = false;
+ if (!shouldalloc)
+ continue;
+
+ /*
+ * try to use cached I/O if page allocation
+ * succeeds or fallback to in-place I/O instead
+ * to avoid any direct reclaim.
+ */
+ newpage = erofs_allocpage(pagepool, gfp);
+ if (!newpage)
+ continue;
+ set_page_private(newpage, Z_EROFS_PREALLOCATED_PAGE);
+ t = (void *)((unsigned long)newpage | 1);
+ }
+
+ if (!cmpxchg_relaxed(&pcl->compressed_bvecs[i].page, NULL, t))
+ continue;
+
+ if (page)
+ put_page(page);
+ else if (newpage)
+ erofs_pagepool_add(pagepool, newpage);
+ }
+
+ /*
+ * don't do inplace I/O if all compressed pages are available in
+ * managed cache since it can be moved to the bypass queue instead.
+ */
+ if (standalone)
+ fe->mode = Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE;
+}
+
+/* called by erofs_shrinker to get rid of all compressed_pages */
+int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
+ struct erofs_workgroup *grp)
+{
+ struct z_erofs_pcluster *const pcl =
+ container_of(grp, struct z_erofs_pcluster, obj);
+ int i;
+
+ DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
+ /*
+ * refcount of workgroup is now freezed as 1,
+ * therefore no need to worry about available decompression users.
+ */
+ for (i = 0; i < pcl->pclusterpages; ++i) {
+ struct page *page = pcl->compressed_bvecs[i].page;
+
+ if (!page)
+ continue;
+
+ /* block other users from reclaiming or migrating the page */
+ if (!trylock_page(page))
+ return -EBUSY;
+
+ if (!erofs_page_is_managed(sbi, page))
+ continue;
+
+ /* barrier is implied in the following 'unlock_page' */
+ WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);
+ detach_page_private(page);
+ unlock_page(page);
+ }
+ return 0;
+}
+
+int erofs_try_to_free_cached_page(struct page *page)
+{
+ struct z_erofs_pcluster *const pcl = (void *)page_private(page);
+ int ret, i;
+
+ if (!erofs_workgroup_try_to_freeze(&pcl->obj, 1))
+ return 0;
+
+ ret = 0;
+ DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
+ for (i = 0; i < pcl->pclusterpages; ++i) {
+ if (pcl->compressed_bvecs[i].page == page) {
+ WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);
+ ret = 1;
+ break;
+ }
+ }
+ erofs_workgroup_unfreeze(&pcl->obj, 1);
+ if (ret)
+ detach_page_private(page);
+ return ret;
+}
+
+static bool z_erofs_try_inplace_io(struct z_erofs_decompress_frontend *fe,
+ struct z_erofs_bvec *bvec)
+{
+ struct z_erofs_pcluster *const pcl = fe->pcl;
+
+ while (fe->icur > 0) {
+ if (!cmpxchg(&pcl->compressed_bvecs[--fe->icur].page,
+ NULL, bvec->page)) {
+ pcl->compressed_bvecs[fe->icur] = *bvec;
+ return true;
+ }
+ }
+ return false;
+}
+
+/* callers must be with pcluster lock held */
+static int z_erofs_attach_page(struct z_erofs_decompress_frontend *fe,
+ struct z_erofs_bvec *bvec, bool exclusive)
+{
+ int ret;
+
+ if (exclusive) {
+ /* give priority for inplaceio to use file pages first */
+ if (z_erofs_try_inplace_io(fe, bvec))
+ return 0;
+ /* otherwise, check if it can be used as a bvpage */
+ if (fe->mode >= Z_EROFS_PCLUSTER_FOLLOWED &&
+ !fe->candidate_bvpage)
+ fe->candidate_bvpage = bvec->page;
+ }
+ ret = z_erofs_bvec_enqueue(&fe->biter, bvec, &fe->candidate_bvpage);
+ fe->pcl->vcnt += (ret >= 0);
+ return ret;
+}
+
+static void z_erofs_try_to_claim_pcluster(struct z_erofs_decompress_frontend *f)
+{
+ struct z_erofs_pcluster *pcl = f->pcl;
+ z_erofs_next_pcluster_t *owned_head = &f->owned_head;
+
+ /* type 1, nil pcluster (this pcluster doesn't belong to any chain.) */
+ if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
+ *owned_head) == Z_EROFS_PCLUSTER_NIL) {
+ *owned_head = &pcl->next;
+ /* so we can attach this pcluster to our submission chain. */
+ f->mode = Z_EROFS_PCLUSTER_FOLLOWED;
+ return;
+ }
+
+ /* type 2, it belongs to an ongoing chain */
+ f->mode = Z_EROFS_PCLUSTER_INFLIGHT;
+}
+
+static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe)
+{
+ struct erofs_map_blocks *map = &fe->map;
+ bool ztailpacking = map->m_flags & EROFS_MAP_META;
+ struct z_erofs_pcluster *pcl;
+ struct erofs_workgroup *grp;
+ int err;
+
+ if (!(map->m_flags & EROFS_MAP_ENCODED) ||
+ (!ztailpacking && !(map->m_pa >> PAGE_SHIFT))) {
+ DBG_BUGON(1);
+ return -EFSCORRUPTED;
+ }
+
+ /* no available pcluster, let's allocate one */
+ pcl = z_erofs_alloc_pcluster(ztailpacking ? 1 :
+ map->m_plen >> PAGE_SHIFT);
+ if (IS_ERR(pcl))
+ return PTR_ERR(pcl);
+
+ atomic_set(&pcl->obj.refcount, 1);
+ pcl->algorithmformat = map->m_algorithmformat;
+ pcl->length = 0;
+ pcl->partial = true;
+
+ /* new pclusters should be claimed as type 1, primary and followed */
+ pcl->next = fe->owned_head;
+ pcl->pageofs_out = map->m_la & ~PAGE_MASK;
+ fe->mode = Z_EROFS_PCLUSTER_FOLLOWED;
+
+ /*
+ * lock all primary followed works before visible to others
+ * and mutex_trylock *never* fails for a new pcluster.
