libmount: (mount) implement remount by new Linux API

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

diff --git a/libmount/src/hook_mount.c b/libmount/src/hook_mount.c
index df5bc573986a9cf771f43bbc375f9f398e42ac54..8d4e593d9a1d8b2e512c1e1710844e9493addcfb 100644 (file)
--- a/libmount/src/hook_mount.c
+++ b/libmount/src/hook_mount.c
@@ -25,7 +25,7 @@
  *
  * remount:
  *     - open_tree     PRE
- *     - reconfigure   MOUNT
+ *     - fsconfig      MOUNT (FS reconfigure)
  *     - mount_setattr MOUNT (VFS flags)
  *     - mount_setattr POST (propagation)
  *
@@ -115,13 +115,6 @@ static inline struct libmnt_sysapi *get_sysapi(struct libmnt_context *cxt,
        return mnt_context_get_hookset_data(cxt, hs);
 }
 
-static int hook_reconfigure_mount(struct libmnt_context *cxt __attribute__((__unused__)),
-                       const struct libmnt_hookset *hs __attribute__((__unused__)),
-                       void *data __attribute__((__unused__)))
-{
-       return 0;
-}
-
 static int configure_superblock(struct libmnt_context *cxt,
                                const struct libmnt_hookset *hs, int fd)
 {
@@ -211,6 +204,37 @@ static int hook_create_mount(struct libmnt_context *cxt,
        return rc;
 }
 
+static int hook_reconfigure_mount(struct libmnt_context *cxt,
+                       const struct libmnt_hookset *hs,
+                       void *data __attribute__((__unused__)))
+{
+       struct libmnt_sysapi *api;
+       int rc = 0;
+
+       assert(cxt);
+
+       api = get_sysapi(cxt, hs);
+       assert(api);
+       assert(api->fd_tree >= 0);
+
+       if (api->fd_fs < 0) {
+               api->fd_fs = fspick(api->fd_tree, "", FSPICK_EMPTY_PATH |
+                                                     FSPICK_NO_AUTOMOUNT);
+               set_syscall_status(cxt, "fspick", api->fd_fs >= 0);
+               if (api->fd_fs < 0)
+                       return -errno;
+       }
+
+       rc = configure_superblock(cxt, hs, api->fd_fs);
+       if (!rc) {
+               rc = fsconfig(api->fd_fs, FSCONFIG_CMD_RECONFIGURE, NULL, NULL, 0);
+               set_syscall_status(cxt, "fsconfig", rc == 0);
+       }
+
+       DBG(HOOK, ul_debugobj(hs, "reconf FS done [rc=%d]", rc));
+       return rc;
+}
+
 static int hook_set_vfsflags(struct libmnt_context *cxt,
                        const struct libmnt_hookset *hs,
                        void *data __attribute__((__unused__)))
@@ -341,21 +365,21 @@ static int init_sysapi(struct libmnt_context *cxt,
 
        DBG(HOOK, ul_debugobj(hs, "initialize API fds"));
 
-       /* A) tree based operation -- the tree is mount source */
-       if ((flags & MS_BIND)
-           || (flags & MS_MOVE)) {
-               DBG(HOOK, ul_debugobj(hs, " BIND/MOVE"));
-               path = mnt_fs_get_srcpath(cxt->fs);
-               if (!path)
-                       return -EINVAL;
-
-       /* B) tree based operation -- the tree is mount point */
-       } else if ((flags & MS_REMOUNT)
+       /* A) tree based operation -- the tree is mount point */
+       if ((flags & MS_REMOUNT)
            || mnt_context_propagation_only(cxt)) {
                DBG(HOOK, ul_debugobj(hs, " REMOUNT/propagation"));
                path = mnt_fs_get_target(cxt->fs);
                if (!path)
                        return -EINVAL;
+
+       /* B) tree based operation -- the tree is mount source */
+       } else if ((flags & MS_BIND)
+           || (flags & MS_MOVE)) {
+               DBG(HOOK, ul_debugobj(hs, " BIND/MOVE"));
+               path = mnt_fs_get_srcpath(cxt->fs);
+               if (!path)
+                       return -EINVAL;
        }
 
        api = new_hookset_data(cxt, hs);
@@ -368,7 +392,9 @@ static int init_sysapi(struct libmnt_context *cxt,
                if (mnt_optlist_is_recursive(cxt->optlist))
                        oflg |= AT_RECURSIVE;
 
-               if (flags & MS_BIND)
+               /* Classic -oremount,bind,ro is not bind operation, it's just
+                * VFS flags update only */
+               if ((flags & MS_BIND) && !(flags & MS_REMOUNT))
                        oflg |= OPEN_TREE_CLONE;
 
                DBG(HOOK, ul_debugobj(hs, "open_tree(path=%s, flgs=0x%08lx)", path, oflg));
@@ -452,7 +478,7 @@ static int hook_prepare(struct libmnt_context *cxt,
        if (!rc && (flags & MS_MOVE) && (flags & MS_REMOUNT))
                return -EINVAL;
 
-       /* classic remount (note -oremount,bind,ro is handled as bind) */
+       /* classic remount (note -oremount,bind,ro is not superblock reconfiguration) */
        if (!rc && (flags & MS_REMOUNT) && !(flags & MS_BIND))
                rc = mnt_context_append_hook(cxt, hs, MNT_STAGE_MOUNT, NULL,
                                        hook_reconfigure_mount);