14 files changed, 720 insertions, 488 deletions

diff --git a/drivers/staging/erofs/Kconfig b/drivers/staging/erofs/Kconfig
index 663b755bf2fb..c8521d71039b 100644
--- a/drivers/staging/erofs/Kconfig
+++ b/drivers/staging/erofs/Kconfig
@@ -78,6 +78,15 @@ config EROFS_FAULT_INJECTION
 	  Test EROFS to inject faults such as ENOMEM, EIO, and so on.
 	  If unsure, say N.
 
+config EROFS_FS_IO_MAX_RETRIES
+	int "EROFS IO Maximum Retries"
+	depends on EROFS_FS
+	default "5"
+	help
+	  Maximum retry count of IO Errors.
+
+	  If unsure, leave the default value (5 retries, 6 IOs at most).
+
 config EROFS_FS_ZIP
 	bool "EROFS Data Compresssion Support"
 	depends on EROFS_FS
diff --git a/drivers/staging/erofs/data.c b/drivers/staging/erofs/data.c
index ac263a180253..6384f73e5418 100644
--- a/drivers/staging/erofs/data.c
+++ b/drivers/staging/erofs/data.c
@@ -25,7 +25,7 @@ static inline void read_endio(struct bio *bio)
 		struct page *page = bvec->bv_page;
 
 		/* page is already locked */
-		BUG_ON(PageUptodate(page));
+		DBG_BUGON(PageUptodate(page));
 
 		if (unlikely(err))
 			SetPageError(page);
@@ -39,38 +39,50 @@ static inline void read_endio(struct bio *bio)
 }
 
 /* prio -- true is used for dir */
-struct page *erofs_get_meta_page(struct super_block *sb,
-	erofs_blk_t blkaddr, bool prio)
+struct page *__erofs_get_meta_page(struct super_block *sb,
+	erofs_blk_t blkaddr, bool prio, bool nofail)
 {
-	struct inode *bd_inode = sb->s_bdev->bd_inode;
-	struct address_space *mapping = bd_inode->i_mapping;
+	struct inode *const bd_inode = sb->s_bdev->bd_inode;
+	struct address_space *const mapping = bd_inode->i_mapping;
+	/* prefer retrying in the allocator to blindly looping below */
+	const gfp_t gfp = mapping_gfp_constraint(mapping, ~__GFP_FS) |
+		(nofail ? __GFP_NOFAIL : 0);
+	unsigned int io_retries = nofail ? EROFS_IO_MAX_RETRIES_NOFAIL : 0;
 	struct page *page;
+	int err;
 
 repeat:
-	page = find_or_create_page(mapping, blkaddr,
-	/*
-	 * Prefer looping in the allocator rather than here,
-	 * at least that code knows what it's doing.
-	 */
-		mapping_gfp_constraint(mapping, ~__GFP_FS) | __GFP_NOFAIL);
-
-	BUG_ON(!page || !PageLocked(page));
+	page = find_or_create_page(mapping, blkaddr, gfp);
+	if (unlikely(page == NULL)) {
+		DBG_BUGON(nofail);
+		return ERR_PTR(-ENOMEM);
+	}
+	DBG_BUGON(!PageLocked(page));
 
 	if (!PageUptodate(page)) {
 		struct bio *bio;
-		int err;
 
-		bio = prepare_bio(sb, blkaddr, 1, read_endio);
+		bio = erofs_grab_bio(sb, blkaddr, 1, read_endio, nofail);
+		if (IS_ERR(bio)) {
+			DBG_BUGON(nofail);
+			err = PTR_ERR(bio);
+			goto err_out;
+		}
+
 		err = bio_add_page(bio, page, PAGE_SIZE, 0);
-		BUG_ON(err != PAGE_SIZE);
+		if (unlikely(err != PAGE_SIZE)) {
+			err = -EFAULT;
+			goto err_out;
+		}
 
 		__submit_bio(bio, REQ_OP_READ,
 			REQ_META | (prio ? REQ_PRIO : 0));
 
 		lock_page(page);
 
-		/* the page has been truncated by others? */
+		/* this page has been truncated by others */
 		if (unlikely(page->mapping != mapping)) {
+unlock_repeat:
 			unlock_page(page);
 			put_page(page);
 			goto repeat;
@@ -78,25 +90,32 @@ repeat:
 
 		/* more likely a read error */
 		if (unlikely(!PageUptodate(page))) {
-			unlock_page(page);
-			put_page(page);
-
-			page = ERR_PTR(-EIO);
+			if (io_retries) {
+				--io_retries;
+				goto unlock_repeat;
+			}
+			err = -EIO;
+			goto err_out;
 		}
 	}
 	return page;
+
+err_out:
+	unlock_page(page);
+	put_page(page);
+	return ERR_PTR(err);
 }
 
 static int erofs_map_blocks_flatmode(struct inode *inode,
 	struct erofs_map_blocks *map,
 	int flags)
 {
+	int err = 0;
 	erofs_blk_t nblocks, lastblk;
 	u64 offset = map->m_la;
 	struct erofs_vnode *vi = EROFS_V(inode);
 
 	trace_erofs_map_blocks_flatmode_enter(inode, map, flags);
-	BUG_ON(is_inode_layout_compression(inode));
 
 	nblocks = DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
 	lastblk = nblocks - is_inode_layout_inline(inode);
@@ -123,18 +142,27 @@ static int erofs_map_blocks_flatmode(struct inode *inode,
 		map->m_plen = inode->i_size - offset;
 
 		/* inline data should locate in one meta block */
-		BUG_ON(erofs_blkoff(map->m_pa) + map->m_plen > PAGE_SIZE);
+		if (erofs_blkoff(map->m_pa) + map->m_plen > PAGE_SIZE) {
+			DBG_BUGON(1);
+			err = -EIO;
+			goto err_out;
+		}
+
 		map->m_flags |= EROFS_MAP_META;
 	} else {
 		errln("internal error @ nid: %llu (size %llu), m_la 0x%llx",
 			vi->nid, inode->i_size, map->m_la);
-		BUG();
+		DBG_BUGON(1);
+		err = -EIO;
+		goto err_out;
 	}
 
 out:
 	map->m_llen = map->m_plen;
+
+err_out:
 	trace_erofs_map_blocks_flatmode_exit(inode, map, flags, 0);
-	return 0;
+	return err;
 }
 
 #ifdef CONFIG_EROFS_FS_ZIP
@@ -183,14 +211,14 @@ static inline struct bio *erofs_read_raw_page(
 	struct address_space *mapping,
 	struct page *page,
 	erofs_off_t *last_block,
-	unsigned nblocks,
+	unsigned int nblocks,
 	bool ra)
 {
 	struct inode *inode = mapping->host;
 	erofs_off_t current_block = (erofs_off_t)page->index;
 	int err;
 
-	BUG_ON(!nblocks);
+	DBG_BUGON(!nblocks);
 
 	if (PageUptodate(page)) {
 		err = 0;
@@ -217,7 +245,7 @@ submit_bio_retry:
 			.m_la = blknr_to_addr(current_block),
 		};
 		erofs_blk_t blknr;
-		unsigned blkoff;
+		unsigned int blkoff;
 
 		err = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
 		if (unlikely(err))
@@ -233,7 +261,7 @@ submit_bio_retry:
 		}
 
 		/* for RAW access mode, m_plen must be equal to m_llen */
-		BUG_ON(map.m_plen != map.m_llen);
+		DBG_BUGON(map.m_plen != map.m_llen);
 
 		blknr = erofs_blknr(map.m_pa);
 		blkoff = erofs_blkoff(map.m_pa);
@@ -243,7 +271,7 @@ submit_bio_retry:
 			void *vsrc, *vto;
 			struct page *ipage;
 
-			BUG_ON(map.m_plen > PAGE_SIZE);
+			DBG_BUGON(map.m_plen > PAGE_SIZE);
 
 			ipage = erofs_get_meta_page(inode->i_sb, blknr, 0);
 
@@ -270,7 +298,7 @@ submit_bio_retry:
 		}
 
 		/* pa must be block-aligned for raw reading */
-		BUG_ON(erofs_blkoff(map.m_pa) != 0);
+		DBG_BUGON(erofs_blkoff(map.m_pa));
 
 		/* max # of continuous pages */
 		if (nblocks > DIV_ROUND_UP(map.m_plen, PAGE_SIZE))
@@ -278,7 +306,14 @@ submit_bio_retry:
 		if (nblocks > BIO_MAX_PAGES)
 			nblocks = BIO_MAX_PAGES;
 
-		bio = prepare_bio(inode->i_sb, blknr, nblocks, read_endio);
+		bio = erofs_grab_bio(inode->i_sb,
+			blknr, nblocks, read_endio, false);
+
+		if (IS_ERR(bio)) {
+			err = PTR_ERR(bio);
+			bio = NULL;
+			goto err_out;
+		}
 	}
 
 	err = bio_add_page(bio, page, PAGE_SIZE, 0);
@@ -331,13 +366,13 @@ static int erofs_raw_access_readpage(struct file *file, struct page *page)
 	if (IS_ERR(bio))
 		return PTR_ERR(bio);
 
-	BUG_ON(bio != NULL);	/* since we have only one bio -- must be NULL */
+	DBG_BUGON(bio);	/* since we have only one bio -- must be NULL */
 	return 0;
 }
 
 static int erofs_raw_access_readpages(struct file *filp,
 	struct address_space *mapping,
-	struct list_head *pages, unsigned nr_pages)
+	struct list_head *pages, unsigned int nr_pages)
 {
 	erofs_off_t last_block;
 	struct bio *bio = NULL;
@@ -369,7 +404,7 @@ static int erofs_raw_access_readpages(struct file *filp,
 		/* pages could still be locked */
 		put_page(page);
 	}
-	BUG_ON(!list_empty(pages));
+	DBG_BUGON(!list_empty(pages));
 
 	/* the rare case (end in gaps) */
 	if (unlikely(bio != NULL))
diff --git a/drivers/staging/erofs/dir.c b/drivers/staging/erofs/dir.c
index be6ae3b1bdbe..d1cb0d78ab84 100644
--- a/drivers/staging/erofs/dir.c
+++ b/drivers/staging/erofs/dir.c
@@ -24,8 +24,8 @@ static const unsigned char erofs_filetype_table[EROFS_FT_MAX] = {
 };
 
 static int erofs_fill_dentries(struct dir_context *ctx,
-	void *dentry_blk, unsigned *ofs,
-	unsigned nameoff, unsigned maxsize)
+	void *dentry_blk, unsigned int *ofs,
+	unsigned int nameoff, unsigned int maxsize)
 {
 	struct erofs_dirent *de = dentry_blk;
 	const struct erofs_dirent *end = dentry_blk + nameoff;
@@ -36,7 +36,7 @@ static int erofs_fill_dentries(struct dir_context *ctx,
 		int de_namelen;
 		unsigned char d_type;
 #ifdef CONFIG_EROFS_FS_DEBUG
-		unsigned dbg_namelen;
+		unsigned int dbg_namelen;
 		unsigned char dbg_namebuf[EROFS_NAME_LEN];
 #endif
 
@@ -81,15 +81,15 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 	struct inode *dir = file_inode(f);
 	struct address_space *mapping = dir->i_mapping;
 	const size_t dirsize = i_size_read(dir);
-	unsigned i = ctx->pos / EROFS_BLKSIZ;
-	unsigned ofs = ctx->pos % EROFS_BLKSIZ;
+	unsigned int i = ctx->pos / EROFS_BLKSIZ;
+	unsigned int ofs = ctx->pos % EROFS_BLKSIZ;
 	int err = 0;
 	bool initial = true;
 
 	while (ctx->pos < dirsize) {
 		struct page *dentry_page;
 		struct erofs_dirent *de;
-		unsigned nameoff, maxsize;
+		unsigned int nameoff, maxsize;
 
 		dentry_page = read_mapping_page(mapping, i, NULL);
 		if (IS_ERR(dentry_page))
@@ -109,7 +109,8 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 			goto skip_this;
 		}
 
-		maxsize = min_t(unsigned, dirsize - ctx->pos + ofs, PAGE_SIZE);
+		maxsize = min_t(unsigned int,
+				dirsize - ctx->pos + ofs, PAGE_SIZE);
 
 		/* search dirents at the arbitrary position */
 		if (unlikely(initial)) {
diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h
index 2f8e2bf70941..d4bffa2852b3 100644
--- a/drivers/staging/erofs/erofs_fs.h
+++ b/drivers/staging/erofs/erofs_fs.h
@@ -202,6 +202,14 @@ struct erofs_extent_header {
  *        di_u.delta[1] = distance to its corresponding tail cluster
  *                (di_advise could be 0, 1 or 2)
  */
+enum {
+	Z_EROFS_VLE_CLUSTER_TYPE_PLAIN,
+	Z_EROFS_VLE_CLUSTER_TYPE_HEAD,
+	Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD,
+	Z_EROFS_VLE_CLUSTER_TYPE_RESERVED,
+	Z_EROFS_VLE_CLUSTER_TYPE_MAX
+};
+
 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS        2
 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT         0
 
