[PATCH] NOMMU: Make SYSV IPC SHM use ramfs facilities on NOMMU

The attached patch makes the SYSV IPC shared memory facilities use the new
ramfs facilities on a no-MMU kernel.

The following changes are made:

 (1) There are now shmem_mmap() and shmem_get_unmapped_area() functions to
     allow the IPC SHM facilities to commune with the tiny-shmem and shmem
     code.

 (2) ramfs files now need resizing using do_truncate() rather than by modifying
     the inode size directly (see shmem_file_setup()). This causes ramfs to
     attempt to bind a block of pages of sufficient size to the inode.

 (3) CONFIG_SYSVIPC is no longer contingent on CONFIG_MMU.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 13 insertions, 5 deletions

diff --git a/ipc/shm.c b/ipc/shm.c
index 587d836d80d9..0ef4a1cf3e27 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -157,14 +157,22 @@ static void shm_close (struct vm_area_struct *shmd)
 
 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 {
-        file_accessed(file);
-        vma->vm_ops = &shm_vm_ops;
-        shm_inc(file->f_dentry->d_inode->i_ino);
-        return 0;
+        int ret;
+
+        ret = shmem_mmap(file, vma);
+        if (ret == 0) {
+                vma->vm_ops = &shm_vm_ops;
+                shm_inc(file->f_dentry->d_inode->i_ino);
+        }
+
+        return ret;
 }
 
 static struct file_operations shm_file_operations = {
-        .mmap   = shm_mmap
+        .mmap   = shm_mmap,
+#ifndef CONFIG_MMU
+        .get_unmapped_area = shmem_get_unmapped_area,
+#endif
 };
 
 static struct vm_operations_struct shm_vm_ops = {