patch-2.3.35 linux/fs/cramfs/inode.c

• Lines: 489
• Date: Mon Dec 27 12:34:02 1999
• Orig file: v2.3.34/linux/fs/cramfs/inode.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.34/linux/fs/cramfs/inode.c linux/fs/cramfs/inode.c
@@ -0,0 +1,488 @@
+/*
+ * Compressed rom filesystem for Linux.
+ *
+ * Copyright (C) 1999 Linus Torvalds.
+ *
+ * This file is released under the GPL.
+ */
+
+/*
+ * These are the VFS interfaces to the compressed rom filesystem.
+ * The actual compression is based on zlib, see the other files.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/locks.h>
+
+#include <asm/uaccess.h>
+
+#include "cramfs.h"
+
+static struct super_operations cramfs_ops;
+static struct inode_operations cramfs_file_inode_operations;
+static struct inode_operations cramfs_dir_inode_operations;
+static struct inode_operations cramfs_symlink_inode_operations;
+
+#define CRAMINO(x)	((x)->offset?(x)->offset<<2:1)
+
+static struct inode *get_cramfs_inode(struct super_block *sb, struct cramfs_inode * cramfs_inode)
+{
+	struct inode * inode = get_empty_inode();
+
+	if (inode) {
+		inode->i_mode = cramfs_inode->mode;
+		inode->i_uid = cramfs_inode->uid;
+		inode->i_size = cramfs_inode->size;
+		inode->i_gid = cramfs_inode->gid;
+		inode->i_ino = CRAMINO(cramfs_inode);
+		inode->i_sb = sb;
+		inode->i_dev = sb->s_dev;
+		insert_inode_hash(inode);
+		if (S_ISREG(inode->i_mode))
+			inode->i_op = &cramfs_file_inode_operations;
+		else if (S_ISDIR(inode->i_mode))
+			inode->i_op = &cramfs_dir_inode_operations;
+		else if (S_ISLNK(inode->i_mode))
+			inode->i_op = &cramfs_symlink_inode_operations;
+		else {
+			inode->i_size = 0;
+			init_special_inode(inode, inode->i_mode, cramfs_inode->size);
+		}
+	}
+	return inode;
+}
+
+/*
+ * We have our own block cache: don't fill up the buffer cache
+ * with the rom-image, because the way the filesystem is set
+ * up the accesses should be fairly regular and cached in the
+ * page cache and dentry tree anyway..
+ *
+ * This also acts as a way to guarantee contiguous areas of
+ * up to 2*PAGE_CACHE_SIZE, so that the caller doesn't need
+ * to worry about end-of-buffer issues even when decompressing
+ * a full page cache.
+ */
+#define READ_BUFFERS (2)
+static unsigned char read_buffers[READ_BUFFERS][PAGE_CACHE_SIZE*4];
+static int buffer_blocknr[READ_BUFFERS];
+static int last_buffer = 0;
+
+static void *cramfs_read(struct super_block *sb, unsigned int offset)
+{
+	struct buffer_head * bh_array[4];
+	int i, blocknr, buffer;
+
+	blocknr = offset >> PAGE_CACHE_SHIFT;
+	offset &= PAGE_CACHE_SIZE-1;
+	for (i = 0; i < READ_BUFFERS; i++) {
+		if (blocknr == buffer_blocknr[i])
+			return read_buffers[i] + offset;
+	}
+
+	/* Ok, read in four buffers completely first */
+	for (i = 0; i < 4; i++)
+		bh_array[i] = bread(sb->s_dev, blocknr + i, PAGE_CACHE_SIZE);
+
+	/* Ok, copy them to the staging area without sleeping.. */
+	buffer = last_buffer;
+	last_buffer = buffer ^ 1;
