[PATCH 2/2] erofs-utils: rebuild: set the appropriate `dev` field for dirs

[Hongzhen Luo]

Currently, setting a default `dev` value (i.e., 0) for directories
during parsing tar files can lead to the following error:

<E> erofs: bogus i_mode (0) @ nid 0
<E> erofs: failed to read inode @ 0

Consider the following incremental build scenario, where the path
"dir1/dir2" is currently being parsed in tarerofs_parse_tar() and
the directory "dir1" has never appeared before. erofs_rebuild_get_dentry()
will call erofs_rebuild_mkdir() to allocate a new inode for "dir1",
with its `dev` field set to 0 by default.

During the dump tree phase, since `dir1->dev` matches `sbi->dev` (both are 0),
erofs_rebuild_load_basedir() will be called to read the contents of directory
"dir1" from the disk. However, since there is no information for the new directory
"dir1" on the disk, the above error occurs.

This patch resolves the above issue by setting the appropriate value
for the directory's `dev` field during the tar file parsing phase.

Fixes: f64d9d02576b ("erofs-utils: introduce incremental builds")
Signed-off-by: Hongzhen Luo <hongzhen at linux.alibaba.com>
---
 include/erofs/rebuild.h | 1 +
 lib/rebuild.c           | 7 +++++--
 lib/tar.c               | 2 ++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/erofs/rebuild.h b/include/erofs/rebuild.h
index b37bc80e8a3c..b71cfdf1fff4 100644
--- a/include/erofs/rebuild.h
+++ b/include/erofs/rebuild.h
@@ -22,6 +22,7 @@ struct erofs_rebuild_getdentry_ctx {
 	bool *whout;
 	bool *opq;
 	bool to_head;
+	int dev;
 };
 
 struct erofs_dentry *erofs_rebuild_get_dentry(struct erofs_rebuild_getdentry_ctx *ctx);
diff --git a/lib/rebuild.c b/lib/rebuild.c
index 58f1701b3721..3fcb5c92b562 100644
--- a/lib/rebuild.c
+++ b/lib/rebuild.c
@@ -27,7 +27,7 @@
 #endif
 
 static struct erofs_dentry *erofs_rebuild_mkdir(struct erofs_inode *dir,
-						const char *s)
+						const char *s, int dev)
 {
 	struct erofs_inode *inode;
 	struct erofs_dentry *d;
@@ -47,6 +47,7 @@ static struct erofs_dentry *erofs_rebuild_mkdir(struct erofs_inode *dir,
 	inode->i_gid = getgid();
 	inode->i_mtime = inode->sbi->build_time;
 	inode->i_mtime_nsec = inode->sbi->build_time_nsec;
+	inode->dev = dev;
 	erofs_init_empty_dir(inode);
 
 	d = erofs_d_alloc(dir, s);
@@ -119,7 +120,7 @@ struct erofs_dentry *erofs_rebuild_get_dentry(struct erofs_rebuild_getdentry_ctx
 				d->type = EROFS_FT_UNKNOWN;
 				d->inode = ctx->pwd;
 			} else {
-				d = erofs_rebuild_mkdir(ctx->pwd, s);
+				d = erofs_rebuild_mkdir(ctx->pwd, s, ctx->dev);
 				if (IS_ERR(d))
 					return d;
 				ctx->pwd = d->inode;
@@ -292,6 +293,7 @@ static int erofs_rebuild_dirent_iter(struct erofs_dir_context *ctx)
 	dctx.aufs = false;
 	dctx.whout = dctx.opq = &dumb;
 	dctx.to_head = false;
+	dctx.dev = dir->sbi->dev;
 	d = erofs_rebuild_get_dentry(&dctx);
 	if (IS_ERR(d)) {
 		ret = PTR_ERR(d);
@@ -460,6 +462,7 @@ static int erofs_rebuild_basedir_dirent_iter(struct erofs_dir_context *ctx)
 	dctx.aufs = false;
 	dctx.whout = dctx.opq = &dumb;
 	dctx.to_head = false;
+	dctx.dev = dir->sbi->dev;
 	d = erofs_rebuild_get_dentry(&dctx);
 	if (IS_ERR(d)) {
 		ret = PTR_ERR(d);
diff --git a/lib/tar.c b/lib/tar.c
index 60f12cc539c9..a118c4fd76de 100644
--- a/lib/tar.c
+++ b/lib/tar.c
@@ -914,6 +914,7 @@ out_eot:
 	dctx.whout = &whout;
 	dctx.opq = &opq;
 	dctx.to_head = true;
+	dctx.dev = tar->dev;
 	d = erofs_rebuild_get_dentry(&dctx);
 	if (IS_ERR(d)) {
 		ret = PTR_ERR(d);
@@ -957,6 +958,7 @@ out_eot:
 		dctx.aufs = tar->aufs;
 		dctx.whout = dctx.opq = &dumb;
 		dctx.to_head = false;
+		dctx.dev = tar->dev;
 		d2 = erofs_rebuild_get_dentry(&dctx);
 		if (IS_ERR(d2)) {
 			ret = PTR_ERR(d2);
-- 
2.43.5