@@ -260,6 +268,9 @@ static inline void erofs_check_ondisk_layout_definitions(void)
 	BUILD_BUG_ON(sizeof(struct erofs_extent_header) != 16);
 	BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
 	BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
+
+	BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
+		     Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
 }
 
 #endif
diff --git a/drivers/staging/erofs/include/trace/events/erofs.h b/drivers/staging/erofs/include/trace/events/erofs.h
index 5aead93a762f..660c92fc1803 100644
--- a/drivers/staging/erofs/include/trace/events/erofs.h
+++ b/drivers/staging/erofs/include/trace/events/erofs.h
@@ -162,7 +162,8 @@ DECLARE_EVENT_CLASS(erofs__map_blocks_enter,
 
 	TP_printk("dev = (%d,%d), nid = %llu, la %llu llen %llu flags %s",
 		  show_dev_nid(__entry),
-		  __entry->la, __entry->llen, show_map_flags(__entry->flags))
+		  __entry->la, __entry->llen,
+		  __entry->flags ? show_map_flags(__entry->flags) : "NULL")
 );
 
 DEFINE_EVENT(erofs__map_blocks_enter, erofs_map_blocks_flatmode_enter,
@@ -172,6 +173,13 @@ DEFINE_EVENT(erofs__map_blocks_enter, erofs_map_blocks_flatmode_enter,
 	TP_ARGS(inode, map, flags)
 );
 
+DEFINE_EVENT(erofs__map_blocks_enter, z_erofs_map_blocks_iter_enter,
+	TP_PROTO(struct inode *inode, struct erofs_map_blocks *map,
+		 unsigned int flags),
+
+	TP_ARGS(inode, map, flags)
+);
+
 DECLARE_EVENT_CLASS(erofs__map_blocks_exit,
 	TP_PROTO(struct inode *inode, struct erofs_map_blocks *map,
 		 unsigned int flags, int ret),
@@ -204,7 +212,8 @@ DECLARE_EVENT_CLASS(erofs__map_blocks_exit,
 
 	TP_printk("dev = (%d,%d), nid = %llu, flags %s "
 		  "la %llu pa %llu llen %llu plen %llu mflags %s ret %d",
-		  show_dev_nid(__entry), show_map_flags(__entry->flags),
+		  show_dev_nid(__entry),
+		  __entry->flags ? show_map_flags(__entry->flags) : "NULL",
 		  __entry->la, __entry->pa, __entry->llen, __entry->plen,
 		  show_mflags(__entry->mflags), __entry->ret)
 );
@@ -216,6 +225,13 @@ DEFINE_EVENT(erofs__map_blocks_exit, erofs_map_blocks_flatmode_exit,
 	TP_ARGS(inode, map, flags, ret)
 );
 
+DEFINE_EVENT(erofs__map_blocks_exit, z_erofs_map_blocks_iter_exit,
+	TP_PROTO(struct inode *inode, struct erofs_map_blocks *map,
+		 unsigned int flags, int ret),
+
+	TP_ARGS(inode, map, flags, ret)
+);
+
 TRACE_EVENT(erofs_destroy_inode,
 	TP_PROTO(struct inode *inode),
 
diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c
index fbf6ff25cd1b..04c61a9d7b76 100644
--- a/drivers/staging/erofs/inode.c
+++ b/drivers/staging/erofs/inode.c
@@ -19,7 +19,7 @@ static int read_inode(struct inode *inode, void *data)
 {
 	struct erofs_vnode *vi = EROFS_V(inode);
 	struct erofs_inode_v1 *v1 = data;
-	const unsigned advise = le16_to_cpu(v1->i_advise);
+	const unsigned int advise = le16_to_cpu(v1->i_advise);
 
 	vi->data_mapping_mode = __inode_data_mapping(advise);
 
@@ -112,7 +112,8 @@ static int read_inode(struct inode *inode, void *data)
  * try_lock since it takes no much overhead and
  * will success immediately.
  */
-static int fill_inline_data(struct inode *inode, void *data, unsigned m_pofs)
+static int fill_inline_data(struct inode *inode, void *data,
+			    unsigned int m_pofs)
 {
 	struct erofs_vnode *vi = EROFS_V(inode);
 	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
@@ -152,7 +153,7 @@ static int fill_inode(struct inode *inode, int isdir)
 	void *data;
 	int err;
 	erofs_blk_t blkaddr;
-	unsigned ofs;
+	unsigned int ofs;
 
 	trace_erofs_fill_inode(inode, isdir);
 
@@ -231,10 +232,45 @@ out_unlock:
 	return err;
 }
 
+/*
+ * erofs nid is 64bits, but i_ino is 'unsigned long', therefore
+ * we should do more for 32-bit platform to find the right inode.
+ */
+#if BITS_PER_LONG == 32
+static int erofs_ilookup_test_actor(struct inode *inode, void *opaque)
+{
+	const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+
+	return EROFS_V(inode)->nid == nid;
+}
+
+static int erofs_iget_set_actor(struct inode *inode, void *opaque)
+{
+	const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+
+	inode->i_ino = erofs_inode_hash(nid);
+	return 0;
+}
+#endif
+
+static inline struct inode *erofs_iget_locked(struct super_block *sb,
+					      erofs_nid_t nid)
+{
+	const unsigned long hashval = erofs_inode_hash(nid);
+
+#if BITS_PER_LONG >= 64
+	/* it is safe to use iget_locked for >= 64-bit platform */
+	return iget_locked(sb, hashval);
+#else
+	return iget5_locked(sb, hashval, erofs_ilookup_test_actor,
+		erofs_iget_set_actor, &nid);
+#endif
+}
+
 struct inode *erofs_iget(struct super_block *sb,
 	erofs_nid_t nid, bool isdir)
 {
-	struct inode *inode = iget_locked(sb, nid);
+	struct inode *inode = erofs_iget_locked(sb, nid);
 
 	if (unlikely(inode == NULL))
 		return ERR_PTR(-ENOMEM);
@@ -259,22 +295,16 @@ struct inode *erofs_iget(struct super_block *sb,
 const struct inode_operations erofs_generic_xattr_iops = {
 	.listxattr = erofs_listxattr,
 };
-#endif
 
-#ifdef CONFIG_EROFS_FS_XATTR
 const struct inode_operations erofs_symlink_xattr_iops = {
 	.get_link = page_get_link,
 	.listxattr = erofs_listxattr,
 };
-#endif
 
 const struct inode_operations erofs_special_inode_operations = {
-#ifdef CONFIG_EROFS_FS_XATTR
 	.listxattr = erofs_listxattr,
-#endif
 };
 
-#ifdef CONFIG_EROFS_FS_XATTR
 const struct inode_operations erofs_fast_symlink_xattr_iops = {
 	.get_link = simple_get_link,
 	.listxattr = erofs_listxattr,
diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 367b39fe46e5..57575c7f5635 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -42,12 +42,12 @@
 #define DBG_BUGON(...)          ((void)0)
 #endif
 
-#ifdef CONFIG_EROFS_FAULT_INJECTION
 enum {
 	FAULT_KMALLOC,
 	FAULT_MAX,
 };
 
+#ifdef CONFIG_EROFS_FAULT_INJECTION
 extern char *erofs_fault_name[FAULT_MAX];
 #define IS_FAULT_SET(fi, type) ((fi)->inject_type & (1 << (type)))
 
@@ -95,6 +95,9 @@ struct erofs_sb_info {
 	/* the dedicated workstation for compression */
 	struct radix_tree_root workstn_tree;
 
+	/* threshold for decompression synchronously */
+	unsigned int max_sync_decompress_pages;
+
 #ifdef EROFS_FS_HAS_MANAGED_CACHE
 	struct inode *managed_cache;
 #endif
@@ -143,17 +146,24 @@ static inline bool time_to_inject(struct erofs_sb_info *sbi, int type)
 	}
 	return false;
 }
+#else
+static inline bool time_to_inject(struct erofs_sb_info *sbi, int type)
+{
+	return false;
+}
+
+static inline void erofs_show_injection_info(int type)
+{
+}
 #endif
 
 static inline void *erofs_kmalloc(struct erofs_sb_info *sbi,
 					size_t size, gfp_t flags)
 {
-#ifdef CONFIG_EROFS_FAULT_INJECTION
 	if (time_to_inject(sbi, FAULT_KMALLOC)) {
 		erofs_show_injection_info(FAULT_KMALLOC);
 		return NULL;
 	}
-#endif
 	return kmalloc(size, flags);
 }
 
@@ -266,6 +276,20 @@ extern int erofs_try_to_free_cached_page(struct address_space *mapping,
 	struct page *page);
 #endif
 
+#define DEFAULT_MAX_SYNC_DECOMPRESS_PAGES	3
+
+static inline bool __should_decompress_synchronously(struct erofs_sb_info *sbi,
+						     unsigned int nr)
+{
+	return nr <= sbi->max_sync_decompress_pages;
+}
+
+int __init z_erofs_init_zip_subsystem(void);
+void z_erofs_exit_zip_subsystem(void);
+#else
+/* dummy initializer/finalizer for the decompression subsystem */
+static inline int z_erofs_init_zip_subsystem(void) { return 0; }
+static inline void z_erofs_exit_zip_subsystem(void) {}
 #endif
 
 /* we strictly follow PAGE_SIZE and no buffer head yet */
@@ -420,30 +444,30 @@ struct erofs_map_blocks {
 #define EROFS_GET_BLOCKS_RAW    0x0001
 
 /* data.c */
-static inline struct bio *prepare_bio(
-	struct super_block *sb,
-	erofs_blk_t blkaddr, unsigned nr_pages,
-	bio_end_io_t endio)
+static inline struct bio *
+erofs_grab_bio(struct super_block *sb,
+	       erofs_blk_t blkaddr, unsigned int nr_pages,
+	       bio_end_io_t endio, bool nofail)
 {
-	gfp_t gfp = GFP_NOIO;
-	struct bio *bio = bio_alloc(gfp, nr_pages);
-
-	if (unlikely(bio == NULL) &&
-		(current->flags & PF_MEMALLOC)) {
-		do {
-			nr_pages /= 2;
-			if (unlikely(!nr_pages)) {
-				bio = bio_alloc(gfp | __GFP_NOFAIL, 1);
-				BUG_ON(bio == NULL);
-				break;
+	const gfp_t gfp = GFP_NOIO;
+	struct bio *bio;
+
+	do {
+		if (nr_pages == 1) {
+			bio = bio_alloc(gfp | (nofail ? __GFP_NOFAIL : 0), 1);
+			if (unlikely(bio == NULL)) {
+				DBG_BUGON(nofail);
+				return ERR_PTR(-ENOMEM);
 			}
-			bio = bio_alloc(gfp, nr_pages);
-		} while (bio == NULL);
-	}
+			break;
+		}
+		bio = bio_alloc(gfp, nr_pages);
+		nr_pages /= 2;
+	} while (unlikely(bio == NULL));
 
 	bio->bi_end_io = endio;
 	bio_set_dev(bio, sb->s_bdev);
-	bio->bi_iter.bi_sector = blkaddr << LOG_SECTORS_PER_BLOCK;
+	bio->bi_iter.bi_sector = (sector_t)blkaddr << LOG_SECTORS_PER_BLOCK;
 	return bio;
 }
 
@@ -453,8 +477,27 @@ static inline void __submit_bio(struct bio *bio, unsigned op, unsigned op_flags)
 	submit_bio(bio);
 }
 
-extern struct page *erofs_get_meta_page(struct super_block *sb,
-	erofs_blk_t blkaddr, bool prio);
+#ifndef CONFIG_EROFS_FS_IO_MAX_RETRIES
+#define EROFS_IO_MAX_RETRIES_NOFAIL	0
+#else
+#define EROFS_IO_MAX_RETRIES_NOFAIL	CONFIG_EROFS_FS_IO_MAX_RETRIES
+#endif
+
+extern struct page *__erofs_get_meta_page(struct super_block *sb,
+	erofs_blk_t blkaddr, bool prio, bool nofail);
+
+static inline struct page *erofs_get_meta_page(struct super_block *sb,
+	erofs_blk_t blkaddr, bool prio)
+{
+	return __erofs_get_meta_page(sb, blkaddr, prio, false);
+}
+
+static inline struct page *erofs_get_meta_page_nofail(struct super_block *sb,
+	erofs_blk_t blkaddr, bool prio)
+{
+	return __erofs_get_meta_page(sb, blkaddr, prio, true);
+}
+
 extern int erofs_map_blocks(struct inode *, struct erofs_map_blocks *, int);
 extern int erofs_map_blocks_iter(struct inode *, struct erofs_map_blocks *,
 	struct page **, int);
@@ -465,14 +508,24 @@ struct erofs_map_blocks_iter {
 };
 
