diff options
Diffstat (limited to 'kernel/fs/romfs/super.c')
| -rw-r--r-- | kernel/fs/romfs/super.c | 659 |
1 files changed, 659 insertions, 0 deletions
diff --git a/kernel/fs/romfs/super.c b/kernel/fs/romfs/super.c new file mode 100644 index 000000000..268733cda --- /dev/null +++ b/kernel/fs/romfs/super.c @@ -0,0 +1,659 @@ +/* Block- or MTD-based romfs + * + * Copyright © 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * Derived from: ROMFS file system, Linux implementation + * + * Copyright © 1997-1999 Janos Farkas <chexum@shadow.banki.hu> + * + * Using parts of the minix filesystem + * Copyright © 1991, 1992 Linus Torvalds + * + * and parts of the affs filesystem additionally + * Copyright © 1993 Ray Burr + * Copyright © 1996 Hans-Joachim Widmaier + * + * Changes + * Changed for 2.1.19 modules + * Jan 1997 Initial release + * Jun 1997 2.1.43+ changes + * Proper page locking in readpage + * Changed to work with 2.1.45+ fs + * Jul 1997 Fixed follow_link + * 2.1.47 + * lookup shouldn't return -ENOENT + * from Horst von Brand: + * fail on wrong checksum + * double unlock_super was possible + * correct namelen for statfs + * spotted by Bill Hawes: + * readlink shouldn't iput() + * Jun 1998 2.1.106 from Avery Pennarun: glibc scandir() + * exposed a problem in readdir + * 2.1.107 code-freeze spellchecker run + * Aug 1998 2.1.118+ VFS changes + * Sep 1998 2.1.122 another VFS change (follow_link) + * Apr 1999 2.2.7 no more EBADF checking in + * lookup/readdir, use ERR_PTR + * Jun 1999 2.3.6 d_alloc_root use changed + * 2.3.9 clean up usage of ENOENT/negative + * dentries in lookup + * clean up page flags setting + * (error, uptodate, locking) in + * in readpage + * use init_special_inode for + * fifos/sockets (and streamline) in + * read_inode, fix _ops table order + * Aug 1999 2.3.16 __initfunc() => __init change + * Oct 1999 2.3.24 page->owner hack obsoleted + * Nov 1999 2.3.27 2.3.25+ page->offset => index change + * + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/string.h> +#include <linux/fs.h> +#include <linux/time.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/blkdev.h> +#include <linux/parser.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/statfs.h> +#include <linux/mtd/super.h> +#include <linux/ctype.h> +#include <linux/highmem.h> +#include <linux/pagemap.h> +#include <linux/uaccess.h> +#include "internal.h" + +static struct kmem_cache *romfs_inode_cachep; + +static const umode_t romfs_modemap[8] = { + 0, /* hard link */ + S_IFDIR | 0644, /* directory */ + S_IFREG | 0644, /* regular file */ + S_IFLNK | 0777, /* symlink */ + S_IFBLK | 0600, /* blockdev */ + S_IFCHR | 0600, /* chardev */ + S_IFSOCK | 0644, /* socket */ + S_IFIFO | 0644 /* FIFO */ +}; + +static const unsigned char romfs_dtype_table[] = { + DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO +}; + +static struct inode *romfs_iget(struct super_block *sb, unsigned long pos); + +/* + * read a page worth of data from the image + */ +static int romfs_readpage(struct file *file, struct page *page) +{ + struct inode *inode = page->mapping->host; + loff_t offset, size; + unsigned long fillsize, pos; + void *buf; + int ret; + + buf = kmap(page); + if (!buf) + return -ENOMEM; + + /* 32 bit warning -- but not for us :) */ + offset = page_offset(page); + size = i_size_read(inode); + fillsize = 0; + ret = 0; + if (offset < size) { + size -= offset; + fillsize = size > PAGE_SIZE ? PAGE_SIZE : size; + + pos = ROMFS_I(inode)->i_dataoffset + offset; + + ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize); + if (ret < 0) { + SetPageError(page); + fillsize = 0; + ret = -EIO; + } + } + + if (fillsize < PAGE_SIZE) + memset(buf + fillsize, 0, PAGE_SIZE - fillsize); + if (ret == 0) + SetPageUptodate(page); + + flush_dcache_page(page); + kunmap(page); + unlock_page(page); + return ret; +} + +static