Merge tag 'erofs-for-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs

Pull erofs updates from Gao Xiang:
 "No outstanding new feature for this cycle.

  Most of these commits are decompression cleanups which are part of the
  ongoing development for subpage/folio compression support as well as
  xattr cleanups for the upcoming xattr bloom filter optimization [1].

  In addition, there are bugfixes to address some corner cases of
  compressed images due to global data de-duplication and arm64 16k
  pages.

  Summary:

   - Fix rare I/O hang on deduplicated compressed images due to loop
     hooked chains

   - Fix compact compression layout of 16k blocks on arm64 devices

   - Fix atomic context detection of async decompression

   - Decompression/Xattr code cleanups"

Link: https://lore.kernel.org/r/20230621083209.116024-1-jefflexu@linux.alibaba.com [1]

* tag 'erofs-for-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: clean up zmap.c
  erofs: remove unnecessary goto
  erofs: Fix detection of atomic context
  erofs: use separate xattr parsers for listxattr/getxattr
  erofs: unify inline/shared xattr iterators for listxattr/getxattr
  erofs: make the size of read data stored in buffer_ofs
  erofs: unify xattr_iter structures
  erofs: use absolute position in xattr iterator
  erofs: fix compact 4B support for 16k block size
  erofs: convert erofs_read_metabuf() to erofs_bread() for xattr
  erofs: use poison pointer to replace the hard-coded address
  erofs: use struct lockref to replace handcrafted approach
  erofs: adapt managed inode operations into folios
  erofs: kill hooked chains to avoid loops on deduplicated compressed images
  erofs: avoid on-stack pagepool directly passed by arguments
  erofs: allocate extra bvec pages directly instead of retrying
  erofs: clean up z_erofs_pcluster_readmore()
  erofs: remove the member readahead from struct z_erofs_decompress_frontend
  erofs: fold in z_erofs_decompress()

8 files changed, 438 insertions, 783 deletions

diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
index 26fa170090b8..b1b846504027 100644
--- a/fs/erofs/compress.h
+++ b/fs/erofs/compress.h
@@ -89,8 +89,7 @@ static inline bool erofs_page_is_managed(const struct erofs_sb_info *sbi,
 
 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
 			 unsigned int padbufsize);
-int z_erofs_decompress(struct z_erofs_decompress_req *rq,
-		       struct page **pagepool);
+extern const struct z_erofs_decompressor erofs_decompressors[];
 
 /* prototypes for specific algorithms */
 int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 7021e2cf6146..2a29943fa5cc 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -363,7 +363,7 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
 	return 0;
 }
 
-static struct z_erofs_decompressor decompressors[] = {
+const struct z_erofs_decompressor erofs_decompressors[] = {
 	[Z_EROFS_COMPRESSION_SHIFTED] = {
 		.decompress = z_erofs_transform_plain,
 		.name = "shifted"
@@ -383,9 +383,3 @@ static struct z_erofs_decompressor decompressors[] = {
 	},
 #endif
 };
-
-int z_erofs_decompress(struct z_erofs_decompress_req *rq,
-		       struct page **pagepool)
-{
-	return decompressors[rq->alg].decompress(rq, pagepool);
-}
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 1e39c03357d1..36e32fa542f0 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -208,46 +208,12 @@ enum {
 	EROFS_ZIP_CACHE_READAROUND
 };
 
-#define EROFS_LOCKED_MAGIC     (INT_MIN | 0xE0F510CCL)
-
 /* basic unit of the workstation of a super_block */
 struct erofs_workgroup {
-	/* the workgroup index in the workstation */
 	pgoff_t index;
-
-	/* overall workgroup reference count */
-	atomic_t refcount;
+	struct lockref lockref;
 };
 
-static inline bool erofs_workgroup_try_to_freeze(struct erofs_workgroup *grp,
-						 int val)
-{
-	preempt_disable();
-	if (val != atomic_cmpxchg(&grp->refcount, val, EROFS_LOCKED_MAGIC)) {
-		preempt_enable();
-		return false;
-	}
-	return true;
-}
-
-static inline void erofs_workgroup_unfreeze(struct erofs_workgroup *grp,
-					    int orig_val)
-{
-	/*
-	 * other observers should notice all modifications
-	 * in the freezing period.
-	 */
-	smp_mb();
-	atomic_set(&grp->refcount, orig_val);
-	preempt_enable();
-}
-
-static inline int erofs_wait_on_workgroup_freezed(struct erofs_workgroup *grp)
-{
-	return atomic_cond_read_relaxed(&grp->refcount,
-					VAL != EROFS_LOCKED_MAGIC);
-}
-
 enum erofs_kmap_type {
 	EROFS_NO_KMAP,		/* don't map the buffer */
 	EROFS_KMAP,		/* use kmap_local_page() to map the buffer */
@@ -486,7 +452,7 @@ static inline void erofs_pagepool_add(struct page **pagepool, struct page *page)
 void erofs_release_pages(struct page **pagepool);
 
 #ifdef CONFIG_EROFS_FS_ZIP
-int erofs_workgroup_put(struct erofs_workgroup *grp);
+void erofs_workgroup_put(struct erofs_workgroup *grp);
 struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
 					     pgoff_t index);
 struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
@@ -500,7 +466,6 @@ int __init z_erofs_init_zip_subsystem(void);
 void z_erofs_exit_zip_subsystem(void);
 int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 				       struct erofs_workgroup *egrp);
-int erofs_try_to_free_cached_page(struct page *page);
 int z_erofs_load_lz4_config(struct super_block *sb,
 			    struct erofs_super_block *dsb,
 			    struct z_erofs_lz4_cfgs *lz4, int len);
@@ -511,6 +476,7 @@ void erofs_put_pcpubuf(void *ptr);
 int erofs_pcpubuf_growsize(unsigned int nrpages);
 void __init erofs_pcpubuf_init(void);
 void erofs_pcpubuf_exit(void);
+int erofs_init_managed_cache(struct super_block *sb);
 #else
 static inline void erofs_shrinker_register(struct super_block *sb) {}
 static inline void erofs_shrinker_unregister(struct super_block *sb) {}
@@ -530,6 +496,7 @@ static inline int z_erofs_load_lz4_config(struct super_block *sb,
 }
 static inline void erofs_pcpubuf_init(void) {}
 static inline void erofs_pcpubuf_exit(void) {}
+static inline int erofs_init_managed_cache(struct super_block *sb) { return 0; }
 #endif	/* !CONFIG_EROFS_FS_ZIP */
 
 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 811ab66d805e..ff18f6b14de5 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -599,68 +599,6 @@ static int erofs_fc_parse_param(struct fs_context *fc,
 	return 0;
 }
 
-#ifdef CONFIG_EROFS_FS_ZIP
-static const struct address_space_operations managed_cache_aops;
-
-static bool erofs_managed_cache_release_folio(struct folio *folio, gfp_t gfp)
-{
-	bool ret = true;
-	struct address_space *const mapping = folio->mapping;
-
-	DBG_BUGON(!folio_test_locked(folio));
-	DBG_BUGON(mapping->a_ops != &managed_cache_aops);
-
-	if (folio_test_private(folio))
-		ret = erofs_try_to_free_cached_page(&folio->page);
-
-	return ret;
-}
-
-/*
- * It will be called only on inode eviction. In case that there are still some
- * decompression requests in progress, wait with rescheduling for a bit here.
- * We could introduce an extra locking instead but it seems unnecessary.
- */
-static void erofs_managed_cache_invalidate_folio(struct folio *folio,
-					       size_t offset, size_t length)
-{
-	const size_t stop = length + offset;
-
-	DBG_BUGON(!folio_test_locked(folio));
-
-	/* Check for potential overflow in debug mode */
-	DBG_BUGON(stop > folio_size(folio) || stop < length);
-
-	if (offset == 0 && stop == folio_size(folio))
-		while (!erofs_managed_cache_release_folio(folio, GFP_NOFS))
-			cond_resched();
-}
-
-static const struct address_space_operations managed_cache_aops = {
-	.release_folio = erofs_managed_cache_release_folio,
-	.invalidate_folio = erofs_managed_cache_invalidate_folio,
-};
-
-static int erofs_init_managed_cache(struct super_block *sb)
-{
-	struct erofs_sb_info *const sbi = EROFS_SB(sb);
-	struct inode *const inode = new_inode(sb);
-
-	if (!inode)
-		return -ENOMEM;
-
-	set_nlink(inode, 1);
-	inode->i_size = OFFSET_MAX;
-
-	inode->i_mapping->a_ops = &managed_cache_aops;
-	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
-	sbi->managed_cache = inode;
-	return 0;
-}
-#else
-static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
-#endif
-
 static struct inode *erofs_nfs_get_inode(struct super_block *sb,
 					 u64 ino, u32 generation)
 {
@@ -1016,10 +954,8 @@ static int __init erofs_module_init(void)
 					       sizeof(struct erofs_inode), 0,
 					       SLAB_RECLAIM_ACCOUNT,
 					       erofs_inode_init_once);
-	if (!erofs_inode_cachep) {
-		err = -ENOMEM;
-		goto icache_err;
-	}
+	if (!erofs_inode_cachep)
+		return -ENOMEM;
 
 	err = erofs_init_shrinker();
 	if (err)
@@ -1054,7 +990,6 @@ lzma_err:
 	erofs_exit_shrinker();
 shrinker_err:
 	kmem_cache_destroy(erofs_inode_cachep);
-icache_err:
 	return err;
 }
 
diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c
index 46627cb69abe..cc6fb9e98899 100644
--- a/fs/erofs/utils.c
+++ b/fs/erofs/utils.c
@@ -4,7 +4,6 @@
  *             https://www.huawei.com/
  */
 #include "internal.h"
-#include <linux/pagevec.h>
 
 struct page *erofs_allocpage(struct page **pagepool, gfp_t gfp)
 {
@@ -33,22 +32,21 @@ void erofs_release_pages(struct page **pagepool)
 /* global shrink count (for all mounted EROFS instances) */
 static atomic_long_t erofs_global_shrink_cnt;
 
