1 files changed, 648 insertions, 0 deletions

diff --git a/fs/romfs/super.c b/fs/romfs/super.c
new file mode 100644
index 000000000000..1e548a4975ba
--- /dev/null
+++ b/fs/romfs/super.c
@@ -0,0 +1,648 @@
+/* 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_strncmp(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)
+{
+        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;
+        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 */