1 files changed, 486 insertions, 151 deletions

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 736db3a4cdef..0bb66927e3d0 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -1,27 +1,30 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2018-2019 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
+ *             https://www.huawei.com/
  */
 #include "internal.h"
 #include <asm/unaligned.h>
 #include <trace/events/erofs.h>
 
+static int z_erofs_do_map_blocks(struct inode *inode,
+				 struct erofs_map_blocks *map,
+				 int flags);
+
 int z_erofs_fill_inode(struct inode *inode)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
+	struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
 
-	if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
+	if (!erofs_sb_has_big_pcluster(sbi) &&
+	    !erofs_sb_has_ztailpacking(sbi) && !erofs_sb_has_fragments(sbi) &&
+	    vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
 		vi->z_advise = 0;
 		vi->z_algorithmtype[0] = 0;
 		vi->z_algorithmtype[1] = 0;
 		vi->z_logical_clusterbits = LOG_BLOCK_SIZE;
-		vi->z_physical_clusterbits[0] = vi->z_logical_clusterbits;
-		vi->z_physical_clusterbits[1] = vi->z_logical_clusterbits;
 		set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
 	}
-
 	inode->i_mapping->a_ops = &z_erofs_aops;
 	return 0;
 }
@@ -30,14 +33,20 @@ static int z_erofs_fill_inode_lazy(struct inode *inode)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
 	struct super_block *const sb = inode->i_sb;
-	int err;
+	int err, headnr;
 	erofs_off_t pos;
-	struct page *page;
+	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
 	void *kaddr;
 	struct z_erofs_map_header *h;
 
-	if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags))
+	if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) {
+		/*
+		 * paired with smp_mb() at the end of the function to ensure
+		 * fields will only be observed after the bit is set.
+		 */
+		smp_mb();
 		return 0;
+	}
 
 	if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_Z_BIT, TASK_KILLABLE))
 		return -ERESTARTSYS;
@@ -46,48 +55,95 @@ static int z_erofs_fill_inode_lazy(struct inode *inode)
 	if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags))
 		goto out_unlock;
 
-	DBG_BUGON(vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY);
-
 	pos = ALIGN(iloc(EROFS_SB(sb), vi->nid) + vi->inode_isize +
 		    vi->xattr_isize, 8);
-	page = erofs_get_meta_page(sb, erofs_blknr(pos));
-	if (IS_ERR(page)) {
-		err = PTR_ERR(page);
+	kaddr = erofs_read_metabuf(&buf, sb, erofs_blknr(pos), EROFS_KMAP);
+	if (IS_ERR(kaddr)) {
+		err = PTR_ERR(kaddr);
 		goto out_unlock;
 	}
 
-	kaddr = kmap_atomic(page);
-
 	h = kaddr + erofs_blkoff(pos);
+	/*
+	 * if the highest bit of the 8-byte map header is set, the whole file
+	 * is stored in the packed inode. The rest bits keeps z_fragmentoff.
+	 */
+	if (h->h_clusterbits >> Z_EROFS_FRAGMENT_INODE_BIT) {
+		vi->z_advise = Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
+		vi->z_fragmentoff = le64_to_cpu(*(__le64 *)h) ^ (1ULL << 63);
+		vi->z_tailextent_headlcn = 0;
+		goto done;
+	}
 	vi->z_advise = le16_to_cpu(h->h_advise);
 	vi->z_algorithmtype[0] = h->h_algorithmtype & 15;
 	vi->z_algorithmtype[1] = h->h_algorithmtype >> 4;
 