-static int erofs_workgroup_get(struct erofs_workgroup *grp)
+static bool erofs_workgroup_get(struct erofs_workgroup *grp)
 {
-	int o;
+	if (lockref_get_not_zero(&grp->lockref))
+		return true;
 
-repeat:
-	o = erofs_wait_on_workgroup_freezed(grp);
-	if (o <= 0)
-		return -1;
-
-	if (atomic_cmpxchg(&grp->refcount, o, o + 1) != o)
-		goto repeat;
+	spin_lock(&grp->lockref.lock);
+	if (__lockref_is_dead(&grp->lockref)) {
+		spin_unlock(&grp->lockref.lock);
+		return false;
+	}
 
-	/* decrease refcount paired by erofs_workgroup_put */
-	if (o == 1)
+	if (!grp->lockref.count++)
 		atomic_long_dec(&erofs_global_shrink_cnt);
-	return 0;
+	spin_unlock(&grp->lockref.lock);
+	return true;
 }
 
 struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
@@ -61,7 +59,7 @@ repeat:
 	rcu_read_lock();
 	grp = xa_load(&sbi->managed_pslots, index);
 	if (grp) {
-		if (erofs_workgroup_get(grp)) {
+		if (!erofs_workgroup_get(grp)) {
 			/* prefer to relax rcu read side */
 			rcu_read_unlock();
 			goto repeat;
@@ -80,11 +78,10 @@ struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
 	struct erofs_workgroup *pre;
 
 	/*
-	 * Bump up a reference count before making this visible
-	 * to others for the XArray in order to avoid potential
-	 * UAF without serialized by xa_lock.
+	 * Bump up before making this visible to others for the XArray in order
+	 * to avoid potential UAF without serialized by xa_lock.
 	 */
-	atomic_inc(&grp->refcount);
+	lockref_get(&grp->lockref);
 
 repeat:
 	xa_lock(&sbi->managed_pslots);
@@ -93,13 +90,13 @@ repeat:
 	if (pre) {
 		if (xa_is_err(pre)) {
 			pre = ERR_PTR(xa_err(pre));
-		} else if (erofs_workgroup_get(pre)) {
+		} else if (!erofs_workgroup_get(pre)) {
 			/* try to legitimize the current in-tree one */
 			xa_unlock(&sbi->managed_pslots);
 			cond_resched();
 			goto repeat;
 		}
-		atomic_dec(&grp->refcount);
+		lockref_put_return(&grp->lockref);
 		grp = pre;
 	}
 	xa_unlock(&sbi->managed_pslots);
@@ -112,38 +109,34 @@ static void  __erofs_workgroup_free(struct erofs_workgroup *grp)
 	erofs_workgroup_free_rcu(grp);
 }
 
-int erofs_workgroup_put(struct erofs_workgroup *grp)
+void erofs_workgroup_put(struct erofs_workgroup *grp)
 {
-	int count = atomic_dec_return(&grp->refcount);
+	if (lockref_put_or_lock(&grp->lockref))
+		return;
 
-	if (count == 1)
+	DBG_BUGON(__lockref_is_dead(&grp->lockref));
+	if (grp->lockref.count == 1)
 		atomic_long_inc(&erofs_global_shrink_cnt);
-	else if (!count)
-		__erofs_workgroup_free(grp);
-	return count;
+	--grp->lockref.count;
+	spin_unlock(&grp->lockref.lock);
 }
 
 static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
 					   struct erofs_workgroup *grp)
 {
-	/*
-	 * If managed cache is on, refcount of workgroups
-	 * themselves could be < 0 (freezed). In other words,
-	 * there is no guarantee that all refcounts > 0.
-	 */
-	if (!erofs_workgroup_try_to_freeze(grp, 1))
-		return false;
+	int free = false;
+
+	spin_lock(&grp->lockref.lock);
+	if (grp->lockref.count)
+		goto out;
 
 	/*
-	 * Note that all cached pages should be unattached
-	 * before deleted from the XArray. Otherwise some
-	 * cached pages could be still attached to the orphan
-	 * old workgroup when the new one is available in the tree.
+	 * Note that all cached pages should be detached before deleted from
+	 * the XArray. Otherwise some cached pages could be still attached to
+	 * the orphan old workgroup when the new one is available in the tree.
 	 */
-	if (erofs_try_to_free_all_cached_pages(sbi, grp)) {
-		erofs_workgroup_unfreeze(grp, 1);
-		return false;
-	}
+	if (erofs_try_to_free_all_cached_pages(sbi, grp))
+		goto out;
 
 	/*
 	 * It's impossible to fail after the workgroup is freezed,
@@ -152,10 +145,13 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
 	 */
 	DBG_BUGON(__xa_erase(&sbi->managed_pslots, grp->index) != grp);
 
-	/* last refcount should be connected with its managed pslot.  */
-	erofs_workgroup_unfreeze(grp, 0);
-	__erofs_workgroup_free(grp);
-	return true;
+	lockref_mark_dead(&grp->lockref);
+	free = true;
+out:
+	spin_unlock(&grp->lockref.lock);
+	if (free)
+		__erofs_workgroup_free(grp);
+	return free;
 }
 
 static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index bbfe7ce170d2..40178b6e0688 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -7,32 +7,27 @@
 #include <linux/security.h>
 #include "xattr.h"
 
-static inline erofs_blk_t erofs_xattr_blkaddr(struct super_block *sb,
-					      unsigned int xattr_id)
-{
-	return EROFS_SB(sb)->xattr_blkaddr +
-	       erofs_blknr(sb, xattr_id * sizeof(__u32));
-}
-
-static inline unsigned int erofs_xattr_blkoff(struct super_block *sb,
-					      unsigned int xattr_id)
-{
-	return erofs_blkoff(sb, xattr_id * sizeof(__u32));
-}
-
-struct xattr_iter {
+struct erofs_xattr_iter {
 	struct super_block *sb;
 	struct erofs_buf buf;
+	erofs_off_t pos;
 	void *kaddr;
 
-	erofs_blk_t blkaddr;
-	unsigned int ofs;
+	char *buffer;
+	int buffer_size, buffer_ofs;
+
+	/* getxattr */
+	int index, infix_len;
+	struct qstr name;
+
+	/* listxattr */
+	struct dentry *dentry;
 };
 
 static int erofs_init_inode_xattrs(struct inode *inode)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
-	struct xattr_iter it;
+	struct erofs_xattr_iter it;
 	unsigned int i;
 	struct erofs_xattr_ibody_header *ih;
 	struct super_block *sb = inode->i_sb;
@@ -81,17 +76,17 @@ static int erofs_init_inode_xattrs(struct inode *inode)
 	}
 
 	it.buf = __EROFS_BUF_INITIALIZER;
-	it.blkaddr = erofs_blknr(sb, erofs_iloc(inode) + vi->inode_isize);
-	it.ofs = erofs_blkoff(sb, erofs_iloc(inode) + vi->inode_isize);
+	erofs_init_metabuf(&it.buf, sb);
+	it.pos = erofs_iloc(inode) + vi->inode_isize;
 
 	/* read in shared xattr array (non-atomic, see kmalloc below) */
-	it.kaddr = erofs_read_metabuf(&it.buf, sb, it.blkaddr, EROFS_KMAP);
+	it.kaddr = erofs_bread(&it.buf, erofs_blknr(sb, it.pos), EROFS_KMAP);
 	if (IS_ERR(it.kaddr)) {
 		ret = PTR_ERR(it.kaddr);
 		goto out_unlock;
 	}
 
