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-rw-r--r--fs/romfs/super.c653
1 files changed, 653 insertions, 0 deletions
diff --git a/fs/romfs/super.c b/fs/romfs/super.c
new file mode 100644
index 000000000000..c53b5ef8a02f
--- /dev/null
+++ b/fs/romfs/super.c
@@ -0,0 +1,653 @@
+/* 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.
+ */
+
+#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 *filp, void *dirent, filldir_t filldir)
+{
+ struct inode *i = filp->f_dentry->d_inode;
+ struct romfs_inode ri;
+ unsigned long offset, maxoff;
+ int j, ino, nextfh;
+ int stored = 0;
+ char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
+ int ret;
+
+ maxoff = romfs_maxsize(i->i_sb);
+
+ offset = filp->f_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;
+ filp->f_pos = offset;
+ goto out;
+ }
+ filp->f_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 (filldir(dirent, fsname, j, offset, ino,
+ romfs_dtype_table[nextfh & ROMFH_TYPE]) < 0)
+ goto out;
+
+ stored++;
+ offset = nextfh & ROMFH_MASK;
+ }
+
+out:
+ return stored;
+}
+
+/*
+ * look up an entry in a directory
+ */
+static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ 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,
+ .readdir = romfs_readdir,
+};
+
+static 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, 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;
+
+ i->i_nlink = 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 (i->i_sb->s_mtd)
+ i->i_data.backing_dev_info =
+ i->i_sb->s_mtd->backing_dev_info;
+ 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:
+ printk(KERN_ERR "ROMFS: 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_destroy_inode(struct inode *inode)
+{
+ kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
+}
+
+/*
+ * 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)
+{
+ *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)
+ printk(KERN_WARNING "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))) {
+ printk(KERN_ERR "ROMFS: 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)
+ printk(KERN_NOTICE "ROMFS: 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 (!root)
+ goto error;
+
+ sb->s_root = d_alloc_root(root);
+ if (!sb->s_root)
+ goto error_i;
+
+ return 0;
+
+error_i:
+ iput(root);
+error:
+ return -EINVAL;
+error_rsb_inval:
+ ret = -EINVAL;
+error_rsb:
+ return ret;
+}
+
+/*
+ * get a superblock for mounting
+ */
+static int romfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name,
+ void *data, struct vfsmount *mnt)
+{
+ int ret = -EINVAL;
+
+#ifdef CONFIG_ROMFS_ON_MTD
+ ret = get_sb_mtd(fs_type, flags, dev_name, data, romfs_fill_super,
+ mnt);
+#endif
+#ifdef CONFIG_ROMFS_ON_BLOCK
+ if (ret == -EINVAL)
+ ret = get_sb_bdev(fs_type, flags, dev_name, data,
+ romfs_fill_super, mnt);
+#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",
+ .get_sb = romfs_get_sb,
+ .kill_sb = romfs_kill_sb,
+ .fs_flags = FS_REQUIRES_DEV,
+};
+
+/*
+ * 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;
+
+ printk(KERN_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) {
+ printk(KERN_ERR
+ "ROMFS error: Failed to initialise inode cache\n");
+ return -ENOMEM;
+ }
+ ret = register_filesystem(&romfs_fs_type);
+ if (ret) {
+ printk(KERN_ERR "ROMFS error: 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);
+ 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 */
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.