-	if (vi->z_algorithmtype[0] >= Z_EROFS_COMPRESSION_MAX) {
-		erofs_err(sb, "unknown compression format %u for nid %llu, please upgrade kernel",
-			  vi->z_algorithmtype[0], vi->nid);
+	headnr = 0;
+	if (vi->z_algorithmtype[0] >= Z_EROFS_COMPRESSION_MAX ||
+	    vi->z_algorithmtype[++headnr] >= Z_EROFS_COMPRESSION_MAX) {
+		erofs_err(sb, "unknown HEAD%u format %u for nid %llu, please upgrade kernel",
+			  headnr + 1, vi->z_algorithmtype[headnr], vi->nid);
 		err = -EOPNOTSUPP;
-		goto unmap_done;
+		goto out_put_metabuf;
 	}
 
 	vi->z_logical_clusterbits = LOG_BLOCK_SIZE + (h->h_clusterbits & 7);
-	vi->z_physical_clusterbits[0] = vi->z_logical_clusterbits +
-					((h->h_clusterbits >> 3) & 3);
+	if (!erofs_sb_has_big_pcluster(EROFS_SB(sb)) &&
+	    vi->z_advise & (Z_EROFS_ADVISE_BIG_PCLUSTER_1 |
+			    Z_EROFS_ADVISE_BIG_PCLUSTER_2)) {
+		erofs_err(sb, "per-inode big pcluster without sb feature for nid %llu",
+			  vi->nid);
+		err = -EFSCORRUPTED;
+		goto out_put_metabuf;
+	}
+	if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION &&
+	    !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1) ^
+	    !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2)) {
+		erofs_err(sb, "big pcluster head1/2 of compact indexes should be consistent for nid %llu",
+			  vi->nid);
+		err = -EFSCORRUPTED;
+		goto out_put_metabuf;
+	}
 
-	if (vi->z_physical_clusterbits[0] != LOG_BLOCK_SIZE) {
-		erofs_err(sb, "unsupported physical clusterbits %u for nid %llu, please upgrade kernel",
-			  vi->z_physical_clusterbits[0], vi->nid);
-		err = -EOPNOTSUPP;
-		goto unmap_done;
+	if (vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER) {
+		struct erofs_map_blocks map = {
+			.buf = __EROFS_BUF_INITIALIZER
+		};
+
+		vi->z_idata_size = le16_to_cpu(h->h_idata_size);
+		err = z_erofs_do_map_blocks(inode, &map,
+					    EROFS_GET_BLOCKS_FINDTAIL);
+		erofs_put_metabuf(&map.buf);
+
+		if (!map.m_plen ||
+		    erofs_blkoff(map.m_pa) + map.m_plen > EROFS_BLKSIZ) {
+			erofs_err(sb, "invalid tail-packing pclustersize %llu",
+				  map.m_plen);
+			err = -EFSCORRUPTED;
+		}
+		if (err < 0)
+			goto out_put_metabuf;
 	}
 
-	vi->z_physical_clusterbits[1] = vi->z_logical_clusterbits +
-					((h->h_clusterbits >> 5) & 7);
+	if (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER &&
+	    !(h->h_clusterbits >> Z_EROFS_FRAGMENT_INODE_BIT)) {
+		struct erofs_map_blocks map = {
+			.buf = __EROFS_BUF_INITIALIZER
+		};
+
+		vi->z_fragmentoff = le32_to_cpu(h->h_fragmentoff);
+		err = z_erofs_do_map_blocks(inode, &map,
+					    EROFS_GET_BLOCKS_FINDTAIL);
+		erofs_put_metabuf(&map.buf);
+		if (err < 0)
+			goto out_put_metabuf;
+	}
+done:
+	/* paired with smp_mb() at the beginning of the function */
+	smp_mb();
 	set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
-unmap_done:
-	kunmap_atomic(kaddr);
-	unlock_page(page);
-	put_page(page);
+out_put_metabuf:
+	erofs_put_metabuf(&buf);
 out_unlock:
 	clear_and_wake_up_bit(EROFS_I_BL_Z_BIT, &vi->flags);
 	return err;
@@ -100,44 +156,14 @@ struct z_erofs_maprecorder {
 
 	unsigned long lcn;
 	/* compression extent information gathered */
-	u8  type;
+	u8  type, headtype;
 	u16 clusterofs;
 	u16 delta[2];
-	erofs_blk_t pblk;
+	erofs_blk_t pblk, compressedblks;
+	erofs_off_t nextpackoff;
+	bool partialref;
 };
 