-	ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
+	ih = it.kaddr + erofs_blkoff(sb, it.pos);
 	vi->xattr_shared_count = ih->h_shared_count;
 	vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
 						sizeof(uint), GFP_KERNEL);
@@ -102,26 +97,20 @@ static int erofs_init_inode_xattrs(struct inode *inode)
 	}
 
 	/* let's skip ibody header */
-	it.ofs += sizeof(struct erofs_xattr_ibody_header);
+	it.pos += sizeof(struct erofs_xattr_ibody_header);
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
-		if (it.ofs >= sb->s_blocksize) {
-			/* cannot be unaligned */
-			DBG_BUGON(it.ofs != sb->s_blocksize);
-
-			it.kaddr = erofs_read_metabuf(&it.buf, sb, ++it.blkaddr,
-						      EROFS_KMAP);
-			if (IS_ERR(it.kaddr)) {
-				kfree(vi->xattr_shared_xattrs);
-				vi->xattr_shared_xattrs = NULL;
-				ret = PTR_ERR(it.kaddr);
-				goto out_unlock;
-			}
-			it.ofs = 0;
+		it.kaddr = erofs_bread(&it.buf, erofs_blknr(sb, it.pos),
+				       EROFS_KMAP);
+		if (IS_ERR(it.kaddr)) {
+			kfree(vi->xattr_shared_xattrs);
+			vi->xattr_shared_xattrs = NULL;
+			ret = PTR_ERR(it.kaddr);
+			goto out_unlock;
 		}
-		vi->xattr_shared_xattrs[i] =
-			le32_to_cpu(*(__le32 *)(it.kaddr + it.ofs));
-		it.ofs += sizeof(__le32);
+		vi->xattr_shared_xattrs[i] = le32_to_cpu(*(__le32 *)
+				(it.kaddr + erofs_blkoff(sb, it.pos)));
+		it.pos += sizeof(__le32);
 	}
 	erofs_put_metabuf(&it.buf);
 
@@ -134,287 +123,6 @@ out_unlock:
 	return ret;
 }
 
-/*
- * the general idea for these return values is
- * if    0 is returned, go on processing the current xattr;
- *       1 (> 0) is returned, skip this round to process the next xattr;
- *    -err (< 0) is returned, an error (maybe ENOXATTR) occurred
- *                            and need to be handled
- */
-struct xattr_iter_handlers {
-	int (*entry)(struct xattr_iter *_it, struct erofs_xattr_entry *entry);
-	int (*name)(struct xattr_iter *_it, unsigned int processed, char *buf,
-		    unsigned int len);
-	int (*alloc_buffer)(struct xattr_iter *_it, unsigned int value_sz);
-	void (*value)(struct xattr_iter *_it, unsigned int processed, char *buf,
-		      unsigned int len);
-};
-
-static inline int xattr_iter_fixup(struct xattr_iter *it)
-{
-	if (it->ofs < it->sb->s_blocksize)
-		return 0;
-
-	it->blkaddr += erofs_blknr(it->sb, it->ofs);
-	it->kaddr = erofs_read_metabuf(&it->buf, it->sb, it->blkaddr,
-				       EROFS_KMAP);
-	if (IS_ERR(it->kaddr))
-		return PTR_ERR(it->kaddr);
-	it->ofs = erofs_blkoff(it->sb, it->ofs);
-	return 0;
-}
-
-static int inline_xattr_iter_begin(struct xattr_iter *it,
-				   struct inode *inode)
-{
-	struct erofs_inode *const vi = EROFS_I(inode);
-	unsigned int xattr_header_sz, inline_xattr_ofs;
-
-	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
-			  sizeof(u32) * vi->xattr_shared_count;
-	if (xattr_header_sz >= vi->xattr_isize) {
-		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
-		return -ENOATTR;
-	}
-
-	inline_xattr_ofs = vi->inode_isize + xattr_header_sz;
-
-	it->blkaddr = erofs_blknr(it->sb, erofs_iloc(inode) + inline_xattr_ofs);
-	it->ofs = erofs_blkoff(it->sb, erofs_iloc(inode) + inline_xattr_ofs);
-	it->kaddr = erofs_read_metabuf(&it->buf, inode->i_sb, it->blkaddr,
-				       EROFS_KMAP);
-	if (IS_ERR(it->kaddr))
-		return PTR_ERR(it->kaddr);
-	return vi->xattr_isize - xattr_header_sz;
-}
-
-/*
- * Regardless of success or failure, `xattr_foreach' will end up with
- * `ofs' pointing to the next xattr item rather than an arbitrary position.
- */
-static int xattr_foreach(struct xattr_iter *it,
-			 const struct xattr_iter_handlers *op,
-			 unsigned int *tlimit)
-{
-	struct erofs_xattr_entry entry;
-	unsigned int value_sz, processed, slice;
-	int err;
-
-	/* 0. fixup blkaddr, ofs, ipage */
-	err = xattr_iter_fixup(it);
-	if (err)
-		return err;
-
-	/*
-	 * 1. read xattr entry to the memory,
-	 *    since we do EROFS_XATTR_ALIGN
-	 *    therefore entry should be in the page
-	 */
-	entry = *(struct erofs_xattr_entry *)(it->kaddr + it->ofs);
-	if (tlimit) {
-		unsigned int entry_sz = erofs_xattr_entry_size(&entry);
-
-		/* xattr on-disk corruption: xattr entry beyond xattr_isize */
-		if (*tlimit < entry_sz) {
-			DBG_BUGON(1);
-			return -EFSCORRUPTED;
-		}
-		*tlimit -= entry_sz;
-	}
-
-	it->ofs += sizeof(struct erofs_xattr_entry);
-	value_sz = le16_to_cpu(entry.e_value_size);
-
-	/* handle entry */
-	err = op->entry(it, &entry);
-	if (err) {
-		it->ofs += entry.e_name_len + value_sz;
-		goto out;
-	}
-
-	/* 2. handle xattr name (ofs will finally be at the end of name) */
-	processed = 0;
-
-	while (processed < entry.e_name_len) {
-		if (it->ofs >= it->sb->s_blocksize) {
-			DBG_BUGON(it->ofs > it->sb->s_blocksize);
-
-			err = xattr_iter_fixup(it);
-			if (err)
-				goto out;
-			it->ofs = 0;
-		}
-
-		slice = min_t(unsigned int, it->sb->s_blocksize - it->ofs,
-			      entry.e_name_len - processed);
-
-		/* handle name */
-		err = op->name(it, processed, it->kaddr + it->ofs, slice);
-		if (err) {
-			it->ofs += entry.e_name_len - processed + value_sz;
-			goto out;
-		}
-
-		it->ofs += slice;
-		processed += slice;
-	}
-
-	/* 3. handle xattr value */
-	processed = 0;
-
-	if (op->alloc_buffer) {
-		err = op->alloc_buffer(it, value_sz);
-		if (err) {
-			it->ofs += value_sz;
-			goto out;
-		}
-	}
-
-	while (processed < value_sz) {
-		if (it->ofs >= it->sb->s_blocksize) {
-			DBG_BUGON(it->ofs > it->sb->s_blocksize);
-
-			err = xattr_iter_fixup(it);
-			if (err)
-				goto out;
-			it->ofs = 0;
-		}
-
-		slice = min_t(unsigned int, it->sb->s_blocksize - it->ofs,
-			      value_sz - processed);
-		op->value(it, processed, it->kaddr + it->ofs, slice);
-		it->ofs += slice;
-		processed += slice;
-	}
-
-out:
-	/* xattrs should be 4-byte aligned (on-disk constraint) */
-	it->ofs = EROFS_XATTR_ALIGN(it->ofs);
-	return err < 0 ? err : 0;
-}
-
-struct getxattr_iter {
-	struct xattr_iter it;
-
-	char *buffer;
-	int buffer_size, index, infix_len;
-	struct qstr name;
-};
-
-static int erofs_xattr_long_entrymatch(struct getxattr_iter *it,
-				       struct erofs_xattr_entry *entry)
-{
-	struct erofs_sb_info *sbi = EROFS_SB(it->it.sb);
-	struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
-		(entry->e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
-
-	if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
-		return -ENOATTR;
-
-	if (it->index != pf->prefix->base_index ||
-	    it->name.len != entry->e_name_len + pf->infix_len)
-		return -ENOATTR;
-
-	if (memcmp(it->name.name, pf->prefix->infix, pf->infix_len))
-		return -ENOATTR;
-
-	it->infix_len = pf->infix_len;
-	return 0;
-}
-
-static int xattr_entrymatch(struct xattr_iter *_it,
-			    struct erofs_xattr_entry *entry)
-{
-	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
-
-	/* should also match the infix for long name prefixes */
-	if (entry->e_name_index & EROFS_XATTR_LONG_PREFIX)
-		return erofs_xattr_long_entrymatch(it, entry);
-
-	if (it->index != entry->e_name_index ||
-	    it->name.len != entry->e_name_len)
-		return -ENOATTR;
-	it->infix_len = 0;
-	return 0;
-}
-
-static int xattr_namematch(struct xattr_iter *_it,
-			   unsigned int processed, char *buf, unsigned int len)
-{
-	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
-
-	if (memcmp(buf, it->name.name + it->infix_len + processed, len))
-		return -ENOATTR;
-	return 0;
-}
-
-static int xattr_checkbuffer(struct xattr_iter *_it,
-			     unsigned int value_sz)
-{
-	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
-	int err = it->buffer_size < value_sz ? -ERANGE : 0;
-
-	it->buffer_size = value_sz;
-	return !it->buffer ? 1 : err;
-}
-
-static void xattr_copyvalue(struct xattr_iter *_it,
-			    unsigned int processed,
-			    char *buf, unsigned int len)
-{
-	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
-
-	memcpy(it->buffer + processed, buf, len);
-}
-
-static const struct xattr_iter_handlers find_xattr_handlers = {
-	.entry = xattr_entrymatch,
-	.name = xattr_namematch,
-	.alloc_buffer = xattr_checkbuffer,
-	.value = xattr_copyvalue
-};
-
-static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
-{
-	int ret;
-	unsigned int remaining;
-
-	ret = inline_xattr_iter_begin(&it->it, inode);
-	if (ret < 0)
-		return ret;
-
-	remaining = ret;
-	while (remaining) {
-		ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
-		if (ret != -ENOATTR)
-			break;
-	}
-	return ret ? ret : it->buffer_size;
-}
-
-static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
-{
-	struct erofs_inode *const vi = EROFS_I(inode);
-	struct super_block *const sb = it->it.sb;
-	unsigned int i, xsid;
-	int ret = -ENOATTR;
-
-	for (i = 0; i < vi->xattr_shared_count; ++i) {
-		xsid = vi->xattr_shared_xattrs[i];
-		it->it.blkaddr = erofs_xattr_blkaddr(sb, xsid);
-		it->it.ofs = erofs_xattr_blkoff(sb, xsid);
-		it->it.kaddr = erofs_read_metabuf(&it->it.buf, sb,
-						  it->it.blkaddr, EROFS_KMAP);
-		if (IS_ERR(it->it.kaddr))
-			return PTR_ERR(it->it.kaddr);
-
-		ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
-		if (ret != -ENOATTR)
-			break;
-	}
-	return ret ? ret : it->buffer_size;
-}
-
 static bool erofs_xattr_user_list(struct dentry *dentry)
 {
 	return test_opt(&EROFS_SB(dentry->d_sb)->opt, XATTR_USER);
@@ -425,39 +133,6 @@ static bool erofs_xattr_trusted_list(struct dentry *dentry)
 	return capable(CAP_SYS_ADMIN);
 }
 
