diff options
Diffstat (limited to 'fs/cramfs')
| -rw-r--r-- | fs/cramfs/Kconfig | 19 | ||||
| -rw-r--r-- | fs/cramfs/Makefile | 7 | ||||
| -rw-r--r-- | fs/cramfs/README | 168 | ||||
| -rw-r--r-- | fs/cramfs/inode.c | 598 | ||||
| -rw-r--r-- | fs/cramfs/uncompress.c | 77 |
5 files changed, 869 insertions, 0 deletions
diff --git a/fs/cramfs/Kconfig b/fs/cramfs/Kconfig new file mode 100644 index 00000000..cd06466f --- /dev/null +++ b/fs/cramfs/Kconfig @@ -0,0 +1,19 @@ +config CRAMFS + tristate "Compressed ROM file system support (cramfs)" + depends on BLOCK + select ZLIB_INFLATE + help + Saying Y here includes support for CramFs (Compressed ROM File + System). CramFs is designed to be a simple, small, and compressed + file system for ROM based embedded systems. CramFs is read-only, + limited to 256MB file systems (with 16MB files), and doesn't support + 16/32 bits uid/gid, hard links and timestamps. + + See <file:Documentation/filesystems/cramfs.txt> and + <file:fs/cramfs/README> for further information. + + To compile this as a module, choose M here: the module will be called + cramfs. Note that the root file system (the one containing the + directory /) cannot be compiled as a module. + + If unsure, say N. diff --git a/fs/cramfs/Makefile b/fs/cramfs/Makefile new file mode 100644 index 00000000..92ebb464 --- /dev/null +++ b/fs/cramfs/Makefile @@ -0,0 +1,7 @@ +# +# Makefile for the linux cramfs routines. +# + +obj-$(CONFIG_CRAMFS) += cramfs.o + +cramfs-objs := inode.o uncompress.o diff --git a/fs/cramfs/README b/fs/cramfs/README new file mode 100644 index 00000000..445d1c2d --- /dev/null +++ b/fs/cramfs/README @@ -0,0 +1,168 @@ +Notes on Filesystem Layout +-------------------------- + +These notes describe what mkcramfs generates. Kernel requirements are +a bit looser, e.g. it doesn't care if the <file_data> items are +swapped around (though it does care that directory entries (inodes) in +a given directory are contiguous, as this is used by readdir). + +All data is currently in host-endian format; neither mkcramfs nor the +kernel ever do swabbing. (See section `Block Size' below.) + +<filesystem>: + <superblock> + <directory_structure> + <data> + +<superblock>: struct cramfs_super (see cramfs_fs.h). + +<directory_structure>: + For each file: + struct cramfs_inode (see cramfs_fs.h). + Filename. Not generally null-terminated, but it is + null-padded to a multiple of 4 bytes. + +The order of inode traversal is described as "width-first" (not to be +confused with breadth-first); i.e. like depth-first but listing all of +a directory's entries before recursing down its subdirectories: the +same order as `ls -AUR' (but without the /^\..*:$/ directory header +lines); put another way, the same order as `find -type d -exec +ls -AU1 {} \;'. + +Beginning in 2.4.7, directory entries are sorted. This optimization +allows cramfs_lookup to return more quickly when a filename does not +exist, speeds up user-space directory sorts, etc. + +<data>: + One <file_data> for each file that's either a symlink or a + regular file of non-zero st_size. + +<file_data>: + nblocks * <block_pointer> + (where nblocks = (st_size - 1) / blksize + 1) + nblocks * <block> + padding to multiple of 4 bytes + +The i'th <block_pointer> for a file stores the byte offset of the +*end* of the i'th <block> (i.e. one past the last byte, which is the +same as the start of the (i+1)'th <block> if there is one). The first +<block> immediately follows the last <block_pointer> for the file. +<block_pointer>s are each 32 bits long. + +The order of <file_data>'s is a depth-first descent of the directory +tree, i.e. the same order as `find -size +0 \( -type f -o -type l \) +-print'. + + +<block>: The i'th <block> is the output of zlib's compress function +applied to the i'th blksize-sized chunk of the input data. +(For the last <block> of the file, the input may of course be smaller.) +Each <block> may be a different size. (See <block_pointer> above.) +<block>s are merely byte-aligned, not generally u32-aligned. + + +Holes +----- + +This kernel supports cramfs holes (i.e. [efficient representation of] +blocks in uncompressed data consisting entirely of NUL bytes), but by +default mkcramfs doesn't test for & create holes, since cramfs in +kernels up to at least 2.3.39 didn't support holes. Run mkcramfs +with -z if you want it to create files that can have holes in them. + + +Tools +----- + +The cramfs user-space