-static int z_erofs_reload_indexes(struct z_erofs_maprecorder *m,
-				  erofs_blk_t eblk)
-{
-	struct super_block *const sb = m->inode->i_sb;
-	struct erofs_map_blocks *const map = m->map;
-	struct page *mpage = map->mpage;
-
-	if (mpage) {
-		if (mpage->index == eblk) {
-			if (!m->kaddr)
-				m->kaddr = kmap_atomic(mpage);
-			return 0;
-		}
-
-		if (m->kaddr) {
-			kunmap_atomic(m->kaddr);
-			m->kaddr = NULL;
-		}
-		put_page(mpage);
-	}
-
-	mpage = erofs_get_meta_page(sb, eblk);
-	if (IS_ERR(mpage)) {
-		map->mpage = NULL;
-		return PTR_ERR(mpage);
-	}
-	m->kaddr = kmap_atomic(mpage);
-	unlock_page(mpage);
-	map->mpage = mpage;
-	return 0;
-}
-
 static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 					 unsigned long lcn)
 {
@@ -150,12 +176,13 @@ static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 		lcn * sizeof(struct z_erofs_vle_decompressed_index);
 	struct z_erofs_vle_decompressed_index *di;
 	unsigned int advise, type;
-	int err;
 
-	err = z_erofs_reload_indexes(m, erofs_blknr(pos));
-	if (err)
-		return err;
+	m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,
+				      erofs_blknr(pos), EROFS_KMAP_ATOMIC);
+	if (IS_ERR(m->kaddr))
+		return PTR_ERR(m->kaddr);
 
+	m->nextpackoff = pos + sizeof(struct z_erofs_vle_decompressed_index);
 	m->lcn = lcn;
 	di = m->kaddr + erofs_blkoff(pos);
 
@@ -166,10 +193,23 @@ static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
 		m->clusterofs = 1 << vi->z_logical_clusterbits;
 		m->delta[0] = le16_to_cpu(di->di_u.delta[0]);
+		if (m->delta[0] & Z_EROFS_VLE_DI_D0_CBLKCNT) {
+			if (!(vi->z_advise & (Z_EROFS_ADVISE_BIG_PCLUSTER_1 |
+					Z_EROFS_ADVISE_BIG_PCLUSTER_2))) {
+				DBG_BUGON(1);
+				return -EFSCORRUPTED;
+			}
+			m->compressedblks = m->delta[0] &
+				~Z_EROFS_VLE_DI_D0_CBLKCNT;
+			m->delta[0] = 1;
+		}
 		m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
 		break;
 	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
-	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
+		if (advise & Z_EROFS_VLE_DI_PARTIAL_REF)
+			m->partialref = true;
 		m->clusterofs = le16_to_cpu(di->di_clusterofs);
 		m->pblk = le32_to_cpu(di->di_u.blkaddr);
 		break;
@@ -192,16 +232,42 @@ static unsigned int decode_compactedbits(unsigned int lobits,
 	return lo;
 }
 
+static int get_compacted_la_distance(unsigned int lclusterbits,
+				     unsigned int encodebits,
+				     unsigned int vcnt, u8 *in, int i)
+{
+	const unsigned int lomask = (1 << lclusterbits) - 1;
+	unsigned int lo, d1 = 0;
+	u8 type;
+
+	DBG_BUGON(i >= vcnt);
+
+	do {
+		lo = decode_compactedbits(lclusterbits, lomask,
+					  in, encodebits * i, &type);
+
+		if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
+			return d1;
+		++d1;
+	} while (++i < vcnt);
+
+	/* vcnt - 1 (Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) item */
+	if (!(lo & Z_EROFS_VLE_DI_D0_CBLKCNT))
+		d1 += lo - 1;
+	return d1;
+}
+
 static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 				  unsigned int amortizedshift,
-				  unsigned int eofs)
+				  erofs_off_t pos, bool lookahead)
 {
 	struct erofs_inode *const vi = EROFS_I(m->inode);
 	const unsigned int lclusterbits = vi->z_logical_clusterbits;
 	const unsigned int lomask = (1 << lclusterbits) - 1;
-	unsigned int vcnt, base, lo, encodebits, nblk;
+	unsigned int vcnt, base, lo, encodebits, nblk, eofs;
 	int i;
 	u8 *in, type;
+	bool big_pcluster;
 