 
-static inline struct page *erofs_get_inline_page(struct inode *inode,
-	erofs_blk_t blkaddr)
+static inline struct page *
+erofs_get_inline_page(struct inode *inode,
+		      erofs_blk_t blkaddr)
 {
 	return erofs_get_meta_page(inode->i_sb,
 		blkaddr, S_ISDIR(inode->i_mode));
 }
 
 /* inode.c */
+static inline unsigned long erofs_inode_hash(erofs_nid_t nid)
+{
+#if BITS_PER_LONG == 32
+	return (nid >> 32) ^ (nid & 0xffffffff);
+#else
+	return nid;
+#endif
+}
+
 extern struct inode *erofs_iget(struct super_block *sb,
 	erofs_nid_t nid, bool dir);
 
@@ -480,13 +533,11 @@ extern struct inode *erofs_iget(struct super_block *sb,
 int erofs_namei(struct inode *dir, struct qstr *name,
 	erofs_nid_t *nid, unsigned *d_type);
 
-/* xattr.c */
 #ifdef CONFIG_EROFS_FS_XATTR
+/* xattr.c */
 extern const struct xattr_handler *erofs_xattr_handlers[];
-#endif
 
-/* symlink */
-#ifdef CONFIG_EROFS_FS_XATTR
+/* symlink and special inode */
 extern const struct inode_operations erofs_symlink_xattr_iops;
 extern const struct inode_operations erofs_fast_symlink_xattr_iops;
 extern const struct inode_operations erofs_special_inode_operations;
diff --git a/drivers/staging/erofs/namei.c b/drivers/staging/erofs/namei.c
index 546a47156101..5596c52e246d 100644
--- a/drivers/staging/erofs/namei.c
+++ b/drivers/staging/erofs/namei.c
@@ -17,9 +17,9 @@
 
 /* based on the value of qn->len is accurate */
 static inline int dirnamecmp(struct qstr *qn,
-	struct qstr *qd, unsigned *matched)
+	struct qstr *qd, unsigned int *matched)
 {
-	unsigned i = *matched, len = min(qn->len, qd->len);
+	unsigned int i = *matched, len = min(qn->len, qd->len);
 loop:
 	if (unlikely(i >= len)) {
 		*matched = i;
@@ -46,8 +46,8 @@ static struct erofs_dirent *find_target_dirent(
 	struct qstr *name,
 	u8 *data, int maxsize)
 {
-	unsigned ndirents, head, back;
-	unsigned startprfx, endprfx;
+	unsigned int ndirents, head, back;
+	unsigned int startprfx, endprfx;
 	struct erofs_dirent *const de = (struct erofs_dirent *)data;
 
 	/* make sure that maxsize is valid */
@@ -63,9 +63,9 @@ static struct erofs_dirent *find_target_dirent(
 	startprfx = endprfx = 0;
 
 	while (head <= back) {
-		unsigned mid = head + (back - head) / 2;
-		unsigned nameoff = le16_to_cpu(de[mid].nameoff);
-		unsigned matched = min(startprfx, endprfx);
+		unsigned int mid = head + (back - head) / 2;
+		unsigned int nameoff = le16_to_cpu(de[mid].nameoff);
+		unsigned int matched = min(startprfx, endprfx);
 
 		struct qstr dname = QSTR_INIT(data + nameoff,
 			unlikely(mid >= ndirents - 1) ?
@@ -95,8 +95,8 @@ static struct page *find_target_block_classic(
 	struct inode *dir,
 	struct qstr *name, int *_diff)
 {
-	unsigned startprfx, endprfx;
-	unsigned head, back;
+	unsigned int startprfx, endprfx;
+	unsigned int head, back;
 	struct address_space *const mapping = dir->i_mapping;
 	struct page *candidate = ERR_PTR(-ENOENT);
 
@@ -105,7 +105,7 @@ static struct page *find_target_block_classic(
 	back = inode_datablocks(dir) - 1;
 
 	while (head <= back) {
-		unsigned mid = head + (back - head) / 2;
+		unsigned int mid = head + (back - head) / 2;
 		struct page *page = read_mapping_page(mapping, mid, NULL);
 
 		if (IS_ERR(page)) {
@@ -115,10 +115,10 @@ exact_out:
 			return page;
 		} else {
 			int diff;
-			unsigned ndirents, matched;
+			unsigned int ndirents, matched;
 			struct qstr dname;
 			struct erofs_dirent *de = kmap_atomic(page);
-			unsigned nameoff = le16_to_cpu(de->nameoff);
+			unsigned int nameoff = le16_to_cpu(de->nameoff);
 
 			ndirents = nameoff / sizeof(*de);
 
@@ -164,7 +164,7 @@ exact_out:
 
 int erofs_namei(struct inode *dir,
 	struct qstr *name,
-	erofs_nid_t *nid, unsigned *d_type)
+	erofs_nid_t *nid, unsigned int *d_type)
 {
 	int diff;
 	struct page *page;
@@ -204,7 +204,7 @@ static struct dentry *erofs_lookup(struct inode *dir,
 {
 	int err;
 	erofs_nid_t nid;
-	unsigned d_type;
+	unsigned int d_type;
 	struct inode *inode;
 
 	DBG_BUGON(!d_really_is_negative(dentry));
@@ -223,18 +223,13 @@ static struct dentry *erofs_lookup(struct inode *dir,
 	if (err == -ENOENT) {
 		/* negative dentry */
 		inode = NULL;
-		goto negative_out;
-	} else if (unlikely(err))
-		return ERR_PTR(err);
-
-	debugln("%s, %s (nid %llu) found, d_type %u", __func__,
-		dentry->d_name.name, nid, d_type);
-
-	inode = erofs_iget(dir->i_sb, nid, d_type == EROFS_FT_DIR);
-	if (IS_ERR(inode))
-		return ERR_CAST(inode);
-
-negative_out:
+	} else if (unlikely(err)) {
+		inode = ERR_PTR(err);
+	} else {
+		debugln("%s, %s (nid %llu) found, d_type %u", __func__,
+			dentry->d_name.name, nid, d_type);
+		inode = erofs_iget(dir->i_sb, nid, d_type == EROFS_FT_DIR);
+	}
 	return d_splice_alias(inode, dentry);
 }
 
diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
index 2df9768edac9..f69e619807a1 100644
--- a/drivers/staging/erofs/super.c
+++ b/drivers/staging/erofs/super.c
@@ -29,7 +29,7 @@ static void init_once(void *ptr)
 	inode_init_once(&vi->vfs_inode);
 }
 
-static int erofs_init_inode_cache(void)
+static int __init erofs_init_inode_cache(void)
 {
 	erofs_inode_cachep = kmem_cache_create("erofs_inode",
 		sizeof(struct erofs_vnode), 0,
@@ -81,7 +81,7 @@ static int superblock_read(struct super_block *sb)
 	struct erofs_sb_info *sbi;
 	struct buffer_head *bh;
 	struct erofs_super_block *layout;
-	unsigned blkszbits;
+	unsigned int blkszbits;
 	int ret;
 
 	bh = sb_bread(sb, 0);
@@ -116,9 +116,10 @@ static int superblock_read(struct super_block *sb)
 #endif
 	sbi->islotbits = ffs(sizeof(struct erofs_inode_v1)) - 1;
 #ifdef CONFIG_EROFS_FS_ZIP
-	sbi->clusterbits = 12;
+	/* TODO: clusterbits should be related to inode */
+	sbi->clusterbits = blkszbits;
 
-	if (1 << (sbi->clusterbits - 12) > Z_EROFS_CLUSTER_MAX_PAGES)
+	if (1 << (sbi->clusterbits - PAGE_SHIFT) > Z_EROFS_CLUSTER_MAX_PAGES)
 		errln("clusterbits %u is not supported on this kernel",
 			sbi->clusterbits);
 #endif
@@ -144,8 +145,8 @@ char *erofs_fault_name[FAULT_MAX] = {
 	[FAULT_KMALLOC]		= "kmalloc",
 };
 
-static void erofs_build_fault_attr(struct erofs_sb_info *sbi,
-						unsigned int rate)
+static void __erofs_build_fault_attr(struct erofs_sb_info *sbi,
+				     unsigned int rate)
 {
 	struct erofs_fault_info *ffi = &sbi->fault_info;
 
@@ -156,11 +157,52 @@ static void erofs_build_fault_attr(struct erofs_sb_info *sbi,
 	} else {
 		memset(ffi, 0, sizeof(struct erofs_fault_info));
 	}
+
+	set_opt(sbi, FAULT_INJECTION);
+}
+
+static int erofs_build_fault_attr(struct erofs_sb_info *sbi,
+				  substring_t *args)
+{
+	int rate = 0;
+
+	if (args->from && match_int(args, &rate))
+		return -EINVAL;
+
+	__erofs_build_fault_attr(sbi, rate);
+	return 0;
+}
+
+static unsigned int erofs_get_fault_rate(struct erofs_sb_info *sbi)
+{
+	return sbi->fault_info.inject_rate;
+}
+#else
+static void __erofs_build_fault_attr(struct erofs_sb_info *sbi,
+				     unsigned int rate)
+{
+}
+
+static int erofs_build_fault_attr(struct erofs_sb_info *sbi,
+				  substring_t *args)
+{
+	infoln("fault_injection options not supported");
+	return 0;
+}
+
+static unsigned int erofs_get_fault_rate(struct erofs_sb_info *sbi)
+{
+	return 0;
 }
 #endif
 
 static void default_options(struct erofs_sb_info *sbi)
 {
+	/* set up some FS parameters */
+#ifdef CONFIG_EROFS_FS_ZIP
+	sbi->max_sync_decompress_pages = DEFAULT_MAX_SYNC_DECOMPRESS_PAGES;
+#endif
+
 #ifdef CONFIG_EROFS_FS_XATTR
 	set_opt(sbi, XATTR_USER);
 #endif
@@ -192,7 +234,7 @@ static int parse_options(struct super_block *sb, char *options)
 {
 	substring_t args[MAX_OPT_ARGS];
 	char *p;
-	int arg = 0;
+	int err;
 
 	if (!options)
 		return 0;
@@ -238,15 +280,11 @@ static int parse_options(struct super_block *sb, char *options)
 			break;
 #endif
 		case Opt_fault_injection:
-			if (args->from && match_int(args, &arg))
-				return -EINVAL;
-#ifdef CONFIG_EROFS_FAULT_INJECTION
-			erofs_build_fault_attr(EROFS_SB(sb), arg);
-			set_opt(EROFS_SB(sb), FAULT_INJECTION);
-#else
-			infoln("FAULT_INJECTION was not selected");
-#endif
+			err = erofs_build_fault_attr(EROFS_SB(sb), args);
+			if (err)
+				return err;
 			break;
+
 		default:
 			errln("Unrecognized mount option \"%s\" "
 					"or missing value", p);
@@ -521,11 +559,6 @@ static struct file_system_type erofs_fs_type = {
 };
 MODULE_ALIAS_FS("erofs");
 
-#ifdef CONFIG_EROFS_FS_ZIP
-extern int z_erofs_init_zip_subsystem(void);
-extern void z_erofs_exit_zip_subsystem(void);
-#endif
-
 static int __init erofs_module_init(void)
 {
 	int err;
@@ -541,11 +574,9 @@ static int __init erofs_module_init(void)
 	if (err)
 		goto shrinker_err;
 
-#ifdef CONFIG_EROFS_FS_ZIP
 	err = z_erofs_init_zip_subsystem();
 	if (err)
 		goto zip_err;
-#endif
 
 	err = register_filesystem(&erofs_fs_type);
 	if (err)
@@ -555,10 +586,8 @@ static int __init erofs_module_init(void)
 	return 0;
 
 fs_err:
-#ifdef CONFIG_EROFS_FS_ZIP
 	z_erofs_exit_zip_subsystem();
 zip_err:
-#endif
 	unregister_shrinker(&erofs_shrinker_info);
 shrinker_err:
 	erofs_exit_inode_cache();
@@ -569,9 +598,7 @@ icache_err:
 static void __exit erofs_module_exit(void)
 {
 	unregister_filesystem(&erofs_fs_type);
-#ifdef CONFIG_EROFS_FS_ZIP
 	z_erofs_exit_zip_subsystem();
-#endif
 	unregister_shrinker(&erofs_shrinker_info);
 	erofs_exit_inode_cache();
 	infoln("successfully finalize erofs");
@@ -615,20 +642,31 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
 	else
 		seq_puts(seq, ",noacl");
 #endif
-#ifdef CONFIG_EROFS_FAULT_INJECTION
 	if (test_opt(sbi, FAULT_INJECTION))
 		seq_printf(seq, ",fault_injection=%u",
-				sbi->fault_info.inject_rate);
-#endif
+			erofs_get_fault_rate(sbi));
 	return 0;
 }
 
 static int erofs_remount(struct super_block *sb, int *flags, char *data)
 {
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	unsigned int org_mnt_opt = sbi->mount_opt;
+	unsigned int org_inject_rate = erofs_get_fault_rate(sbi);
+	int err;
+
 	BUG_ON(!sb_rdonly(sb));
+	err = parse_options(sb, data);
+	if (err)
+		goto out;
 