+ */
+ mutex_init(&pcl->lock);
+ DBG_BUGON(!mutex_trylock(&pcl->lock));
+
+ if (ztailpacking) {
+ pcl->obj.index = 0; /* which indicates ztailpacking */
+ pcl->pageofs_in = erofs_blkoff(map->m_pa);
+ pcl->tailpacking_size = map->m_plen;
+ } else {
+ pcl->obj.index = map->m_pa >> PAGE_SHIFT;
+
+ grp = erofs_insert_workgroup(fe->inode->i_sb, &pcl->obj);
+ if (IS_ERR(grp)) {
+ err = PTR_ERR(grp);
+ goto err_out;
+ }
+
+ if (grp != &pcl->obj) {
+ fe->pcl = container_of(grp,
+ struct z_erofs_pcluster, obj);
+ err = -EEXIST;
+ goto err_out;
+ }
+ }
+ fe->owned_head = &pcl->next;
+ fe->pcl = pcl;
+ return 0;
+
+err_out:
+ mutex_unlock(&pcl->lock);
+ z_erofs_free_pcluster(pcl);
+ return err;
+}
+
+static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe)
+{
+ struct erofs_map_blocks *map = &fe->map;
+ struct erofs_workgroup *grp = NULL;
+ int ret;
+
+ DBG_BUGON(fe->pcl);
+
+ /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous pcluster */
+ DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_NIL);
+
+ if (!(map->m_flags & EROFS_MAP_META)) {
+ grp = erofs_find_workgroup(fe->inode->i_sb,
+ map->m_pa >> PAGE_SHIFT);
+ } else if ((map->m_pa & ~PAGE_MASK) + map->m_plen > PAGE_SIZE) {
+ DBG_BUGON(1);
+ return -EFSCORRUPTED;
+ }
+
+ if (grp) {
+ fe->pcl = container_of(grp, struct z_erofs_pcluster, obj);
+ ret = -EEXIST;
+ } else {
+ ret = z_erofs_register_pcluster(fe);
+ }
+
+ if (ret == -EEXIST) {
+ mutex_lock(&fe->pcl->lock);
+ z_erofs_try_to_claim_pcluster(fe);
+ } else if (ret) {
+ return ret;
+ }
+ z_erofs_bvec_iter_begin(&fe->biter, &fe->pcl->bvset,
+ Z_EROFS_INLINE_BVECS, fe->pcl->vcnt);
+ /* since file-backed online pages are traversed in reverse order */
+ fe->icur = z_erofs_pclusterpages(fe->pcl);
+ 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)
+{
+ z_erofs_free_pcluster(container_of(head,
+ struct z_erofs_pcluster, rcu));
+}
+
+void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
+{
+ struct z_erofs_pcluster *const pcl =
+ container_of(grp, struct z_erofs_pcluster, obj);
+
+ call_rcu(&pcl->rcu, z_erofs_rcu_callback);
+}
+
+static bool z_erofs_collector_end(struct z_erofs_decompress_frontend *fe)
+{
+ struct z_erofs_pcluster *pcl = fe->pcl;
+
+ if (!pcl)
+ return false;
+
+ z_erofs_bvec_iter_end(&fe->biter);
+ mutex_unlock(&pcl->lock);
+
+ if (fe->candidate_bvpage) {
+ DBG_BUGON(z_erofs_is_shortlived_page(fe->candidate_bvpage));
+ fe->candidate_bvpage = NULL;
+ }
+
+ /*
+ * if all pending pages are added, don't hold its reference
+ * any longer if the pcluster isn't hosted by ourselves.
