From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- fs/cramfs/inode.c | 525 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 525 insertions(+) create mode 100644 fs/cramfs/inode.c (limited to 'fs/cramfs/inode.c') 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +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"); -- cgit v1.2.3-59-g8ed1b