 	*flags |= SB_RDONLY;
 	return 0;
+out:
+	__erofs_build_fault_attr(sbi, org_inject_rate);
+	sbi->mount_opt = org_mnt_opt;
+
+	return err;
 }
 
 const struct super_operations erofs_sops = {
diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
index 8721f0a41d15..79d3ba62b298 100644
--- a/drivers/staging/erofs/unzip_vle.c
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -13,6 +13,8 @@
 #include "unzip_vle.h"
 #include <linux/prefetch.h>
 
+#include <trace/events/erofs.h>
+
 static struct workqueue_struct *z_erofs_workqueue __read_mostly;
 static struct kmem_cache *z_erofs_workgroup_cachep __read_mostly;
 
@@ -27,7 +29,7 @@ void z_erofs_exit_zip_subsystem(void)
 
 static inline int init_unzip_workqueue(void)
 {
-	const unsigned onlinecpus = num_possible_cpus();
+	const unsigned int onlinecpus = num_possible_cpus();
 
 	/*
 	 * we don't need too many threads, limiting threads
@@ -40,7 +42,7 @@ static inline int init_unzip_workqueue(void)
 	return z_erofs_workqueue != NULL ? 0 : -ENOMEM;
 }
 
-int z_erofs_init_zip_subsystem(void)
+int __init z_erofs_init_zip_subsystem(void)
 {
 	z_erofs_workgroup_cachep =
 		kmem_cache_create("erofs_compress",
@@ -89,7 +91,7 @@ struct z_erofs_vle_work_builder {
 
 	/* pages used for reading the compressed data */
 	struct page **compressed_pages;
-	unsigned compressed_deficit;
+	unsigned int compressed_deficit;
 };
 
 #define VLE_WORK_BUILDER_INIT()	\
@@ -232,7 +234,7 @@ static int z_erofs_vle_work_add_page(
 
 	ret = z_erofs_pagevec_ctor_enqueue(&builder->vector,
 		page, type, &occupied);
-	builder->work->vcnt += (unsigned)ret;
+	builder->work->vcnt += (unsigned int)ret;
 
 	return ret ? 0 : -EAGAIN;
 }
@@ -271,36 +273,39 @@ retry:
 	return true;	/* lucky, I am the followee :) */
 }
 
+struct z_erofs_vle_work_finder {
+	struct super_block *sb;
+	pgoff_t idx;
+	unsigned int pageofs;
+
+	struct z_erofs_vle_workgroup **grp_ret;
+	enum z_erofs_vle_work_role *role;
+	z_erofs_vle_owned_workgrp_t *owned_head;
+	bool *hosted;
+};
+
 static struct z_erofs_vle_work *
-z_erofs_vle_work_lookup(struct super_block *sb,
-			pgoff_t idx, unsigned pageofs,
-			struct z_erofs_vle_workgroup **grp_ret,
-			enum z_erofs_vle_work_role *role,
-			z_erofs_vle_owned_workgrp_t *owned_head,
-			bool *hosted)
+z_erofs_vle_work_lookup(const struct z_erofs_vle_work_finder *f)
 {
 	bool tag, primary;
 	struct erofs_workgroup *egrp;
 	struct z_erofs_vle_workgroup *grp;
 	struct z_erofs_vle_work *work;
 
-	egrp = erofs_find_workgroup(sb, idx, &tag);
+	egrp = erofs_find_workgroup(f->sb, f->idx, &tag);
 	if (egrp == NULL) {
-		*grp_ret = NULL;
+		*f->grp_ret = NULL;
 		return NULL;
 	}
 
-	*grp_ret = grp = container_of(egrp,
-		struct z_erofs_vle_workgroup, obj);
+	grp = container_of(egrp, struct z_erofs_vle_workgroup, obj);
+	*f->grp_ret = grp;
 
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
-	work = z_erofs_vle_grab_work(grp, pageofs);
+	work = z_erofs_vle_grab_work(grp, f->pageofs);
+	/* if multiref is disabled, `primary' is always true */
 	primary = true;
-#else
-	BUG();
-#endif
 
-	DBG_BUGON(work->pageofs != pageofs);
+	DBG_BUGON(work->pageofs != f->pageofs);
 
 	/*
 	 * lock must be taken first to avoid grp->next == NIL between
@@ -340,43 +345,35 @@ z_erofs_vle_work_lookup(struct super_block *sb,
 	 */
 	mutex_lock(&work->lock);
 
-	*hosted = false;
+	*f->hosted = false;
 	if (!primary)
-		*role = Z_EROFS_VLE_WORK_SECONDARY;
+		*f->role = Z_EROFS_VLE_WORK_SECONDARY;
 	/* claim the workgroup if possible */
-	else if (try_to_claim_workgroup(grp, owned_head, hosted))
-		*role = Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED;
+	else if (try_to_claim_workgroup(grp, f->owned_head, f->hosted))
+		*f->role = Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED;
 	else
-		*role = Z_EROFS_VLE_WORK_PRIMARY;
+		*f->role = Z_EROFS_VLE_WORK_PRIMARY;
 
 	return work;
 }
 
 static struct z_erofs_vle_work *
-z_erofs_vle_work_register(struct super_block *sb,
-			  struct z_erofs_vle_workgroup **grp_ret,
-			  struct erofs_map_blocks *map,
-			  pgoff_t index, unsigned pageofs,
-			  enum z_erofs_vle_work_role *role,
-			  z_erofs_vle_owned_workgrp_t *owned_head,
-			  bool *hosted)
+z_erofs_vle_work_register(const struct z_erofs_vle_work_finder *f,
+			  struct erofs_map_blocks *map)
 {
-	bool newgrp = false;
-	struct z_erofs_vle_workgroup *grp = *grp_ret;
+	bool gnew = false;
+	struct z_erofs_vle_workgroup *grp = *f->grp_ret;
 	struct z_erofs_vle_work *work;
 
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
+	/* if multiref is disabled, grp should never be nullptr */
 	BUG_ON(grp != NULL);
-#else
-	if (grp != NULL)
-		goto skip;
-#endif
+
 	/* no available workgroup, let's allocate one */
 	grp = kmem_cache_zalloc(z_erofs_workgroup_cachep, GFP_NOFS);
 	if (unlikely(grp == NULL))
 		return ERR_PTR(-ENOMEM);
 
-	grp->obj.index = index;
+	grp->obj.index = f->idx;
 	grp->llen = map->m_llen;
 
 	z_erofs_vle_set_workgrp_fmt(grp,
@@ -386,26 +383,20 @@ z_erofs_vle_work_register(struct super_block *sb,
 	atomic_set(&grp->obj.refcount, 1);
 
 	/* new workgrps have been claimed as type 1 */
-	WRITE_ONCE(grp->next, *owned_head);
+	WRITE_ONCE(grp->next, *f->owned_head);
 	/* primary and followed work for all new workgrps */
-	*role = Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED;
+	*f->role = Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED;
 	/* it should be submitted by ourselves */
-	*hosted = true;
+	*f->hosted = true;
 
-	newgrp = true;
-#ifdef CONFIG_EROFS_FS_ZIP_MULTIREF
-skip:
-	/* currently unimplemented */
-	BUG();
-#else
+	gnew = true;
 	work = z_erofs_vle_grab_primary_work(grp);
-#endif
-	work->pageofs = pageofs;
+	work->pageofs = f->pageofs;
 
 	mutex_init(&work->lock);
 
-	if (newgrp) {
-		int err = erofs_register_workgroup(sb, &grp->obj, 0);
+	if (gnew) {
+		int err = erofs_register_workgroup(f->sb, &grp->obj, 0);
 
 		if (err) {
 			kmem_cache_free(z_erofs_workgroup_cachep, grp);
@@ -413,24 +404,12 @@ skip:
 		}
 	}
 
-	*owned_head = *grp_ret = grp;
+	*f->owned_head = *f->grp_ret = grp;
 
 	mutex_lock(&work->lock);
 	return work;
 }
 
-static inline void __update_workgrp_llen(struct z_erofs_vle_workgroup *grp,
-					 unsigned int llen)
-{
-	while (1) {
-		unsigned int orig_llen = grp->llen;
-
-		if (orig_llen >= llen || orig_llen ==
-			cmpxchg(&grp->llen, orig_llen, llen))
-			break;
-	}
-}
-
 #define builder_is_followed(builder) \
 	((builder)->role >= Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED)
 
@@ -439,10 +418,17 @@ static int z_erofs_vle_work_iter_begin(struct z_erofs_vle_work_builder *builder,
 				       struct erofs_map_blocks *map,
 				       z_erofs_vle_owned_workgrp_t *owned_head)
 {
-	const unsigned clusterpages = erofs_clusterpages(EROFS_SB(sb));
-	const erofs_blk_t index = erofs_blknr(map->m_pa);
-	const unsigned pageofs = map->m_la & ~PAGE_MASK;
+	const unsigned int clusterpages = erofs_clusterpages(EROFS_SB(sb));
 	struct z_erofs_vle_workgroup *grp;
+	const struct z_erofs_vle_work_finder finder = {
+		.sb = sb,
+		.idx = erofs_blknr(map->m_pa),
+		.pageofs = map->m_la & ~PAGE_MASK,
+		.grp_ret = &grp,
+		.role = &builder->role,
+		.owned_head = owned_head,
+		.hosted = &builder->hosted
+	};
 	struct z_erofs_vle_work *work;
 
 	DBG_BUGON(builder->work != NULL);
@@ -454,16 +440,19 @@ static int z_erofs_vle_work_iter_begin(struct z_erofs_vle_work_builder *builder,
 	DBG_BUGON(erofs_blkoff(map->m_pa));
 
 repeat:
-	work = z_erofs_vle_work_lookup(sb, index,
-		pageofs, &grp, &builder->role, owned_head, &builder->hosted);
+	work = z_erofs_vle_work_lookup(&finder);
 	if (work != NULL) {
-		__update_workgrp_llen(grp, map->m_llen);
+		unsigned int orig_llen;
+
+		/* increase workgroup `llen' if needed */
+		while ((orig_llen = READ_ONCE(grp->llen)) < map->m_llen &&
+		       orig_llen != cmpxchg_relaxed(&grp->llen,
+						    orig_llen, map->m_llen))
+			cpu_relax();
 		goto got_it;
 	}
 
-	work = z_erofs_vle_work_register(sb, &grp, map, index, pageofs,
-		&builder->role, owned_head, &builder->hosted);
-
+	work = z_erofs_vle_work_register(&finder, map);
 	if (unlikely(work == ERR_PTR(-EAGAIN)))
 		goto repeat;
 
@@ -605,8 +594,10 @@ static int z_erofs_do_read_page(struct z_erofs_vle_frontend *fe,
 #endif
 
 	enum z_erofs_page_type page_type;
-	unsigned cur, end, spiltted, index;
-	int err;
+	unsigned int cur, end, spiltted, index;
+	int err = 0;
+
+	trace_erofs_readpage(page, false);
 
 	/* register locked file pages as online pages in pack */
 	z_erofs_onlinepage_init(page);
@@ -624,7 +615,7 @@ repeat:
 	/* go ahead the next map_blocks */
 	debugln("%s: [out-of-range] pos %llu", __func__, offset + cur);
 
-	if (!z_erofs_vle_work_iter_end(builder))
+	if (z_erofs_vle_work_iter_end(builder))
 		fe->initial = false;
 
 	map->m_la = offset + cur;
@@ -633,12 +624,11 @@ repeat:
 	if (unlikely(err))
 		goto err_out;
 
-	/* deal with hole (FIXME! broken now) */
 	if (unlikely(!(map->m_flags & EROFS_MAP_MAPPED)))
 		goto hitted;
 