tools, including mkcramfs and cramfsck, are +located at <http://sourceforge.net/projects/cramfs/>. + + +Future Development +================== + +Block Size +---------- + +(Block size in cramfs refers to the size of input data that is +compressed at a time. It's intended to be somewhere around +PAGE_CACHE_SIZE for cramfs_readpage's convenience.) + +The superblock ought to indicate the block size that the fs was +written for, since comments in <linux/pagemap.h> indicate that +PAGE_CACHE_SIZE may grow in future (if I interpret the comment +correctly). + +Currently, mkcramfs #define's PAGE_CACHE_SIZE as 4096 and uses that +for blksize, whereas Linux-2.3.39 uses its PAGE_CACHE_SIZE, which in +turn is defined as PAGE_SIZE (which can be as large as 32KB on arm). +This discrepancy is a bug, though it's not clear which should be +changed. + +One option is to change mkcramfs to take its PAGE_CACHE_SIZE from +<asm/page.h>. Personally I don't like this option, but it does +require the least amount of change: just change `#define +PAGE_CACHE_SIZE (4096)' to `#include <asm/page.h>'. The disadvantage +is that the generated cramfs cannot always be shared between different +kernels, not even necessarily kernels of the same architecture if +PAGE_CACHE_SIZE is subject to change between kernel versions +(currently possible with arm and ia64). + +The remaining options try to make cramfs more sharable. + +One part of that is addressing endianness. The two options here are +`always use little-endian' (like ext2fs) or `writer chooses +endianness; kernel adapts at runtime'. Little-endian wins because of +code simplicity and little CPU overhead even on big-endian machines. + +The cost of swabbing is changing the code to use the le32_to_cpu +etc. macros as used by ext2fs. We don't need to swab the compressed +data, only the superblock, inodes and block pointers. + + +The other part of making cramfs more sharable is choosing a block +size. The options are: + + 1. Always 4096 bytes. + + 2. Writer chooses blocksize; kernel adapts but rejects blocksize > + PAGE_CACHE_SIZE. + + 3. Writer chooses blocksize; kernel adapts even to blocksize > + PAGE_CACHE_SIZE. + +It's easy enough to change the kernel to use a smaller value than +PAGE_CACHE_SIZE: just make cramfs_readpage read multiple blocks. + +The cost of option 1 is that kernels with a larger PAGE_CACHE_SIZE +value don't get as good compression as they can. + +The cost of option 2 relative to option 1 is that the code uses +variables instead of #define'd constants. The gain is that people +with kernels having larger PAGE_CACHE_SIZE can make use of that if +they don't mind their cramfs being inaccessible to kernels with +smaller PAGE_CACHE_SIZE values. + +Option 3 is easy to implement if we don't mind being CPU-inefficient: +e.g. get readpage to decompress to a buffer of size MAX_BLKSIZE (which +must be no larger than 32KB) and discard what it doesn't need. +Getting readpage to read into all the covered pages is harder. + +The main advantage of option 3 over 1, 2, is better compression. The +cost is greater complexity. Probably not worth it, but I hope someone +will disagree. (If it is implemented, then I'll re-use that code in +e2compr.) + + +Another cost of 2 and 3 over 1 is making mkcramfs use a different +block size, but that just means adding and parsing a -b option. + + +Inode Size +---------- + +Given that cramfs will probably be used for CDs etc. as well as just +silicon ROMs, it might make sense to expand the inode a little from +its current 12 bytes. Inodes other than the root inode are followed +by filename, so the expansion doesn't even have to be a multiple of 4 +bytes. diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c new file mode 100644 index 00000000..d013c464 --- /dev/null +++ b/fs/cramfs/inode.c @@ -0,0 +1,598 @@ +/* + * 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/vfs.h> +#include <linux/mutex.h> + +#include <asm/uaccess.h> + +static const struct super_operations cramfs_ops; +static const struct inode_operations cramfs_dir_inode_operations; +static const struct file_operations cramfs_directory_operations; +static const struct address_space_operations cramfs_aops; + +static DEFINE_MUTEX(read_mutex); + + +/* These macros may change in future, to provide better st_ino semantics. */ +#define OFFSET(x) ((x)->i_ino) + +static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset) +{ + if (!cino->offset) + return