super.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

 * NOTE: @sb->s_flags contains the mount options flags.
 */
static int ntfs_fill_super(struct super_block *sb, void *opt, const int silent)
{
	ntfs_volume *vol;
	struct buffer_head *bh;
	struct inode *tmp_ino;
	int result;

	ntfs_debug("Entering.");
#ifndef NTFS_RW
	sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
#endif
	/* Allocate a new ntfs_volume and place it in sb->s_fs_info. */
	sb->s_fs_info = kmalloc(sizeof(ntfs_volume), GFP_NOFS);
	vol = NTFS_SB(sb);
	if (!vol) {
		if (!silent)
			ntfs_error(sb, "Allocation of NTFS volume structure "
					"failed. Aborting mount...");
		return -ENOMEM;
	}
	/* Initialize ntfs_volume structure. */
	memset(vol, 0, sizeof(ntfs_volume));
	vol->sb = sb;
	vol->upcase = NULL;
	vol->mft_ino = NULL;
	vol->mftbmp_ino = NULL;
	init_rwsem(&vol->mftbmp_lock);
	vol->mftmirr_ino = NULL;
	vol->lcnbmp_ino = NULL;
	init_rwsem(&vol->lcnbmp_lock);
	vol->vol_ino = NULL;
	vol->root_ino = NULL;
	vol->secure_ino = NULL;
	vol->uid = vol->gid = 0;
	vol->flags = 0;
	vol->on_errors = 0;
	vol->mft_zone_multiplier = 0;
	vol->nls_map = NULL;

	/*
	 * Default is group and other don't have any access to files or
	 * directories while owner has full access. Further, files by default
	 * are not executable but directories are of course browseable.
	 */
	vol->fmask = 0177;
	vol->dmask = 0077;

	/* Important to get the mount options dealt with now. */
	if (!parse_options(vol, (char*)opt))
		goto err_out_now;

	/*
	 * TODO: Fail safety check. In the future we should really be able to
	 * cope with this being the case, but for now just bail out.
	 */
	if (bdev_hardsect_size(sb->s_bdev) > NTFS_BLOCK_SIZE) {
		if (!silent)
			ntfs_error(sb, "Device has unsupported hardsect_size.");
		goto err_out_now;
	}

	/* Setup the device access block size to NTFS_BLOCK_SIZE. */
	if (sb_set_blocksize(sb, NTFS_BLOCK_SIZE) != NTFS_BLOCK_SIZE) {
		if (!silent)
			ntfs_error(sb, "Unable to set block size.");
		goto err_out_now;
	}

	/* Get the size of the device in units of NTFS_BLOCK_SIZE bytes. */
	vol->nr_blocks = sb->s_bdev->bd_inode->i_size >> NTFS_BLOCK_SIZE_BITS;

	/* Read the boot sector and return unlocked buffer head to it. */
	if (!(bh = read_ntfs_boot_sector(sb, silent))) {
		if (!silent)
			ntfs_error(sb, "Not an NTFS volume.");
		goto err_out_now;
	}

	/*
	 * Extract the data from the boot sector and setup the ntfs super block
	 * using it.
	 */
	result = parse_ntfs_boot_sector(vol, (NTFS_BOOT_SECTOR*)bh->b_data);

	brelse(bh);

	if (!result) {
		if (!silent)
			ntfs_error(sb, "Unsupported NTFS filesystem.");
		goto err_out_now;
	}

	/*
	 * TODO: When we start coping with sector sizes different from
	 * NTFS_BLOCK_SIZE, we now probably need to set the blocksize of the
	 * device (probably to NTFS_BLOCK_SIZE).
	 */

	/* Setup remaining fields in the super block. */
	sb->s_magic = NTFS_SB_MAGIC;

	/*
	 * Ntfs allows 63 bits for the file size, i.e. correct would be:
	 * 	sb->s_maxbytes = ~0ULL >> 1;
	 * But the kernel uses a long as the page cache page index which on
	 * 32-bit architectures is only 32-bits. MAX_LFS_FILESIZE is kernel
	 * defined to the maximum the page cache page index can cope with
	 * without overflowing the index or to 2^63 - 1, whichever is smaller.
	 */
	sb->s_maxbytes = MAX_LFS_FILESIZE;

	/*
	 * Now load the metadata required for the page cache and our address
	 * space operations to function. We do this by setting up a specialised
	 * read_inode method and then just calling the normal iget() to obtain
	 * the inode for $MFT which is sufficient to allow our normal inode
	 * operations and associated address space operations to function.
	 */
	/*
	 * Poison vol->mft_ino so we know whether iget() called into our
	 * ntfs_read_inode_mount() method.
	 */
#define OGIN	((struct inode*)le32_to_cpu(0x4e49474f))	/* OGIN */
	vol->mft_ino = OGIN;
	sb->s_op = &ntfs_mount_sops;
	tmp_ino = iget(vol->sb, FILE_MFT);
	if (!tmp_ino || tmp_ino != vol->mft_ino || is_bad_inode(tmp_ino)) {
		if (!silent)
			ntfs_error(sb, "Failed to load essential metadata.");
		if (tmp_ino && vol->mft_ino == OGIN)
			ntfs_error(sb, "BUG: iget() did not call "
					"ntfs_read_inode_mount() method!\n");
		if (!tmp_ino)
			goto cond_iput_mft_ino_err_out_now;
		goto iput_tmp_ino_err_out_now;
	}
	/*
	 * Note: sb->s_op has already been set to &ntfs_sops by our specialized
	 * ntfs_read_inode_mount() method when it was invoked by iget().
	 */
	down(&ntfs_lock);
	/*
	 * The current mount is a compression user if the cluster size is
	 * less than or equal 4kiB.
	 */
	if (vol->cluster_size <= 4096 && !ntfs_nr_compression_users++) {
		result = allocate_compression_buffers();
		if (result) {
			ntfs_error(NULL, "Failed to allocate buffers "
					"for compression engine.");
			ntfs_nr_compression_users--;
			up(&ntfs_lock);
			goto iput_tmp_ino_err_out_now;
		}
	}
	/*
	 * Increment the number of mounts and generate the global default
	 * upcase table if necessary. Also temporarily increment the number of
	 * upcase users to avoid race conditions with concurrent (u)mounts.
	 */
	if (!ntfs_nr_mounts++)
		default_upcase = generate_default_upcase();
	ntfs_nr_upcase_users++;

