f2fs: support SEEK_DATA and SEEK_HOLE for compression files

Fix to support SEEK_DATA and SEEK_HOLE for compression files
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -394,9 +394,20 @@ int f2fs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	return f2fs_do_sync_file(file, start, end, datasync, false);
 }
 
-static bool __found_offset(struct address_space *mapping, block_t blkaddr,
-				pgoff_t index, int whence)
+static bool __found_offset(struct address_space *mapping,
+		struct dnode_of_data *dn, pgoff_t index, int whence)
 {
+	block_t blkaddr = f2fs_data_blkaddr(dn);
+	struct inode *inode = mapping->host;
+	bool compressed_cluster = false;
+
+	if (f2fs_compressed_file(inode)) {
+		block_t first_blkaddr = data_blkaddr(dn->inode, dn->node_page,
+		    ALIGN_DOWN(dn->ofs_in_node, F2FS_I(inode)->i_cluster_size));
+
+		compressed_cluster = first_blkaddr == COMPRESS_ADDR;
+	}
+
 	switch (whence) {
 	case SEEK_DATA:
 		if (__is_valid_data_blkaddr(blkaddr))
@@ -404,8 +415,12 @@ static bool __found_offset(struct address_space *mapping, block_t blkaddr,
 		if (blkaddr == NEW_ADDR &&
 		    xa_get_mark(&mapping->i_pages, index, PAGECACHE_TAG_DIRTY))
 			return true;
+		if (compressed_cluster)
+			return true;
 		break;
 	case SEEK_HOLE:
+		if (compressed_cluster)
+			return false;
 		if (blkaddr == NULL_ADDR)
 			return true;
 		break;
@@ -474,7 +489,7 @@ static loff_t f2fs_seek_block(struct file *file, loff_t offset, int whence)
 				goto fail;
 			}
 
-			if (__found_offset(file->f_mapping, blkaddr,
+			if (__found_offset(file->f_mapping, &dn,
 							pgofs, whence)) {
 				f2fs_put_dnode(&dn);
 				goto found;