libmount: fix "already mounted" detection on systems with mtab

For systems with regular mtab the fs->root should be ignored in
"already mounted" heuristic.

Reported-by: Matt Burgess <matthew@linuxfromscratch.org>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/include/list.h b/include/list.h
index 3ce46caa254697f2e187aa36f5b71cc6e5de4add..d8c3bf018c20ec3f6fe4338153cc7193b4cfd37c 100644 (file)
--- a/include/list.h
+++ b/include/list.h
@@ -166,6 +166,10 @@ _INLINE_ void list_splice(struct list_head *list, struct list_head *head)
 #define list_entry(ptr, type, member) \
        ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
 
+
+#define list_first_entry(head, type, member) \
+       ((head) && (head)->next != (head) ? list_entry((head)->next, type, member) : NULL)
+
 /**
  * list_for_each - iterate over elements in a list
  * @pos:       the &struct list_head to use as a loop counter.

diff --git a/libmount/src/tab.c b/libmount/src/tab.c
index 54d58c88015cb5b39aed88623935c999f40df551..f3ec573816fe208a0affa1f26e2c59a7bc022240 100644 (file)
--- a/libmount/src/tab.c
+++ b/libmount/src/tab.c
@@ -704,16 +704,18 @@ struct libmnt_fs *mnt_table_find_pair(struct libmnt_table *tb, const char *sourc
 }
 
 /*
- * @tb: /proc/self/mountinfo
- * @fs: filesystem
- * @mountflags: MS_BIND or 0
- * @fsroot: fs-root that will be probably used in the mountinfo file
+ * tb: /proc/self/mountinfo
+ * fs: filesystem
+ * mountflags: MS_BIND or 0
+ * fsroot: fs-root that will be probably used in the mountinfo file
  *          for @fs after mount(2)
  *
  * For btrfs subvolumes this function returns NULL, but @fsroot properly set.
  *
  * Returns: entry from @tb that will be used as a source for @fs if the @fs is
  *          bindmount.
+ *
+ * Don't export to library API!
  */
 struct libmnt_fs *mnt_table_get_fs_root(struct libmnt_table *tb,
                                        struct libmnt_fs *fs,
@@ -816,6 +818,20 @@ err:
        return NULL;
 }
 
+static int is_mountinfo(struct libmnt_table *tb)
+{
+       struct libmnt_fs *fs;
+
+       if (!tb)
+               return 0;
+
+       fs = list_first_entry(&tb->ents, struct libmnt_fs, ents);
+       if (fs && mnt_fs_is_kernel(fs) && mnt_fs_get_root(fs))
+               return 1;
+
+       return 0;
+}
+
 /**
  * mnt_table_is_mounted:
  * @tb: /proc/self/mountinfo file
@@ -831,10 +847,9 @@ err:
 int mnt_table_is_fs_mounted(struct libmnt_table *tb, struct libmnt_fs *fstab_fs)
 {
        char *root = NULL;
-       struct libmnt_fs *src_fs;
-       const char *src;
+       const char *src = NULL;
        char *xsrc = NULL, *tgt;
-       int flags = 0, rc = 0;
+       int rc = 0;
 
        assert(tb);
        assert(fstab_fs);
@@ -842,12 +857,21 @@ int mnt_table_is_fs_mounted(struct libmnt_table *tb, struct libmnt_fs *fstab_fs)
        if (mnt_fs_is_swaparea(fstab_fs))
                return 0;
 
-       if (mnt_fs_get_option(fstab_fs, "bind", NULL, NULL) == 0)
-               flags = MS_BIND;
+       if (is_mountinfo(tb)) {
+               /* @tb is mountinfo, so we can try to use fs-roots */
+               struct libmnt_fs *fs;
+               int flags = 0;
 
-       src_fs = mnt_table_get_fs_root(tb, fstab_fs, flags, &root);
-       if (src_fs)
-               src = mnt_fs_get_srcpath(src_fs);
+               if (mnt_fs_get_option(fstab_fs, "bind", NULL, NULL) == 0)
+                       flags = MS_BIND;
+
+               fs = mnt_table_get_fs_root(tb, fstab_fs, flags, &root);
+               if (fs)
+                       src = mnt_fs_get_srcpath(fs);
+       }
+
+       if (src)
+               src = xsrc = mnt_resolve_spec(src, tb->cache);
        else if (mnt_fs_is_pseudofs(fstab_fs))
                src = mnt_fs_get_source(fstab_fs);
        else
@@ -856,18 +880,26 @@ int mnt_table_is_fs_mounted(struct libmnt_table *tb, struct libmnt_fs *fstab_fs)
 
        tgt = mnt_resolve_path(mnt_fs_get_target(fstab_fs), tb->cache);
 
-       if (tgt && src && root) {
+       if (tgt && src) {
                struct libmnt_iter itr;
                struct libmnt_fs *fs;
 
                mnt_reset_iter(&itr, MNT_ITER_FORWARD);
 
                while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
-                       const char *r = mnt_fs_get_root(fs);
 
-                       if (r && strcmp(r, root) == 0
-                           && mnt_fs_streq_srcpath(fs, src)
-                           && mnt_fs_streq_target(fs, tgt))
+                       if (root) {
+                               /* mountinfo: compare root, source and target */
+                               const char *r = mnt_fs_get_root(fs);
+
+                               if (r && strcmp(r, root) == 0 &&
+                                   mnt_fs_streq_srcpath(fs, src) &&
+                                   mnt_fs_streq_target(fs, tgt))
+                                       break;
+                       }
+                       /* mtab: compare source and target */
+                       else if (mnt_fs_streq_srcpath(fs, src) &&
+                                mnt_fs_streq_target(fs, tgt))
                                break;
                }
                if (fs)