-int erofs_getxattr(struct inode *inode, int index,
-		   const char *name,
-		   void *buffer, size_t buffer_size)
-{
-	int ret;
-	struct getxattr_iter it;
-
-	if (!name)
-		return -EINVAL;
-
-	ret = erofs_init_inode_xattrs(inode);
-	if (ret)
-		return ret;
-
-	it.index = index;
-	it.name.len = strlen(name);
-	if (it.name.len > EROFS_NAME_LEN)
-		return -ERANGE;
-
-	it.it.buf = __EROFS_BUF_INITIALIZER;
-	it.name.name = name;
-
-	it.buffer = buffer;
-	it.buffer_size = buffer_size;
-
-	it.it.sb = inode->i_sb;
-	ret = inline_getxattr(inode, &it);
-	if (ret == -ENOATTR)
-		ret = shared_getxattr(inode, &it);
-	erofs_put_metabuf(&it.it.buf);
-	return ret;
-}
-
 static int erofs_xattr_generic_get(const struct xattr_handler *handler,
 				   struct dentry *unused, struct inode *inode,
 				   const char *name, void *buffer, size_t size)
@@ -500,30 +175,49 @@ const struct xattr_handler *erofs_xattr_handlers[] = {
 	NULL,
 };
 
-struct listxattr_iter {
-	struct xattr_iter it;
-
-	struct dentry *dentry;
-	char *buffer;
-	int buffer_size, buffer_ofs;
-};
+static int erofs_xattr_copy_to_buffer(struct erofs_xattr_iter *it,
+				      unsigned int len)
+{
+	unsigned int slice, processed;
+	struct super_block *sb = it->sb;
+	void *src;
+
+	for (processed = 0; processed < len; processed += slice) {
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr))
+			return PTR_ERR(it->kaddr);
+
+		src = it->kaddr + erofs_blkoff(sb, it->pos);
+		slice = min_t(unsigned int, sb->s_blocksize -
+				erofs_blkoff(sb, it->pos), len - processed);
+		memcpy(it->buffer + it->buffer_ofs, src, slice);
+		it->buffer_ofs += slice;
+		it->pos += slice;
+	}
+	return 0;
+}
 
-static int xattr_entrylist(struct xattr_iter *_it,
-			   struct erofs_xattr_entry *entry)
+static int erofs_listxattr_foreach(struct erofs_xattr_iter *it)
 {
-	struct listxattr_iter *it =
-		container_of(_it, struct listxattr_iter, it);
-	unsigned int base_index = entry->e_name_index;
-	unsigned int prefix_len, infix_len = 0;
+	struct erofs_xattr_entry entry;
+	unsigned int base_index, name_total, prefix_len, infix_len = 0;
 	const char *prefix, *infix = NULL;
+	int err;
+
+	/* 1. handle xattr entry */
+	entry = *(struct erofs_xattr_entry *)
+			(it->kaddr + erofs_blkoff(it->sb, it->pos));
+	it->pos += sizeof(struct erofs_xattr_entry);
 
-	if (entry->e_name_index & EROFS_XATTR_LONG_PREFIX) {
-		struct erofs_sb_info *sbi = EROFS_SB(_it->sb);
+	base_index = entry.e_name_index;
+	if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
+		struct erofs_sb_info *sbi = EROFS_SB(it->sb);
 		struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
-			(entry->e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
+			(entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
 
 		if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
-			return 1;
+			return 0;
 		infix = pf->prefix->infix;
 		infix_len = pf->infix_len;
 		base_index = pf->prefix->base_index;
@@ -531,120 +225,228 @@ static int xattr_entrylist(struct xattr_iter *_it,
 
 	prefix = erofs_xattr_prefix(base_index, it->dentry);
 	if (!prefix)
-		return 1;
+		return 0;
 	prefix_len = strlen(prefix);
+	name_total = prefix_len + infix_len + entry.e_name_len + 1;
 
 	if (!it->buffer) {
-		it->buffer_ofs += prefix_len + infix_len +
-					entry->e_name_len + 1;
-		return 1;
+		it->buffer_ofs += name_total;
+		return 0;
 	}
 
-	if (it->buffer_ofs + prefix_len + infix_len +
-		+ entry->e_name_len + 1 > it->buffer_size)
+	if (it->buffer_ofs + name_total > it->buffer_size)
 		return -ERANGE;
 
 	memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len);
 	memcpy(it->buffer + it->buffer_ofs + prefix_len, infix, infix_len);
 	it->buffer_ofs += prefix_len + infix_len;
-	return 0;
-}
 
-static int xattr_namelist(struct xattr_iter *_it,
-			  unsigned int processed, char *buf, unsigned int len)
-{
-	struct listxattr_iter *it =
-		container_of(_it, struct listxattr_iter, it);
+	/* 2. handle xattr name */
+	err = erofs_xattr_copy_to_buffer(it, entry.e_name_len);
+	if (err)
+		return err;
 
-	memcpy(it->buffer + it->buffer_ofs, buf, len);
-	it->buffer_ofs += len;
+	it->buffer[it->buffer_ofs++] = '\0';
 	return 0;
 }
 
-static int xattr_skipvalue(struct xattr_iter *_it,
-			   unsigned int value_sz)
+static int erofs_getxattr_foreach(struct erofs_xattr_iter *it)
 {
-	struct listxattr_iter *it =
-		container_of(_it, struct listxattr_iter, it);
+	struct super_block *sb = it->sb;
+	struct erofs_xattr_entry entry;
+	unsigned int slice, processed, value_sz;
 
-	it->buffer[it->buffer_ofs++] = '\0';
-	return 1;
-}
+	/* 1. handle xattr entry */
+	entry = *(struct erofs_xattr_entry *)
+			(it->kaddr + erofs_blkoff(sb, it->pos));
+	it->pos += sizeof(struct erofs_xattr_entry);
+	value_sz = le16_to_cpu(entry.e_value_size);
 