 	DBG_BUGON(map->m_plen != 1 << sbi->clusterbits);
-	BUG_ON(erofs_blkoff(map->m_pa));
+	DBG_BUGON(erofs_blkoff(map->m_pa));
 
 	err = z_erofs_vle_work_iter_begin(builder, sb, map, &fe->owned_head);
 	if (unlikely(err))
@@ -662,7 +652,7 @@ repeat:
 	tight &= builder_is_followed(builder);
 	work = builder->work;
 hitted:
-	cur = end - min_t(unsigned, offset + end - map->m_la, end);
+	cur = end - min_t(unsigned int, offset + end - map->m_la, end);
 	if (unlikely(!(map->m_flags & EROFS_MAP_MAPPED))) {
 		zero_user_segment(page, cur, end);
 		goto next_part;
@@ -683,7 +673,7 @@ retry:
 
 		err = z_erofs_vle_work_add_page(builder,
 			newpage, Z_EROFS_PAGE_TYPE_EXCLUSIVE);
-		if (!err)
+		if (likely(!err))
 			goto retry;
 	}
 
@@ -694,9 +684,10 @@ retry:
 
 	/* FIXME! avoid the last relundant fixup & endio */
 	z_erofs_onlinepage_fixup(page, index, true);
-	++spiltted;
 
-	/* also update nr_pages and increase queued_pages */
+	/* bump up the number of spiltted parts of a page */
+	++spiltted;
+	/* also update nr_pages */
 	work->nr_pages = max_t(pgoff_t, work->nr_pages, index + 1);
 next_part:
 	/* can be used for verification */
@@ -706,16 +697,18 @@ next_part:
 	if (end > 0)
 		goto repeat;
 
+out:
 	/* FIXME! avoid the last relundant fixup & endio */
 	z_erofs_onlinepage_endio(page);
 
 	debugln("%s, finish page: %pK spiltted: %u map->m_llen %llu",
 		__func__, page, spiltted, map->m_llen);
-	return 0;
+	return err;
 
+	/* if some error occurred while processing this page */
 err_out:
-	/* TODO: the missing error handing cases */
-	return err;
+	SetPageError(page);
+	goto out;
 }
 
 static void z_erofs_vle_unzip_kickoff(void *ptr, int bios)
@@ -736,7 +729,7 @@ static void z_erofs_vle_unzip_kickoff(void *ptr, int bios)
 static inline void z_erofs_vle_read_endio(struct bio *bio)
 {
 	const blk_status_t err = bio->bi_status;
-	unsigned i;
+	unsigned int i;
 	struct bio_vec *bvec;
 #ifdef EROFS_FS_HAS_MANAGED_CACHE
 	struct address_space *mngda = NULL;
@@ -788,16 +781,14 @@ static int z_erofs_vle_unzip(struct super_block *sb,
 #ifdef EROFS_FS_HAS_MANAGED_CACHE
 	struct address_space *const mngda = sbi->managed_cache->i_mapping;
 #endif
-	const unsigned clusterpages = erofs_clusterpages(sbi);
+	const unsigned int clusterpages = erofs_clusterpages(sbi);
 
 	struct z_erofs_pagevec_ctor ctor;
-	unsigned nr_pages;
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
-	unsigned sparsemem_pages = 0;
-#endif
+	unsigned int nr_pages;
+	unsigned int sparsemem_pages = 0;
 	struct page *pages_onstack[Z_EROFS_VLE_VMAP_ONSTACK_PAGES];
 	struct page **pages, **compressed_pages, *page;
-	unsigned i, llen;
+	unsigned int i, llen;
 
 	enum z_erofs_page_type page_type;
 	bool overlapped;
@@ -806,11 +797,7 @@ static int z_erofs_vle_unzip(struct super_block *sb,
 	int err;
 
 	might_sleep();
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
 	work = z_erofs_vle_grab_primary_work(grp);
-#else
-	BUG();
-#endif
 	BUG_ON(!READ_ONCE(work->nr_pages));
 
 	mutex_lock(&work->lock);
@@ -844,7 +831,7 @@ repeat:
 		Z_EROFS_VLE_INLINE_PAGEVECS, work->pagevec, 0);
 
 	for (i = 0; i < work->vcnt; ++i) {
-		unsigned pagenr;
+		unsigned int pagenr;
 
 		page = z_erofs_pagevec_ctor_dequeue(&ctor, &page_type);
 
@@ -861,13 +848,11 @@ repeat:
 			pagenr = z_erofs_onlinepage_index(page);
 
 		BUG_ON(pagenr >= nr_pages);
-
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
 		BUG_ON(pages[pagenr] != NULL);
-		++sparsemem_pages;
-#endif
+
 		pages[pagenr] = page;
 	}
+	sparsemem_pages = i;
 
 	z_erofs_pagevec_ctor_exit(&ctor, true);
 
@@ -875,7 +860,7 @@ repeat:
 	compressed_pages = grp->compressed_pages;
 
 	for (i = 0; i < clusterpages; ++i) {
-		unsigned pagenr;
+		unsigned int pagenr;
 
 		page = compressed_pages[i];
 
@@ -897,10 +882,8 @@ repeat:
 		pagenr = z_erofs_onlinepage_index(page);
 
 		BUG_ON(pagenr >= nr_pages);
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
 		BUG_ON(pages[pagenr] != NULL);
 		++sparsemem_pages;
-#endif
 		pages[pagenr] = page;
 
 		overlapped = true;
@@ -926,12 +909,10 @@ repeat:
 	if (err != -ENOTSUPP)
 		goto out_percpu;
 
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
 	if (sparsemem_pages >= nr_pages) {
 		BUG_ON(sparsemem_pages > nr_pages);
 		goto skip_allocpage;
 	}
-#endif
 
 	for (i = 0; i < nr_pages; ++i) {
 		if (pages[i] != NULL)
@@ -940,9 +921,7 @@ repeat:
 		pages[i] = __stagingpage_alloc(page_pool, GFP_NOFS);
 	}
 
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
 skip_allocpage:
-#endif
 	vout = erofs_vmap(pages, nr_pages);
 
 	err = z_erofs_vle_unzip_vmap(compressed_pages,
@@ -1100,7 +1079,7 @@ static bool z_erofs_vle_submit_all(struct super_block *sb,
 				   bool force_fg)
 {
 	struct erofs_sb_info *const sbi = EROFS_SB(sb);
-	const unsigned clusterpages = erofs_clusterpages(sbi);
+	const unsigned int clusterpages = erofs_clusterpages(sbi);
 	const gfp_t gfp = GFP_NOFS;
 #ifdef EROFS_FS_HAS_MANAGED_CACHE
 	struct address_space *const mngda = sbi->managed_cache->i_mapping;
@@ -1112,7 +1091,7 @@ static bool z_erofs_vle_submit_all(struct super_block *sb,
 	/* since bio will be NULL, no need to initialize last_index */
 	pgoff_t uninitialized_var(last_index);
 	bool force_submit = false;
-	unsigned nr_bios;
+	unsigned int nr_bios;
 
 	if (unlikely(owned_head == Z_EROFS_VLE_WORKGRP_TAIL))
 		return false;
@@ -1144,7 +1123,7 @@ static bool z_erofs_vle_submit_all(struct super_block *sb,
 		struct z_erofs_vle_workgroup *grp;
 		struct page **compressed_pages, *oldpage, *page;
 		pgoff_t first_index;
-		unsigned i = 0;
+		unsigned int i = 0;
 #ifdef EROFS_FS_HAS_MANAGED_CACHE
 		unsigned int noio = 0;
 		bool cachemngd;
@@ -1213,8 +1192,8 @@ submit_bio_retry:
 		}
 
 		if (bio == NULL) {
-			bio = prepare_bio(sb, first_index + i,
-				BIO_MAX_PAGES, z_erofs_vle_read_endio);
+			bio = erofs_grab_bio(sb, first_index + i,
+				BIO_MAX_PAGES, z_erofs_vle_read_endio, true);
 			bio->bi_private = tagptr_cast_ptr(bi_private);
 
 			++nr_bios;
@@ -1309,7 +1288,7 @@ static int z_erofs_vle_normalaccess_readpage(struct file *file,
 	LIST_HEAD(pagepool);
 
 #if (EROFS_FS_ZIP_CACHE_LVL >= 2)
-	f.cachedzone_la = page->index << PAGE_SHIFT;
+	f.cachedzone_la = (erofs_off_t)page->index << PAGE_SHIFT;
 #endif
 	err = z_erofs_do_read_page(&f, page, &pagepool);
 	(void)z_erofs_vle_work_iter_end(&f.builder);
@@ -1329,20 +1308,25 @@ out:
 	return 0;
 }
 
-static inline int __z_erofs_vle_normalaccess_readpages(
-	struct file *filp,
-	struct address_space *mapping,
-	struct list_head *pages, unsigned nr_pages, bool sync)
+static int z_erofs_vle_normalaccess_readpages(struct file *filp,
+					      struct address_space *mapping,
+					      struct list_head *pages,
+					      unsigned int nr_pages)
 {
 	struct inode *const inode = mapping->host;
+	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
+	const bool sync = __should_decompress_synchronously(sbi, nr_pages);
 
 	struct z_erofs_vle_frontend f = VLE_FRONTEND_INIT(inode);
 	gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
 	struct page *head = NULL;
 	LIST_HEAD(pagepool);
 
+	trace_erofs_readpages(mapping->host, lru_to_page(pages),
+			      nr_pages, false);
+
 #if (EROFS_FS_ZIP_CACHE_LVL >= 2)
-	f.cachedzone_la = lru_to_page(pages)->index << PAGE_SHIFT;
+	f.cachedzone_la = (erofs_off_t)lru_to_page(pages)->index << PAGE_SHIFT;
 #endif
 	for (; nr_pages; --nr_pages) {
 		struct page *page = lru_to_page(pages);
@@ -1390,56 +1374,45 @@ static inline int __z_erofs_vle_normalaccess_readpages(
 	return 0;
 }
 
-static int z_erofs_vle_normalaccess_readpages(
-	struct file *filp,
-	struct address_space *mapping,
-	struct list_head *pages, unsigned nr_pages)
-{
-	return __z_erofs_vle_normalaccess_readpages(filp,
-		mapping, pages, nr_pages,
-		nr_pages < 4 /* sync */);
-}
-
 const struct address_space_operations z_erofs_vle_normalaccess_aops = {
 	.readpage = z_erofs_vle_normalaccess_readpage,
 	.readpages = z_erofs_vle_normalaccess_readpages,
 };
 
+/*
+ * Variable-sized Logical Extent (Fixed Physical Cluster) Compression Mode
+ * ---
+ * VLE compression mode attempts to compress a number of logical data into
+ * a physical cluster with a fixed size.
+ * VLE compression mode uses "struct z_erofs_vle_decompressed_index".
+ */
 #define __vle_cluster_advise(x, bit, bits) \
 	((le16_to_cpu(x) >> (bit)) & ((1 << (bits)) - 1))
 
 #define __vle_cluster_type(advise) __vle_cluster_advise(advise, \
 	Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT, Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS)
 
-enum {
-	Z_EROFS_VLE_CLUSTER_TYPE_PLAIN,
-	Z_EROFS_VLE_CLUSTER_TYPE_HEAD,
-	Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD,
-	Z_EROFS_VLE_CLUSTER_TYPE_RESERVED,
-	Z_EROFS_VLE_CLUSTER_TYPE_MAX
-};
-
 #define vle_cluster_type(di)	\
 	__vle_cluster_type((di)->di_advise)
 
-static inline unsigned
-vle_compressed_index_clusterofs(unsigned clustersize,
-	struct z_erofs_vle_decompressed_index *di)
+static int
+vle_decompressed_index_clusterofs(unsigned int *clusterofs,
+				  unsigned int clustersize,
+				  struct z_erofs_vle_decompressed_index *di)
 {
-	debugln("%s, vle=%pK, advise=%x (type %u), clusterofs=%x blkaddr=%x",
-		__func__, di, di->di_advise, vle_cluster_type(di),
-		di->di_clusterofs, di->di_u.blkaddr);
-
 	switch (vle_cluster_type(di)) {
 	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		*clusterofs = clustersize;
 		break;
 	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
 	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
-		return di->di_clusterofs;
+		*clusterofs = le16_to_cpu(di->di_clusterofs);
+		break;
 	default:
-		BUG_ON(1);
+		DBG_BUGON(1);
+		return -EIO;
 	}
-	return clustersize;
+	return 0;
 }
 
 static inline erofs_blk_t
@@ -1448,7 +1421,7 @@ vle_extent_blkaddr(struct inode *inode, pgoff_t index)
 	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
 	struct erofs_vnode *vi = EROFS_V(inode);
 
-	unsigned ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
+	unsigned int ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
 		vi->xattr_isize) + sizeof(struct erofs_extent_header) +
 		index * sizeof(struct z_erofs_vle_decompressed_index);
 
@@ -1461,95 +1434,117 @@ vle_extent_blkoff(struct inode *inode, pgoff_t index)
 	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
 	struct erofs_vnode *vi = EROFS_V(inode);
 