const struct address_space_operations romfs_aops = { + .readpage = romfs_readpage +}; + +/* + * read the entries from a directory + */ +static int romfs_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *i = file_inode(file); + struct romfs_inode ri; + unsigned long offset, maxoff; + int j, ino, nextfh; + char fsname[ROMFS_MAXFN]; /* XXX dynamic? */ + int ret; + + maxoff = romfs_maxsize(i->i_sb); + + offset = ctx->pos; + if (!offset) { + offset = i->i_ino & ROMFH_MASK; + ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE); + if (ret < 0) + goto out; + offset = be32_to_cpu(ri.spec) & ROMFH_MASK; + } + + /* Not really failsafe, but we are read-only... */ + for (;;) { + if (!offset || offset >= maxoff) { + offset = maxoff; + ctx->pos = offset; + goto out; + } + ctx->pos = offset; + + /* Fetch inode info */ + ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE); + if (ret < 0) + goto out; + + j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE, + sizeof(fsname) - 1); + if (j < 0) + goto out; + + ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j); + if (ret < 0) + goto out; + fsname[j] = '\0'; + + ino = offset; + nextfh = be32_to_cpu(ri.next); + if ((nextfh & ROMFH_TYPE) == ROMFH_HRD) + ino = be32_to_cpu(ri.spec); + if (!dir_emit(ctx, fsname, j, ino, + romfs_dtype_table[nextfh & ROMFH_TYPE])) + goto out; + + offset = nextfh & ROMFH_MASK; + } +out: + return 0; +} + +/* + * look up an entry in a directory + */ +static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry, + unsigned int flags) +{ + unsigned long offset, maxoff; + struct inode *inode; + struct romfs_inode ri; + const char *name; /* got from dentry */ + int len, ret; + + offset = dir->i_ino & ROMFH_MASK; + ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE); + if (ret < 0) + goto error; + + /* search all the file entries in the list starting from the one + * pointed to by the directory's special data */ + maxoff = romfs_maxsize(dir->i_sb); + offset = be32_to_cpu(ri.spec) & ROMFH_MASK; + + name = dentry->d_name.name; + len = dentry->d_name.len; + + for (;;) { + if (!offset || offset >= maxoff) + goto out0; + + ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri)); + if (ret < 0) + goto error; + + /* try to match the first 16 bytes of name */ + ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name, + len); + if (ret < 0) + goto error; + if (ret == 1) + break; + + /* next entry */ + offset = be32_to_cpu(ri.next) & ROMFH_MASK; + } + + /* Hard link handling */ + if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD) + offset = be32_to_cpu(ri.spec) & ROMFH_MASK; + + inode = romfs_iget(dir->i_sb, offset); + if (IS_ERR(inode)) { + ret = PTR_ERR(inode); + goto error; + } + goto outi; + + /* + * it's a bit funky, _lookup needs to return an error code + * (negative) or a NULL, both as a dentry. ENOENT should not + * be returned, instead we need to create a negative dentry by + * d_add(dentry, NULL); and return 0 as no error. + * (Although as I see, it only matters on writable file + * systems). + */ +out0: + inode = NULL; +outi: + d_add(dentry, inode); + ret = 0; +error: + return ERR_PTR(ret); +} + +static const struct file_operations romfs_dir_operations = { + .read = generic_read_dir, + .iterate = romfs_readdir, + .llseek = default_llseek, +}; + +static const struct inode_operations romfs_dir_inode_operations = { + .lookup = romfs_lookup, +}; + +/* + * get a romfs inode based on its position in the image (which doubles as the + * inode number) + */ +static struct inode *romfs_iget(struct super_block *sb, unsigned long pos) +{ + struct romfs_inode_info *inode; + struct romfs_inode ri; + struct inode *i; + unsigned long nlen; + unsigned nextfh; + int ret; + umode_t mode; + + /* we might have to traverse a chain of "hard link" file entries to get + * to the actual file */ + for (;;) { + ret = romfs_dev_read(sb, pos, &ri, sizeof(ri)); + if (ret < 0) + goto error; + + /* XXX: do romfs_checksum here too (with name) */ + + nextfh = be32_to_cpu(ri.next); + if ((nextfh & ROMFH_TYPE) != ROMFH_HRD) + break; + + pos = be32_to_cpu(ri.spec) & ROMFH_MASK; + } + + /* determine the length of the filename */ + nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN); + if (IS_ERR_VALUE(nlen)) + goto eio; + + /* get an inode for this image position */ + i = iget_locked(sb, pos); + if (!i) + return ERR_PTR(-ENOMEM); + + if (!