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-rw-r--r--fs/cramfs/inode.c525
1 files changed, 525 insertions, 0 deletions
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
new file mode 100644
index 000000000000..6c285efa2004
--- /dev/null
+++ b/fs/cramfs/inode.c
@@ -0,0 +1,525 @@
+/*
+ * 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/blkdev.h>
+#include <linux/cramfs_fs.h>
+#include <linux/slab.h>
+#include <linux/cramfs_fs_sb.h>
+#include <linux/buffer_head.h>
+#include <linux/vfs.h>
+#include <asm/semaphore.h>
+
+#include <asm/uaccess.h>
+
+static struct super_operations cramfs_ops;
+static struct inode_operations cramfs_dir_inode_operations;
+static struct file_operations cramfs_directory_operations;
+static struct address_space_operations cramfs_aops;
+
+static DECLARE_MUTEX(read_mutex);
+
+
+/* These two macros may change in future, to provide better st_ino
+ semantics. */
+#define CRAMINO(x) ((x)->offset?(x)->offset<<2:1)
+#define OFFSET(x) ((x)->i_ino)
+
+static struct inode *get_cramfs_inode(struct super_block *sb, struct cramfs_inode * cramfs_inode)
+{
+ struct inode * inode = new_inode(sb);
+ static struct timespec zerotime;
+
+ if (inode) {
+ inode->i_mode = cramfs_inode->mode;
+ inode->i_uid = cramfs_inode->uid;
+ inode->i_size = cramfs_inode->size;
+ inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
+ inode->i_blksize = PAGE_CACHE_SIZE;
+ inode->i_gid = cramfs_inode->gid;
+ /* Struct copy intentional */
+ inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
+ inode->i_ino = CRAMINO(cramfs_inode);
+ /* inode->i_nlink is left 1 - arguably wrong for directories,
+ but it's the best we can do without reading the directory
+ contents. 1 yields the right result in GNU find, even
+ without -noleaf option. */
+ insert_inode_hash(inode);
+ if (S_ISREG(inode->i_mode)) {
+ inode->i_fop = &generic_ro_fops;
+ inode->i_data.a_ops = &cramfs_aops;
+ } else if (S_ISDIR(inode->i_mode)) {
+ inode->i_op = &cramfs_dir_inode_operations;
+ inode->i_fop = &cramfs_directory_operations;
+ } else if (S_ISLNK(inode->i_mode)) {
+ inode->i_op = &page_symlink_inode_operations;
+ inode->i_data.a_ops = &cramfs_aops;
+ } else {
+ inode->i_size = 0;
+ inode->i_blocks = 0;
+ init_special_inode(inode, inode->i_mode,
+ old_decode_dev(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
+ * BLKS_PER_BUF*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)
+/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
+#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
+
+/*
+ * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
+ * data that takes up more space than the original and with unlucky
+ * alignment.
+ */
+#define BLKS_PER_BUF_SHIFT (2)
+#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
+#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
+
+static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
+static unsigned buffer_blocknr[READ_BUFFERS];
+static struct super_block * buffer_dev[READ_BUFFERS];
+static int next_buffer;
+
+/*
+ * Returns a pointer to a buffer containing at least LEN bytes of
+ * filesystem starting at byte offset OFFSET into the filesystem.
