5 files changed, 368 insertions, 22 deletions

diff --git a/fs/ramfs/Makefile b/fs/ramfs/Makefile
index f096f300709..5a0236e02ee 100644
--- a/fs/ramfs/Makefile
+++ b/fs/ramfs/Makefile
@@ -4,4 +4,6 @@
 
 obj-$(CONFIG_RAMFS) += ramfs.o
 
-ramfs-objs := inode.o
+file-mmu-y := file-nommu.o
+file-mmu-$(CONFIG_MMU) := file-mmu.o
+ramfs-objs += inode.o $(file-mmu-y)
diff --git a/fs/ramfs/file-mmu.c b/fs/ramfs/file-mmu.c
new file mode 100644
index 00000000000..2115383dcc8
--- /dev/null
+++ b/fs/ramfs/file-mmu.c
@@ -0,0 +1,57 @@
+/* file-mmu.c: ramfs MMU-based file operations
+ *
+ * Resizable simple ram filesystem for Linux.
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ *               2000 Transmeta Corp.
+ *
+ * Usage limits added by David Gibson, Linuxcare Australia.
+ * This file is released under the GPL.
+ */
+
+/*
+ * NOTE! This filesystem is probably most useful
+ * not as a real filesystem, but as an example of
+ * how virtual filesystems can be written.
+ *
+ * It doesn't get much simpler than this. Consider
+ * that this file implements the full semantics of
+ * a POSIX-compliant read-write filesystem.
+ *
+ * Note in particular how the filesystem does not
+ * need to implement any data structures of its own
+ * to keep track of the virtual data: using the VFS
+ * caches is sufficient.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+#include <linux/ramfs.h>
+
+#include <asm/uaccess.h>
+#include "internal.h"
+
+struct address_space_operations ramfs_aops = {
+	.readpage	= simple_readpage,
+	.prepare_write	= simple_prepare_write,
+	.commit_write	= simple_commit_write
+};
+
+struct file_operations ramfs_file_operations = {
+	.read		= generic_file_read,
+	.write		= generic_file_write,
+	.mmap		= generic_file_mmap,
+	.fsync		= simple_sync_file,
+	.sendfile	= generic_file_sendfile,
+	.llseek		= generic_file_llseek,
+};
+
+struct inode_operations ramfs_file_inode_operations = {
+	.getattr	= simple_getattr,
+};
diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
new file mode 100644
index 00000000000..3f810acd0bf
--- /dev/null
+++ b/fs/ramfs/file-nommu.c
@@ -0,0 +1,292 @@
+/* file-nommu.c: no-MMU version of ramfs
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+#include <linux/ramfs.h>
+#include <linux/quotaops.h>
+#include <linux/pagevec.h>
+#include <linux/mman.h>
+
+#include <asm/uaccess.h>
+#include "internal.h"
+
+static int ramfs_nommu_setattr(struct dentry *, struct iattr *);
+
+struct address_space_operations ramfs_aops = {
+	.readpage		= simple_readpage,
+	.prepare_write		= simple_prepare_write,
+	.commit_write		= simple_commit_write
+};
+
+struct file_operations ramfs_file_operations = {
+	.mmap			= ramfs_nommu_mmap,
+	.get_unmapped_area	= ramfs_nommu_get_unmapped_area,
+	.read			= generic_file_read,
+	.write			= generic_file_write,
+	.fsync			= simple_sync_file,
+	.sendfile		= generic_file_sendfile,
+	.llseek			= generic_file_llseek,
+};
+
+struct inode_operations ramfs_file_inode_operations = {
+	.setattr		= ramfs_nommu_setattr,
+	.getattr		= simple_getattr,
+};
+
+/*****************************************************************************/
+/*
+ * add a contiguous set of pages into a ramfs inode when it's truncated from
+ * size 0 on the assumption that it's going to be used for an mmap of shared
+ * memory
+ */
+static int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
+{
+	struct pagevec lru_pvec;
+	unsigned long npages, xpages, loop, limit;
+	struct page *pages;
+	unsigned order;
+	void *data;
+	int ret;
+
+	/* make various checks */
+	order = get_order(newsize);
+	if (unlikely(order >= MAX_ORDER))
+		goto too_big;
+
+	limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+	if (limit != RLIM_INFINITY && newsize > limit)
+		goto fsize_exceeded;
+
+	if (newsize > inode->i_sb->s_maxbytes)
+		goto too_big;
+
+	i_size_write(inode, newsize);
+
+	/* allocate enough contiguous pages to be able to satisfy the
+	 * request */
+	pages = alloc_pages(mapping_gfp_mask(inode->i_mapping), order);
+	if (!pages)
+		return -ENOMEM;
+
+	/* split the high-order page into an array of single pages */
+	xpages = 1UL << order;
+	npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+	for (loop = 0; loop < npages; loop++)
+		set_page_count(pages + loop, 1);
+
+	/* trim off any pages we don't actually require */
+	for (loop = npages; loop < xpages; loop++)
+		__free_page(pages + loop);
+
+	/* clear the memory we allocated */
+	newsize = PAGE_SIZE * npages;
+	data = page_address(pages);
+	memset(data, 0, newsize);
+
+	/* attach all the pages to the inode's address space */
+	pagevec_init(&lru_pvec, 0);
+	for (loop = 0; loop < npages; loop++) {
+		struct page *page = pages + loop;
+
+		ret = add_to_page_cache(page, inode->i_mapping, loop, GFP_KERNEL);
+		if (ret < 0)
+			goto add_error;
+