-static const struct xattr_iter_handlers list_xattr_handlers = {
-	.entry = xattr_entrylist,
-	.name = xattr_namelist,
-	.alloc_buffer = xattr_skipvalue,
-	.value = NULL
-};
+	/* should also match the infix for long name prefixes */
+	if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
+		struct erofs_sb_info *sbi = EROFS_SB(sb);
+		struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
+			(entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
+
+		if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
+			return -ENOATTR;
+
+		if (it->index != pf->prefix->base_index ||
+		    it->name.len != entry.e_name_len + pf->infix_len)
+			return -ENOATTR;
+
+		if (memcmp(it->name.name, pf->prefix->infix, pf->infix_len))
+			return -ENOATTR;
+
+		it->infix_len = pf->infix_len;
+	} else {
+		if (it->index != entry.e_name_index ||
+		    it->name.len != entry.e_name_len)
+			return -ENOATTR;
 
-static int inline_listxattr(struct listxattr_iter *it)
+		it->infix_len = 0;
+	}
+
+	/* 2. handle xattr name */
+	for (processed = 0; processed < entry.e_name_len; processed += slice) {
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr))
+			return PTR_ERR(it->kaddr);
+
+		slice = min_t(unsigned int,
+				sb->s_blocksize - erofs_blkoff(sb, it->pos),
+				entry.e_name_len - processed);
+		if (memcmp(it->name.name + it->infix_len + processed,
+			   it->kaddr + erofs_blkoff(sb, it->pos), slice))
+			return -ENOATTR;
+		it->pos += slice;
+	}
+
+	/* 3. handle xattr value */
+	if (!it->buffer) {
+		it->buffer_ofs = value_sz;
+		return 0;
+	}
+
+	if (it->buffer_size < value_sz)
+		return -ERANGE;
+
+	return erofs_xattr_copy_to_buffer(it, value_sz);
+}
+
+static int erofs_xattr_iter_inline(struct erofs_xattr_iter *it,
+				   struct inode *inode, bool getxattr)
 {
+	struct erofs_inode *const vi = EROFS_I(inode);
+	unsigned int xattr_header_sz, remaining, entry_sz;
+	erofs_off_t next_pos;
 	int ret;
-	unsigned int remaining;
 
-	ret = inline_xattr_iter_begin(&it->it, d_inode(it->dentry));
-	if (ret < 0)
-		return ret;
+	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
+			  sizeof(u32) * vi->xattr_shared_count;
+	if (xattr_header_sz >= vi->xattr_isize) {
+		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
+		return -ENOATTR;
+	}
+
+	remaining = vi->xattr_isize - xattr_header_sz;
+	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
 
-	remaining = ret;
 	while (remaining) {
-		ret = xattr_foreach(&it->it, &list_xattr_handlers, &remaining);
-		if (ret)
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr))
+			return PTR_ERR(it->kaddr);
+
+		entry_sz = erofs_xattr_entry_size(it->kaddr +
+				erofs_blkoff(it->sb, it->pos));
+		/* xattr on-disk corruption: xattr entry beyond xattr_isize */
+		if (remaining < entry_sz) {
+			DBG_BUGON(1);
+			return -EFSCORRUPTED;
+		}
+		remaining -= entry_sz;
+		next_pos = it->pos + entry_sz;
+
+		if (getxattr)
+			ret = erofs_getxattr_foreach(it);
+		else
+			ret = erofs_listxattr_foreach(it);
+		if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
 			break;
+
+		it->pos = next_pos;
 	}
-	return ret ? ret : it->buffer_ofs;
+	return ret;
 }
 
-static int shared_listxattr(struct listxattr_iter *it)
+static int erofs_xattr_iter_shared(struct erofs_xattr_iter *it,
+				   struct inode *inode, bool getxattr)
 {
-	struct inode *const inode = d_inode(it->dentry);
 	struct erofs_inode *const vi = EROFS_I(inode);
-	struct super_block *const sb = it->it.sb;
-	unsigned int i, xsid;
-	int ret = 0;
+	struct super_block *const sb = it->sb;
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	unsigned int i;
+	int ret = -ENOATTR;
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
-		xsid = vi->xattr_shared_xattrs[i];
-		it->it.blkaddr = erofs_xattr_blkaddr(sb, xsid);
-		it->it.ofs = erofs_xattr_blkoff(sb, xsid);
-		it->it.kaddr = erofs_read_metabuf(&it->it.buf, sb,
-						  it->it.blkaddr, EROFS_KMAP);
-		if (IS_ERR(it->it.kaddr))
-			return PTR_ERR(it->it.kaddr);
-
-		ret = xattr_foreach(&it->it, &list_xattr_handlers, NULL);
-		if (ret)
+		it->pos = erofs_pos(sb, sbi->xattr_blkaddr) +
+				vi->xattr_shared_xattrs[i] * sizeof(__le32);
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr))
+			return PTR_ERR(it->kaddr);
+
+		if (getxattr)
+			ret = erofs_getxattr_foreach(it);
+		else
+			ret = erofs_listxattr_foreach(it);
+		if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
 			break;
 	}
-	return ret ? ret : it->buffer_ofs;
+	return ret;
+}
+
+int erofs_getxattr(struct inode *inode, int index, const char *name,
+		   void *buffer, size_t buffer_size)
+{
+	int ret;
+	struct erofs_xattr_iter it;
+
+	if (!name)
+		return -EINVAL;
+
+	ret = erofs_init_inode_xattrs(inode);
+	if (ret)
+		return ret;
+
+	it.index = index;
+	it.name = (struct qstr)QSTR_INIT(name, strlen(name));
+	if (it.name.len > EROFS_NAME_LEN)
+		return -ERANGE;
+
+	it.sb = inode->i_sb;
+	it.buf = __EROFS_BUF_INITIALIZER;
+	erofs_init_metabuf(&it.buf, it.sb);
+	it.buffer = buffer;
+	it.buffer_size = buffer_size;
+	it.buffer_ofs = 0;
+
+	ret = erofs_xattr_iter_inline(&it, inode, true);
+	if (ret == -ENOATTR)
+		ret = erofs_xattr_iter_shared(&it, inode, true);
+	erofs_put_metabuf(&it.buf);
+	return ret ? ret : it.buffer_ofs;
 }
 
-ssize_t erofs_listxattr(struct dentry *dentry,
-			char *buffer, size_t buffer_size)
+ssize_t erofs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 {
 	int ret;
-	struct listxattr_iter it;
+	struct erofs_xattr_iter it;
+	struct inode *inode = d_inode(dentry);
 
-	ret = erofs_init_inode_xattrs(d_inode(dentry));
+	ret = erofs_init_inode_xattrs(inode);
 	if (ret == -ENOATTR)
 		return 0;
 	if (ret)
 		return ret;
 
-	it.it.buf = __EROFS_BUF_INITIALIZER;
+	it.sb = dentry->d_sb;
+	it.buf = __EROFS_BUF_INITIALIZER;
+	erofs_init_metabuf(&it.buf, it.sb);
 	it.dentry = dentry;
 	it.buffer = buffer;
 	it.buffer_size = buffer_size;
 	it.buffer_ofs = 0;
 
-	it.it.sb = dentry->d_sb;
-
-	ret = inline_listxattr(&it);
-	if (ret >= 0 || ret == -ENOATTR)
-		ret = shared_listxattr(&it);
-	erofs_put_metabuf(&it.it.buf);
-	return ret;
+	ret = erofs_xattr_iter_inline(&it, inode, false);
+	if (!ret || ret == -ENOATTR)
+		ret = erofs_xattr_iter_shared(&it, inode, false);
+	if (ret == -ENOATTR)
+		ret = 0;
+	erofs_put_metabuf(&it.buf);
+	return ret ? ret : it.buffer_ofs;
 }
 
 void erofs_xattr_prefixes_cleanup(struct super_block *sb)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 160b3da43aec..5f1890e309c6 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -5,7 +5,6 @@
  * Copyright (C) 2022 Alibaba Cloud
  */
 #include "compress.h"
-#include <linux/prefetch.h>
 #include <linux/psi.h>
 #include <linux/cpuhotplug.h>
 #include <trace/events/erofs.h>
@@ -92,13 +91,8 @@ struct z_erofs_pcluster {
 	struct z_erofs_bvec compressed_bvecs[];
 };
 