+ */
+ if (fe->mode < Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE)
+ erofs_workgroup_put(&pcl->obj);
+
+ fe->pcl = NULL;
+ return true;
+}
+
+static int z_erofs_read_fragment(struct inode *inode, erofs_off_t pos,
+ struct page *page, unsigned int pageofs,
+ unsigned int len)
+{
+ struct inode *packed_inode = EROFS_I_SB(inode)->packed_inode;
+ struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+ u8 *src, *dst;
+ unsigned int i, cnt;
+
+ if (!packed_inode)
+ return -EFSCORRUPTED;
+
+ pos += EROFS_I(inode)->z_fragmentoff;
+ for (i = 0; i < len; i += cnt) {
+ cnt = min_t(unsigned int, len - i,
+ EROFS_BLKSIZ - erofs_blkoff(pos));
+ src = erofs_bread(&buf, packed_inode,
+ erofs_blknr(pos), EROFS_KMAP);
+ if (IS_ERR(src)) {
+ erofs_put_metabuf(&buf);
+ return PTR_ERR(src);
+ }
+
+ dst = kmap_local_page(page);
+ memcpy(dst + pageofs + i, src + erofs_blkoff(pos), cnt);
+ kunmap_local(dst);
+ pos += cnt;
+ }
+ erofs_put_metabuf(&buf);
+ return 0;
+}
+
+static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
+ struct page *page, struct page **pagepool)
+{
+ struct inode *const inode = fe->inode;
+ struct erofs_map_blocks *const map = &fe->map;
+ const loff_t offset = page_offset(page);
+ bool tight = true, exclusive;
+ unsigned int cur, end, spiltted;
+ 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;
+
+ if (offset + cur < map->m_la ||
+ offset + cur >= map->m_la + map->m_llen) {
+ erofs_dbg("out-of-range map @ pos %llu", offset + cur);
+
+ if (z_erofs_collector_end(fe))
+ fe->backmost = false;
+ map->m_la = offset + cur;
+ map->m_llen = 0;
+ err = z_erofs_map_blocks_iter(inode, map, 0);
+ if (err)
+ goto out;
+ } else {
+ if (fe->pcl)
+ goto hitted;
+ /* didn't get a valid pcluster previously (very rare) */
+ }
+
+ if (!(map->m_flags & EROFS_MAP_MAPPED) ||
+ map->m_flags & EROFS_MAP_FRAGMENT)
+ goto hitted;
+
+ err = z_erofs_collector_begin(fe);
+ if (err)
+ goto out;
+
+ if (z_erofs_is_inline_pcluster(fe->pcl)) {
+ void *mp;
+
+ mp = erofs_read_metabuf(&fe->map.buf, inode->i_sb,
+ erofs_blknr(map->m_pa), EROFS_NO_KMAP);
+ if (IS_ERR(mp)) {
+ err = PTR_ERR(mp);
+ erofs_err(inode->i_sb,
+ "failed to get inline page, err %d", err);
+ goto out;
+ }
+ get_page(fe->map.buf.page);
+ WRITE_ONCE(fe->pcl->compressed_bvecs[0].page,
+ fe->map.buf.page);
+ fe->mode = Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE;
+ } else {
+ /* bind cache first when cached decompression is preferred */
+ z_erofs_bind_cache(fe, pagepool);
+ }
+hitted:
+ /*
+ * Ensure the current partial page belongs to this submit chain rather
+ * than other concurrent submit chains or the noio(bypass) chain since
+ * those chains are handled asynchronously thus the page cannot be used
+ * for inplace I/O or bvpage (should be processed in a strict order.)
+ */
+ tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
+
+ cur = end - min_t(erofs_off_t, offset + end - map->m_la, end);
+ if (!(map->m_flags & EROFS_MAP_MAPPED)) {
+ zero_user_segment(page, cur, end);
+ ++spiltted;
+ tight = false;
+ goto next_part;
+ }
+ if (map->m_flags & EROFS_MAP_FRAGMENT) {
+ unsigned int pageofs, skip, len;
+
+ if (offset > map->m_la) {
+ pageofs = 0;
+ skip = offset - map->m_la;
+ } else {
+ pageofs = map->m_la & ~PAGE_MASK;
+ skip = 0;
+ }
+ len = min_t(unsigned int, map->m_llen - skip, end - cur);
+ err = z_erofs_read_fragment(inode, skip, page, pageofs, len);
+ if (err)
+ goto out;
+ ++spiltted;
+ tight = false;
+ goto next_part;
+ }
+
+ exclusive = (!cur && (!spiltted || tight));
+ if (cur)
+ tight &= (fe->mode >= Z_EROFS_PCLUSTER_FOLLOWED);
+
+retry:
+ err = z_erofs_attach_page(fe, &((struct z_erofs_bvec) {
+ .page = page,
+ .offset = offset - map->m_la,
+ .end = end,
+ }), exclusive);
+ /* should allocate an additional short-lived page for bvset */
+ if (err == -EAGAIN && !fe->candidate_bvpage) {
+ fe->candidate_bvpage = alloc_page(GFP_NOFS | __GFP_NOFAIL);
+ set_page_private(fe->candidate_bvpage,
+ Z_EROFS_SHORTLIVED_PAGE);
+ goto retry;
+ }
+
+ if (err) {