+		if (!pagevec_add(&lru_pvec, page))
+			__pagevec_lru_add(&lru_pvec);
+
+		unlock_page(page);
+	}
+
+	pagevec_lru_add(&lru_pvec);
+	return 0;
+
+ fsize_exceeded:
+	send_sig(SIGXFSZ, current, 0);
+ too_big:
+	return -EFBIG;
+
+ add_error:
+	page_cache_release(pages + loop);
+	for (loop++; loop < npages; loop++)
+		__free_page(pages + loop);
+	return ret;
+}
+
+/*****************************************************************************/
+/*
+ * check that file shrinkage doesn't leave any VMAs dangling in midair
+ */
+static int ramfs_nommu_check_mappings(struct inode *inode,
+				      size_t newsize, size_t size)
+{
+	struct vm_area_struct *vma;
+	struct prio_tree_iter iter;
+
+	/* search for VMAs that fall within the dead zone */
+	vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
+			      newsize >> PAGE_SHIFT,
+			      (size + PAGE_SIZE - 1) >> PAGE_SHIFT
+			      ) {
+		/* found one - only interested if it's shared out of the page
+		 * cache */
+		if (vma->vm_flags & VM_SHARED)
+			return -ETXTBSY; /* not quite true, but near enough */
+	}
+
+	return 0;
+}
+
+/*****************************************************************************/
+/*
+ *
+ */
+static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
+{
+	int ret;
+
+	/* assume a truncate from zero size is going to be for the purposes of
+	 * shared mmap */
+	if (size == 0) {
+		if (unlikely(newsize >> 32))
+			return -EFBIG;
+
+		return ramfs_nommu_expand_for_mapping(inode, newsize);
+	}
+
+	/* check that a decrease in size doesn't cut off any shared mappings */
+	if (newsize < size) {
+		ret = ramfs_nommu_check_mappings(inode, newsize, size);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = vmtruncate(inode, size);
+
+	return ret;
+}
+
+/*****************************************************************************/
+/*
+ * handle a change of attributes
+ * - we're specifically interested in a change of size
+ */
+static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia)
+{
+	struct inode *inode = dentry->d_inode;
+	unsigned int old_ia_valid = ia->ia_valid;
+	int ret = 0;
+
+	/* by providing our own setattr() method, we skip this quotaism */
+	if ((old_ia_valid & ATTR_UID && ia->ia_uid != inode->i_uid) ||
+	    (old_ia_valid & ATTR_GID && ia->ia_gid != inode->i_gid))
+		ret = DQUOT_TRANSFER(inode, ia) ? -EDQUOT : 0;
+
+	/* pick out size-changing events */
+	if (ia->ia_valid & ATTR_SIZE) {
+		loff_t size = i_size_read(inode);
+		if (ia->ia_size != size) {
+			ret = ramfs_nommu_resize(inode, ia->ia_size, size);
+			if (ret < 0 || ia->ia_valid == ATTR_SIZE)
+				goto out;
+		} else {
+			/* we skipped the truncate but must still update
+			 * timestamps
+			 */
+			ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
+		}
+	}
+
+	ret = inode_setattr(inode, ia);
+ out:
+	ia->ia_valid = old_ia_valid;
+	return ret;
+}
+
+/*****************************************************************************/
+/*
+ * try to determine where a shared mapping can be made
+ * - we require that:
+ *   - the pages to be mapped must exist
+ *   - the pages be physically contiguous in sequence
+ */
+unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
+					    unsigned long addr, unsigned long len,
+					    unsigned long pgoff, unsigned long flags)
+{
+	unsigned long maxpages, lpages, nr, loop, ret;
+	struct inode *inode = file->f_dentry->d_inode;
+	struct page **pages = NULL, **ptr, *page;
+	loff_t isize;
+
+	if (!(flags & MAP_SHARED))
+		return addr;
+
+	/* the mapping mustn't extend beyond the EOF */
+	lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	isize = i_size_read(inode);
+
+	ret = -EINVAL;
+	maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	if (pgoff >= maxpages)
+		goto out;
+
+	if (maxpages - pgoff < lpages)
+		goto out;
+
+	/* gang-find the pages */
+	ret = -ENOMEM;
+	pages = kzalloc(lpages * sizeof(struct page *), GFP_KERNEL);
+	if (!pages)
+		goto out;
+
+	nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
+	if (nr != lpages)
+		goto out; /* leave if some pages were missing */
+
+	/* check the pages for physical adjacency */
+	ptr = pages;
+	page = *ptr++;
+	page++;
+	for (loop = lpages; loop > 1; loop--)
+		if (*ptr++ != page++)
+			goto out;
+
+	/* okay - all conditions fulfilled */
+	ret = (unsigned long) page_address(pages[0]);
+
+ out:
+	if (pages) {
+		ptr = pages;
+		for (loop = lpages; loop > 0; loop--)
+			put_page(*ptr++);
+		kfree(pages);
+	}
+
+	return ret;
+}
+
+/*****************************************************************************/
+/*
+ * set up a mapping
+ */
+int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return 0;
+}
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index 0a88917605a..c66bd5e4c05 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -34,13 +34,12 @@
 #include <linux/ramfs.h>
 
