mountpoint-util: statx() may return EINVAL if the kernel does not support the syscall

When statx() is called with AT_STATX_DONT_SYNC, glibc's fallback code
returns EINVAL. See statx_generic() in glibc.

diff --git a/src/basic/mountpoint-util.c b/src/basic/mountpoint-util.c
index 3584f317876f533a00c84c61d8eab849b88171dd..d7b182f6dd0084170815fad510e9383b8e466a77 100644 (file)
--- a/src/basic/mountpoint-util.c
+++ b/src/basic/mountpoint-util.c
@@ -223,7 +223,9 @@ int fd_is_mount_point(int fd, const char *filename, int flags) {
                   AT_STATX_DONT_SYNC,          /* don't go to the network for this – for similar reasons */
                   STATX_TYPE,
                   &sx) < 0) {
-                if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno))
+                if (!ERRNO_IS_NOT_SUPPORTED(errno) && /* statx() is not supported by the kernel. */
+                    !ERRNO_IS_PRIVILEGE(errno) &&     /* maybe filtered by seccomp. */
+                    errno != EINVAL)                  /* glibc's fallback method returns EINVAL when AT_STATX_DONT_SYNC is set. */
                         return -errno;
 
                 /* If statx() is not available or forbidden, fall back to name_to_handle_at() below */
@@ -371,7 +373,9 @@ int path_get_mnt_id_at(int dir_fd, const char *path, int *ret) {
                   AT_STATX_DONT_SYNC,  /* don't go to the network, mnt_id is a local concept */
                   STATX_MNT_ID,
                   &buf.sx) < 0) {
-                if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno))
+                if (!ERRNO_IS_NOT_SUPPORTED(errno) && /* statx() is not supported by the kernel. */
+                    !ERRNO_IS_PRIVILEGE(errno) &&     /* maybe filtered by seccomp. */
+                    errno != EINVAL)                  /* glibc's fallback method returns EINVAL when AT_STATX_DONT_SYNC is set. */
                         return -errno;
 
                 /* Fall back to name_to_handle_at() and then fdinfo if statx is not supported or we lack