9pfs: improve portability to older systems

Small requirements on "new" features have percolated to virtio-9p-local.c.
In particular, the utimensat wrapper actually only supports dirfd = AT_FDCWD
and flags = AT_SYMLINK_NOFOLLOW in the fallback code.  Remove the arguments
so that virtio-9p-local.c will not use AT_* constants.

At the same time, fail local_ioc_getversion if the ioctl is not supported
by the host.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/9pfs/virtio-9p-local.c

@@ -583,8 +583,7 @@ static int local_utimensat(FsContext *s, V9fsPath *fs_path,
     char buffer[PATH_MAX];
     char *path = fs_path->data;
 
-    return qemu_utimensat(AT_FDCWD, rpath(s, path, buffer), buf,
-                          AT_SYMLINK_NOFOLLOW);
+    return qemu_utimens(rpath(s, path, buffer), buf);
 }
 
 static int local_remove(FsContext *ctx, const char *path)
@@ -694,6 +693,7 @@ static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
                                 mode_t st_mode, uint64_t *st_gen)
 {
     int err;
+#ifdef FS_IOC_GETVERSION
     V9fsFidOpenState fid_open;
 
     /*
@@ -709,6 +709,9 @@ static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
     }
     err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
     local_close(ctx, &fid_open);
+#else
+    err = -ENOTTY;
+#endif
     return err;
 }
 

oslib-posix.c

@@ -162,8 +162,7 @@ int qemu_pipe(int pipefd[2])
     return ret;
 }
 
-int qemu_utimensat(int dirfd, const char *path, const struct timespec *times,
-                   int flags)
+int qemu_utimens(const char *path, const struct timespec *times)
 {
     struct timeval tv[2], tv_now;
     struct stat st;
@@ -171,7 +170,7 @@ int qemu_utimensat(int dirfd, const char *path, const struct timespec *times,
 #ifdef CONFIG_UTIMENSAT
     int ret;
 
-    ret = utimensat(dirfd, path, times, flags);
+    ret = utimensat(AT_FDCWD, path, times, AT_SYMLINK_NOFOLLOW);
     if (ret != -1 || errno != ENOSYS) {
         return ret;
     }

qemu-os-posix.h

@@ -44,7 +44,6 @@ typedef struct timeval qemu_timeval;
 #endif
 #endif
 typedef struct timespec qemu_timespec;
-int qemu_utimensat(int dirfd, const char *path, const qemu_timespec *times,
-    int flags);
+int qemu_utimens(const char *path, const qemu_timespec *times);
 
 #endif