 #include <asm/uaccess.h>
+#include "internal.h"
 
 /* some random number */
 #define RAMFS_MAGIC	0x858458f6
 
 static struct super_operations ramfs_ops;
-static struct address_space_operations ramfs_aops;
-static struct inode_operations ramfs_file_inode_operations;
 static struct inode_operations ramfs_dir_inode_operations;
 
 static struct backing_dev_info ramfs_backing_dev_info = {
@@ -142,25 +141,6 @@ static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char *
 	return error;
 }
 
-static struct address_space_operations ramfs_aops = {
-	.readpage	= simple_readpage,
-	.prepare_write	= simple_prepare_write,
-	.commit_write	= simple_commit_write
-};
-
-struct file_operations ramfs_file_operations = {
-	.read		= generic_file_read,
-	.write		= generic_file_write,
-	.mmap		= generic_file_mmap,
-	.fsync		= simple_sync_file,
-	.sendfile	= generic_file_sendfile,
-	.llseek		= generic_file_llseek,
-};
-
-static struct inode_operations ramfs_file_inode_operations = {
-	.getattr	= simple_getattr,
-};
-
 static struct inode_operations ramfs_dir_inode_operations = {
 	.create		= ramfs_create,
 	.lookup		= simple_lookup,
diff --git a/fs/ramfs/internal.h b/fs/ramfs/internal.h
new file mode 100644
index 00000000000..272c8a7120b
--- /dev/null
+++ b/fs/ramfs/internal.h
@@ -0,0 +1,15 @@
+/* internal.h: ramfs internal definitions
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+
+extern struct address_space_operations ramfs_aops;
+extern struct file_operations ramfs_file_operations;
+extern struct inode_operations ramfs_file_inode_operations;