hw/9pfs: Improve portability to older systems

handle fs driver require a set of newly added syscalls. Don't
Compile handle FS driver if those syscalls are not available.
Instead of adding #ifdef for all those syscalls we check for
open by handle syscall. If that is available then rest of the
syscalls used by the driver should be available.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Makefile.objs

@@ -310,8 +310,8 @@ hw-obj-$(CONFIG_SOUND) += $(sound-obj-y)
 9pfs-nested-$(CONFIG_VIRTFS) += virtio-9p-local.o virtio-9p-xattr.o
 9pfs-nested-$(CONFIG_VIRTFS) += virtio-9p-xattr-user.o virtio-9p-posix-acl.o
 9pfs-nested-$(CONFIG_VIRTFS) += virtio-9p-coth.o cofs.o codir.o cofile.o
-9pfs-nested-$(CONFIG_VIRTFS) += coxattr.o virtio-9p-handle.o
-9pfs-nested-$(CONFIG_VIRTFS) += virtio-9p-synth.o
+9pfs-nested-$(CONFIG_VIRTFS) += coxattr.o virtio-9p-synth.o
+9pfs-nested-$(CONFIG_OPEN_BY_HANDLE) +=  virtio-9p-handle.o
 
 hw-obj-$(CONFIG_REALLY_VIRTFS) += $(addprefix 9pfs/, $(9pfs-nested-y))
 $(addprefix 9pfs/, $(9pfs-nested-y)): QEMU_CFLAGS+=$(GLIB_CFLAGS)

fsdev/qemu-fsdev.c

@@ -23,7 +23,9 @@ static QTAILQ_HEAD(FsDriverEntry_head, FsDriverListEntry) fsdriver_entries =
 
 static FsDriverTable FsDrivers[] = {
     { .name = "local", .ops = &local_ops},
+#ifdef CONFIG_OPEN_BY_HANDLE
     { .name = "handle", .ops = &handle_ops},
+#endif
     { .name = "synth", .ops = &synth_ops},
 };
 

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

@@ -45,7 +45,6 @@ struct handle_data {
     int handle_bytes;
 };
 
-#ifdef CONFIG_OPEN_BY_HANDLE
 static inline int name_to_handle(int dirfd, const char *name,
                                  struct file_handle *fh, int *mnt_id, int flags)
 {
@@ -56,38 +55,6 @@ static inline int open_by_handle(int mountfd, const char *fh, int flags)
 {
     return open_by_handle_at(mountfd, (struct file_handle *)fh, flags);
 }
-#else
-
-struct rpl_file_handle {
-    unsigned int handle_bytes;
-    int handle_type;
-    unsigned char handle[0];
-};
-#define file_handle rpl_file_handle
-
-#ifndef AT_REMOVEDIR
-#define AT_REMOVEDIR    0x200
-#endif
-#ifndef AT_EMPTY_PATH
-#define AT_EMPTY_PATH   0x1000  /* Allow empty relative pathname */
-#endif
-#ifndef O_PATH
-#define O_PATH    010000000
-#endif
-
-static inline int name_to_handle(int dirfd, const char *name,
-                                 struct file_handle *fh, int *mnt_id, int flags)
-{
-    errno = ENOSYS;
-    return -1;
-}
-
-static inline int open_by_handle(int mountfd, const char *fh, int flags)
-{
-    errno = ENOSYS;
-    return -1;
-}
-#endif
 
 static int handle_update_file_cred(int dirfd, const char *name, FsCred *credp)
 {