 	if (1 << amortizedshift == 4)
 		vcnt = 2;
@@ -210,7 +276,12 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	else
 		return -EOPNOTSUPP;
 
+	/* it doesn't equal to round_up(..) */
+	m->nextpackoff = round_down(pos, vcnt << amortizedshift) +
+			 (vcnt << amortizedshift);
+	big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1;
 	encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt;
+	eofs = erofs_blkoff(pos);
 	base = round_down(eofs, vcnt << amortizedshift);
 	in = m->kaddr + base;
 
@@ -221,7 +292,20 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	m->type = type;
 	if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
 		m->clusterofs = 1 << lclusterbits;
-		if (i + 1 != vcnt) {
+
+		/* figure out lookahead_distance: delta[1] if needed */
+		if (lookahead)
+			m->delta[1] = get_compacted_la_distance(lclusterbits,
+						encodebits, vcnt, in, i);
+		if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
+			if (!big_pcluster) {
+				DBG_BUGON(1);
+				return -EFSCORRUPTED;
+			}
+			m->compressedblks = lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;
+			m->delta[0] = 1;
+			return 0;
+		} else if (i + 1 != (int)vcnt) {
 			m->delta[0] = lo;
 			return 0;
 		}
@@ -234,22 +318,48 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 					  in, encodebits * (i - 1), &type);
 		if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
 			lo = 0;
+		else if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT)
+			lo = 1;
 		m->delta[0] = lo + 1;
 		return 0;
 	}
 	m->clusterofs = lo;
 	m->delta[0] = 0;
 	/* figout out blkaddr (pblk) for HEAD lclusters */
-	nblk = 1;
-	while (i > 0) {
-		--i;
-		lo = decode_compactedbits(lclusterbits, lomask,
-					  in, encodebits * i, &type);
-		if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
-			i -= lo;
-
-		if (i >= 0)
+	if (!big_pcluster) {
+		nblk = 1;
+		while (i > 0) {
+			--i;
+			lo = decode_compactedbits(lclusterbits, lomask,
+						  in, encodebits * i, &type);
+			if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
+				i -= lo;
+
+			if (i >= 0)
+				++nblk;
+		}
+	} else {
+		nblk = 0;
+		while (i > 0) {
+			--i;
+			lo = decode_compactedbits(lclusterbits, lomask,
+						  in, encodebits * i, &type);
+			if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
+				if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
+					--i;
+					nblk += lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;
+					continue;
+				}
+				/* bigpcluster shouldn't have plain d0 == 1 */
+				if (lo <= 1) {
+					DBG_BUGON(1);
+					return -EFSCORRUPTED;
+				}
+				i -= lo - 2;
+				continue;
+			}
 			++nblk;
+		}
 	}
 	in += (vcnt << amortizedshift) - sizeof(__le32);
 	m->pblk = le32_to_cpu(*(__le32 *)in) + nblk;
@@ -257,7 +367,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 }
 
 static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
-					    unsigned long lcn)
+					    unsigned long lcn, bool lookahead)
 {
 	struct inode *const inode = m->inode;
 	struct erofs_inode *const vi = EROFS_I(inode);
@@ -269,7 +379,6 @@ static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 	unsigned int compacted_4b_initial, compacted_2b;
 	unsigned int amortizedshift;
 	erofs_off_t pos;
-	int err;
 
 	if (lclusterbits != 12)
 		return -EOPNOTSUPP;
@@ -283,7 +392,8 @@ static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 	if (compacted_4b_initial == 32 / 4)
 		compacted_4b_initial = 0;
 