-	unsigned ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
+	unsigned int ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
 		vi->xattr_isize) + sizeof(struct erofs_extent_header) +
 		index * sizeof(struct z_erofs_vle_decompressed_index);
 
 	return erofs_blkoff(iloc(sbi, vi->nid) + ofs);
 }
 
-/*
- * Variable-sized Logical Extent (Fixed Physical Cluster) Compression Mode
- * ---
- * VLE compression mode attempts to compress a number of logical data into
- * a physical cluster with a fixed size.
- * VLE compression mode uses "struct z_erofs_vle_decompressed_index".
- */
-static erofs_off_t vle_get_logical_extent_head(
-	struct inode *inode,
-	struct page **page_iter,
-	void **kaddr_iter,
-	unsigned lcn,	/* logical cluster number */
-	erofs_blk_t *pcn,
-	unsigned *flags)
+struct vle_map_blocks_iter_ctx {
+	struct inode *inode;
+	struct super_block *sb;
+	unsigned int clusterbits;
+
+	struct page **mpage_ret;
+	void **kaddr_ret;
+};
+
+static int
+vle_get_logical_extent_head(const struct vle_map_blocks_iter_ctx *ctx,
+			    unsigned int lcn,	/* logical cluster number */
+			    unsigned long long *ofs,
+			    erofs_blk_t *pblk,
+			    unsigned int *flags)
 {
-	/* for extent meta */
-	struct page *page = *page_iter;
-	erofs_blk_t blkaddr = vle_extent_blkaddr(inode, lcn);
+	const unsigned int clustersize = 1 << ctx->clusterbits;
+	const erofs_blk_t mblk = vle_extent_blkaddr(ctx->inode, lcn);
+	struct page *mpage = *ctx->mpage_ret;	/* extent metapage */
+
 	struct z_erofs_vle_decompressed_index *di;
-	unsigned long long ofs;
-	const unsigned int clusterbits = EROFS_SB(inode->i_sb)->clusterbits;
-	const unsigned int clustersize = 1 << clusterbits;
+	unsigned int cluster_type, delta0;
 
-	if (page->index != blkaddr) {
-		kunmap_atomic(*kaddr_iter);
-		unlock_page(page);
-		put_page(page);
+	if (mpage->index != mblk) {
+		kunmap_atomic(*ctx->kaddr_ret);
+		unlock_page(mpage);
+		put_page(mpage);
 
-		*page_iter = page = erofs_get_meta_page(inode->i_sb,
-			blkaddr, false);
-		*kaddr_iter = kmap_atomic(page);
+		mpage = erofs_get_meta_page(ctx->sb, mblk, false);
+		if (IS_ERR(mpage)) {
+			*ctx->mpage_ret = NULL;
+			return PTR_ERR(mpage);
+		}
+		*ctx->mpage_ret = mpage;
+		*ctx->kaddr_ret = kmap_atomic(mpage);
 	}
 
-	di = *kaddr_iter + vle_extent_blkoff(inode, lcn);
-	switch (vle_cluster_type(di)) {
-	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
-		BUG_ON(!di->di_u.delta[0]);
-		BUG_ON(lcn < di->di_u.delta[0]);
+	di = *ctx->kaddr_ret + vle_extent_blkoff(ctx->inode, lcn);
 
-		ofs = vle_get_logical_extent_head(inode,
-			page_iter, kaddr_iter,
-			lcn - di->di_u.delta[0], pcn, flags);
-		break;
+	cluster_type = vle_cluster_type(di);
+	switch (cluster_type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		delta0 = le16_to_cpu(di->di_u.delta[0]);
+		if (unlikely(!delta0 || delta0 > lcn)) {
+			errln("invalid NONHEAD dl0 %u at lcn %u of nid %llu",
+			      delta0, lcn, EROFS_V(ctx->inode)->nid);
+			DBG_BUGON(1);
+			return -EIO;
+		}
+		return vle_get_logical_extent_head(ctx,
+			lcn - delta0, ofs, pblk, flags);
 	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
 		*flags ^= EROFS_MAP_ZIPPED;
+		/* fallthrough */
 	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
 		/* clustersize should be a power of two */
-		ofs = ((unsigned long long)lcn << clusterbits) +
+		*ofs = ((u64)lcn << ctx->clusterbits) +
 			(le16_to_cpu(di->di_clusterofs) & (clustersize - 1));
-		*pcn = le32_to_cpu(di->di_u.blkaddr);
+		*pblk = le32_to_cpu(di->di_u.blkaddr);
 		break;
 	default:
-		BUG_ON(1);
+		errln("unknown cluster type %u at lcn %u of nid %llu",
+		      cluster_type, lcn, EROFS_V(ctx->inode)->nid);
+		DBG_BUGON(1);
+		return -EIO;
 	}
-	return ofs;
+	return 0;
 }
 
 int z_erofs_map_blocks_iter(struct inode *inode,
 	struct erofs_map_blocks *map,
 	struct page **mpage_ret, int flags)
 {
+	void *kaddr;
+	const struct vle_map_blocks_iter_ctx ctx = {
+		.inode = inode,
+		.sb = inode->i_sb,
+		.clusterbits = EROFS_I_SB(inode)->clusterbits,
+		.mpage_ret = mpage_ret,
+		.kaddr_ret = &kaddr
+	};
+	const unsigned int clustersize = 1 << ctx.clusterbits;
+	/* if both m_(l,p)len are 0, regularize l_lblk, l_lofs, etc... */
+	const bool initial = !map->m_llen;
+
 	/* logicial extent (start, end) offset */
 	unsigned long long ofs, end;
-	struct z_erofs_vle_decompressed_index *di;
-	erofs_blk_t e_blkaddr, pcn;
-	unsigned lcn, logical_cluster_ofs, cluster_type;
+	unsigned int lcn;
 	u32 ofs_rem;
+
+	/* initialize `pblk' to keep gcc from printing foolish warnings */
+	erofs_blk_t mblk, pblk = 0;
 	struct page *mpage = *mpage_ret;
-	void *kaddr;
-	bool initial;
-	const unsigned int clusterbits = EROFS_SB(inode->i_sb)->clusterbits;
-	const unsigned int clustersize = 1 << clusterbits;
+	struct z_erofs_vle_decompressed_index *di;
+	unsigned int cluster_type, logical_cluster_ofs;
 	int err = 0;
 
-	/* if both m_(l,p)len are 0, regularize l_lblk, l_lofs, etc... */
-	initial = !map->m_llen;
+	trace_z_erofs_map_blocks_iter_enter(inode, map, flags);
 
 	/* when trying to read beyond EOF, leave it unmapped */
 	if (unlikely(map->m_la >= inode->i_size)) {
-		BUG_ON(!initial);
+		DBG_BUGON(!initial);
 		map->m_llen = map->m_la + 1 - inode->i_size;
-		map->m_la = inode->i_size - 1;
+		map->m_la = inode->i_size;
 		map->m_flags = 0;
 		goto out;
 	}
@@ -1560,16 +1555,20 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 	ofs = map->m_la + map->m_llen;
 
 	/* clustersize should be power of two */
-	lcn = ofs >> clusterbits;
+	lcn = ofs >> ctx.clusterbits;
 	ofs_rem = ofs & (clustersize - 1);
 
-	e_blkaddr = vle_extent_blkaddr(inode, lcn);
+	mblk = vle_extent_blkaddr(inode, lcn);
 
-	if (mpage == NULL || mpage->index != e_blkaddr) {
+	if (!mpage || mpage->index != mblk) {
 		if (mpage != NULL)
 			put_page(mpage);
 
-		mpage = erofs_get_meta_page(inode->i_sb, e_blkaddr, false);
+		mpage = erofs_get_meta_page(ctx.sb, mblk, false);
+		if (IS_ERR(mpage)) {
+			err = PTR_ERR(mpage);
+			goto out;
+		}
 		*mpage_ret = mpage;
 	} else {
 		lock_page(mpage);
@@ -1579,10 +1578,14 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 	kaddr = kmap_atomic(mpage);
 	di = kaddr + vle_extent_blkoff(inode, lcn);
 
-	debugln("%s, lcn %u e_blkaddr %u e_blkoff %u", __func__, lcn,
-		e_blkaddr, vle_extent_blkoff(inode, lcn));
+	debugln("%s, lcn %u mblk %u e_blkoff %u", __func__, lcn,
+		mblk, vle_extent_blkoff(inode, lcn));
+
+	err = vle_decompressed_index_clusterofs(&logical_cluster_ofs,
+						clustersize, di);
+	if (unlikely(err))
+		goto unmap_out;
 
-	logical_cluster_ofs = vle_compressed_index_clusterofs(clustersize, di);
 	if (!initial) {
 		/* [walking mode] 'map' has been already initialized */
 		map->m_llen += logical_cluster_ofs;
@@ -1592,7 +1595,7 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 	/* by default, compressed */
 	map->m_flags |= EROFS_MAP_ZIPPED;
 
-	end = (u64)(lcn + 1) * clustersize;
+	end = ((u64)lcn + 1) * clustersize;
 
 	cluster_type = vle_cluster_type(di);
 
@@ -1603,13 +1606,13 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 		/* fallthrough */
 	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
 		if (ofs_rem == logical_cluster_ofs) {
-			pcn = le32_to_cpu(di->di_u.blkaddr);
+			pblk = le32_to_cpu(di->di_u.blkaddr);
 			goto exact_hitted;
 		}
 
 		if (ofs_rem > logical_cluster_ofs) {
-			ofs = lcn * clustersize | logical_cluster_ofs;
-			pcn = le32_to_cpu(di->di_u.blkaddr);
+			ofs = (u64)lcn * clustersize | logical_cluster_ofs;
+			pblk = le32_to_cpu(di->di_u.blkaddr);
 			break;
 		}
 
@@ -1620,13 +1623,19 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 			err = -EIO;
 			goto unmap_out;
 		}
-		end = (lcn-- * clustersize) | logical_cluster_ofs;
+		end = ((u64)lcn-- * clustersize) | logical_cluster_ofs;
 		/* fallthrough */
 	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
 		/* get the correspoinding first chunk */
-		ofs = vle_get_logical_extent_head(inode, mpage_ret,
-			&kaddr, lcn, &pcn, &map->m_flags);
+		err = vle_get_logical_extent_head(&ctx, lcn, &ofs,
+						  &pblk, &map->m_flags);
 		mpage = *mpage_ret;
+
+		if (unlikely(err)) {
+			if (mpage)
+				goto unmap_out;
+			goto out;
+		}
 		break;
 	default:
 		errln("unknown cluster type %u at offset %llu of nid %llu",
@@ -1639,7 +1648,7 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 exact_hitted:
 	map->m_llen = end - ofs;
 	map->m_plen = clustersize;
-	map->m_pa = blknr_to_addr(pcn);
+	map->m_pa = blknr_to_addr(pblk);
 	map->m_flags |= EROFS_MAP_MAPPED;
 unmap_out:
 	kunmap_atomic(kaddr);
@@ -1649,8 +1658,10 @@ out:
 		__func__, map->m_la, map->m_pa,
 		map->m_llen, map->m_plen, map->m_flags);
 
+	trace_z_erofs_map_blocks_iter_exit(inode, map, flags, err);
+
 	/* aggressively BUG_ON iff CONFIG_EROFS_FS_DEBUG is on */
-	DBG_BUGON(err < 0);
+	DBG_BUGON(err < 0 && err != -ENOMEM);
 	return err;
 }
 
diff --git a/drivers/staging/erofs/unzip_vle.h b/drivers/staging/erofs/unzip_vle.h
index 393998500865..3316bc36965d 100644
--- a/drivers/staging/erofs/unzip_vle.h
+++ b/drivers/staging/erofs/unzip_vle.h
@@ -47,13 +47,6 @@ static inline bool z_erofs_gather_if_stagingpage(struct list_head *page_pool,
 #define Z_EROFS_VLE_INLINE_PAGEVECS     3
 
 struct z_erofs_vle_work {
-	/* struct z_erofs_vle_work *left, *right; */
-
-#ifdef CONFIG_EROFS_FS_ZIP_MULTIREF
-	struct list_head list;
-
-	atomic_t refcount;
-#endif
 	struct mutex lock;
 
 	/* I: decompression offset in page */
@@ -107,10 +100,8 @@ static inline void z_erofs_vle_set_workgrp_fmt(
 	grp->flags = fmt | (grp->flags & ~Z_EROFS_VLE_WORKGRP_FMT_MASK);
 }
 
-#ifdef CONFIG_EROFS_FS_ZIP_MULTIREF
-#error multiref decompression is unimplemented yet
-#else
 
+/* definitions if multiref is disabled */
 #define z_erofs_vle_grab_primary_work(grp)	(&(grp)->work)
 #define z_erofs_vle_grab_work(grp, pageofs)	(&(grp)->work)
 #define z_erofs_vle_work_workgroup(wrk, primary)	\
@@ -118,7 +109,6 @@ static inline void z_erofs_vle_set_workgrp_fmt(
 		struct z_erofs_vle_workgroup, work) : \
 		({ BUG(); (void *)NULL; }))
 