+	buffer_blocknr[buffer] = blocknr;
+	for (i = 0; i < 4; i++) {
+		struct buffer_head * bh = bh_array[i];
+		if (bh) {
+			memcpy(read_buffers[buffer] + i*PAGE_CACHE_SIZE, bh->b_data, PAGE_CACHE_SIZE);
+			bforget(bh);
+		}
+		blocknr++;
+	}
+	return read_buffers[buffer] + offset;
+}
+			
+
+static struct super_block * cramfs_read_super(struct super_block *sb, void *data, int silent)
+{
+	int i;
+	struct cramfs_super super;
+	unsigned long root_offset;
+	struct super_block * retval = NULL;
+
+	lock_super(sb);
+	set_blocksize(sb->s_dev, PAGE_CACHE_SIZE);
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+
+	/* Invalidate the read buffers on mount: think disk change.. */
+	for (i = 0; i < READ_BUFFERS; i++)
+		buffer_blocknr[i] = -1;
+
+	/* Read the first block and get the superblock from it */
+	memcpy(&super, cramfs_read(sb, 0), sizeof(super));
+
+	/* Do sanity checks on the superblock */
+	if (super.magic != CRAMFS_MAGIC) {
+		printk("wrong magic\n");
+		goto out;
+	}
+	if (memcmp(super.signature, CRAMFS_SIGNATURE, sizeof(super.signature))) {
+		printk("wrong signature\n");
+		goto out;
+	}
+
+	/* Check that the root inode is in a sane state */
+	root_offset = super.root.offset << 2;
+	if (root_offset < sizeof(struct cramfs_super)) {
+		printk("root offset too small\n");
+		goto out;
+	}
+	if (root_offset >= super.size) {
+		printk("root offset too large (%lu %u)\n", root_offset, super.size);
+		goto out;
+	}
+	if (!S_ISDIR(super.root.mode)) {
+		printk("root is not a directory\n");
+		goto out;
+	}
+
+	/* Set it all up.. */
+	sb->s_op	= &cramfs_ops;
+	sb->s_root = d_alloc_root(get_cramfs_inode(sb, &super.root));
+	retval = sb;
+
+out:
+	unlock_super(sb);
+	return retval;
+}
+
+/* Nothing to do.. */
+static void cramfs_put_super(struct super_block *sb)
+{
+	return;
+}
+
+static int cramfs_statfs(struct super_block *sb, struct statfs *buf, int bufsize)
+{
+	struct statfs tmp;
+
+	memset(&tmp, 0, sizeof(tmp));
+	tmp.f_type = CRAMFS_MAGIC;
+	tmp.f_bsize = PAGE_CACHE_SIZE;
+	tmp.f_blocks = 0;
+	tmp.f_namelen = 255;
+	return copy_to_user(buf, &tmp, bufsize) ? -EFAULT : 0;
+}
+
+/*
+ * Read a cramfs directory entry..
+ *
+ * Remember: the inode number is the byte offset of the start
+ * of the directory..
+ */
+static int cramfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	struct inode *inode = filp->f_dentry->d_inode;
+	struct super_block *sb = inode->i_sb;
+	unsigned int offset;
+	int copied;
+
+	/* Offset within the thing.. */
+	offset = filp->f_pos;
+	if (offset >= inode->i_size)
+		return 0;
+	/* Directory entries are always 4-byte aligned */
+	if (offset & 3)
+		return -EINVAL;
+
+	copied = 0;
+	while (offset < inode->i_size) {
+		struct cramfs_inode *de;
+		unsigned long nextoffset;
+		char *name;
+		int namelen, error;
+
+		de = cramfs_read(sb, offset + inode->i_ino);
+		name = (char *)(de+1);
+
+		/*
+		 * Namelengths on disk are shifted by two
+		 * and the name padded out to 4-byte boundaries
+		 * with zeroes.