+ */
+static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
+{
+ struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
+ struct page *pages[BLKS_PER_BUF];
+ unsigned i, blocknr, buffer, unread;
+ unsigned long devsize;
+ char *data;
+
+ if (!len)
+ return NULL;
+ blocknr = offset >> PAGE_CACHE_SHIFT;
+ offset &= PAGE_CACHE_SIZE - 1;
+
+ /* Check if an existing buffer already has the data.. */
+ for (i = 0; i < READ_BUFFERS; i++) {
+ unsigned int blk_offset;
+
+ if (buffer_dev[i] != sb)
+ continue;
+ if (blocknr < buffer_blocknr[i])
+ continue;
+ blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
+ blk_offset += offset;
+ if (blk_offset + len > BUFFER_SIZE)
+ continue;
+ return read_buffers[i] + blk_offset;
+ }
+
+ devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
+
+ /* Ok, read in BLKS_PER_BUF pages completely first. */
+ unread = 0;
+ for (i = 0; i < BLKS_PER_BUF; i++) {
+ struct page *page = NULL;
+
+ if (blocknr + i < devsize) {
+ page = read_cache_page(mapping, blocknr + i,
+ (filler_t *)mapping->a_ops->readpage,
+ NULL);
+ /* synchronous error? */
+ if (IS_ERR(page))
+ page = NULL;
+ }
+ pages[i] = page;
+ }
+
+ for (i = 0; i < BLKS_PER_BUF; i++) {
+ struct page *page = pages[i];
+ if (page) {
+ wait_on_page_locked(page);
+ if (!PageUptodate(page)) {
+ /* asynchronous error */
+ page_cache_release(page);
+ pages[i] = NULL;
+ }
+ }
+ }
+
+ buffer = next_buffer;
+ next_buffer = NEXT_BUFFER(buffer);
+ buffer_blocknr[buffer] = blocknr;
+ buffer_dev[buffer] = sb;
+
+ data = read_buffers[buffer];
+ for (i = 0; i < BLKS_PER_BUF; i++) {
+ struct page *page = pages[i];
+ if (page) {
+ memcpy(data, kmap(page), PAGE_CACHE_SIZE);
+ kunmap(page);
+ page_cache_release(page);
+ } else
+ memset(data, 0, PAGE_CACHE_SIZE);
+ data += PAGE_CACHE_SIZE;
+ }
+ return read_buffers[buffer] + offset;
+}
+
+static void cramfs_put_super(struct super_block *sb)
+{
+ kfree(sb->s_fs_info);
+ sb->s_fs_info = NULL;
+}
+
+static int cramfs_remount(struct super_block *sb, int *flags, char *data)
+{
+ *flags |= MS_RDONLY;
+ return 0;
+}
+
+static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+ int i;
+ struct cramfs_super super;
+ unsigned long root_offset;
+ struct cramfs_sb_info *sbi;
+ struct inode *root;
+
+ sb->s_flags |= MS_RDONLY;
+
+ sbi = kmalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
+ if (!sbi)
+ return -ENOMEM;
+ sb->s_fs_info = sbi;
+ memset(sbi, 0, sizeof(struct cramfs_sb_info));
+
+ /* Invalidate the read buffers on mount: think disk change.. */
+ down(&read_mutex);
+ 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)), sizeof(super));
+ up(&read_mutex);
+
+ /* Do sanity checks on the superblock */
+ if (super.magic != CRAMFS_MAGIC) {
+ /* check at 512 byte offset */
+ down(&read_mutex);
+ memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
+ up(&read_mutex);
+ if (super.magic != CRAMFS_MAGIC) {
+ if (!silent)
+ printk(KERN_ERR "cramfs: wrong magic\n");
+ goto out;
+ }
+ }
+
+ /* get feature flags first */
+ if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
+ printk(KERN_ERR "cramfs: unsupported filesystem features\n");
+ goto out;
+ }
+
+ /* Check that the root inode is in a sane state */
+ if (!S_ISDIR(super.root.mode)) {
+ printk(KERN_ERR "cramfs: root is not a directory\n");
+ goto out;
+ }
+ root_offset = super.root.offset << 2;
+ if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
+ sbi->size=super.size;
+ sbi->blocks=super.fsid.blocks;
+ sbi->files=super.fsid.files;
+ } else {
+ sbi->size=1<<28;
+ sbi->blocks=0;
+ sbi->files=0;
+ }
+ sbi->magic=super.magic;
+ sbi->flags=super.flags;
+ if (root_offset == 0)
+ printk(KERN_INFO "cramfs: empty filesystem");
+ else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
+ ((root_offset != sizeof(struct cramfs_super)) &&
+ (root_offset != 512 + sizeof(struct cramfs_super))))
+ {
+ printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
+ goto out;
+ }
+
+ /* Set it all up.. */
+ sb->s_op = &cramfs_ops;
+ root = get_cramfs_inode(sb, &super.root);
+ if (!root)
+ goto out;
+ sb->s_root = d_alloc_root(root);
+ if (!sb->s_root) {
+ iput(root);
+ goto out;
+ }
+ return 0;
+out:
+ kfree(sbi);
+ sb->s_fs_info = NULL;
+ return -EINVAL;
+}
+
+static int cramfs_statfs(struct super_block *sb, struct kstatfs *buf)
+{
+ buf->f_type = CRAMFS_MAGIC;
+ buf->f_bsize = PAGE_CACHE_SIZE;
+ buf->f_blocks = CRAMFS_SB(sb)->blocks;
+ buf->f_bfree = 0;
+ buf->f_bavail = 0;
+ buf->f_files = CRAMFS_SB(sb)->files;
+ buf->f_ffree = 0;
+ buf->f_namelen = CRAMFS_MAXPATHLEN;
+ return 0;
+}
+
+/*
+ * Read a cramfs directory entry.