offset + 1; + if (!cino->size) + return offset + 1; + + /* + * The file mode test fixes buggy mkcramfs implementations where + * cramfs_inode->offset is set to a non zero value for entries + * which did not contain data, like devices node and fifos. + */ + switch (cino->mode & S_IFMT) { + case S_IFREG: + case S_IFDIR: + case S_IFLNK: + return cino->offset << 2; + default: + break; + } + return offset + 1; +} + +static struct inode *get_cramfs_inode(struct super_block *sb, + const struct cramfs_inode *cramfs_inode, unsigned int offset) +{ + struct inode *inode; + static struct timespec zerotime; + + inode = iget_locked(sb, cramino(cramfs_inode, offset)); + if (!inode) + return ERR_PTR(-ENOMEM); + if (!(inode->i_state & I_NEW)) + return inode; + + switch (cramfs_inode->mode & S_IFMT) { + case S_IFREG: + inode->i_fop = &generic_ro_fops; + inode->i_data.a_ops = &cramfs_aops; + break; + case S_IFDIR: + inode->i_op = &cramfs_dir_inode_operations; + inode->i_fop = &cramfs_directory_operations; + break; + case S_IFLNK: + inode->i_op = &page_symlink_inode_operations; + inode->i_data.a_ops = &cramfs_aops; + break; + default: + init_special_inode(inode, cramfs_inode->mode, + old_decode_dev(cramfs_inode->size)); + } + + inode->i_mode = cramfs_inode->mode; + inode->i_uid = cramfs_inode->uid; + inode->i_gid = cramfs_inode->gid; + + /* if the lower 2 bits are zero, the inode contains data */ + if (!(inode->i_ino & 3)) { + inode->i_size = cramfs_inode->size; + inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1; + } + + /* Struct copy intentional */ + inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime; + /* 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. */ + + unlock_new_inode(inode); + + 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; + 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. */ + for (i = 0; i < BLKS_PER_BUF; i++) { + struct page *page = NULL; + + if (blocknr + i < devsize) { + page = read_mapping_page_async(mapping, blocknr + i, + 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 = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); + if (!sbi) + return -ENOMEM; + sb->s_fs_info = sbi; + + /* Invalidate the read buffers on mount: think disk change.. */ + mutex_lock(&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)); + mutex_unlock(&read_mutex); + + /* Do sanity checks on the superblock */ + if (super.magic != CRAMFS_MAGIC) { + /* check for wrong endianness */ + if (super.magic == CRAMFS_MAGIC_WEND) { + if (!silent) + printk(KERN_ERR "cramfs: wrong endianness\n"); + goto out; + } + + /* check at 512 byte offset */ + mutex_lock(&read_mutex); + memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super)); + mutex_unlock(&read_mutex); + if (super.magic != CRAMFS_MAGIC) { + if (super.magic == CRAMFS_MAGIC_WEND && !silent) + printk(KERN_ERR "cramfs: wrong endianness\n"); + else 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; + } + /* correct strange, hard-coded permissions of mkcramfs */ + super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH); + + 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, 0); + if (IS_ERR(root)) + goto out; + sb->s_root = d_make_root(root); + if (!sb->s_root) + goto out; + return 0; +out: + kfree(sbi); + sb->s_fs_info = NULL; + return -EINVAL; +} + +static int cramfs_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 = 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_fsid.val[0] = (u32)id; + buf->f_fsid.val[1] = (u32)(id >> 32); + 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_path.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(CRAMFS_MAXPATHLEN, 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; + umode_t mode; + int namelen, error; + + mutex_lock(&read_mutex); + de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN); + 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, OFFSET(inode) + offset); + mode = de->mode; + mutex_unlock(&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; + struct inode *inode = NULL; + int sorted; + + mutex_lock(&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; + int dir_off = OFFSET(dir) + offset; + + de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN); + 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) { + inode = ERR_PTR(-EIO); + goto out; + } + 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) { + inode = get_cramfs_inode(dir->i_sb, de, dir_off); + break; + } + /* else (retval < 