[RFC PATCH v0 3/3] erofs-utils: fuse: support multiple block compression

[Gao Xiang via Linux-erofs <linux-erofs@lists.ozlabs.org>]

From: Gao Xiang <hsiangkao@aol.com>

Add multiple block compression runtime support for erofsfuse.

Signed-off-by: Gao Xiang <hsiangkao@aol.com>
---
 lib/data.c |  4 +--
 lib/zmap.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 68 insertions(+), 8 deletions(-)

diff --git a/lib/data.c b/lib/data.c
index 3781846743aa..b330a91e4e34 100644
--- a/lib/data.c
+++ b/lib/data.c
@@ -127,7 +127,7 @@ static int z_erofs_read_data(struct erofs_inode *inode, char *buffer,
 	};
 	bool partial;
 	unsigned int algorithmformat;
-	char raw[EROFS_BLKSIZ];
+	char raw[1024 * EROFS_BLKSIZ];
 
 	end = offset + size;
 	while (end > offset) {
@@ -142,7 +142,7 @@ static int z_erofs_read_data(struct erofs_inode *inode, char *buffer,
 			continue;
 		}
 
-		ret = dev_read(raw, map.m_pa, EROFS_BLKSIZ);
+		ret = dev_read(raw, map.m_pa, map.m_plen);
 		if (ret < 0)
 			return -EIO;
 
diff --git a/lib/zmap.c b/lib/zmap.c
index ee63de74cab2..096fd35cdeb3 100644
--- a/lib/zmap.c
+++ b/lib/zmap.c
@@ -14,7 +14,8 @@
 
 int z_erofs_fill_inode(struct erofs_inode *vi)
 {
-	if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
+	if (!erofs_sb_has_big_pcluster() &&
+	    vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
 		vi->z_advise = 0;
 		vi->z_algorithmtype[0] = 0;
 		vi->z_algorithmtype[1] = 0;
@@ -37,7 +38,8 @@ static int z_erofs_fill_inode_lazy(struct erofs_inode *vi)
 	if (vi->flags & EROFS_I_Z_INITED)
 		return 0;
 
-	DBG_BUGON(vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY);
+	DBG_BUGON(!erofs_sb_has_big_pcluster() &&
+		  vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY);
 	pos = round_up(iloc(vi->nid) + vi->inode_isize + vi->xattr_isize, 8);
 
 	ret = dev_read(buf, pos, sizeof(buf));
@@ -81,7 +83,7 @@ struct z_erofs_maprecorder {
 	u8  type;
 	u16 clusterofs;
 	u16 delta[2];
-	erofs_blk_t pblk;
+	erofs_blk_t pblk, compressedlcs;
 };
 
 static int z_erofs_reload_indexes(struct z_erofs_maprecorder *m,
@@ -130,6 +132,15 @@ 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)) {
+				DBG_BUGON(1);
+				return -EFSCORRUPTED;
+			}
+			m->compressedlcs = 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:
@@ -333,6 +344,51 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 	return 0;
 }
 
+static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
+					    unsigned int initial_lcn)
+{
+	struct erofs_inode *const vi = m->inode;
+	struct erofs_map_blocks *const map = m->map;
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+	unsigned long lcn;
+	int err;
+
+	DBG_BUGON(m->type != Z_EROFS_VLE_CLUSTER_TYPE_PLAIN &&
+		  m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD);
+	if (!((map->m_flags & EROFS_MAP_ZIPPED) &&
+	      (vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1))) {
+		map->m_plen = 1 << lclusterbits;
+		return 0;
+	}
+
+	lcn = m->lcn + 1;
+	if (lcn == initial_lcn && !m->compressedlcs)
+		m->compressedlcs = 2;
+
+	if (m->compressedlcs)
+		goto out;
+
+	err = z_erofs_load_cluster_from_disk(m, lcn);
+	if (err)
+		return err;
+
+	switch (m->type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		DBG_BUGON(m->delta[0] != 1);
+		if (m->compressedlcs) {
+			break;
+		}
+	default:
+		erofs_err("cannot found CBLKCNT @ lcn %lu of nid %llu",
+			  lcn, (unsigned long long)vi->nid);
+		DBG_BUGON(1);
+		return -EFSCORRUPTED;
+	}
+out:
+	map->m_plen = m->compressedlcs << lclusterbits;
+	return 0;
+}
+
 int z_erofs_map_blocks_iter(struct erofs_inode *vi,
 			    struct erofs_map_blocks *map)
 {
@@ -343,6 +399,7 @@ int z_erofs_map_blocks_iter(struct erofs_inode *vi,
 	};
 	int err = 0;
 	unsigned int lclusterbits, endoff;
+	unsigned long initial_lcn;
 	unsigned long long ofs, end;
 
 	/* when trying to read beyond EOF, leave it unmapped */
@@ -359,10 +416,10 @@ int z_erofs_map_blocks_iter(struct erofs_inode *vi,
 
 	lclusterbits = vi->z_logical_clusterbits;
 	ofs = map->m_la;
-	m.lcn = ofs >> lclusterbits;
+	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);
 	if (err)
 		goto out;
 
@@ -401,8 +458,11 @@ int z_erofs_map_blocks_iter(struct erofs_inode *vi,
 	}
 
 	map->m_llen = end - map->m_la;
-	map->m_plen = 1 << lclusterbits;
 	map->m_pa = blknr_to_addr(m.pblk);
+
+	err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
+	if (err)
+		goto out;
 	map->m_flags |= EROFS_MAP_MAPPED;
 
 out:
-- 
2.24.0