-	if (vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B)
+	if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) &&
+	    compacted_4b_initial < totalidx)
 		compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);
 	else
 		compacted_2b = 0;
@@ -305,14 +415,15 @@ static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 	amortizedshift = 2;
 out:
 	pos += lcn * (1 << amortizedshift);
-	err = z_erofs_reload_indexes(m, erofs_blknr(pos));
-	if (err)
-		return err;
-	return unpack_compacted_index(m, amortizedshift, erofs_blkoff(pos));
+	m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,
+				      erofs_blknr(pos), EROFS_KMAP_ATOMIC);
+	if (IS_ERR(m->kaddr))
+		return PTR_ERR(m->kaddr);
+	return unpack_compacted_index(m, amortizedshift, pos, lookahead);
 }
 
 static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
-					  unsigned int lcn)
+					  unsigned int lcn, bool lookahead)
 {
 	const unsigned int datamode = EROFS_I(m->inode)->datalayout;
 
@@ -320,7 +431,7 @@ static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 		return legacy_load_cluster_from_disk(m, lcn);
 
 	if (datamode == EROFS_INODE_FLAT_COMPRESSION)
-		return compacted_load_cluster_from_disk(m, lcn);
+		return compacted_load_cluster_from_disk(m, lcn, lookahead);
 
 	return -EINVAL;
 }
@@ -329,97 +440,212 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 				   unsigned int lookback_distance)
 {
 	struct erofs_inode *const vi = EROFS_I(m->inode);
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+
+	while (m->lcn >= lookback_distance) {
+		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);
+		if (err)
+			return err;
+
+		switch (m->type) {
+		case Z_EROFS_VLE_CLUSTER_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];
+			continue;
+		case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+		case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
+		case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
+			m->headtype = m->type;
+			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",
+				  m->type, lcn, vi->nid);
+			DBG_BUGON(1);
+			return -EOPNOTSUPP;
+		}
+	}
+
+	erofs_err(m->inode->i_sb, "bogus lookback distance @ nid %llu",
+		  vi->nid);
+	DBG_BUGON(1);
+	return -EFSCORRUPTED;
+}
+
+static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
+					    unsigned int initial_lcn)
+{
+	struct erofs_inode *const vi = EROFS_I(m->inode);
 	struct erofs_map_blocks *const map = m->map;
 	const unsigned int lclusterbits = vi->z_logical_clusterbits;
-	unsigned long lcn = m->lcn;
+	unsigned long lcn;
 	int err;
 
-	if (lcn < lookback_distance) {
-		erofs_err(m->inode->i_sb,
-			  "bogus lookback distance @ nid %llu", vi->nid);
-		DBG_BUGON(1);
-		return -EFSCORRUPTED;
+	DBG_BUGON(m->type != Z_EROFS_VLE_CLUSTER_TYPE_PLAIN &&
+		  m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 &&
+		  m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD2);
+	DBG_BUGON(m->type != m->headtype);
+
+	if (m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
+	    ((m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD1) &&
+	     !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) ||
+	    ((m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) &&
+	     !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2))) {
+		map->m_plen = 1ULL << lclusterbits;
+		return 0;
 	}
+	lcn = m->lcn + 1;
+	if (m->compressedblks)
+		goto out;
 
-	/* load extent head logical cluster if needed */
-	lcn -= lookback_distance;
-	err = z_erofs_load_cluster_from_disk(m, lcn);
+	err = z_erofs_load_cluster_from_disk(m, lcn, false);
 	if (err)
 		return err;
 