+		 */
+		namelen = de->namelen << 2;
+		nextoffset = offset + sizeof(*de) + namelen;
+		for (;;) {
+			if (!namelen)
+				return -EIO;
+			if (name[namelen-1])
+				break;
+			namelen--;
+		}
+		error = filldir(dirent, name, namelen, offset, CRAMINO(de));
+		if (error)
+			break;
+
+		offset = nextoffset;
+		filp->f_pos = offset;
+		copied++;
+	}
+	return 0;
+}
+
+/*
+ * Lookup and fill in the inode data..
+ */
+static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry)
+{
+	unsigned int offset = 0;
+
+	while (offset < dir->i_size) {
+		struct cramfs_inode *de;
+		char *name;
+		int namelen;
+
+		de = cramfs_read(dir->i_sb, offset + dir->i_ino);
+		name = (char *)(de+1);
+		namelen = de->namelen << 2;
+		offset += sizeof(*de) + namelen;
+
+		/* Quick check that the name is roughly the right length */
+		if (((dentry->d_name.len + 3) & ~3) != namelen)
+			continue;
+
+		for (;;) {
+			if (!namelen)
+				return ERR_PTR(-EIO);
+			if (name[namelen-1])
+				break;
+			namelen--;
+		}
+		if (namelen != dentry->d_name.len)
+			continue;
+		if (memcmp(dentry->d_name.name, name, namelen))
+			continue;
+		d_add(dentry, get_cramfs_inode(dir->i_sb, de));
+		return NULL;
+	}
+	d_add(dentry, NULL);
+	return NULL;
+}
+
+static int cramfs_readpage(struct dentry *dentry, struct page * page)
+{
+	struct inode *inode = dentry->d_inode;
+	unsigned long maxblock, bytes;
+
+	maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+	bytes = 0;
+	if (page->index < maxblock) {
+		struct super_block *sb = inode->i_sb;
+		unsigned long block_offset = inode->i_ino + page->index*4;
+		unsigned long start_offset = inode->i_ino + maxblock*4;
+		unsigned long end_offset;
+
+		end_offset = *(u32 *) cramfs_read(sb, block_offset);
+		if (page->index)
+			start_offset = *(u32 *) cramfs_read(sb, block_offset-4);
+
+		bytes = inode->i_size & (PAGE_CACHE_SIZE - 1);
+		if (page->index < maxblock)
+			bytes = PAGE_CACHE_SIZE;
+
+		cramfs_uncompress_block((void *) page_address(page), PAGE_CACHE_SIZE, cramfs_read(sb, start_offset), end_offset - start_offset);
+	}
+	memset((void *) (page_address(page) + bytes), 0, PAGE_CACHE_SIZE - bytes);
+	SetPageUptodate(page);
+	UnlockPage(page);
+	return 0;
+}
+
+static struct page *get_symlink_page(struct dentry *dentry)
+{
+	return read_cache_page(&dentry->d_inode->i_data, 0, (filler_t *)cramfs_readpage, dentry);
+}
+
+static int cramfs_readlink(struct dentry *dentry, char *buffer, int len)
+{
+	struct inode *inode = dentry->d_inode;
+	int retval;
+
+	if (!inode || !S_ISLNK(inode->i_mode))
+		return -EBADF;
+
+	retval = inode->i_size;
+	if (retval) {
+		int len;
+		struct page *page = get_symlink_page(dentry);
+
+		if (IS_ERR(page))
+			return PTR_ERR(page);
+		wait_on_page(page);
+		len = retval;
+		retval = -EIO;
+		if (Page_Uptodate(page)) {
+			retval = -EFAULT;
+			if (!copy_to_user(buffer, (void *) page_address(page), len))
+				retval = len;
+		}
+		page_cache_release(page);
+	}
+	return retval;
+}
+
+static struct dentry *cramfs_follow_link(struct dentry *dentry, struct dentry *base, unsigned int follow)
+{
+	struct page *page = get_symlink_page(dentry);
+	struct dentry *result;
+
+	if (IS_ERR(page)) {
+		dput(base);
+		return ERR_PTR(PTR_ERR(page));
+	}
+
+	result = lookup_dentry((void *) page_address(page), base, follow);
+	page_cache_release(page);
+	return result;
+}
+
+/*
+ * Our operations:
+ *
+ * A regular file can be read and mmap'ed.