+ DBG_BUGON(err == -EAGAIN && fe->candidate_bvpage);
+ goto out;
+ }
+
+ z_erofs_onlinepage_split(page);
+ /* bump up the number of spiltted parts of a page */
+ ++spiltted;
+ if (fe->pcl->pageofs_out != (map->m_la & ~PAGE_MASK))
+ fe->pcl->multibases = true;
+ if (fe->pcl->length < offset + end - map->m_la) {
+ fe->pcl->length = offset + end - map->m_la;
+ fe->pcl->pageofs_out = map->m_la & ~PAGE_MASK;
+ }
+ if ((map->m_flags & EROFS_MAP_FULL_MAPPED) &&
+ !(map->m_flags & EROFS_MAP_PARTIAL_REF) &&
+ fe->pcl->length == map->m_llen)
+ fe->pcl->partial = false;
+next_part:
+ /* shorten the remaining extent to update progress */
+ map->m_llen = offset + cur - map->m_la;
+ map->m_flags &= ~EROFS_MAP_FULL_MAPPED;
+
+ end = cur;
+ if (end > 0)
+ goto repeat;
+
+out:
+ if (err)
+ z_erofs_page_mark_eio(page);
+ z_erofs_onlinepage_endio(page);
+
+ erofs_dbg("%s, finish page: %pK spiltted: %u map->m_llen %llu",
+ __func__, page, spiltted, map->m_llen);
+ return err;
+}
+
+static bool z_erofs_get_sync_decompress_policy(struct erofs_sb_info *sbi,
+ unsigned int readahead_pages)
+{
+ /* auto: enable for read_folio, disable for readahead */
+ if ((sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO) &&
+ !readahead_pages)
+ return true;
+
+ if ((sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_FORCE_ON) &&
+ (readahead_pages <= sbi->opt.max_sync_decompress_pages))
+ return true;
+
+ return false;
+}
+
+static bool z_erofs_page_is_invalidated(struct page *page)
+{
+ return !page->mapping && !z_erofs_is_shortlived_page(page);
+}
+
+struct z_erofs_decompress_backend {
+ struct page *onstack_pages[Z_EROFS_ONSTACK_PAGES];
+ struct super_block *sb;
+ struct z_erofs_pcluster *pcl;
+
+ /* pages with the longest decompressed length for deduplication */
+ struct page **decompressed_pages;
+ /* pages to keep the compressed data */
+ struct page **compressed_pages;
+
+ struct list_head decompressed_secondary_bvecs;
+ struct page **pagepool;
+ unsigned int onstack_used, nr_pages;
+};
+
+struct z_erofs_bvec_item {
+ struct z_erofs_bvec bvec;
+ struct list_head list;
+};
+
+static void z_erofs_do_decompressed_bvec(struct z_erofs_decompress_backend *be,
+ struct z_erofs_bvec *bvec)
+{
+ struct z_erofs_bvec_item *item;
+ unsigned int pgnr;
+
+ if (!((bvec->offset + be->pcl->pageofs_out) & ~PAGE_MASK) &&
+ (bvec->end == PAGE_SIZE ||
+ bvec->offset + bvec->end == be->pcl->length)) {
+ pgnr = (bvec->offset + be->pcl->pageofs_out) >> PAGE_SHIFT;
+ DBG_BUGON(pgnr >= be->nr_pages);
+ if (!be->decompressed_pages[pgnr]) {
+ be->decompressed_pages[pgnr] = bvec->page;
+ return;
+ }
+ }
+
+ /* (cold path) one pcluster is requested multiple times */
+ item = kmalloc(sizeof(*item), GFP_KERNEL | __GFP_NOFAIL);
+ item->bvec = *bvec;
+ list_add(&item->list, &be->decompressed_secondary_bvecs);
+}
+
+static void z_erofs_fill_other_copies(struct z_erofs_decompress_backend *be,
+ int err)
+{
+ unsigned int off0 = be->pcl->pageofs_out;
+ struct list_head *p, *n;
+
+ list_for_each_safe(p, n, &be->decompressed_secondary_bvecs) {
+ struct z_erofs_bvec_item *bvi;
+ unsigned int end, cur;
+ void *dst, *src;
+
+ bvi = container_of(p, struct z_erofs_bvec_item, list);
+ cur = bvi->bvec.offset < 0 ? -bvi->bvec.offset : 0;
+ end = min_t(unsigned int, be->pcl->length - bvi->bvec.offset,
+ bvi->bvec.end);
+ dst = kmap_local_page(bvi->bvec.page);
+ while (cur < end) {
+ unsigned int pgnr, scur, len;
+
+ pgnr = (bvi->bvec.offset + cur + off0) >> PAGE_SHIFT;
+ DBG_BUGON(pgnr >= be->nr_pages);
+
+ scur = bvi->bvec.offset + cur -
+ ((pgnr << PAGE_SHIFT) - off0);
+ len = min_t(unsigned int, end - cur, PAGE_SIZE - scur);
+ if (!be->decompressed_pages[pgnr]) {
+ err = -EFSCORRUPTED;
+ cur += len;
+ continue;
+ }
+ src = kmap_local_page(be->decompressed_pages[pgnr]);
+ memcpy(dst + cur, src + scur, len);
+ kunmap_local(src);
+ cur += len;
+ }
+ kunmap_local(dst);
+ if (err)
+ z_erofs_page_mark_eio(bvi->bvec.page);
+ z_erofs_onlinepage_endio(bvi->bvec.page);
+ list_del(p);
+ kfree(bvi);
+ }
+}
+
+static void z_erofs_parse_out_bvecs(struct z_erofs_decompress_backend *be)
