[CRIU] [PATCH v3 1/6] files-reg: Account number of unlinked parent components of ghost file

[Kirill Tkhai]

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 files-reg.c               |   69 ++++++++++++++++++++++++++++++++++++++-------
 protobuf/ghost-file.proto |    1 +
 2 files changed, 60 insertions(+), 10 deletions(-)

diff --git a/files-reg.c b/files-reg.c
index 0f89be5..3e09ae0 100644
--- a/files-reg.c
+++ b/files-reg.c
@@ -48,6 +48,7 @@ struct ghost_file {
 
 	u32			dev;
 	u32			ino;
+	u32			nr_up;
 
 	struct file_remap	remap;
 };
@@ -223,6 +224,7 @@ static int open_remap_ghost(struct reg_file_info *rfi,
 	gf->dev = gfe->dev;
 	gf->ino = gfe->ino;
 	gf->remap.rmnt_id = rfi->rfe->mnt_id;
+	gf->nr_up = gfe->has_nr_up ? gfe->nr_up : 0;
 
 	if (S_ISDIR(gfe->mode))
 		strncpy(gf->remap.rpath, rfi->path, PATH_MAX);
@@ -526,7 +528,50 @@ static struct collect_image_info remap_cinfo = {
 	.collect = collect_one_remap,
 };
 
-static int dump_ghost_file(int _fd, u32 id, const struct stat *st, dev_t phys_dev)
+static int count_unlinked_parents(GhostFileEntry *gfe, const char *path, int mntns_root)
+{
+	struct stat st;
+	char buf[PATH_MAX], *p;
+	int count = 0;
+
+	strcpy(buf, path);
+
+	p = strrchr(buf, '/');
+	if (!p) {
+		pr_err("No parent for %s", buf);
+		count = -1;
+		goto out;
+	}
+
+	while (p > buf) {
+		*p = '\0';
+		if (fstatat(mntns_root, buf, &st, 0) == 0)
+			goto populate;
+
+		if (errno != ENOENT) {
+			pr_perror("Can't stat %s", buf);
+			count = -1;
+			goto out;
+		}
+
+		count++;
+
+		while (--p > buf && *p != '/')
+			continue;
+	}
+
+populate:
+	if (count) {
+		gfe->has_nr_up = true;
+		gfe->nr_up = count;
+		pr_debug("Ghost file %s has %d unlinked parent component(s)", path, count);
+	}
+out:
+	return count;
+}
+
+static int dump_ghost_file(char *path, int _fd, u32 id, const struct stat *st,
+			   dev_t phys_dev, int mntns_root)
 {
 	struct cr_img *img;
 	GhostFileEntry gfe = GHOST_FILE_ENTRY__INIT;
@@ -553,6 +598,9 @@ static int dump_ghost_file(int _fd, u32 id, const struct stat *st, dev_t phys_de
 	gfe.dev = phys_dev;
 	gfe.ino = st->st_ino;
 
+	if (count_unlinked_parents(&gfe, path, mntns_root) < 0)
+		return -1;
+
 	if (S_ISCHR(st->st_mode) || S_ISBLK(st->st_mode)) {
 		gfe.has_rdev = true;
 		gfe.rdev = st->st_rdev;
@@ -616,8 +664,8 @@ struct file_remap *lookup_ghost_remap(u32 dev, u32 ino)
 	return NULL;
 }
 
-static int dump_ghost_remap(char *path, const struct stat *st,
-				int lfd, u32 id, struct ns_id *nsid)
+static int dump_ghost_remap(char *path, const struct stat *st, int lfd,
+			    u32 id, struct ns_id *nsid, int mntns_root)
 {
 	struct ghost_file *gf;
 	RemapFilePathEntry rpe = REMAP_FILE_PATH_ENTRY__INIT;
@@ -631,7 +679,7 @@ static int dump_ghost_remap(char *path, const struct stat *st,
 		return -1;
 	}
 
-	phys_dev = phys_stat_resolve_dev(nsid, st->st_dev, path);
+	phys_dev = phys_stat_resolve_dev(nsid, st->st_dev, path + 1);
 	list_for_each_entry(gf, &ghost_files, list)
 		if ((gf->dev == phys_dev) && (gf->ino == st->st_ino))
 			goto dump_entry;
@@ -645,7 +693,7 @@ static int dump_ghost_remap(char *path, const struct stat *st,
 	gf->id = ghost_file_ids++;
 	list_add_tail(&gf->list, &ghost_files);
 
-	if (dump_ghost_file(lfd, gf->id, st, phys_dev))
+	if (dump_ghost_file(path, lfd, gf->id, st, phys_dev, mntns_root))
 		return -1;
 
 dump_entry:
@@ -918,6 +966,10 @@ static int check_path_remap(struct fd_link *link, const struct fd_parms *parms,
 		return 0;
 	}
 
+	mntns_root = mntns_get_root_fd(nsid);
+	if (mntns_root < 0)
+		return -1;
+
 	if (ost->st_nlink == 0) {
 		/*
 		 * Unpleasant, but easy case. File is completely invisible
@@ -926,7 +978,8 @@ static int check_path_remap(struct fd_link *link, const struct fd_parms *parms,
 		 * also open.
 		 */
 		strip_deleted(link);
-		return dump_ghost_remap(rpath + 1, ost, lfd, id, nsid);
+
+		return dump_ghost_remap(rpath, ost, lfd, id, nsid, mntns_root);
 	}
 
 	if (nfs_silly_rename(rpath, parms)) {
@@ -941,10 +994,6 @@ static int check_path_remap(struct fd_link *link, const struct fd_parms *parms,
 		return dump_linked_remap(rpath + 1, plen - 1, ost, lfd, id, nsid);
 	}
 
-	mntns_root = mntns_get_root_fd(nsid);
-	if (mntns_root < 0)
-		return -1;
-
 	ret = fstatat(mntns_root, rpath, &pst, 0);
 	if (ret < 0) {
 		/*
diff --git a/protobuf/ghost-file.proto b/protobuf/ghost-file.proto
index db056db..6325c99 100644
--- a/protobuf/ghost-file.proto
+++ b/protobuf/ghost-file.proto
@@ -11,4 +11,5 @@ message ghost_file_entry {
 	optional uint32		rdev		= 6 [(criu).dev = true, (criu).odev = true];
 	optional timeval	atim		= 7;
 	optional timeval	mtim		= 8;
+	optional uint32		nr_up		= 9; /* Number of unlinked parent directories */
 }