(i->i_state & I_NEW)) + return i; + + /* precalculate the data offset */ + inode = ROMFS_I(i); + inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK; + inode->i_dataoffset = pos + inode->i_metasize; + + set_nlink(i, 1); /* Hard to decide.. */ + i->i_size = be32_to_cpu(ri.size); + i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0; + i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0; + + /* set up mode and ops */ + mode = romfs_modemap[nextfh & ROMFH_TYPE]; + + switch (nextfh & ROMFH_TYPE) { + case ROMFH_DIR: + i->i_size = ROMFS_I(i)->i_metasize; + i->i_op = &romfs_dir_inode_operations; + i->i_fop = &romfs_dir_operations; + if (nextfh & ROMFH_EXEC) + mode |= S_IXUGO; + break; + case ROMFH_REG: + i->i_fop = &romfs_ro_fops; + i->i_data.a_ops = &romfs_aops; + if (nextfh & ROMFH_EXEC) + mode |= S_IXUGO; + break; + case ROMFH_SYM: + i->i_op = &page_symlink_inode_operations; + i->i_data.a_ops = &romfs_aops; + mode |= S_IRWXUGO; + break; + default: + /* depending on MBZ for sock/fifos */ + nextfh = be32_to_cpu(ri.spec); + init_special_inode(i, mode, MKDEV(nextfh >> 16, + nextfh & 0xffff)); + break; + } + + i->i_mode = mode; + + unlock_new_inode(i); + return i; + +eio: + ret = -EIO; +error: + pr_err("read error for inode 0x%lx\n", pos); + return ERR_PTR(ret); +} + +/* + * allocate a new inode + */ +static struct inode *romfs_alloc_inode(struct super_block *sb) +{ + struct romfs_inode_info *inode; + + inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL); + return inode ? &inode->vfs_inode : NULL; +} + +/* + * return a spent inode to the slab cache + */ +static void romfs_i_callback(struct rcu_head *head) +{ + struct inode *inode = container_of(head, struct inode, i_rcu); + + kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode)); +} + +static void romfs_destroy_inode(struct inode *inode) +{ + call_rcu(&inode->i_rcu, romfs_i_callback); +} + +/* + * get filesystem statistics + */ +static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf) +{ + struct super_block *sb = dentry->d_sb; + u64 id = huge_encode_dev(sb->s_bdev->bd_dev); + + buf->f_type = ROMFS_MAGIC; + buf->f_namelen = ROMFS_MAXFN; + buf->f_bsize = ROMBSIZE; + buf->f_bfree = buf->f_bavail = buf->f_ffree; + buf->f_blocks = + (romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS; + buf->f_fsid.val[0] = (u32)id; + buf->f_fsid.val[1] = (u32)(id >> 32); + return 0; +} + +/* + * remounting must involve read-only + */ +static int romfs_remount(struct super_block *sb, int *flags, char *data) +{ + sync_filesystem(sb); + *flags |= MS_RDONLY; + return 0; +} + +static const struct super_operations romfs_super_ops = { + .alloc_inode = romfs_alloc_inode, + .destroy_inode = romfs_destroy_inode, + .statfs = romfs_statfs, + .remount_fs = romfs_remount, +}; + +/* + * checksum check on part of a romfs filesystem + */ +static __u32 romfs_checksum(const void *data, int size) +{ + const __be32 *ptr = data; + __u32 sum; + + sum = 0; + size >>= 2; + while (size > 0) { + sum += be32_to_cpu(*ptr++); + size--; + } + return sum; +} + +/* + * fill in the superblock + */ +static int romfs_fill_super(struct super_block *sb, void *data, int silent) +{ + struct romfs_super_block *rsb; + struct inode *root; + unsigned long pos, img_size; + const char *storage; + size_t len; + int ret; + +#ifdef