+{
+ struct z_erofs_pcluster *pcl = be->pcl;
+ struct z_erofs_bvec_iter biter;
+ struct page *old_bvpage;
+ int i;
+
+ z_erofs_bvec_iter_begin(&biter, &pcl->bvset, Z_EROFS_INLINE_BVECS, 0);
+ for (i = 0; i < pcl->vcnt; ++i) {
+ struct z_erofs_bvec bvec;
+
+ z_erofs_bvec_dequeue(&biter, &bvec, &old_bvpage);
+
+ if (old_bvpage)
+ z_erofs_put_shortlivedpage(be->pagepool, old_bvpage);
+
+ DBG_BUGON(z_erofs_page_is_invalidated(bvec.page));
+ z_erofs_do_decompressed_bvec(be, &bvec);
+ }
+
+ old_bvpage = z_erofs_bvec_iter_end(&biter);
+ if (old_bvpage)
+ z_erofs_put_shortlivedpage(be->pagepool, old_bvpage);
+}
+
+static int z_erofs_parse_in_bvecs(struct z_erofs_decompress_backend *be,
+ bool *overlapped)
+{
+ struct z_erofs_pcluster *pcl = be->pcl;
+ unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
+ int i, err = 0;
+
+ *overlapped = false;
+ for (i = 0; i < pclusterpages; ++i) {
+ struct z_erofs_bvec *bvec = &pcl->compressed_bvecs[i];
+ struct page *page = bvec->page;
+
+ /* compressed pages ought to be present before decompressing */
+ if (!page) {
+ DBG_BUGON(1);
+ continue;
+ }
+ be->compressed_pages[i] = page;
+
+ if (z_erofs_is_inline_pcluster(pcl)) {
+ if (!PageUptodate(page))
+ err = -EIO;
+ continue;
+ }
+
+ DBG_BUGON(z_erofs_page_is_invalidated(page));
+ if (!z_erofs_is_shortlived_page(page)) {
+ if (erofs_page_is_managed(EROFS_SB(be->sb), page)) {
+ if (!PageUptodate(page))
+ err = -EIO;
+ continue;
+ }
+ z_erofs_do_decompressed_bvec(be, bvec);
+ *overlapped = true;
+ }
+ }
+
+ if (err)
+ return err;
+ return 0;
+}
+
+static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
+ int err)
+{
+ struct erofs_sb_info *const sbi = EROFS_SB(be->sb);
+ struct z_erofs_pcluster *pcl = be->pcl;
+ unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
+ unsigned int i, inputsize;
+ int err2;
+ struct page *page;
+ bool overlapped;
+
+ mutex_lock(&pcl->lock);
+ be->nr_pages = PAGE_ALIGN(pcl->length + pcl->pageofs_out) >> PAGE_SHIFT;
+
+ /* allocate (de)compressed page arrays if cannot be kept on stack */
+ be->decompressed_pages = NULL;
+ be->compressed_pages = NULL;
+ be->onstack_used = 0;
+ if (be->nr_pages <= Z_EROFS_ONSTACK_PAGES) {
+ be->decompressed_pages = be->onstack_pages;
+ be->onstack_used = be->nr_pages;
+ memset(be->decompressed_pages, 0,
+ sizeof(struct page *) * be->nr_pages);
+ }
+
+ if (pclusterpages + be->onstack_used <= Z_EROFS_ONSTACK_PAGES)
+ be->compressed_pages = be->onstack_pages + be->onstack_used;
+
+ if (!be->decompressed_pages)
+ be->decompressed_pages =
+ kvcalloc(be->nr_pages, sizeof(struct page *),
+ GFP_KERNEL | __GFP_NOFAIL);
+ if (!be->compressed_pages)
+ be->compressed_pages =
+ kvcalloc(pclusterpages, sizeof(struct page *),
+ GFP_KERNEL | __GFP_NOFAIL);
+
+ z_erofs_parse_out_bvecs(be);
+ err2 = z_erofs_parse_in_bvecs(be, &overlapped);
+ if (err2)
+ err = err2;
+ if (err)
+ goto out;
+
+ if (z_erofs_is_inline_pcluster(pcl))
+ inputsize = pcl->tailpacking_size;
+ else
+ inputsize = pclusterpages * PAGE_SIZE;
+
+ err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
+ .sb = be->sb,
+ .in = be->compressed_pages,
+ .out = be->decompressed_pages,
+ .pageofs_in = pcl->pageofs_in,
+ .pageofs_out = pcl->pageofs_out,
+ .inputsize = inputsize,
+ .outputsize = pcl->length,
+ .alg = pcl->algorithmformat,
+ .inplace_io = overlapped,
+ .partial_decoding = pcl->partial,
+ .fillgaps = pcl->multibases,
+ }, be->pagepool);
+
+out:
+ /* must handle all compressed pages before actual file pages */
+ if (z_erofs_is_inline_pcluster(pcl)) {
+ page = pcl->compressed_bvecs[0].page;
+ WRITE_ONCE(pcl->compressed_bvecs[0].page, NULL);
+ put_page(page);
+ } else {
+ for (i = 0; i < pclusterpages; ++i) {
+ /* consider shortlived pages added when decompressing */
+ page = be->compressed_pages[i];
+
+ if (erofs_page_is_managed(sbi, page))
+ continue;
+ (void)z_erofs_put_shortlivedpage(be->pagepool, page);
+ WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);
+ }
+ }
+ if (be->compressed_pages < be->onstack_pages ||
+ be->compressed_pages >= be->onstack_pages + Z_EROFS_ONSTACK_PAGES)
+ kvfree(be->compressed_pages);
+ z_erofs_fill_other_copies(be, err);
+
+ for (i = 0; i < be->nr_pages; ++i) {
+ page = be->decompressed_pages[i];
+ if (!page)
+ continue;
+
+ DBG_BUGON(z_erofs_page_is_invalidated(page));
+
+ /* recycle all individual short-lived pages */
+ if (z_erofs_put_shortlivedpage(be->pagepool, page))
+ continue;
+ if (err)
+ z_erofs_page_mark_eio(page);
+ z_erofs_onlinepage_endio(page);
+ }
+
+ if (be->decompressed_pages != be->onstack_pages)
+ kvfree(be->decompressed_pages);
+
+ pcl->length = 0;
+ pcl->partial = true;
+ pcl->multibases = false;
+ pcl->bvset.nextpage = NULL;
+ pcl->vcnt = 0;
+
+ /* pcluster lock MUST be taken before the following line */
+ WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
+ mutex_unlock(&pcl->lock);
+ return err;
+}
+
+static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
+ struct page **pagepool)
+{
+ struct z_erofs_decompress_backend be = {
+ .sb = io->sb,
+ .pagepool = pagepool,
+ .decompressed_secondary_bvecs =
+ LIST_HEAD_INIT(be.decompressed_secondary_bvecs),
+ };
+ z_erofs_next_pcluster_t owned = io->head;
+
+ while (owned != Z_EROFS_PCLUSTER_TAIL) {
+ DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
+
+ be.pcl = container_of(owned, struct z_erofs_pcluster, next);
+ owned = READ_ONCE(be.pcl->next);
+
+ z_erofs_decompress_pcluster(&be, io->eio ? -EIO : 0);
+ erofs_workgroup_put(&be.pcl->obj);
+ }
+}
+
+static void z_erofs_decompressqueue_work(struct work_struct *work)
+{
+ struct z_erofs_decompressqueue *bgq =
+ container_of(work, struct z_erofs_decompressqueue, u.work);
+ struct page *pagepool = NULL;
+
+ DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL);
+ z_erofs_decompress_queue(bgq, &pagepool);
+
+ erofs_release_pages(&pagepool);
+ kvfree(bgq);
+}
+
+static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
+ int bios)
+{
+ struct erofs_sb_info *const sbi = EROFS_SB(io->sb);
+
+ /* wake up the caller thread for sync decompression */
+ if (io->sync) {
+ if (!atomic_add_return(bios, &io->pending_bios))
+ complete(&io->u.done);
+ return;
+ }
+
+ if (atomic_add_return(bios, &io->pending_bios))
+ return;
+ /* Use workqueue and sync decompression for atomic contexts only */
+ if (in_atomic() || irqs_disabled()) {
+ queue_work(z_erofs_workqueue, &io->u.work);
+ /* enable sync decompression for readahead */
+ if (sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO)
+ sbi->opt.sync_decompress = EROFS_SYNC_DECOMPRESS_FORCE_ON;
+ return;
+ }
+ z_erofs_decompressqueue_work(&io->u.work);
+}
+
+static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
+ unsigned int nr,
+ struct page **pagepool,
+ struct address_space *mc)
+{
+ const pgoff_t index = pcl->obj.index;
+ gfp_t gfp = mapping_gfp_mask(mc);
+ bool tocache = false;
+
+ struct address_space *mapping;
+ struct page *oldpage, *page;
+ int justfound;
+
+repeat:
+ page = READ_ONCE(pcl->compressed_bvecs[nr].page);
+ oldpage = page;
+
+ if (!page)
+ goto out_allocpage;
+
+ justfound = (unsigned long)page & 1UL;
+ page = (struct page *)((unsigned long)page & ~1UL);
+
+ /*
+ * preallocated cached pages, which is used to avoid direct reclaim
+ * otherwise, it will go inplace I/O path instead.
+ */
+ if (page->private == Z_EROFS_PREALLOCATED_PAGE) {
+ WRITE_ONCE(pcl->compressed_bvecs[nr].page, page);
+ set_page_private(page, 0);
+ tocache = true;
+ goto out_tocache;
+ }
+ mapping = READ_ONCE(page->mapping);
+
+ /*
+ * file-backed online pages in plcuster are all locked steady,
+ * therefore it is impossible for `mapping' to be NULL.
+ */
+ if (mapping && mapping != mc)
+ /* ought to be unmanaged pages */
+ goto out;
+
+ /* directly return for shortlived page as well */
+ if (z_erofs_is_shortlived_page(page))
+ 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_bvecs[nr].page, page);
+
+ if (!PagePrivate(page)) {
+ /*
+ * impossible to be !PagePrivate(page) for
+ * the current restriction as well if
+ * the page is already in compressed_bvecs[].
+ */
+ 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 = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
+ if (oldpage != cmpxchg(&pcl->compressed_bvecs[nr].page,
+ oldpage, page)) {
+ erofs_pagepool_add(pagepool, page);
+ cond_resched();
+ goto repeat;
+ }
+out_tocache:
+ if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
+ /* turn into temporary page if fails (1 ref) */
+ set_page_private(page, Z_EROFS_SHORTLIVED_PAGE);
+ goto out;
+ }
+ attach_page_private(page, pcl);
+ /* drop a refcount added by allocpage (then we have 2 refs here) */
+ put_page(page);
+
+out: /* the only exit (for tracing and debugging) */
+ return page;
+}
+
+static struct z_erofs_decompressqueue *jobqueue_init(struct super_block *sb,
+ struct z_erofs_decompressqueue *fgq, bool *fg)
+{
+ struct z_erofs_decompressqueue *q;
+
+ if (fg && !*fg) {
+ q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
+ if (!q) {
+ *fg = true;
+ goto fg_out;
+ }
+ INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
+ } else {
+fg_out:
+ q = fgq;
+ init_completion(&fgq->u.done);
+ atomic_set(&fgq->pending_bios, 0);
+ q->eio = false;
+ q->sync = true;
+ }
+ q->sb = sb;
+ q->head = Z_EROFS_PCLUSTER_TAIL;
+ return q;
+}
+
+/* define decompression jobqueue types */
+enum {
+ JQ_BYPASS,
+ JQ_SUBMIT,
+ NR_JOBQUEUES,
+};
+
+static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
+ z_erofs_next_pcluster_t qtail[],
+ z_erofs_next_pcluster_t owned_head)
+{
+ z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
+ z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
+
+ WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL);
+
+ WRITE_ONCE(*submit_qtail, owned_head);
+ WRITE_ONCE(*bypass_qtail, &pcl->next);
+
+ qtail[JQ_BYPASS] = &pcl->next;
+}
+
+static void z_erofs_decompressqueue_endio(struct bio *bio)
+{
+ struct z_erofs_decompressqueue *q = bio->bi_private;
+ 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;
+
+ DBG_BUGON(PageUptodate(page));
+ DBG_BUGON(z_erofs_page_is_invalidated(page));
+
+ if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
+ if (!err)
+ SetPageUptodate(page);
+ unlock_page(page);
+ }
+ }
+ if (err)
+ q->eio = true;
+ z_erofs_decompress_kickoff(q, -1);
+ bio_put(bio);
+}
+
+static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
+ struct page **pagepool,
+ struct z_erofs_decompressqueue *fgq,
+ bool *force_fg)
+{
+ struct super_block *sb = f->inode->i_sb;
+ struct address_space *mc = MNGD_MAPPING(EROFS_SB(sb));
+ z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
+ struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
+ z_erofs_next_pcluster_t owned_head = f->owned_head;
+ /* bio is NULL initially, so no need to initialize last_{index,bdev} */
+ pgoff_t last_index;
+ struct block_device *last_bdev;
+ unsigned int nr_bios = 0;
+ struct bio *bio = NULL;
+ unsigned long pflags;
+ int memstall = 0;
+
+ /*
+ * if managed cache is enabled, bypass jobqueue is needed,
+ * no need to read from device for all pclusters in this queue.
+ */
+ q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
+ q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, force_fg);
+
+ qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
+ qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
+
+ /* by default, all need io submission */
+ q[JQ_SUBMIT]->head = owned_head;
+
+ do {
+ struct erofs_map_dev mdev;
+ struct z_erofs_pcluster *pcl;
+ pgoff_t cur, end;
+ unsigned int i = 0;
+ bool bypass = true;
+
+ DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
+ pcl = container_of(owned_head, struct z_erofs_pcluster, next);
+ owned_head = READ_ONCE(pcl->next);
+
+ if (z_erofs_is_inline_pcluster(pcl)) {
+ move_to_bypass_jobqueue(pcl, qtail, owned_head);
+ continue;
+ }
+
+ /* no device id here, thus it will always succeed */
+ mdev = (struct erofs_map_dev) {
+ .m_pa = blknr_to_addr(pcl->obj.index),
+ };
+ (void)erofs_map_dev(sb, &mdev);
+
+ cur = erofs_blknr(mdev.m_pa);
+ end = cur + pcl->pclusterpages;
+
+ do {
+ struct page *page;
+
+ page = pickup_page_for_submission(pcl, i++, pagepool,
+ mc);
+ if (!page)
+ continue;
+
+ if (bio && (cur != last_index + 1 ||
+ last_bdev != mdev.m_bdev)) {
+submit_bio_retry:
+ submit_bio(bio);
+ if (memstall) {
+ psi_memstall_leave(&pflags);
+ memstall = 0;
+ }
+ bio = NULL;
+ }
+
+ if (unlikely(PageWorkingset(page)) && !memstall) {
+ psi_memstall_enter(&pflags);
+ memstall = 1;
+ }
+
+ if (!bio) {
+ bio = bio_alloc(mdev.m_bdev, BIO_MAX_VECS,
+ REQ_OP_READ, GFP_NOIO);
+ bio->bi_end_io = z_erofs_decompressqueue_endio;
+
+ last_bdev = mdev.m_bdev;
+ bio->bi_iter.bi_sector = (sector_t)cur <<
+ LOG_SECTORS_PER_BLOCK;
+ bio->bi_private = q[JQ_SUBMIT];
+ if (f->readahead)
+ bio->bi_opf |= REQ_RAHEAD;
+ ++nr_bios;
+ }
+
+ if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
+ goto submit_bio_retry;
+
+ last_index = cur;
+ bypass = false;
+ } while (++cur < end);
+
+ if (!bypass)
+ 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);
+ if (memstall)
+ psi_memstall_leave(&pflags);
+ }
+
+ /*
+ * although background is preferred, no one is pending for submission.
+ * don't issue workqueue for decompression but drop it directly instead.
+ */
+ if (!*force_fg && !nr_bios) {
+ kvfree(q[JQ_SUBMIT]);
+ return;
+ }
+ z_erofs_decompress_kickoff(q[JQ_SUBMIT], nr_bios);
+}
+
+static void z_erofs_runqueue(struct z_erofs_decompress_frontend *f,
+ struct page **pagepool, bool force_fg)
+{
+ struct z_erofs_decompressqueue io[NR_JOBQUEUES];
+
+ if (f->owned_head == Z_EROFS_PCLUSTER_TAIL)
+ return;
+ z_erofs_submit_queue(f, pagepool, io, &force_fg);
+
+ /* handle bypass queue (no i/o pclusters) immediately */
+ z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
+
+ if (!force_fg)
+ return;
+
+ /* wait until all bios are completed */
+ wait_for_completion_io(&io[JQ_SUBMIT].u.done);
+
+ /* handle synchronous decompress queue in the caller context */
+ z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
+}
+
+/*
+ * Since partial uptodate is still unimplemented for now, we have to use
+ * approximate readmore strategies as a start.
+ */
+static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
+ struct readahead_control *rac,
+ erofs_off_t end,
+ struct page **pagepool,
+ bool backmost)
+{
+ struct inode *inode = f->inode;
+ struct erofs_map_blocks *map = &f->map;
+ erofs_off_t cur;
+ int err;
+
+ if (backmost) {
+ map->m_la = end;
+ err = z_erofs_map_blocks_iter(inode, map,
+ EROFS_GET_BLOCKS_READMORE);
+ if (err)
+ return;
+
+ /* expend ra for the trailing edge if readahead */
+ if (rac) {
+ loff_t newstart = readahead_pos(rac);
+
+ cur = round_up(map->m_la + map->m_llen, PAGE_SIZE);
+ readahead_expand(rac, newstart, cur - newstart);
+ return;
+ }
+ end = round_up(end, PAGE_SIZE);
+ } else {
+ end = round_up(map->m_la, PAGE_SIZE);
+
+ if (!map->m_llen)
+ return;
+ }
+
+ cur = map->m_la + map->m_llen - 1;
+ while ((cur >= end) && (cur < i_size_read(inode))) {
+ pgoff_t index = cur >> PAGE_SHIFT;
+ struct page *page;
+
+ page = erofs_grab_cache_page_nowait(inode->i_mapping, index);
+ if (page) {
+ if (PageUptodate(page)) {
+ unlock_page(page);
+ } else {
+ err = z_erofs_do_read_page(f, page, pagepool);
+ if (err)
+ erofs_err(inode->i_sb,
+ "readmore error at page %lu @ nid %llu",
+ index, EROFS_I(inode)->nid);
+ }
+ put_page(page);
+ }
+
+ if (cur < PAGE_SIZE)
+ break;
+ cur = (index << PAGE_SHIFT) - 1;
+ }
+}
+
+static int z_erofs_read_folio(struct file *file, struct folio *folio)
+{
+ struct page *page = &folio->page;
+ struct inode *const inode = page->mapping->host;
+ struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
+ struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
+ struct page *pagepool = NULL;
+ int err;
+
+ trace_erofs_readpage(page, false);
+ f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
+
+ z_erofs_pcluster_readmore(&f, NULL, f.headoffset + PAGE_SIZE - 1,
+ &pagepool, true);
+ err = z_erofs_do_read_page(&f, page, &pagepool);
+ z_erofs_pcluster_readmore(&f, NULL, 0, &pagepool, false);
+
+ (void)z_erofs_collector_end(&f);
+
+ /* if some compressed cluster ready, need submit them anyway */
+ z_erofs_runqueue(&f, &pagepool,
+ z_erofs_get_sync_decompress_policy(sbi, 0));
+
+ if (err)
+ erofs_err(inode->i_sb, "failed to read, err [%d]", err);
+
+ erofs_put_metabuf(&f.map.buf);
+ erofs_release_pages(&pagepool);
+ return err;
+}
+
+static void z_erofs_readahead(struct readahead_control *rac)
+{
+ struct inode *const inode = rac->mapping->host;
+ struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
+ struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
+ struct page *pagepool = NULL, *head = NULL, *page;
+ unsigned int nr_pages;
+
+ f.readahead = true;
+ f.headoffset = readahead_pos(rac);
+
+ z_erofs_pcluster_readmore(&f, rac, f.headoffset +
+ readahead_length(rac) - 1, &pagepool, true);
+ nr_pages = readahead_count(rac);
+ trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
+
+ while ((page = readahead_page(rac))) {
+ 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)
+ erofs_err(inode->i_sb,
+ "readahead error at page %lu @ nid %llu",
+ page->index, EROFS_I(inode)->nid);
+ put_page(page);
+ }
+ z_erofs_pcluster_readmore(&f, rac, 0, &pagepool, false);
+ (void)z_erofs_collector_end(&f);
+
+ z_erofs_runqueue(&f, &pagepool,
+ z_erofs_get_sync_decompress_policy(sbi, nr_pages));
+ erofs_put_metabuf(&f.map.buf);
+ erofs_release_pages(&pagepool);
+}
+
+const struct address_space_operations z_erofs_aops = {
+ .read_folio = z_erofs_read_folio,
+ .readahead = z_erofs_readahead,
+};