-#endif
 
 #define Z_EROFS_WORKGROUP_SIZE       sizeof(struct z_erofs_vle_workgroup)
 
diff --git a/drivers/staging/erofs/unzip_vle_lz4.c b/drivers/staging/erofs/unzip_vle_lz4.c
index f5b665f15be5..1a428658cbea 100644
--- a/drivers/staging/erofs/unzip_vle_lz4.c
+++ b/drivers/staging/erofs/unzip_vle_lz4.c
@@ -23,14 +23,14 @@ static struct {
 } erofs_pcpubuf[NR_CPUS];
 
 int z_erofs_vle_plain_copy(struct page **compressed_pages,
-			   unsigned clusterpages,
+			   unsigned int clusterpages,
 			   struct page **pages,
-			   unsigned nr_pages,
+			   unsigned int nr_pages,
 			   unsigned short pageofs)
 {
-	unsigned i, j;
+	unsigned int i, j;
 	void *src = NULL;
-	const unsigned righthalf = PAGE_SIZE - pageofs;
+	const unsigned int righthalf = PAGE_SIZE - pageofs;
 	char *percpu_data;
 	bool mirrored[Z_EROFS_CLUSTER_MAX_PAGES] = { 0 };
 
@@ -42,8 +42,8 @@ int z_erofs_vle_plain_copy(struct page **compressed_pages,
 		struct page *page = pages[i];
 		void *dst;
 
-		if (page == NULL) {
-			if (src != NULL) {
+		if (!page) {
+			if (src) {
 				if (!mirrored[j])
 					kunmap_atomic(src);
 				src = NULL;
@@ -64,14 +64,14 @@ int z_erofs_vle_plain_copy(struct page **compressed_pages,
 		}
 
 		if (i) {
-			if (src == NULL)
-				src = mirrored[i-1] ?
-					percpu_data + (i-1) * PAGE_SIZE :
-					kmap_atomic(compressed_pages[i-1]);
+			if (!src)
+				src = mirrored[i - 1] ?
+					percpu_data + (i - 1) * PAGE_SIZE :
+					kmap_atomic(compressed_pages[i - 1]);
 
 			memcpy(dst, src + righthalf, pageofs);
 
-			if (!mirrored[i-1])
+			if (!mirrored[i - 1])
 				kunmap_atomic(src);
 
 			if (unlikely(i >= clusterpages)) {
@@ -80,9 +80,9 @@ int z_erofs_vle_plain_copy(struct page **compressed_pages,
 			}
 		}
 
-		if (!righthalf)
+		if (!righthalf) {
 			src = NULL;
-		else {
+		} else {
 			src = mirrored[i] ? percpu_data + i * PAGE_SIZE :
 				kmap_atomic(compressed_pages[i]);
 
@@ -92,7 +92,7 @@ int z_erofs_vle_plain_copy(struct page **compressed_pages,
 		kunmap_atomic(dst);
 	}
 
-	if (src != NULL && !mirrored[j])
+	if (src && !mirrored[j])
 		kunmap_atomic(src);
 
 	preempt_enable();
@@ -102,14 +102,14 @@ int z_erofs_vle_plain_copy(struct page **compressed_pages,
 extern int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen);
 
 int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
-				  unsigned clusterpages,
+				  unsigned int clusterpages,
 				  struct page **pages,
-				  unsigned outlen,
+				  unsigned int outlen,
 				  unsigned short pageofs,
 				  void (*endio)(struct page *))
 {
 	void *vin, *vout;
-	unsigned nr_pages, i, j;
+	unsigned int nr_pages, i, j;
 	int ret;
 
 	if (outlen + pageofs > EROFS_PERCPU_NR_PAGES * PAGE_SIZE)
@@ -126,7 +126,7 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
 	vout = erofs_pcpubuf[smp_processor_id()].data;
 
 	ret = z_erofs_unzip_lz4(vin, vout + pageofs,
-		clusterpages * PAGE_SIZE, outlen);
+				clusterpages * PAGE_SIZE, outlen);
 
 	if (ret >= 0) {
 		outlen = ret;
@@ -134,14 +134,15 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
 	}
 
 	for (i = 0; i < nr_pages; ++i) {
-		j = min((unsigned)PAGE_SIZE - pageofs, outlen);
+		j = min((unsigned int)PAGE_SIZE - pageofs, outlen);
 
-		if (pages[i] != NULL) {
-			if (ret < 0)
+		if (pages[i]) {
+			if (ret < 0) {
 				SetPageError(pages[i]);
-			else if (clusterpages == 1 && pages[i] == compressed_pages[0])
+			} else if (clusterpages == 1 &&
+				   pages[i] == compressed_pages[0]) {
 				memcpy(vin + pageofs, vout + pageofs, j);
-			else {
+			} else {
 				void *dst = kmap_atomic(pages[i]);
 
 				memcpy(dst + pageofs, vout + pageofs, j);
@@ -164,14 +165,14 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
 }
 
 int z_erofs_vle_unzip_vmap(struct page **compressed_pages,
-			   unsigned clusterpages,
+			   unsigned int clusterpages,
 			   void *vout,
-			   unsigned llen,
+			   unsigned int llen,
 			   unsigned short pageofs,
 			   bool overlapped)
 {
 	void *vin;
-	unsigned i;
+	unsigned int i;
 	int ret;
 
 	if (overlapped) {
@@ -181,29 +182,27 @@ int z_erofs_vle_unzip_vmap(struct page **compressed_pages,
 		for (i = 0; i < clusterpages; ++i) {
 			void *t = kmap_atomic(compressed_pages[i]);
 
-			memcpy(vin + PAGE_SIZE *i, t, PAGE_SIZE);
+			memcpy(vin + PAGE_SIZE * i, t, PAGE_SIZE);
 			kunmap_atomic(t);
 		}
-	} else if (clusterpages == 1)
+	} else if (clusterpages == 1) {
 		vin = kmap_atomic(compressed_pages[0]);
-	else {
+	} else {
 		vin = erofs_vmap(compressed_pages, clusterpages);
 	}
 
 	ret = z_erofs_unzip_lz4(vin, vout + pageofs,
-		clusterpages * PAGE_SIZE, llen);
+				clusterpages * PAGE_SIZE, llen);
 	if (ret > 0)
 		ret = 0;
 
 	if (!overlapped) {
 		if (clusterpages == 1)
 			kunmap_atomic(vin);
-		else {
+		else
 			erofs_vunmap(vin, clusterpages);
-		}
-	} else
+	} else {
 		preempt_enable();
-
+	}
 	return ret;
 }
-
diff --git a/drivers/staging/erofs/utils.c b/drivers/staging/erofs/utils.c
index 595cf90af9bb..ea8a962e5c95 100644
--- a/drivers/staging/erofs/utils.c
+++ b/drivers/staging/erofs/utils.c
@@ -35,7 +35,6 @@ static atomic_long_t erofs_global_shrink_cnt;
 
 #ifdef CONFIG_EROFS_FS_ZIP
 
-/* radix_tree and the future XArray both don't use tagptr_t yet */
 struct erofs_workgroup *erofs_find_workgroup(
 	struct super_block *sb, pgoff_t index, bool *tag)
 {
@@ -47,9 +46,8 @@ repeat:
 	rcu_read_lock();
 	grp = radix_tree_lookup(&sbi->workstn_tree, index);
 	if (grp != NULL) {
-		*tag = radix_tree_exceptional_entry(grp);
-		grp = (void *)((unsigned long)grp &
-			~RADIX_TREE_EXCEPTIONAL_ENTRY);
+		*tag = xa_pointer_tag(grp);
+		grp = xa_untag_pointer(grp);
 
 		if (erofs_workgroup_get(grp, &oldcount)) {
 			/* prefer to relax rcu read side */
@@ -83,9 +81,7 @@ int erofs_register_workgroup(struct super_block *sb,
 	sbi = EROFS_SB(sb);
 	erofs_workstn_lock(sbi);
 
-	if (tag)
-		grp = (void *)((unsigned long)grp |
-			1UL << RADIX_TREE_EXCEPTIONAL_SHIFT);
+	grp = xa_tag_pointer(grp, tag);
 
 	err = radix_tree_insert(&sbi->workstn_tree,
 		grp->index, grp);
@@ -120,7 +116,7 @@ unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
 {
 	pgoff_t first_index = 0;
 	void *batch[PAGEVEC_SIZE];
-	unsigned freed = 0;
+	unsigned int freed = 0;
 
 	int i, found;
 repeat:
@@ -131,9 +127,7 @@ repeat:
 
 	for (i = 0; i < found; ++i) {
 		int cnt;
-		struct erofs_workgroup *grp = (void *)
-			((unsigned long)batch[i] &
-				~RADIX_TREE_EXCEPTIONAL_ENTRY);
+		struct erofs_workgroup *grp = xa_untag_pointer(batch[i]);
 
 		first_index = grp->index + 1;
 
@@ -150,8 +144,8 @@ repeat:
 #endif
 			continue;
 
-		if (radix_tree_delete(&sbi->workstn_tree,
-			grp->index) != grp) {
+		if (xa_untag_pointer(radix_tree_delete(&sbi->workstn_tree,
+			grp->index)) != grp) {
 #ifdef EROFS_FS_HAS_MANAGED_CACHE
 skip:
 			erofs_workgroup_unfreeze(grp, 1);
diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index 0e9cfeccdf99..80dca6a4adbe 100644
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -19,41 +19,53 @@ struct xattr_iter {
 	void *kaddr;
 
 	erofs_blk_t blkaddr;
-	unsigned ofs;
+	unsigned int ofs;
 };
 
 static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
 {
-	/* only init_inode_xattrs use non-atomic once */
+	/* the only user of kunmap() is 'init_inode_xattrs' */
 	if (unlikely(!atomic))
 		kunmap(it->page);
 	else
 		kunmap_atomic(it->kaddr);
+
 	unlock_page(it->page);
 	put_page(it->page);
 }
 
-static void init_inode_xattrs(struct inode *inode)
+static inline void xattr_iter_end_final(struct xattr_iter *it)
+{
+	if (it->page == NULL)
+		return;
+
+	xattr_iter_end(it, true);
+}
+
+static int init_inode_xattrs(struct inode *inode)
 {
 	struct xattr_iter it;
-	unsigned i;
+	unsigned int i;
 	struct erofs_xattr_ibody_header *ih;
+	struct super_block *sb;
 	struct erofs_sb_info *sbi;
 	struct erofs_vnode *vi;
 	bool atomic_map;
 
 	if (likely(inode_has_inited_xattr(inode)))
-		return;
+		return 0;
 
 	vi = EROFS_V(inode);
 	BUG_ON(!vi->xattr_isize);
 
-	sbi = EROFS_I_SB(inode);
+	sb = inode->i_sb;
+	sbi = EROFS_SB(sb);
 	it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
 	it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
 
 	it.page = erofs_get_inline_page(inode, it.blkaddr);
-	BUG_ON(IS_ERR(it.page));
+	if (IS_ERR(it.page))
+		return PTR_ERR(it.page);
 
 	/* read in shared xattr array (non-atomic, see kmalloc below) */
 	it.kaddr = kmap(it.page);
@@ -62,9 +74,12 @@ static void init_inode_xattrs(struct inode *inode)
 	ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
 
 	vi->xattr_shared_count = ih->h_shared_count;
-	vi->xattr_shared_xattrs = (unsigned *)kmalloc_array(
-		vi->xattr_shared_count, sizeof(unsigned),
-		GFP_KERNEL | __GFP_NOFAIL);
+	vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
+						sizeof(uint), GFP_KERNEL);
+	if (vi->xattr_shared_xattrs == NULL) {
+		xattr_iter_end(&it, atomic_map);
+		return -ENOMEM;
+	}
 
 	/* let's skip ibody header */
 	it.ofs += sizeof(struct erofs_xattr_ibody_header);
@@ -75,9 +90,10 @@ static void init_inode_xattrs(struct inode *inode)
 			BUG_ON(it.ofs != EROFS_BLKSIZ);
 			xattr_iter_end(&it, atomic_map);
 