-/* 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)
-
+/* the end of a chain of pclusters */
+#define Z_EROFS_PCLUSTER_TAIL           ((void *) 0x700 + POISON_POINTER_DELTA)
 #define Z_EROFS_PCLUSTER_NIL            (NULL)
 
 struct z_erofs_decompressqueue {
@@ -241,14 +235,20 @@ static void z_erofs_bvec_iter_begin(struct z_erofs_bvec_iter *iter,
 
 static int z_erofs_bvec_enqueue(struct z_erofs_bvec_iter *iter,
 				struct z_erofs_bvec *bvec,
-				struct page **candidate_bvpage)
+				struct page **candidate_bvpage,
+				struct page **pagepool)
 {
-	if (iter->cur == iter->nr) {
-		if (!*candidate_bvpage)
-			return -EAGAIN;
-
+	if (iter->cur >= iter->nr) {
+		struct page *nextpage = *candidate_bvpage;
+
+		if (!nextpage) {
+			nextpage = erofs_allocpage(pagepool, GFP_NOFS);
+			if (!nextpage)
+				return -ENOMEM;
+			set_page_private(nextpage, Z_EROFS_SHORTLIVED_PAGE);
+		}
 		DBG_BUGON(iter->bvset->nextpage);
-		iter->bvset->nextpage = *candidate_bvpage;
+		iter->bvset->nextpage = nextpage;
 		z_erofs_bvset_flip(iter);
 
 		iter->bvset->nextpage = NULL;
@@ -500,20 +500,6 @@ out_error_pcluster_pool:
 enum z_erofs_pclustermode {
 	Z_EROFS_PCLUSTER_INFLIGHT,
 	/*
-	 * The current pclusters was the tail of an exist chain, in addition
-	 * that the previous processed chained pclusters are all decided to
-	 * be hooked up to it.
-	 * A new chain will be created for the remaining pclusters which are
-	 * not processed yet, so different from Z_EROFS_PCLUSTER_FOLLOWED,
-	 * the next pcluster cannot reuse the whole page safely for inplace I/O
-	 * in the following scenario:
-	 *  ________________________________________________________________
-	 * |      tail (partial) page     |       head (partial) page       |
-	 * |   (belongs to the next pcl)  |   (belongs to the current pcl)  |
-	 * |_______PCLUSTER_FOLLOWED______|________PCLUSTER_HOOKED__________|
-	 */
-	Z_EROFS_PCLUSTER_HOOKED,
-	/*
 	 * 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
@@ -530,8 +516,8 @@ enum z_erofs_pclustermode {
 	 *  ________________________________________________________________
 	 * |  tail (partial) page |          head (partial) page           |
 	 * |  (of the current cl) |      (of the previous collection)      |
-	 * | PCLUSTER_FOLLOWED or |                                        |
-	 * |_____PCLUSTER_HOOKED__|___________PCLUSTER_FOLLOWED____________|
+	 * |                      |                                        |
+	 * |__PCLUSTER_FOLLOWED___|___________PCLUSTER_FOLLOWED____________|
 	 *
 	 * [  (*) the above page can be used as inplace I/O.               ]
 	 */
@@ -543,12 +529,12 @@ struct z_erofs_decompress_frontend {
 	struct erofs_map_blocks map;
 	struct z_erofs_bvec_iter biter;
 
+	struct page *pagepool;
 	struct page *candidate_bvpage;
-	struct z_erofs_pcluster *pcl, *tailpcl;
+	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;
@@ -578,8 +564,7 @@ static bool z_erofs_should_alloc_cache(struct z_erofs_decompress_frontend *fe)
 	return false;
 }
 
-static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,
-			       struct page **pagepool)
+static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe)
 {
 	struct address_space *mc = MNGD_MAPPING(EROFS_I_SB(fe->inode));
 	struct z_erofs_pcluster *pcl = fe->pcl;
@@ -620,7 +605,7 @@ static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,
 			 * succeeds or fallback to in-place I/O instead
 			 * to avoid any direct reclaim.
 			 */
-			newpage = erofs_allocpage(pagepool, gfp);
+			newpage = erofs_allocpage(&fe->pagepool, gfp);
 			if (!newpage)
 				continue;
 			set_page_private(newpage, Z_EROFS_PREALLOCATED_PAGE);
@@ -633,7 +618,7 @@ static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,
 		if (page)
 			put_page(page);
 		else if (newpage)
-			erofs_pagepool_add(pagepool, newpage);
+			erofs_pagepool_add(&fe->pagepool, newpage);
 	}
 
 	/*
@@ -654,7 +639,7 @@ int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 
 	DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
 	/*
-	 * refcount of workgroup is now freezed as 1,
+	 * refcount of workgroup is now freezed as 0,
 	 * therefore no need to worry about available decompression users.
 	 */
 	for (i = 0; i < pcl->pclusterpages; ++i) {
@@ -678,29 +663,73 @@ int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 	return 0;
 }
 
-int erofs_try_to_free_cached_page(struct page *page)
+static bool z_erofs_cache_release_folio(struct folio *folio, gfp_t gfp)
 {
-	struct z_erofs_pcluster *const pcl = (void *)page_private(page);
-	int ret, i;
+	struct z_erofs_pcluster *pcl = folio_get_private(folio);
+	bool ret;
+	int i;
 
-	if (!erofs_workgroup_try_to_freeze(&pcl->obj, 1))
-		return 0;
+	if (!folio_test_private(folio))
+		return true;
+
+	ret = false;
+	spin_lock(&pcl->obj.lockref.lock);
+	if (pcl->obj.lockref.count > 0)
+		goto out;
 
-	ret = 0;
 	DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
 	for (i = 0; i < pcl->pclusterpages; ++i) {
-		if (pcl->compressed_bvecs[i].page == page) {
+		if (pcl->compressed_bvecs[i].page == &folio->page) {
 			WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);
-			ret = 1;
+			ret = true;
 			break;
 		}
 	}
-	erofs_workgroup_unfreeze(&pcl->obj, 1);
 	if (ret)
-		detach_page_private(page);
+		folio_detach_private(folio);
+out:
+	spin_unlock(&pcl->obj.lockref.lock);
 	return ret;
 }
 
+/*
+ * It will be called only on inode eviction. In case that there are still some
+ * decompression requests in progress, wait with rescheduling for a bit here.
+ * An extra lock could be introduced instead but it seems unnecessary.
+ */
+static void z_erofs_cache_invalidate_folio(struct folio *folio,
+					   size_t offset, size_t length)
+{
+	const size_t stop = length + offset;
+
+	/* Check for potential overflow in debug mode */
+	DBG_BUGON(stop > folio_size(folio) || stop < length);
+
+	if (offset == 0 && stop == folio_size(folio))
+		while (!z_erofs_cache_release_folio(folio, GFP_NOFS))
+			cond_resched();
+}
+
+static const struct address_space_operations z_erofs_cache_aops = {
+	.release_folio = z_erofs_cache_release_folio,
+	.invalidate_folio = z_erofs_cache_invalidate_folio,
+};
+
+int erofs_init_managed_cache(struct super_block *sb)
+{
+	struct inode *const inode = new_inode(sb);
+
+	if (!inode)
+		return -ENOMEM;
+
+	set_nlink(inode, 1);
+	inode->i_size = OFFSET_MAX;
+	inode->i_mapping->a_ops = &z_erofs_cache_aops;
+	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
+	EROFS_SB(sb)->managed_cache = inode;
+	return 0;
+}
+
 static bool z_erofs_try_inplace_io(struct z_erofs_decompress_frontend *fe,
 				   struct z_erofs_bvec *bvec)
 {
@@ -731,7 +760,8 @@ static int z_erofs_attach_page(struct z_erofs_decompress_frontend *fe,
 		    !fe->candidate_bvpage)
 			fe->candidate_bvpage = bvec->page;
 	}
-	ret = z_erofs_bvec_enqueue(&fe->biter, bvec, &fe->candidate_bvpage);
+	ret = z_erofs_bvec_enqueue(&fe->biter, bvec, &fe->candidate_bvpage,
+				   &fe->pagepool);
 	fe->pcl->vcnt += (ret >= 0);
 	return ret;
 }
@@ -750,19 +780,7 @@ static void z_erofs_try_to_claim_pcluster(struct z_erofs_decompress_frontend *f)
 		return;
 	}
 
-	/*
-	 * type 2, link to the end of an existing open chain, be careful
-	 * that its submission is controlled by the original attached chain.
-	 */
-	if (*owned_head != &pcl->next && pcl != f->tailpcl &&
-	    cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
-		    *owned_head) == Z_EROFS_PCLUSTER_TAIL) {
-		*owned_head = Z_EROFS_PCLUSTER_TAIL;
-		f->mode = Z_EROFS_PCLUSTER_HOOKED;
-		f->tailpcl = NULL;
-		return;
-	}
-	/* type 3, it belongs to a chain, but it isn't the end of the chain */
+	/* type 2, it belongs to an ongoing chain */
 	f->mode = Z_EROFS_PCLUSTER_INFLIGHT;
 }
 
@@ -786,7 +804,7 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe)
 	if (IS_ERR(pcl))
 		return PTR_ERR(pcl);
 
-	atomic_set(&pcl->obj.refcount, 1);
+	spin_lock_init(&pcl->obj.lockref.lock);
 	pcl->algorithmformat = map->m_algorithmformat;
 	pcl->length = 0;
 	pcl->partial = true;
@@ -823,9 +841,6 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe)
 			goto err_out;
 		}
 	}
-	/* used to check tail merging loop due to corrupted images */
-	if (fe->owned_head == Z_EROFS_PCLUSTER_TAIL)
-		fe->tailpcl = pcl;
 	fe->owned_head = &pcl->next;
 	fe->pcl = pcl;
 	return 0;
@@ -846,7 +861,6 @@ static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe)
 
