[PATCH v7 13/13] erofs-utils: mkfs: add `--ovlfs-strip` option

[Gao Xiang]

From: Jingbo Xu <jefflexu at linux.alibaba.com>

Add `--ovlfs-strip=[0|1]` option for tarfs and rebuild mode for now
in order to control whether some overlayfs related stuffs (e.g.
whiteout files and OVL_XATTR_ORIGIN xattrs) are finally stripped.

Actually all overlayfs unnecessary xattrs should be stripped, but it
isn't implemented in this commit due to complexity.

This option is disabled by default for mkfs, that is, whiteout files
and OVL_XATTR_ORIGIN xattrs are kept in the image by default.

Specify `--ovlfs-strip=1` explicitly to strip these stuffs.

Signed-off-by: Jingbo Xu <jefflexu at linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
---
 include/erofs/config.h |  1 +
 lib/inode.c            | 14 +++++++++++---
 mkfs/main.c            |  8 ++++++++
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/erofs/config.h b/include/erofs/config.h
index c51f0cd..dea5d74 100644
--- a/include/erofs/config.h
+++ b/include/erofs/config.h
@@ -54,6 +54,7 @@ struct erofs_configure {
 	bool c_showprogress;
 	bool c_extra_ea_name_prefixes;
 	bool c_xattr_name_filter;
+	bool c_ovlfs_strip;
 
 #ifdef HAVE_LIBSELINUX
 	struct selabel_handle *sehnd;
diff --git a/lib/inode.c b/lib/inode.c
index 74c3c32..d393602 100644
--- a/lib/inode.c
+++ b/lib/inode.c
@@ -1326,7 +1326,7 @@ struct erofs_inode *erofs_mkfs_build_special_from_fd(int fd, const char *name)
 
 int erofs_rebuild_dump_tree(struct erofs_inode *dir)
 {
-	struct erofs_dentry *d;
+	struct erofs_dentry *d, *n;
 	unsigned int nr_subdirs;
 	int ret;
 
@@ -1341,7 +1341,7 @@ int erofs_rebuild_dump_tree(struct erofs_inode *dir)
 		dir->inode_isize = sizeof(struct erofs_inode_compact);
 	}
 
-	if (dir->whiteouts)
+	if (!cfg.c_ovlfs_strip && dir->whiteouts)
 		erofs_set_origin_xattr(dir);
 
 	ret = erofs_prepare_xattr_ibody(dir);
@@ -1373,8 +1373,16 @@ int erofs_rebuild_dump_tree(struct erofs_inode *dir)
 	}
 
 	nr_subdirs = 0;
-	list_for_each_entry(d, &dir->i_subdirs, d_child)
+	list_for_each_entry_safe(d, n, &dir->i_subdirs, d_child) {
+		if (cfg.c_ovlfs_strip && erofs_inode_is_whiteout(d->inode)) {
+			erofs_dbg("remove whiteout %s", d->inode->i_srcpath);
+			list_del(&d->d_child);
+			erofs_d_invalidate(d);
+			free(d);
+			continue;
+		}
 		++nr_subdirs;
+	}
 
 	ret = erofs_prepare_dir_layout(dir, nr_subdirs);
 	if (ret)
diff --git a/mkfs/main.c b/mkfs/main.c
index 571cf19..8f34e57 100644
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -64,6 +64,7 @@ static struct option long_options[] = {
 	{"fs-config-file", required_argument, NULL, 514},
 	{"block-list-file", required_argument, NULL, 515},
 #endif
+	{"ovlfs-strip", optional_argument, NULL, 516},
 	{0, 0, 0, 0},
 };
 
@@ -115,6 +116,7 @@ static void usage(void)
 	      " --preserve-mtime      keep per-file modification time strictly\n"
 	      " --aufs                replace aufs special files with overlayfs metadata\n"
 	      " --tar=[fi]            generate an image from tarball(s)\n"
+	      " --ovlfs-strip=[01]    strip overlayfs metadata in the target image (e.g. whiteouts)\n"
 	      " --quiet               quiet execution (do not write anything to standard output.)\n"
 #ifndef NDEBUG
 	      " --random-pclusterblks randomize pclusterblks for big pcluster (debugging only)\n"
@@ -530,6 +532,12 @@ static int mkfs_parse_options_cfg(int argc, char *argv[])
 		case 21:
 			erofstar.aufs = true;
 			break;
+		case 516:
+			if (!optarg || !strcmp(optarg, "1"))
+				cfg.c_ovlfs_strip = true;
+			else
+				cfg.c_ovlfs_strip = false;
+			break;
 		case 1:
 			usage();
 			exit(0);
-- 
2.24.4