Previously, the X-mount.subdir option would fail (mount exited with
code 0, but the target was not mounted) when a helper was used.
In addition to fixing X-mount.subdir, this allows dropping the
fallback behaviour previously implemented specifically by the
set_vfsflags and set_propagation hooks.
I realise this patch is not acceptable as is, since I just exported
the previously private open_mount_tree symbol from hook_mount.c
without even adding it to a header (so builds with sensible warning
configurations, with -Werror=implicit-function-declaration, won't even
compile this); but I'm submitting this as is in hopes that someone who
knows their way around libmount will suggest a sensible way to shuffle
the code around.
---
libmount/src/context_mount.c | 15 ++++++++++++++-
libmount/src/hook_mount.c | 20 +-------------------
2 files changed, 15 insertions(+), 20 deletions(-)
diff --git a/libmount/src/context_mount.c b/libmount/src/context_mount.c
index 676287733..ef66f47af 100644
--- a/libmount/src/context_mount.c
+++ b/libmount/src/context_mount.c
@@ -482,8 +482,21 @@ static int exec_helper(struct libmnt_context *cxt)
DBG(CXT, ul_debugobj(cxt, "%s forked [status=%d, rc=%d]",
cxt->helper,
cxt->helper_status, rc));
+
+ struct libmnt_sysapi *api = mnt_context_get_sysapi(cxt);
+ assert(api);
+
+ /* a mount helper, unlike an internal mount, won't provide the mount fd.
+ * This is, however, needed by hooks like subdir -- so let's open the tree
+ * that was mounted by our helper child. */
+ if (api->fd_tree < 0 && mnt_fs_get_target(cxt->fs)) {
+ api->fd_tree = open_mount_tree(cxt, NULL, (unsigned long) -1);
+ if (api->fd_tree > 0) {
+ rc = 0;
+ }
+ }
+ break;
}
- break;
}
case -1:
diff --git a/libmount/src/hook_mount.c b/libmount/src/hook_mount.c
index 6b7caff85..b80fe4839 100644
--- a/libmount/src/hook_mount.c
+++ b/libmount/src/hook_mount.c
@@ -255,7 +255,7 @@ static int open_fs_configuration_context(struct libmnt_context *cxt,
return api->fd_fs;
}
-static int open_mount_tree(struct libmnt_context *cxt, const char *path, unsigned long mflg)
+int open_mount_tree(struct libmnt_context *cxt, const char *path, unsigned long mflg)
{
unsigned long oflg = OPEN_TREE_CLOEXEC;
int rc = 0, fd = -1;
@@ -416,15 +416,6 @@ static int set_vfsflags(struct libmnt_context *cxt,
api = get_sysapi(cxt);
assert(api);
- /* fallback only; necessary when init_sysapi() during preparation
- * cannot open the tree -- for example when we call /sbin/mount.<type> */
- if (api->fd_tree < 0 && mnt_fs_get_target(cxt->fs)) {
- rc = api->fd_tree = open_mount_tree(cxt, NULL, (unsigned long) -1);
- if (rc < 0)
- return rc;
- rc = 0;
- }
-
if (recursive)
callflags |= AT_RECURSIVE;
@@ -494,15 +485,6 @@ static int hook_set_propagation(struct libmnt_context *cxt,
api = get_sysapi(cxt);
assert(api);
- /* fallback only; necessary when init_sysapi() during preparation
- * cannot open the tree -- for example when we call /sbin/mount.<type> */
- if (api->fd_tree < 0 && mnt_fs_get_target(cxt->fs)) {
- rc = api->fd_tree = open_mount_tree(cxt, NULL, (unsigned long) -1);
- if (rc < 0)
- goto done;
- rc = 0;
- }
-
mnt_reset_iter(&itr, MNT_ITER_FORWARD);
while (mnt_optlist_next_opt(ol, &itr, &opt) == 0) {
--
2.42.0