+ */
+static struct file_operations cramfs_file_operations = {
+	NULL,			/* lseek - default */
+	generic_file_read,	/* read */
+	NULL,			/* write - bad */
+	NULL,			/* readdir */
+	NULL,			/* poll - default */
+	NULL,			/* ioctl */
+	generic_file_mmap,	/* mmap */
+	NULL,			/* open */
+	NULL,			/* flush */
+	NULL,			/* release */
+	NULL,			/* fsync */
+	NULL,			/* fasync */
+	NULL,			/* check_media_change */
+	NULL			/* revalidate */
+};
+
+/*
+ * A directory can only readdir
+ */
+static struct file_operations cramfs_directory_operations = {
+	NULL,			/* lseek - default */
+	NULL,			/* read */
+	NULL,			/* write - bad */
+	cramfs_readdir,		/* readdir */
+	NULL,			/* poll - default */
+	NULL,			/* ioctl */
+	NULL,			/* mmap */
+	NULL,			/* open */
+	NULL,			/* flush */
+	NULL,			/* release */
+	NULL,			/* fsync */
+	NULL,			/* fasync */
+	NULL,			/* check_media_change */
+	NULL			/* revalidate */
+};
+
+static struct inode_operations cramfs_file_inode_operations = {
+	&cramfs_file_operations,
+	NULL,			/* create */
+	NULL,			/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	NULL,			/* readlink */
+	NULL,			/* follow_link */
+	NULL,			/* get_block */
+	cramfs_readpage,	/* readpage */
+	NULL,			/* writepage */
+	NULL,			/* truncate */
+	NULL,			/* permission */
+	NULL			/* revalidate */
+};
+
+static struct inode_operations cramfs_dir_inode_operations = {
+	&cramfs_directory_operations,
+	NULL,			/* create */
+	cramfs_lookup,		/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	NULL,			/* readlink */
+	NULL,			/* follow_link */
+	NULL,			/* get_block */
+	NULL,			/* readpage */
+	NULL,			/* writepage */
+	NULL,			/* truncate */
+	NULL,			/* permission */
+	NULL			/* revalidate */
+};
+
+static struct inode_operations cramfs_symlink_inode_operations = {
+	NULL,			/* symlinks do not have files */
+	NULL,			/* create */
+	NULL,			/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	cramfs_readlink,		/* readlink */
+	cramfs_follow_link,	/* follow_link */
+	NULL,			/* get_block */
+	NULL,			/* readpage */
+	NULL,			/* writepage */
+	NULL,			/* truncate */
+	NULL,			/* permission */
+	NULL			/* revalidate */
+};
+
+static struct super_operations cramfs_ops = {
+	NULL,			/* read inode */
+	NULL,			/* write inode */
+	NULL,			/* put inode */
+	NULL,			/* delete inode */
+	NULL,			/* notify change */
+	cramfs_put_super,		/* put super */
+	NULL,			/* write super */
+	cramfs_statfs,		/* statfs */
+	NULL			/* remount */
+};
+
+static struct file_system_type cramfs_fs_type = {
+	"cramfs",
+	FS_REQUIRES_DEV,
+	cramfs_read_super,
+	NULL
+};
+
+static int __init init_cramfs_fs(void)
+{
+	cramfs_uncompress_init();
+	return register_filesystem(&cramfs_fs_type);
+}
+
+static void __exit exit_cramfs_fs(void)
+{
+	cramfs_uncompress_exit();
+	unregister_filesystem(&cramfs_fs_type);
+}
+
+module_init(init_cramfs_fs)
+module_exit(exit_cramfs_fs)