-			it.page = erofs_get_meta_page(inode->i_sb,
+			it.page = erofs_get_meta_page(sb,
 				++it.blkaddr, S_ISDIR(inode->i_mode));
-			BUG_ON(IS_ERR(it.page));
+			if (IS_ERR(it.page))
+				return PTR_ERR(it.page);
 
 			it.kaddr = kmap_atomic(it.page);
 			atomic_map = true;
@@ -90,27 +106,43 @@ static void init_inode_xattrs(struct inode *inode)
 	xattr_iter_end(&it, atomic_map);
 
 	inode_set_inited_xattr(inode);
+	return 0;
 }
 
+/*
+ * 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 *, struct erofs_xattr_entry *);
-	int (*name)(struct xattr_iter *, unsigned, char *, unsigned);
-	int (*alloc_buffer)(struct xattr_iter *, unsigned);
-	void (*value)(struct xattr_iter *, unsigned, char *, unsigned);
+	int (*name)(struct xattr_iter *, unsigned int, char *, unsigned int);
+	int (*alloc_buffer)(struct xattr_iter *, unsigned int);
+	void (*value)(struct xattr_iter *, unsigned int, char *, unsigned int);
 };
 
-static void xattr_iter_fixup(struct xattr_iter *it)
+static inline int xattr_iter_fixup(struct xattr_iter *it)
 {
-	if (unlikely(it->ofs >= EROFS_BLKSIZ)) {
-		xattr_iter_end(it, true);
+	if (it->ofs < EROFS_BLKSIZ)
+		return 0;
+
+	xattr_iter_end(it, true);
+
+	it->blkaddr += erofs_blknr(it->ofs);
 
-		it->blkaddr += erofs_blknr(it->ofs);
-		it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
-		BUG_ON(IS_ERR(it->page));
+	it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
+	if (IS_ERR(it->page)) {
+		int err = PTR_ERR(it->page);
 
-		it->kaddr = kmap_atomic(it->page);
-		it->ofs = erofs_blkoff(it->ofs);
+		it->page = NULL;
+		return err;
 	}
+
+	it->kaddr = kmap_atomic(it->page);
+	it->ofs = erofs_blkoff(it->ofs);
+	return 0;
 }
 
 static int inline_xattr_iter_begin(struct xattr_iter *it,
@@ -118,7 +150,7 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
 {
 	struct erofs_vnode *const vi = EROFS_V(inode);
 	struct erofs_sb_info *const sbi = EROFS_SB(inode->i_sb);
-	unsigned xattr_header_sz, inline_xattr_ofs;
+	unsigned int xattr_header_sz, inline_xattr_ofs;
 
 	xattr_header_sz = inlinexattr_header_size(inode);
 	if (unlikely(xattr_header_sz >= vi->xattr_isize)) {
@@ -132,21 +164,28 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
 	it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);
 
 	it->page = erofs_get_inline_page(inode, it->blkaddr);
-	BUG_ON(IS_ERR(it->page));
-	it->kaddr = kmap_atomic(it->page);
+	if (IS_ERR(it->page))
+		return PTR_ERR(it->page);
 
+	it->kaddr = kmap_atomic(it->page);
 	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,
-	struct xattr_iter_handlers *op, unsigned *tlimit)
+	const struct xattr_iter_handlers *op, unsigned int *tlimit)
 {
 	struct erofs_xattr_entry entry;
-	unsigned value_sz, processed, slice;
+	unsigned int value_sz, processed, slice;
 	int err;
 
 	/* 0. fixup blkaddr, ofs, ipage */
-	xattr_iter_fixup(it);
+	err = xattr_iter_fixup(it);
+	if (err)
+		return err;
 
 	/*
 	 * 1. read xattr entry to the memory,
@@ -155,7 +194,7 @@ static int xattr_foreach(struct xattr_iter *it,
 	 */
 	entry = *(struct erofs_xattr_entry *)(it->kaddr + it->ofs);
 	if (tlimit != NULL) {
-		unsigned entry_sz = EROFS_XATTR_ENTRY_SIZE(&entry);
+		unsigned int entry_sz = EROFS_XATTR_ENTRY_SIZE(&entry);
 
 		BUG_ON(*tlimit < entry_sz);
 		*tlimit -= entry_sz;
@@ -178,12 +217,14 @@ static int xattr_foreach(struct xattr_iter *it,
 		if (it->ofs >= EROFS_BLKSIZ) {
 			BUG_ON(it->ofs > EROFS_BLKSIZ);
 
-			xattr_iter_fixup(it);
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
 			it->ofs = 0;
 		}
 
-		slice = min_t(unsigned, PAGE_SIZE - it->ofs,
-			entry.e_name_len - processed);
+		slice = min_t(unsigned int, PAGE_SIZE - it->ofs,
+			      entry.e_name_len - processed);
 
 		/* handle name */
 		err = op->name(it, processed, it->kaddr + it->ofs, slice);
@@ -210,21 +251,24 @@ static int xattr_foreach(struct xattr_iter *it,
 	while (processed < value_sz) {
 		if (it->ofs >= EROFS_BLKSIZ) {
 			BUG_ON(it->ofs > EROFS_BLKSIZ);
-			xattr_iter_fixup(it);
+
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
 			it->ofs = 0;
 		}
 
-		slice = min_t(unsigned, PAGE_SIZE - it->ofs,
-			value_sz - processed);
+		slice = min_t(unsigned int, PAGE_SIZE - it->ofs,
+			      value_sz - processed);
 		op->value(it, processed, it->kaddr + it->ofs, slice);
 		it->ofs += slice;
 		processed += slice;
 	}
 
 out:
-	/* we assume that ofs is aligned with 4 bytes */
+	/* xattrs should be 4-byte aligned (on-disk constraint) */
 	it->ofs = EROFS_XATTR_ALIGN(it->ofs);
-	return err;
+	return err < 0 ? err : 0;
 }
 
 struct getxattr_iter {
@@ -245,7 +289,7 @@ static int xattr_entrymatch(struct xattr_iter *_it,
 }
 
 static int xattr_namematch(struct xattr_iter *_it,
-	unsigned processed, char *buf, unsigned len)
+	unsigned int processed, char *buf, unsigned int len)
 {
 	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 
@@ -253,7 +297,7 @@ static int xattr_namematch(struct xattr_iter *_it,
 }
 
 static int xattr_checkbuffer(struct xattr_iter *_it,
-	unsigned value_sz)
+	unsigned int value_sz)
 {
 	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 	int err = it->buffer_size < value_sz ? -ERANGE : 0;
@@ -263,14 +307,14 @@ static int xattr_checkbuffer(struct xattr_iter *_it,
 }
 
 static void xattr_copyvalue(struct xattr_iter *_it,
-	unsigned processed, char *buf, unsigned len)
+	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 struct xattr_iter_handlers find_xattr_handlers = {
+static const struct xattr_iter_handlers find_xattr_handlers = {
 	.entry = xattr_entrymatch,
 	.name = xattr_namematch,
 	.alloc_buffer = xattr_checkbuffer,
@@ -280,7 +324,7 @@ static struct xattr_iter_handlers find_xattr_handlers = {
 static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
 {
 	int ret;
-	unsigned remaining;
+	unsigned int remaining;
 
 	ret = inline_xattr_iter_begin(&it->it, inode);
 	if (ret < 0)
@@ -289,19 +333,20 @@ static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
 	remaining = ret;
 	while (remaining) {
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
-		if (ret >= 0)
+		if (ret != -ENOATTR)
 			break;
 	}
-	xattr_iter_end(&it->it, true);
+	xattr_iter_end_final(&it->it);
 
-	return ret < 0 ? ret : it->buffer_size;
+	return ret ? ret : it->buffer_size;
 }
 
 static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 {
 	struct erofs_vnode *const vi = EROFS_V(inode);
-	struct erofs_sb_info *const sbi = EROFS_SB(inode->i_sb);
-	unsigned i;
+	struct super_block *const sb = inode->i_sb;
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	unsigned int i;
 	int ret = -ENOATTR;
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
@@ -314,21 +359,22 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 			if (i)
 				xattr_iter_end(&it->it, true);
 
-			it->it.page = erofs_get_meta_page(inode->i_sb,
-				blkaddr, false);
-			BUG_ON(IS_ERR(it->it.page));
+			it->it.page = erofs_get_meta_page(sb, blkaddr, false);
+			if (IS_ERR(it->it.page))
+				return PTR_ERR(it->it.page);
+
 			it->it.kaddr = kmap_atomic(it->it.page);
 			it->it.blkaddr = blkaddr;
 		}
 
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
-		if (ret >= 0)
+		if (ret != -ENOATTR)
 			break;
 	}
 	if (vi->xattr_shared_count)
-		xattr_iter_end(&it->it, true);
+		xattr_iter_end_final(&it->it);
 
-	return ret < 0 ? ret : it->buffer_size;
+	return ret ? ret : it->buffer_size;
 }
 
 static bool erofs_xattr_user_list(struct dentry *dentry)
@@ -351,7 +397,9 @@ int erofs_getxattr(struct inode *inode, int index,
 	if (unlikely(name == NULL))
 		return -EINVAL;
 
-	init_inode_xattrs(inode);
+	ret = init_inode_xattrs(inode);
+	if (ret)
+		return ret;
 
 	it.index = index;
 
@@ -446,7 +494,7 @@ static int xattr_entrylist(struct xattr_iter *_it,
 {
 	struct listxattr_iter *it =
 		container_of(_it, struct listxattr_iter, it);
-	unsigned prefix_len;
+	unsigned int prefix_len;
 	const char *prefix;
 
 	const struct xattr_handler *h =
@@ -474,7 +522,7 @@ static int xattr_entrylist(struct xattr_iter *_it,
 }
 
 static int xattr_namelist(struct xattr_iter *_it,
-	unsigned processed, char *buf, unsigned len)
+	unsigned int processed, char *buf, unsigned int len)
 {
 	struct listxattr_iter *it =
 		container_of(_it, struct listxattr_iter, it);
@@ -485,7 +533,7 @@ static int xattr_namelist(struct xattr_iter *_it,
 }
 
 static int xattr_skipvalue(struct xattr_iter *_it,
-	unsigned value_sz)
+	unsigned int value_sz)
 {
 	struct listxattr_iter *it =
 		container_of(_it, struct listxattr_iter, it);
@@ -494,7 +542,7 @@ static int xattr_skipvalue(struct xattr_iter *_it,
 	return 1;
 }
 
-static struct xattr_iter_handlers list_xattr_handlers = {
+static const struct xattr_iter_handlers list_xattr_handlers = {
 	.entry = xattr_entrylist,
 	.name = xattr_namelist,
 	.alloc_buffer = xattr_skipvalue,
@@ -504,7 +552,7 @@ static struct xattr_iter_handlers list_xattr_handlers = {
 static int inline_listxattr(struct listxattr_iter *it)
 {
 	int ret;
-	unsigned remaining;
+	unsigned int remaining;
 
 	ret = inline_xattr_iter_begin(&it->it, d_inode(it->dentry));
 	if (ret < 0)
@@ -513,19 +561,20 @@ static int inline_listxattr(struct listxattr_iter *it)
 	remaining = ret;
 	while (remaining) {
 		ret = xattr_foreach(&it->it, &list_xattr_handlers, &remaining);
-		if (ret < 0)
+		if (ret)
 			break;
 	}
-	xattr_iter_end(&it->it, true);
-	return ret < 0 ? ret : it->buffer_ofs;
+	xattr_iter_end_final(&it->it);
+	return ret ? ret : it->buffer_ofs;
 }
 
 static int shared_listxattr(struct listxattr_iter *it)
 {
 	struct inode *const inode = d_inode(it->dentry);
 	struct erofs_vnode *const vi = EROFS_V(inode);
-	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
-	unsigned i;
+	struct super_block *const sb = inode->i_sb;
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	unsigned int i;
 	int ret = 0;
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
@@ -537,21 +586,22 @@ static int shared_listxattr(struct listxattr_iter *it)
 			if (i)
 				xattr_iter_end(&it->it, true);
 
-			it->it.page = erofs_get_meta_page(inode->i_sb,
-				blkaddr, false);
-			BUG_ON(IS_ERR(it->it.page));
+			it->it.page = erofs_get_meta_page(sb, blkaddr, false);
+			if (IS_ERR(it->it.page))
+				return PTR_ERR(it->it.page);
+
 			it->it.kaddr = kmap_atomic(it->it.page);
 			it->it.blkaddr = blkaddr;
 		}
 
 		ret = xattr_foreach(&it->it, &list_xattr_handlers, NULL);
-		if (ret < 0)
+		if (ret)
 			break;
 	}
 	if (vi->xattr_shared_count)
-		xattr_iter_end(&it->it, true);
+		xattr_iter_end_final(&it->it);
 
-	return ret < 0 ? ret : it->buffer_ofs;
+	return ret ? ret : it->buffer_ofs;
 }
 
 ssize_t erofs_listxattr(struct dentry *dentry,
@@ -560,7 +610,9 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 	int ret;
 	struct listxattr_iter it;
 
-	init_inode_xattrs(d_inode(dentry));
+	ret = init_inode_xattrs(d_inode(dentry));
+	if (ret)
+		return ret;
 
 	it.dentry = dentry;
 	it.buffer = buffer;