+	/*
+	 * If the 1st NONHEAD lcluster has already been handled initially w/o
+	 * valid compressedblks, which means at least it mustn't be CBLKCNT, or
+	 * an internal implemenatation error is detected.
+	 *
+	 * The following code can also handle it properly anyway, but let's
+	 * BUG_ON in the debugging mode only for developers to notice that.
+	 */
+	DBG_BUGON(lcn == initial_lcn &&
+		  m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD);
+
 	switch (m->type) {
-	case Z_EROFS_VLE_CLUSTER_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;
-		}
-		return z_erofs_extent_lookback(m, m->delta[0]);
 	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
-		map->m_flags &= ~EROFS_MAP_ZIPPED;
-		/* fallthrough */
-	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
-		map->m_la = (lcn << lclusterbits) | m->clusterofs;
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
+		/*
+		 * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type
+		 * rather than CBLKCNT, it's a 1 lcluster-sized pcluster.
+		 */
+		m->compressedblks = 1 << (lclusterbits - LOG_BLOCK_SIZE);
 		break;
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		if (m->delta[0] != 1)
+			goto err_bonus_cblkcnt;
+		if (m->compressedblks)
+			break;
+		fallthrough;
 	default:
 		erofs_err(m->inode->i_sb,
-			  "unknown type %u @ lcn %lu of nid %llu",
-			  m->type, lcn, vi->nid);
+			  "cannot found CBLKCNT @ lcn %lu of nid %llu",
+			  lcn, vi->nid);
 		DBG_BUGON(1);
-		return -EOPNOTSUPP;
+		return -EFSCORRUPTED;
 	}
+out:
+	map->m_plen = (u64)m->compressedblks << LOG_BLOCK_SIZE;
 	return 0;
+err_bonus_cblkcnt:
+	erofs_err(m->inode->i_sb,
+		  "bogus CBLKCNT @ lcn %lu of nid %llu",
+		  lcn, vi->nid);
+	DBG_BUGON(1);
+	return -EFSCORRUPTED;
 }
 
-int z_erofs_map_blocks_iter(struct inode *inode,
-			    struct erofs_map_blocks *map,
-			    int flags)
+static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
+{
+	struct inode *inode = m->inode;
+	struct erofs_inode *vi = EROFS_I(inode);
+	struct erofs_map_blocks *map = m->map;
+	unsigned int lclusterbits = vi->z_logical_clusterbits;
+	u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits;
+	int err;
+
+	do {
+		/* handle the last EOF pcluster (no next HEAD lcluster) */
+		if ((lcn << lclusterbits) >= inode->i_size) {
+			map->m_llen = inode->i_size - map->m_la;
+			return 0;
+		}
+
+		err = z_erofs_load_cluster_from_disk(m, lcn, true);
+		if (err)
+			return err;
+
+		if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
+			DBG_BUGON(!m->delta[1] &&
+				  m->clusterofs != 1 << lclusterbits);
+		} else if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
+			   m->type == Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 ||
+			   m->type == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) {
+			/* go on until the next HEAD lcluster */
+			if (lcn != headlcn)
+				break;
+			m->delta[1] = 1;
+		} else {
+			erofs_err(inode->i_sb, "unknown type %u @ lcn %llu of nid %llu",
+				  m->type, lcn, vi->nid);
+			DBG_BUGON(1);
+			return -EOPNOTSUPP;
+		}
+		lcn += m->delta[1];
+	} while (m->delta[1]);
+
+	map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la;
+	return 0;
+}
+
+static int z_erofs_do_map_blocks(struct inode *inode,
+				 struct erofs_map_blocks *map,
+				 int flags)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
+	bool ztailpacking = vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER;
+	bool fragment = vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
 	struct z_erofs_maprecorder m = {
 		.inode = inode,
 		.map = map,
 	};
 	int err = 0;
 	unsigned int lclusterbits, endoff;
+	unsigned long initial_lcn;
 	unsigned long long ofs, end;
 
