nommu: fix SYSV SHM for NOMMU

Commit c4caa778157dbbf04116f0ac2111e389b5cd7a29 ("file
->get_unmapped_area() shouldn't duplicate work of get_unmapped_area()")
broke SYSV SHM for NOMMU by taking away the pointer to
shm_get_unmapped_area() from shm_file_operations.

Put it back conditionally on CONFIG_MMU=n.

file->f_ops->get_unmapped_area() is used to find out the base address for a
mapping of a mappable chardev device or mappable memory-based file (such as a
ramfs file).  It needs to be called prior to file->f_ops->mmap() being called.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/ipc/shm.c b/ipc/shm.c
index 92fe9236258b..23256b855819 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -298,6 +298,9 @@ static const struct file_operations shm_file_operations = {
         .mmap           = shm_mmap,
         .fsync          = shm_fsync,
         .release        = shm_release,
+#ifndef CONFIG_MMU
+        .get_unmapped_area      = shm_get_unmapped_area,
+#endif
 };
 
 static const struct file_operations shm_file_operations_huge = {