--- /dev/null
+/* 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
+};
+
+const 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;
+
+ split_page(pages, order);
+
+ /* 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;
+}
git://git.onelab.eu / linux-2.6.git / blobdiff