-	trace_z_erofs_map_blocks_iter_enter(inode, map, flags);
-
-	/* when trying to read beyond EOF, leave it unmapped */
-	if (map->m_la >= inode->i_size) {
-		map->m_llen = map->m_la + 1 - inode->i_size;
-		map->m_la = inode->i_size;
-		map->m_flags = 0;
-		goto out;
-	}
-
-	err = z_erofs_fill_inode_lazy(inode);
-	if (err)
-		goto out;
-
 	lclusterbits = vi->z_logical_clusterbits;
-	ofs = map->m_la;
-	m.lcn = ofs >> lclusterbits;
+	ofs = flags & EROFS_GET_BLOCKS_FINDTAIL ? inode->i_size - 1 : map->m_la;
+	initial_lcn = ofs >> lclusterbits;
 	endoff = ofs & ((1 << lclusterbits) - 1);
 
-	err = z_erofs_load_cluster_from_disk(&m, m.lcn);
+	err = z_erofs_load_cluster_from_disk(&m, initial_lcn, false);
 	if (err)
 		goto unmap_out;
 
-	map->m_flags = EROFS_MAP_ZIPPED;	/* by default, compressed */
+	if (ztailpacking && (flags & EROFS_GET_BLOCKS_FINDTAIL))
+		vi->z_idataoff = m.nextpackoff;
+
+	map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_ENCODED;
 	end = (m.lcn + 1ULL) << lclusterbits;
 
 	switch (m.type) {
 	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
-		if (endoff >= m.clusterofs)
-			map->m_flags &= ~EROFS_MAP_ZIPPED;
-		/* fallthrough */
-	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
 		if (endoff >= m.clusterofs) {
+			m.headtype = m.type;
 			map->m_la = (m.lcn << lclusterbits) | m.clusterofs;
+			/*
+			 * For ztailpacking files, in order to inline data more
+			 * effectively, special EOF lclusters are now supported
+			 * which can have three parts at most.
+			 */
+			if (ztailpacking && end > inode->i_size)
+				end = inode->i_size;
 			break;
 		}
 		/* m.lcn should be >= 1 if endoff < m.clusterofs */
@@ -433,9 +659,9 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 		end = (m.lcn << lclusterbits) | m.clusterofs;
 		map->m_flags |= EROFS_MAP_FULL_MAPPED;
 		m.delta[0] = 1;
-		/* fallthrough */
+		fallthrough;
 	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
-		/* get the correspoinding first chunk */
+		/* get the corresponding first chunk */
 		err = z_erofs_extent_lookback(&m, m.delta[0]);
 		if (err)
 			goto unmap_out;
@@ -447,21 +673,93 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 		err = -EOPNOTSUPP;
 		goto unmap_out;
 	}
-
+	if (m.partialref)
+		map->m_flags |= EROFS_MAP_PARTIAL_REF;
 	map->m_llen = end - map->m_la;
-	map->m_plen = 1 << lclusterbits;
-	map->m_pa = blknr_to_addr(m.pblk);
-	map->m_flags |= EROFS_MAP_MAPPED;
 
