[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>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 75ec04e..26f3094 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -654,9 +654,18 @@
}
#endif
struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags);
+extern int shmem_mmap(struct file *file, struct vm_area_struct *vma);
int shmem_zero_setup(struct vm_area_struct *);
+#ifndef CONFIG_MMU
+extern unsigned long shmem_get_unmapped_area(struct file *file,
+ unsigned long addr,
+ unsigned long len,
+ unsigned long pgoff,
+ unsigned long flags);
+#endif
+
static inline int can_do_mlock(void)
{
if (capable(CAP_IPC_LOCK))
diff --git a/init/Kconfig b/init/Kconfig
index ce737e0..24e0f7c 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -105,7 +105,6 @@
config SYSVIPC
bool "System V IPC"
- depends on MMU
---help---
Inter Process Communication is a suite of library functions and
system calls which let processes (running programs) synchronize and
diff --git a/ipc/shm.c b/ipc/shm.c
index 587d836..0ef4a1c 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -157,14 +157,22 @@
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 = {
diff --git a/mm/nommu.c b/mm/nommu.c
index c119681..c10262d 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1177,3 +1177,10 @@
{
return 0;
}
+
+struct page *filemap_nopage(struct vm_area_struct *area,
+ unsigned long address, int *type)
+{
+ BUG();
+ return NULL;
+}
diff --git a/mm/shmem.c b/mm/shmem.c
index 65c148e..a1f2f02 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1270,7 +1270,7 @@
return retval;
}
-static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
+int shmem_mmap(struct file *file, struct vm_area_struct *vma)
{
file_accessed(file);
vma->vm_ops = &shmem_vm_ops;
diff --git a/mm/tiny-shmem.c b/mm/tiny-shmem.c
index b58abcf..cdc6d43 100644
--- a/mm/tiny-shmem.c
+++ b/mm/tiny-shmem.c
@@ -81,13 +81,19 @@
goto close_file;
d_instantiate(dentry, inode);
- inode->i_size = size;
inode->i_nlink = 0; /* It is unlinked */
+
file->f_vfsmnt = mntget(shm_mnt);
file->f_dentry = dentry;
file->f_mapping = inode->i_mapping;
file->f_op = &ramfs_file_operations;
file->f_mode = FMODE_WRITE | FMODE_READ;
+
+ /* notify everyone as to the change of file size */
+ error = do_truncate(dentry, size, file);
+ if (error < 0)
+ goto close_file;
+
return file;
close_file:
@@ -123,3 +129,24 @@
{
return 0;
}
+
+int shmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ file_accessed(file);
+#ifndef CONFIG_MMU
+ return ramfs_nommu_mmap(file, vma);
+#else
+ return 0;
+#endif
+}
+
+#ifndef CONFIG_MMU
+unsigned long shmem_get_unmapped_area(struct file *file,
+ unsigned long addr,
+ unsigned long len,
+ unsigned long pgoff,
+ unsigned long flags)
+{
+ return ramfs_nommu_get_unmapped_area(file, addr, len, pgoff, flags);
+}
+#endif