 	/* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous pcluster */
 	DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_NIL);
-	DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 
 	if (!(map->m_flags & EROFS_MAP_META)) {
 		grp = erofs_find_workgroup(fe->inode->i_sb,
@@ -865,10 +879,6 @@ static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe)
 
 	if (ret == -EEXIST) {
 		mutex_lock(&fe->pcl->lock);
-		/* used to check tail merging loop due to corrupted images */
-		if (fe->owned_head == Z_EROFS_PCLUSTER_TAIL)
-			fe->tailpcl = fe->pcl;
-
 		z_erofs_try_to_claim_pcluster(fe);
 	} else if (ret) {
 		return ret;
@@ -908,10 +918,8 @@ static bool z_erofs_collector_end(struct z_erofs_decompress_frontend *fe)
 	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));
+	if (fe->candidate_bvpage)
 		fe->candidate_bvpage = NULL;
-	}
 
 	/*
 	 * if all pending pages are added, don't hold its reference
@@ -958,7 +966,7 @@ static int z_erofs_read_fragment(struct inode *inode, erofs_off_t pos,
 }
 
 static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
-				struct page *page, struct page **pagepool)
+				struct page *page)
 {
 	struct inode *const inode = fe->inode;
 	struct erofs_map_blocks *const map = &fe->map;
@@ -1016,7 +1024,7 @@ repeat:
 		fe->mode = Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE;
 	} else {
 		/* bind cache first when cached decompression is preferred */
-		z_erofs_bind_cache(fe, pagepool);
+		z_erofs_bind_cache(fe);
 	}
 hitted:
 	/*
@@ -1025,8 +1033,7 @@ hitted:
 	 * 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_HOOKED &&
-		  fe->mode != Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
+	tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
 
 	cur = end - min_t(unsigned int, offset + end - map->m_la, end);
 	if (!(map->m_flags & EROFS_MAP_MAPPED)) {
@@ -1056,24 +1063,13 @@ hitted:
 	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);
+	if (err)
 		goto out;
-	}
 
 	z_erofs_onlinepage_split(page);
 	/* bump up the number of spiltted parts of a page */
@@ -1104,7 +1100,7 @@ out:
 	return err;
 }
 
-static bool z_erofs_get_sync_decompress_policy(struct erofs_sb_info *sbi,
+static bool z_erofs_is_sync_decompress(struct erofs_sb_info *sbi,
 				       unsigned int readahead_pages)
 {
 	/* auto: enable for read_folio, disable for readahead */
@@ -1283,6 +1279,8 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
 	struct erofs_sb_info *const sbi = EROFS_SB(be->sb);
 	struct z_erofs_pcluster *pcl = be->pcl;
 	unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
+	const struct z_erofs_decompressor *decompressor =
+				&erofs_decompressors[pcl->algorithmformat];
 	unsigned int i, inputsize;
 	int err2;
 	struct page *page;
@@ -1326,7 +1324,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
 	else
 		inputsize = pclusterpages * PAGE_SIZE;
 
-	err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
+	err = decompressor->decompress(&(struct z_erofs_decompress_req) {
 					.sb = be->sb,
 					.in = be->compressed_pages,
 					.out = be->decompressed_pages,
@@ -1404,10 +1402,7 @@ static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
 	};
 	z_erofs_next_pcluster_t owned = io->head;
 
-	while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
-		/* impossible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
-		DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
-		/* impossible that 'owned' equals Z_EROFS_PCLUSTER_NIL */
+	while (owned != Z_EROFS_PCLUSTER_TAIL) {
 		DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
 
 		be.pcl = container_of(owned, struct z_erofs_pcluster, next);
@@ -1424,7 +1419,7 @@ static void z_erofs_decompressqueue_work(struct work_struct *work)
 		container_of(work, struct z_erofs_decompressqueue, u.work);
 	struct page *pagepool = NULL;
 
-	DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
+	DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL);
 	z_erofs_decompress_queue(bgq, &pagepool);
 	erofs_release_pages(&pagepool);
 	kvfree(bgq);
@@ -1452,7 +1447,7 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
 	if (atomic_add_return(bios, &io->pending_bios))
 		return;
 	/* Use (kthread_)work and sync decompression for atomic contexts only */
-	if (in_atomic() || irqs_disabled()) {
+	if (!in_task() || irqs_disabled() || rcu_read_lock_any_held()) {
 #ifdef CONFIG_EROFS_FS_PCPU_KTHREAD
 		struct kthread_worker *worker;
 
@@ -1612,7 +1607,7 @@ fg_out:
 		q->sync = true;
 	}
 	q->sb = sb;
-	q->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
+	q->head = Z_EROFS_PCLUSTER_TAIL;
 	return q;
 }
 
@@ -1630,11 +1625,7 @@ static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
 	z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
 	z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
 
-	DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
-	if (owned_head == Z_EROFS_PCLUSTER_TAIL)
-		owned_head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
-
-	WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL_CLOSED);
+	WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL);
 
 	WRITE_ONCE(*submit_qtail, owned_head);
 	WRITE_ONCE(*bypass_qtail, &pcl->next);
@@ -1668,9 +1659,8 @@ static void z_erofs_decompressqueue_endio(struct bio *bio)
 }
 
 static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
-				 struct page **pagepool,
 				 struct z_erofs_decompressqueue *fgq,
-				 bool *force_fg)
+				 bool *force_fg, bool readahead)
 {
 	struct super_block *sb = f->inode->i_sb;
 	struct address_space *mc = MNGD_MAPPING(EROFS_SB(sb));
@@ -1705,15 +1695,10 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
 		unsigned int i = 0;
 		bool bypass = true;
 
-		/* 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);
+		owned_head = READ_ONCE(pcl->next);
 
-		/* close the main owned chain at first */
-		owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
-				     Z_EROFS_PCLUSTER_TAIL_CLOSED);
 		if (z_erofs_is_inline_pcluster(pcl)) {
 			move_to_bypass_jobqueue(pcl, qtail, owned_head);
 			continue;
@@ -1731,8 +1716,8 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
 		do {
 			struct page *page;
 
-			page = pickup_page_for_submission(pcl, i++, pagepool,
-							  mc);
+			page = pickup_page_for_submission(pcl, i++,
+					&f->pagepool, mc);
 			if (!page)
 				continue;
 
@@ -1761,7 +1746,7 @@ submit_bio_retry:
 				bio->bi_iter.bi_sector = (sector_t)cur <<
 					(sb->s_blocksize_bits - 9);
 				bio->bi_private = q[JQ_SUBMIT];
-				if (f->readahead)
+				if (readahead)
 					bio->bi_opf |= REQ_RAHEAD;
 				++nr_bios;
 			}
@@ -1797,16 +1782,16 @@ submit_bio_retry:
 }
 
 static void z_erofs_runqueue(struct z_erofs_decompress_frontend *f,
-			     struct page **pagepool, bool force_fg)
+			     bool force_fg, bool ra)
 {
 	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);
+	z_erofs_submit_queue(f, io, &force_fg, ra);
 
 	/* handle bypass queue (no i/o pclusters) immediately */
-	z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
+	z_erofs_decompress_queue(&io[JQ_BYPASS], &f->pagepool);
 
 	if (!force_fg)
 		return;
@@ -1815,7 +1800,7 @@ static void z_erofs_runqueue(struct z_erofs_decompress_frontend *f,
 	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);
+	z_erofs_decompress_queue(&io[JQ_SUBMIT], &f->pagepool);
 }
 
 /*
@@ -1823,29 +1808,28 @@ static void z_erofs_runqueue(struct z_erofs_decompress_frontend *f,
  * 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 readahead_control *rac, bool backmost)
 {
 	struct inode *inode = f->inode;
 	struct erofs_map_blocks *map = &f->map;
-	erofs_off_t cur;
+	erofs_off_t cur, end, headoffset = f->headoffset;
 	int err;
 
 	if (backmost) {
+		if (rac)
+			end = headoffset + readahead_length(rac) - 1;
+		else
+			end = headoffset + PAGE_SIZE - 1;
 		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 */
+		/* expand 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);
+			readahead_expand(rac, headoffset, cur - headoffset);
 			return;
 		}
 		end = round_up(end, PAGE_SIZE);
@@ -1866,7 +1850,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
 			if (PageUptodate(page)) {
 				unlock_page(page);
 			} else {
-				err = z_erofs_do_read_page(f, page, pagepool);
+				err = z_erofs_do_read_page(f, page);
 				if (err)
 					erofs_err(inode->i_sb,
 						  "readmore error at page %lu @ nid %llu",
@@ -1887,28 +1871,24 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
 	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);
-
+	z_erofs_pcluster_readmore(&f, NULL, true);
+	err = z_erofs_do_read_page(&f, page);
+	z_erofs_pcluster_readmore(&f, NULL, 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));
+	z_erofs_runqueue(&f, z_erofs_is_sync_decompress(sbi, 0), false);
 
 	if (err)
 		erofs_err(inode->i_sb, "failed to read, err [%d]", err);
 
 	erofs_put_metabuf(&f.map.buf);
-	erofs_release_pages(&pagepool);
+	erofs_release_pages(&f.pagepool);
 	return err;
 }
 