+	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_FLAT_COMPRESSION_LEGACY)
+			vi->z_fragmentoff |= (u64)m.pblk << 32;
+	}
+	if (ztailpacking && m.lcn == vi->z_tailextent_headlcn) {
+		map->m_flags |= EROFS_MAP_META;
+		map->m_pa = vi->z_idataoff;
+		map->m_plen = vi->z_idata_size;
+	} else if (fragment && m.lcn == vi->z_tailextent_headlcn) {
+		map->m_flags |= EROFS_MAP_FRAGMENT;
+	} else {
+		map->m_pa = blknr_to_addr(m.pblk);
+		err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
+		if (err)
+			goto out;
+	}
+
+	if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN) {
+		if (vi->z_advise & Z_EROFS_ADVISE_INTERLACED_PCLUSTER)
+			map->m_algorithmformat =
+				Z_EROFS_COMPRESSION_INTERLACED;
+		else
+			map->m_algorithmformat =
+				Z_EROFS_COMPRESSION_SHIFTED;
+	} else if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) {
+		map->m_algorithmformat = vi->z_algorithmtype[1];
+	} else {
+		map->m_algorithmformat = vi->z_algorithmtype[0];
+	}
+
+	if ((flags & EROFS_GET_BLOCKS_FIEMAP) ||
+	    ((flags & EROFS_GET_BLOCKS_READMORE) &&
+	     map->m_algorithmformat == Z_EROFS_COMPRESSION_LZMA &&
+	     map->m_llen >= EROFS_BLKSIZ)) {
+		err = z_erofs_get_extent_decompressedlen(&m);
+		if (!err)
+			map->m_flags |= EROFS_MAP_FULL_MAPPED;
+	}
 unmap_out:
-	if (m.kaddr)
-		kunmap_atomic(m.kaddr);
+	erofs_unmap_metabuf(&m.map->buf);
 
 out:
 	erofs_dbg("%s, m_la %llu m_pa %llu m_llen %llu m_plen %llu m_flags 0%o",
 		  __func__, map->m_la, map->m_pa,
 		  map->m_llen, map->m_plen, map->m_flags);
 
+	return err;
+}
+
+int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map,
+			    int flags)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+	int err = 0;
+
+	trace_z_erofs_map_blocks_iter_enter(inode, map, flags);
+
+	/* when trying to read beyond EOF, leave it unmapped */
+	if (map->m_la >= inode->i_size) {
+		map->m_llen = map->m_la + 1 - inode->i_size;
+		map->m_la = inode->i_size;
+		map->m_flags = 0;
+		goto out;
+	}
+
+	err = z_erofs_fill_inode_lazy(inode);
+	if (err)
+		goto out;
+
+	if ((vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER) &&
+	    !vi->z_tailextent_headlcn) {
+		map->m_la = 0;
+		map->m_llen = inode->i_size;
+		map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_FULL_MAPPED |
+				EROFS_MAP_FRAGMENT;
+		goto out;
+	}
+
+	err = z_erofs_do_map_blocks(inode, map, flags);
+out:
 	trace_z_erofs_map_blocks_iter_exit(inode, map, flags, err);
 
 	/* aggressively BUG_ON iff CONFIG_EROFS_FS_DEBUG is on */
@@ -469,3 +767,40 @@ out:
 	return err;
 }
 
+static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset,
+				loff_t length, unsigned int flags,
+				struct iomap *iomap, struct iomap *srcmap)
+{
+	int ret;
+	struct erofs_map_blocks map = { .m_la = offset };
+
+	ret = z_erofs_map_blocks_iter(inode, &map, EROFS_GET_BLOCKS_FIEMAP);
+	erofs_put_metabuf(&map.buf);
+	if (ret < 0)
+		return ret;
+
+	iomap->bdev = inode->i_sb->s_bdev;
+	iomap->offset = map.m_la;
+	iomap->length = map.m_llen;
+	if (map.m_flags & EROFS_MAP_MAPPED) {
+		iomap->type = IOMAP_MAPPED;
+		iomap->addr = map.m_flags & EROFS_MAP_FRAGMENT ?
+			      IOMAP_NULL_ADDR : map.m_pa;
+	} else {
+		iomap->type = IOMAP_HOLE;
+		iomap->addr = IOMAP_NULL_ADDR;
+		/*
+		 * No strict rule how to describe extents for post EOF, yet
+		 * we need do like below. Otherwise, iomap itself will get
+		 * into an endless loop on post EOF.
+		 */
+		if (iomap->offset >= inode->i_size)
+			iomap->length = length + map.m_la - offset;
+	}
+	iomap->flags = 0;
+	return 0;
+}
+
+const struct iomap_ops z_erofs_iomap_report_ops = {
+	.iomap_begin = z_erofs_iomap_begin_report,
+};