libmount: don't update utab when moving /run

It's bad idea to try update /run/mount/utab when moving any directory
in way to the file (like /run).

It's also unnecessary to prepare any updates if the utab file is
empty. This is already done for umount, and we can use it for mount
move as well.

Fixes: https://github.com/util-linux/util-linux/issues/3619
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/src/context.c b/libmount/src/context.c
index 46bbe378a3d8e72e290ce55361ebe9dc09cbb2ae..dfecab788d1d1675d0cf4c598985fd10ee4769ac 100644 (file)
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -2201,8 +2201,9 @@ int mnt_context_merge_mflags(struct libmnt_context *cxt)
 int mnt_context_prepare_update(struct libmnt_context *cxt)
 {
        int rc;
-       const char *target, *name;
+       const char *target, *source, *name;
        unsigned long flags = 0;
+       struct libmnt_optlist *ol;
 
        assert(cxt);
        assert(cxt->fs);
@@ -2217,6 +2218,7 @@ int mnt_context_prepare_update(struct libmnt_context *cxt)
        }
 
        target = mnt_fs_get_target(cxt->fs);
+       source = mnt_fs_get_srcpath(cxt->fs);
 
        if (cxt->action == MNT_ACT_UMOUNT && target && !strcmp(target, "/")) {
                DBG(CXT, ul_debugobj(cxt, "root umount: setting NOMTAB"));
@@ -2231,6 +2233,7 @@ int mnt_context_prepare_update(struct libmnt_context *cxt)
                DBG(CXT, ul_debugobj(cxt, "skip update: no writable destination"));
                return 0;
        }
+
        /* 0 = success, 1 = not called yet */
        if (cxt->syscall_status != 1 && cxt->syscall_status != 0) {
                DBG(CXT, ul_debugobj(cxt,
@@ -2239,12 +2242,24 @@ int mnt_context_prepare_update(struct libmnt_context *cxt)
                return 0;
        }
 
-       if (!cxt->update) {
-               if (cxt->action == MNT_ACT_UMOUNT && is_file_empty(name)) {
-                       DBG(CXT, ul_debugobj(cxt, "skip update: umount, no table"));
-                       return 0;
-               }
+       ol = mnt_context_get_optlist(cxt);
+       if (!ol)
+               return -ENOMEM;
 
+       if ((cxt->action == MNT_ACT_UMOUNT || mnt_optlist_is_move(ol))
+           && is_file_empty(name)) {
+               DBG(CXT, ul_debugobj(cxt, "skip update: umount/move, empty table"));
+               return 0;
+       }
+
+       if (mnt_optlist_is_move(ol) &&
+           ((target && startswithpath(name, target))
+            || (source && startswithpath(name, source)))) {
+               DBG(CXT, ul_debugobj(cxt, "skip update: utab move"));
+               return 0;
+       }
+
+       if (!cxt->update) {
                cxt->update = mnt_new_update();
                if (!cxt->update)
                        return -ENOMEM;