@@ -1917,14 +1897,12 @@ 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;
+	struct page *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);
+	z_erofs_pcluster_readmore(&f, rac, true);
 	nr_pages = readahead_count(rac);
 	trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
 
@@ -1940,20 +1918,19 @@ static void z_erofs_readahead(struct readahead_control *rac)
 		/* traversal in reverse order */
 		head = (void *)page_private(page);
 
-		err = z_erofs_do_read_page(&f, page, &pagepool);
+		err = z_erofs_do_read_page(&f, page);
 		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);
+	z_erofs_pcluster_readmore(&f, rac, false);
 	(void)z_erofs_collector_end(&f);
 
-	z_erofs_runqueue(&f, &pagepool,
-			 z_erofs_get_sync_decompress_policy(sbi, nr_pages));
+	z_erofs_runqueue(&f, z_erofs_is_sync_decompress(sbi, nr_pages), true);
 	erofs_put_metabuf(&f.map.buf);
-	erofs_release_pages(&pagepool);
+	erofs_release_pages(&f.pagepool);
 }
 
 const struct address_space_operations z_erofs_aops = {
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index d37c5c89c728..1909ddafd9c7 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -22,8 +22,8 @@ struct z_erofs_maprecorder {
 	bool partialref;
 };
 
-static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
-					 unsigned long lcn)
+static int z_erofs_load_full_lcluster(struct z_erofs_maprecorder *m,
+				      unsigned long lcn)
 {
 	struct inode *const inode = m->inode;
 	struct erofs_inode *const vi = EROFS_I(inode);
@@ -129,7 +129,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	u8 *in, type;
 	bool big_pcluster;
 
-	if (1 << amortizedshift == 4)
+	if (1 << amortizedshift == 4 && lclusterbits <= 14)
 		vcnt = 2;
 	else if (1 << amortizedshift == 2 && lclusterbits == 12)
 		vcnt = 16;
@@ -226,12 +226,11 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	return 0;
 }
 
-static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
-					    unsigned long lcn, bool lookahead)
+static int z_erofs_load_compact_lcluster(struct z_erofs_maprecorder *m,
+					 unsigned long lcn, bool lookahead)
 {
 	struct inode *const inode = m->inode;
 	struct erofs_inode *const vi = EROFS_I(inode);
-	const unsigned int lclusterbits = vi->z_logical_clusterbits;
 	const erofs_off_t ebase = sizeof(struct z_erofs_map_header) +
 		ALIGN(erofs_iloc(inode) + vi->inode_isize + vi->xattr_isize, 8);
 	unsigned int totalidx = erofs_iblks(inode);
@@ -239,9 +238,6 @@ static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 	unsigned int amortizedshift;
 	erofs_off_t pos;
 
-	if (lclusterbits != 12)
-		return -EOPNOTSUPP;
-
 	if (lcn >= totalidx)
 		return -EINVAL;
 
@@ -281,23 +277,23 @@ out:
 	return unpack_compacted_index(m, amortizedshift, pos, lookahead);
 }
 
-static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
-					  unsigned int lcn, bool lookahead)
+static int z_erofs_load_lcluster_from_disk(struct z_erofs_maprecorder *m,
+					   unsigned int lcn, bool lookahead)
 {
-	const unsigned int datamode = EROFS_I(m->inode)->datalayout;
-
-	if (datamode == EROFS_INODE_COMPRESSED_FULL)
-		return legacy_load_cluster_from_disk(m, lcn);
-
-	if (datamode == EROFS_INODE_COMPRESSED_COMPACT)
-		return compacted_load_cluster_from_disk(m, lcn, lookahead);
-
-	return -EINVAL;
+	switch (EROFS_I(m->inode)->datalayout) {
+	case EROFS_INODE_COMPRESSED_FULL:
+		return z_erofs_load_full_lcluster(m, lcn);
+	case EROFS_INODE_COMPRESSED_COMPACT:
+		return z_erofs_load_compact_lcluster(m, lcn, lookahead);
+	default:
+		return -EINVAL;
+	}
 }
 
 static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 				   unsigned int lookback_distance)
 {
+	struct super_block *sb = m->inode->i_sb;
 	struct erofs_inode *const vi = EROFS_I(m->inode);
 	const unsigned int lclusterbits = vi->z_logical_clusterbits;
 
@@ -305,21 +301,15 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 		unsigned long lcn = m->lcn - lookback_distance;
 		int err;
 
-		/* load extent head logical cluster if needed */
-		err = z_erofs_load_cluster_from_disk(m, lcn, false);
+		err = z_erofs_load_lcluster_from_disk(m, lcn, false);
 		if (err)
 			return err;
 
 		switch (m->type) {
 		case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
-			if (!m->delta[0]) {
-				erofs_err(m->inode->i_sb,
-					  "invalid lookback distance 0 @ nid %llu",
-					  vi->nid);
-				DBG_BUGON(1);
-				return -EFSCORRUPTED;
-			}
 			lookback_distance = m->delta[0];
+			if (!lookback_distance)
+				goto err_bogus;
 			continue;
 		case Z_EROFS_LCLUSTER_TYPE_PLAIN:
 		case Z_EROFS_LCLUSTER_TYPE_HEAD1:
@@ -328,16 +318,15 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 			m->map->m_la = (lcn << lclusterbits) | m->clusterofs;
 			return 0;
 		default:
-			erofs_err(m->inode->i_sb,
-				  "unknown type %u @ lcn %lu of nid %llu",
+			erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
 				  m->type, lcn, vi->nid);
 			DBG_BUGON(1);
 			return -EOPNOTSUPP;
 		}
 	}
-
-	erofs_err(m->inode->i_sb, "bogus lookback distance @ nid %llu",
-		  vi->nid);
+err_bogus:
+	erofs_err(sb, "bogus lookback distance %u @ lcn %lu of nid %llu",
+		  lookback_distance, m->lcn, vi->nid);
 	DBG_BUGON(1);
 	return -EFSCORRUPTED;
 }
@@ -369,7 +358,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 	if (m->compressedblks)
 		goto out;
 
-	err = z_erofs_load_cluster_from_disk(m, lcn, false);
+	err = z_erofs_load_lcluster_from_disk(m, lcn, false);
 	if (err)
 		return err;
 
@@ -401,9 +390,8 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 			break;
 		fallthrough;
 	default:
-		erofs_err(m->inode->i_sb,
-			  "cannot found CBLKCNT @ lcn %lu of nid %llu",
-			  lcn, vi->nid);
+		erofs_err(sb, "cannot found CBLKCNT @ lcn %lu of nid %llu", lcn,
+			  vi->nid);
 		DBG_BUGON(1);
 		return -EFSCORRUPTED;
 	}
@@ -411,9 +399,7 @@ out:
 	map->m_plen = erofs_pos(sb, m->compressedblks);
 	return 0;
 err_bonus_cblkcnt:
-	erofs_err(m->inode->i_sb,
-		  "bogus CBLKCNT @ lcn %lu of nid %llu",
-		  lcn, vi->nid);
+	erofs_err(sb, "bogus CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);
 	DBG_BUGON(1);
 	return -EFSCORRUPTED;
 }
@@ -434,7 +420,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
 			return 0;
 		}
 
-		err = z_erofs_load_cluster_from_disk(m, lcn, true);
+		err = z_erofs_load_lcluster_from_disk(m, lcn, true);
 		if (err)
 			return err;
 
@@ -481,7 +467,7 @@ static int z_erofs_do_map_blocks(struct inode *inode,
 	initial_lcn = ofs >> lclusterbits;
 	endoff = ofs & ((1 << lclusterbits) - 1);
 
-	err = z_erofs_load_cluster_from_disk(&m, initial_lcn, false);
+	err = z_erofs_load_lcluster_from_disk(&m, initial_lcn, false);
 	if (err)
 		goto unmap_out;
 
@@ -539,8 +525,7 @@ static int z_erofs_do_map_blocks(struct inode *inode,
 	if (flags & EROFS_GET_BLOCKS_FINDTAIL) {
 		vi->z_tailextent_headlcn = m.lcn;
 		/* for non-compact indexes, fragmentoff is 64 bits */
-		if (fragment &&
-		    vi->datalayout == EROFS_INODE_COMPRESSED_FULL)
+		if (fragment && vi->datalayout == EROFS_INODE_COMPRESSED_FULL)
 			vi->z_fragmentoff |= (u64)m.pblk << 32;
 	}
 	if (ztailpacking && m.lcn == vi->z_tailextent_headlcn) {