libmount: use mount ID to merge utab and mountinfo files

Signed-off-by: Karel Zak <kzak@redhat.com>

libmount/src/hook_mount.c

@@ -254,10 +254,16 @@ static int hook_create_mount(struct libmnt_context *cxt,
 
 		rc = statx(api->fd_tree, "", AT_EMPTY_PATH, STATX_MNT_ID, &st);
 		cxt->fs->id = (int) st.stx_mnt_id;
+
+		if (cxt->update) {
+			struct libmnt_fs *fs = mnt_update_get_fs(cxt->update);
+			if (fs)
+				fs->id = cxt->fs->id;
+		}
 	}
 
 done:
-	DBG(HOOK, ul_debugobj(hs, "create FS done [rc=%d]", rc));
+	DBG(HOOK, ul_debugobj(hs, "create FS done [rc=%d, id=%d]", rc, cxt->fs ? cxt->fs->id : -1));
 	return rc;
 }
 

libmount/src/tab_parse.c

@@ -323,7 +323,14 @@ static int mnt_parse_utab_line(struct libmnt_fs *fs, const char *s)
 		if (!*p)
 			break;
 
-		if (!fs->source && !strncmp(p, "SRC=", 4)) {
+		if (!fs->id && !strncmp(p, "ID=", 3)) {
+			int rc = 0;
+
+			end = next_s32(p + 3, &fs->id, &rc);
+			if (!end || rc)
+				return rc;
+
+		} else if (!fs->source && !strncmp(p, "SRC=", 4)) {
 			char *v = unmangle(p + 4, &end);
 			if (!v)
 				goto enomem;
@@ -1171,6 +1178,7 @@ static struct libmnt_fs *mnt_table_merge_user_fs(struct libmnt_table *tb, struct
 	struct libmnt_fs *fs;
 	struct libmnt_iter itr;
 	const char *optstr, *src, *target, *root, *attrs;
+	int id;
 
 	if (!tb || !uf)
 		return NULL;
@@ -1182,6 +1190,7 @@ static struct libmnt_fs *mnt_table_merge_user_fs(struct libmnt_table *tb, struct
 	optstr = mnt_fs_get_user_options(uf);
 	attrs = mnt_fs_get_attributes(uf);
 	root = mnt_fs_get_root(uf);
+	id = mnt_fs_get_id(uf);
 
 	if (!src || !target || !root || (!attrs && !optstr))
 		return NULL;
@@ -1194,20 +1203,23 @@ static struct libmnt_fs *mnt_table_merge_user_fs(struct libmnt_table *tb, struct
 		if (fs->flags & MNT_FS_MERGED)
 			continue;
 
-		if (r && strcmp(r, root) == 0
+		if (id > 0 && mnt_fs_get_id(fs)) {
+			DBG(TAB, ul_debugobj(tb, " using ID"));
+			if (mnt_fs_get_id(fs) == id)
+				break;
+		} else if (r && strcmp(r, root) == 0
 		    && mnt_fs_streq_target(fs, target)
 		    && mnt_fs_streq_srcpath(fs, src))
 			break;
 	}
 
 	if (fs) {
-		DBG(TAB, ul_debugobj(tb, "found fs -- appending user optstr"));
+		DBG(TAB, ul_debugobj(tb, " found"));
 		mnt_fs_append_options(fs, optstr);
 		mnt_fs_append_attributes(fs, attrs);
 		mnt_fs_set_bindsrc(fs, mnt_fs_get_bindsrc(uf));
 		fs->flags |= MNT_FS_MERGED;
 
-		DBG(TAB, ul_debugobj(tb, "found fs:"));
 		DBG(TAB, mnt_fs_print_debug(fs, stderr));
 	}
 	return fs;

libmount/src/tab_update.c

@@ -435,10 +435,15 @@ static int fprintf_utab_fs(FILE *f, struct libmnt_fs *fs)
 	if (!fs || !f)
 		return -EINVAL;
 
-	p = mangle(mnt_fs_get_source(fs));
-	if (p) {
-		rc = fprintf(f, "SRC=%s ", p);
-		free(p);
+	if (mnt_fs_get_id(fs) > 0) {
+		rc = fprintf(f, "ID=%d ", mnt_fs_get_id(fs));
+	}
+	if (rc >= 0) {
+		p = mangle(mnt_fs_get_source(fs));
+		if (p) {
+			rc = fprintf(f, "SRC=%s ", p);
+			free(p);
+		}
 	}
 	if (rc >= 0) {
 		p = mangle(mnt_fs_get_target(fs));