f2fs: change fiemap way in printing compression chunk

When we print out a discontinuous compression chunk, it shows like a
continuous chunk now. To show it more correctly, I've changed the way of
printing fiemap info like below. Plus, eliminated NEW_ADDR(-1) in fiemap
info, since it is not in fiemap user api manual.

Let's assume 16KB compression cluster.

<before>
   Logical          Physical         Length           Flags
0:  0000000000000000 00000002c091f000 0000000000004000 1008
1:  0000000000004000 00000002c0920000 0000000000004000 1008
  ...
9:  0000000000034000 0000000f8c623000 0000000000004000 1008
10: 0000000000038000 000000101a6eb000 0000000000004000 1008

<after>
0:  0000000000000000 00000002c091f000 0000000000004000 1008
1:  0000000000004000 00000002c0920000 0000000000004000 1008
  ...
9:  0000000000034000 0000000f8c623000 0000000000001000 1008
10: 0000000000035000 000000101a6ea000 0000000000003000 1008
11: 0000000000038000 000000101a6eb000 0000000000002000 1008
12: 000000000003a000 00000002c3544000 0000000000002000 1008

Flags
0x1000 => FIEMAP_EXTENT_MERGED
0x0008 => FIEMAP_EXTENT_ENCODED
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Tested-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -1843,8 +1843,9 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	u64 logical = 0, phys = 0, size = 0;
 	u32 flags = 0;
 	int ret = 0;
-	bool compr_cluster = false;
+	bool compr_cluster = false, compr_appended;
 	unsigned int cluster_size = F2FS_I(inode)->i_cluster_size;
+	unsigned int count_in_cluster = 0;
 	loff_t maxbytes;
 
 	if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
@@ -1892,15 +1893,17 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	map.m_next_pgofs = &next_pgofs;
 	map.m_seg_type = NO_CHECK_TYPE;
 
-	if (compr_cluster)
-		map.m_len = cluster_size - 1;
+	if (compr_cluster) {
+		map.m_lblk += 1;
+		map.m_len = cluster_size - count_in_cluster;
+	}
 
 	ret = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_FIEMAP);
 	if (ret)
 		goto out;
 
 	/* HOLE */
-	if (!(map.m_flags & F2FS_MAP_FLAGS)) {
+	if (!compr_cluster && !(map.m_flags & F2FS_MAP_FLAGS)) {
 		start_blk = next_pgofs;
 
 		if (blks_to_bytes(inode, start_blk) < blks_to_bytes(inode,
@@ -1910,6 +1913,14 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		flags |= FIEMAP_EXTENT_LAST;
 	}
 
+	compr_appended = false;
+	/* In a case of compressed cluster, append this to the last extent */
+	if (compr_cluster && ((map.m_flags & F2FS_MAP_UNWRITTEN) ||
+			!(map.m_flags & F2FS_MAP_FLAGS))) {
+		compr_appended = true;
+		goto skip_fill;
+	}
+
 	if (size) {
 		flags |= FIEMAP_EXTENT_MERGED;
 		if (IS_ENCRYPTED(inode))
@@ -1926,38 +1937,36 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	if (start_blk > last_blk)
 		goto out;
 
-	if (compr_cluster) {
-		compr_cluster = false;
-
-
-		logical = blks_to_bytes(inode, start_blk - 1);
-		phys = blks_to_bytes(inode, map.m_pblk);
-		size = blks_to_bytes(inode, cluster_size);
-
-		flags |= FIEMAP_EXTENT_ENCODED;
-
-		start_blk += cluster_size - 1;
-
-		if (start_blk > last_blk)
-			goto out;
-
-		goto prep_next;
-	}
-
+skip_fill:
 	if (map.m_pblk == COMPRESS_ADDR) {
 		compr_cluster = true;
-		start_blk++;
-		goto prep_next;
-	}
-
+		count_in_cluster = 1;
+	} else if (compr_appended) {
+		unsigned int appended_blks = cluster_size -
+						count_in_cluster + 1;
+		size += blks_to_bytes(inode, appended_blks);
+		start_blk += appended_blks;
+		compr_cluster = false;
+	} else {
 		logical = blks_to_bytes(inode, start_blk);
-	phys = blks_to_bytes(inode, map.m_pblk);
+		phys = __is_valid_data_blkaddr(map.m_pblk) ?
+			blks_to_bytes(inode, map.m_pblk) : 0;
 		size = blks_to_bytes(inode, map.m_len);
 		flags = 0;
-	if (map.m_flags & F2FS_MAP_UNWRITTEN)
+
+		if (compr_cluster) {
+			flags = FIEMAP_EXTENT_ENCODED;
+			count_in_cluster += map.m_len;
+			if (count_in_cluster == cluster_size) {
+				compr_cluster = false;
+				size += blks_to_bytes(inode, 1);
+			}
+		} else if (map.m_flags & F2FS_MAP_UNWRITTEN) {
 			flags = FIEMAP_EXTENT_UNWRITTEN;
+		}
 
 		start_blk += bytes_to_blks(inode, size);
+	}
 
 prep_next:
 	cond_resched();