CONFIG_BLOCK + if (!sb->s_mtd) { + sb_set_blocksize(sb, ROMBSIZE); + } else { + sb->s_blocksize = ROMBSIZE; + sb->s_blocksize_bits = blksize_bits(ROMBSIZE); + } +#endif + + sb->s_maxbytes = 0xFFFFFFFF; + sb->s_magic = ROMFS_MAGIC; + sb->s_flags |= MS_RDONLY | MS_NOATIME; + sb->s_op = &romfs_super_ops; + + /* read the image superblock and check it */ + rsb = kmalloc(512, GFP_KERNEL); + if (!rsb) + return -ENOMEM; + + sb->s_fs_info = (void *) 512; + ret = romfs_dev_read(sb, 0, rsb, 512); + if (ret < 0) + goto error_rsb; + + img_size = be32_to_cpu(rsb->size); + + if (sb->s_mtd && img_size > sb->s_mtd->size) + goto error_rsb_inval; + + sb->s_fs_info = (void *) img_size; + + if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 || + img_size < ROMFH_SIZE) { + if (!silent) + pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n", + sb->s_id); + goto error_rsb_inval; + } + + if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) { + pr_err("bad initial checksum on dev %s.\n", sb->s_id); + goto error_rsb_inval; + } + + storage = sb->s_mtd ? "MTD" : "the block layer"; + + len = strnlen(rsb->name, ROMFS_MAXFN); + if (!silent) + pr_notice("Mounting image '%*.*s' through %s\n", + (unsigned) len, (unsigned) len, rsb->name, storage); + + kfree(rsb); + rsb = NULL; + + /* find the root directory */ + pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK; + + root = romfs_iget(sb, pos); + if (IS_ERR(root)) + return PTR_ERR(root); + + sb->s_root = d_make_root(root); + if (!sb->s_root) + return -ENOMEM; + + return 0; + +error_rsb_inval: + ret = -EINVAL; +error_rsb: + kfree(rsb); + return ret; +} + +/* + * get a superblock for mounting + */ +static struct dentry *romfs_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, + void *data) +{ + struct dentry *ret = ERR_PTR(-EINVAL); + +#ifdef CONFIG_ROMFS_ON_MTD + ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (ret == ERR_PTR(-EINVAL)) + ret = mount_bdev(fs_type, flags, dev_name, data, + romfs_fill_super); +#endif + return ret; +} + +/* + * destroy a romfs superblock in the appropriate manner + */ +static void romfs_kill_sb(struct super_block *sb) +{ +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) { + kill_mtd_super(sb); + return; + } +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) { + kill_block_super(sb); + return; + } +#endif +} + +static struct file_system_type romfs_fs_type = { + .owner = THIS_MODULE, + .name = "romfs", + .mount = romfs_mount, + .kill_sb = romfs_kill_sb, + .fs_flags = FS_REQUIRES_DEV, +}; +MODULE_ALIAS_FS("romfs"); + +/* + * inode storage initialiser + */ +static void romfs_i_init_once(void *_inode) +{ + struct romfs_inode_info *inode = _inode; + + inode_init_once(&inode->vfs_inode); +} + +/* + * romfs module initialisation + */ +static int __init init_romfs_fs(void) +{ + int ret; + + pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n"); + + romfs_inode_cachep = + kmem_cache_create("romfs_i", + sizeof(struct romfs_inode_info), 0, + SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, + romfs_i_init_once); + + if (!romfs_inode_cachep) { + pr_err("Failed to initialise inode cache\n"); + return -ENOMEM; + } + ret = register_filesystem(&romfs_fs_type); + if (ret) { + pr_err("Failed to register filesystem\n"); + goto error_register; + } + return 0; + +error_register: + kmem_cache_destroy(romfs_inode_cachep); + return ret; +} + +/* + * romfs module removal + */ +static void __exit exit_romfs_fs(void) +{ + unregister_filesystem(&romfs_fs_type); + /* + * Make sure all delayed rcu free inodes are flushed before we + * destroy cache. + */ + rcu_barrier(); + kmem_cache_destroy(romfs_inode_cachep); +} + +module_init(init_romfs_fs); +module_exit(exit_romfs_fs); + +MODULE_DESCRIPTION("Direct-MTD Capable RomFS"); +MODULE_AUTHOR("Red Hat, Inc."); +MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */ |