diff options
Diffstat (limited to 'fs/ramfs')
| -rw-r--r-- | fs/ramfs/Makefile | 4 | ||||
| -rw-r--r-- | fs/ramfs/file-mmu.c | 57 | ||||
| -rw-r--r-- | fs/ramfs/file-nommu.c | 292 | ||||
| -rw-r--r-- | fs/ramfs/inode.c | 22 | ||||
| -rw-r--r-- | fs/ramfs/internal.h | 15 |
5 files changed, 368 insertions, 22 deletions
diff --git a/fs/ramfs/Makefile b/fs/ramfs/Makefile index f096f30..5a0236e 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 0000000..2115383 --- /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 0000000..3f810ac --- /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 0a88917..c66bd5e 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 0000000..272c8a7 --- /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; |