0) */ + if (sorted) + break; + } +out: + mutex_unlock(&read_mutex); + if (IS_ERR(inode)) + return ERR_CAST(inode); + d_add(dentry, inode); + return NULL; +} + +static int cramfs_readpage(struct file *file, struct page * page) +{ + struct inode *inode = page->mapping->host; + u32 maxblock; + int bytes_filled; + void *pgdata; + + maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + bytes_filled = 0; + pgdata = kmap(page); + + 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; + mutex_lock(&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); + mutex_unlock(&read_mutex); + + if (compr_len == 0) + ; /* hole */ + else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) { + pr_err("cramfs: bad compressed blocksize %u\n", + compr_len); + goto err; + } else { + mutex_lock(&read_mutex); + bytes_filled = cramfs_uncompress_block(pgdata, + PAGE_CACHE_SIZE, + cramfs_read(sb, start_offset, compr_len), + compr_len); + mutex_unlock(&read_mutex); + if (unlikely(bytes_filled < 0)) + goto err; + } + } + + memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled); + flush_dcache_page(page); + kunmap(page); + SetPageUptodate(page); + unlock_page(page); + return 0; + +err: + kunmap(page); + ClearPageUptodate(page); + SetPageError(page); + unlock_page(page); + return 0; +} + +static const struct address_space_operations cramfs_aops = { + .readpage = cramfs_readpage +}; + +/* + * Our operations: + */ + +/* + * A directory can only readdir + */ +static const struct file_operations cramfs_directory_operations = { + .llseek = generic_file_llseek, + .read = generic_read_dir, + .readdir = cramfs_readdir, +}; + +static const struct inode_operations cramfs_dir_inode_operations = { + .lookup = cramfs_lookup, +}; + +static const struct super_operations cramfs_ops = { + .put_super = cramfs_put_super, + .remount_fs = cramfs_remount, + .statfs = cramfs_statfs, +}; + +static struct dentry *cramfs_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data) +{ + return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super); +} + +static struct file_system_type cramfs_fs_type = { + .owner = THIS_MODULE, + .name = "cramfs", + .mount = cramfs_mount, + .kill_sb = kill_block_super, + .fs_flags = FS_REQUIRES_DEV, +}; + +static int __init init_cramfs_fs(void) +{ + int rv; + + rv = cramfs_uncompress_init(); + if (rv < 0) + return rv; + rv = register_filesystem(&cramfs_fs_type); + if (rv < 0) + cramfs_uncompress_exit(); + return rv; +} + +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"); diff --git a/fs/cramfs/uncompress.c b/fs/cramfs/uncompress.c new file mode 100644 index 00000000..02332980 --- /dev/null +++ b/fs/cramfs/uncompress.c @@ -0,0 +1,77 @@ +/* + * uncompress.c + * + * (C) Copyright 1999 Linus Torvalds + * + * cramfs interfaces to the uncompression library. There's really just + * three entrypoints: + * + * - cramfs_uncompress_init() - called to initialize the thing. + * - cramfs_uncompress_exit() - tell me when you're done + * - cramfs_uncompress_block() - uncompress a block. + * + * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We + * only have one stream, and we'll initialize it only once even if it + * then is used by multiple filesystems. + */ + +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/vmalloc.h> +#include <linux/zlib.h> +#include <linux/cramfs_fs.h> + +static z_stream stream; +static int initialized; + +/* Returns length of decompressed data. */ +int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen) +{ + int err; + + stream.next_in = src; + stream.avail_in = srclen; + + stream.next_out = dst; + stream.avail_out = dstlen; + + err = zlib_inflateReset(&stream); + if (err != Z_OK) { + printk("zlib_inflateReset error %d\n", err); + zlib_inflateEnd(&stream); + zlib_inflateInit(&stream); + } + + err = zlib_inflate(&stream, Z_FINISH); + if (err != Z_STREAM_END) + goto err; + return stream.total_out; + +err: + printk("Error %d while decompressing!\n", err); + printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen); + return -EIO; +} + +int cramfs_uncompress_init(void) +{ + if (!initialized++) { + stream.workspace = vmalloc(zlib_inflate_workspacesize()); + if ( !stream.workspace ) { + initialized = 0; + return -ENOMEM; + } + stream.next_in = NULL; + stream.avail_in = 0; + zlib_inflateInit(&stream); + } + return 0; +} + +void cramfs_uncompress_exit(void) +{ + if (!--initialized) { + zlib_inflateEnd(&stream); + vfree(stream.workspace); + } +} |