+ */
+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;
+ char *buf;
+ 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;
+
+ buf = kmalloc(256, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ copied = 0;
+ while (offset < inode->i_size) {
+ struct cramfs_inode *de;
+ unsigned long nextoffset;
+ char *name;
+ ino_t ino;
+ mode_t mode;
+ int namelen, error;
+
+ down(&read_mutex);
+ de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+256);
+ 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;
+ memcpy(buf, name, namelen);
+ ino = CRAMINO(de);
+ mode = de->mode;
+ up(&read_mutex);
+ nextoffset = offset + sizeof(*de) + namelen;
+ for (;;) {
+ if (!namelen) {
+ kfree(buf);
+ return -EIO;
+ }
+ if (buf[namelen-1])
+ break;
+ namelen--;
+ }
+ error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
+ if (error)
+ break;
+
+ offset = nextoffset;
+ filp->f_pos = offset;
+ copied++;
+ }
+ kfree(buf);
+ return 0;
+}
+
+/*
+ * Lookup and fill in the inode data..
+ */
+static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
+{
+ unsigned int offset = 0;
+ int sorted;
+
+ down(&read_mutex);
+ sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
+ while (offset < dir->i_size) {
+ struct cramfs_inode *de;
+ char *name;
+ int namelen, retval;
+
+ de = cramfs_read(dir->i_sb, OFFSET(dir) + offset, sizeof(*de)+256);
+ name = (char *)(de+1);
+
+ /* Try to take advantage of sorted directories */
+ if (sorted && (dentry->d_name.name[0] < name[0]))
+ break;
+
+ 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) {
+ up(&read_mutex);
+ return ERR_PTR(-EIO);
+ }
+ if (name[namelen-1])
+ break;
+ namelen--;
+ }
+ if (namelen != dentry->d_name.len)
+ continue;
+ retval = memcmp(dentry->d_name.name, name, namelen);
+ if (retval > 0)
+ continue;
+ if (!retval) {
+ struct cramfs_inode entry = *de;
+ up(&read_mutex);
+ d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
+ return NULL;
+ }
+ /* else (retval < 0) */
+ if (sorted)
+ break;
+ }
+ up(&read_mutex);
+ d_add(dentry, NULL);
+ return NULL;
+}
+
+static int cramfs_readpage(struct file *file, struct page * page)
+{
+ struct inode *inode = page->mapping->host;
+ u32 maxblock, bytes_filled;
+ void *pgdata;
+
+ maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ bytes_filled = 0;
+ if (page->index < maxblock) {
+ struct super_block *sb = inode->i_sb;
+ u32 blkptr_offset = OFFSET(inode) + page->index*4;
+ u32 start_offset, compr_len;
+
+ start_offset = OFFSET(inode) + maxblock*4;
+ down(&read_mutex);
+ if (page->index)
+ start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4, 4);
+ compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) - start_offset);
+ up(&read_mutex);
+ pgdata = kmap(page);
+ if (compr_len == 0)
+ ; /* hole */
+ else {
+ down(&read_mutex);
+ bytes_filled = cramfs_uncompress_block(pgdata,
+ PAGE_CACHE_SIZE,
+ cramfs_read(sb, start_offset, compr_len),
+ compr_len);
+ up(&read_mutex);
+ }
+ } else
+ pgdata = kmap(page);
+ memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
+ kunmap(page);
+ flush_dcache_page(page);
+ SetPageUptodate(page);
+ unlock_page(page);
+ return 0;
+}
+
+static struct address_space_operations cramfs_aops = {
+ .readpage = cramfs_readpage
+};
+
+/*
+ * Our operations:
+ */
+
+/*
+ * A directory can only readdir
+ */
+static struct file_operations cramfs_directory_operations = {
+ .llseek = generic_file_llseek,
+ .read = generic_read_dir,
+ .readdir = cramfs_readdir,
+};
+
+static struct inode_operations cramfs_dir_inode_operations = {
+ .lookup = cramfs_lookup,
+};
+
+static struct super_operations cramfs_ops = {
+ .put_super = cramfs_put_super,
+ .remount_fs = cramfs_remount,
+ .statfs = cramfs_statfs,
+};
+
+static struct super_block *cramfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ return get_sb_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
+}
+
+static struct file_system_type cramfs_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "cramfs",
+ .get_sb = cramfs_get_sb,
+ .kill_sb = kill_block_super,
+ .fs_flags = FS_REQUIRES_DEV,
+};
+
+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)
+MODULE_LICENSE("GPL");
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-02 19:43:29 +0000