	up(&ntfs_lock);
	/*
	 * From now on, ignore @silent parameter. If we fail below this line,
	 * it will be due to a corrupt fs or a system error, so we report it.
	 */
	/*
	 * Open the system files with normal access functions and complete
	 * setting up the ntfs super block.
	 */
	if (!load_system_files(vol)) {
		ntfs_error(sb, "Failed to load system files.");
		goto unl_upcase_iput_tmp_ino_err_out_now;
	}
	if ((sb->s_root = d_alloc_root(vol->root_ino))) {
		/* We increment i_count simulating an ntfs_iget(). */
		atomic_inc(&vol->root_ino->i_count);
		ntfs_debug("Exiting, status successful.");
		/* Release the default upcase if it has no users. */
		down(&ntfs_lock);
		if (!--ntfs_nr_upcase_users && default_upcase) {
			ntfs_free(default_upcase);
			default_upcase = NULL;
		}
		up(&ntfs_lock);
		return 0;
	}
	ntfs_error(sb, "Failed to allocate root directory.");
	/* Clean up after the successful load_system_files() call from above. */
	iput(vol->vol_ino);
	vol->vol_ino = NULL;
	/* NTFS 3.0+ specific clean up. */
	if (vol->major_ver >= 3) {
		iput(vol->secure_ino);
		vol->secure_ino = NULL;
	}
	iput(vol->root_ino);
	vol->root_ino = NULL;
	iput(vol->lcnbmp_ino);
	vol->lcnbmp_ino = NULL;
	iput(vol->mftmirr_ino);
	vol->mftmirr_ino = NULL;
	iput(vol->mftbmp_ino);
	vol->mftbmp_ino = NULL;
	vol->upcase_len = 0;
	if (vol->upcase != default_upcase)
		ntfs_free(vol->upcase);
	vol->upcase = NULL;
	if (vol->nls_map) {
		unload_nls(vol->nls_map);
		vol->nls_map = NULL;
	}
	/* Error exit code path. */
unl_upcase_iput_tmp_ino_err_out_now:
	/*
	 * Decrease the number of mounts and destroy the global default upcase
	 * table if necessary.
	 */
	down(&ntfs_lock);
	ntfs_nr_mounts--;
	if (!--ntfs_nr_upcase_users && default_upcase) {
		ntfs_free(default_upcase);
		default_upcase = NULL;
	}
	if (vol->cluster_size <= 4096 && !--ntfs_nr_compression_users)
		free_compression_buffers();
	up(&ntfs_lock);
iput_tmp_ino_err_out_now:
	iput(tmp_ino);
cond_iput_mft_ino_err_out_now:
	if (vol->mft_ino && vol->mft_ino != OGIN && vol->mft_ino != tmp_ino) {
		iput(vol->mft_ino);
		vol->mft_ino = NULL;
	}
#undef OGIN
	/*
	 * This is needed to get ntfs_clear_extent_inode() called for each
	 * inode we have ever called ntfs_iget()/iput() on, otherwise we A)
	 * leak resources and B) a subsequent mount fails automatically due to
	 * ntfs_iget() never calling down into our ntfs_read_locked_inode()
	 * method again... FIXME: Do we need to do this twice now because of
	 * attribute inodes? I think not, so leave as is for now... (AIA)
	 */
	if (invalidate_inodes(sb)) {
		ntfs_error(sb, "Busy inodes left. This is most likely a NTFS "
				"driver bug.");
		/* Copied from fs/super.c. I just love this message. (-; */
		printk("NTFS: Busy inodes after umount. Self-destruct in 5 "
				"seconds.  Have a nice day...\n");
	}
	/* Errors at this stage are irrelevant. */
err_out_now:
	sb->s_fs_info = NULL;
	kfree(vol);
	ntfs_debug("Failed, returning -EINVAL.");
	return -EINVAL;
}

/*
 * This is a slab cache to optimize allocations and deallocations of Unicode
 * strings of the maximum length allowed by NTFS, which is NTFS_MAX_NAME_LEN
 * (255) Unicode characters + a terminating NULL Unicode character.
 */
kmem_cache_t *ntfs_name_cache;

/* Slab caches for efficient allocation/deallocation of of inodes. */
kmem_cache_t *ntfs_inode_cache;
kmem_cache_t *ntfs_big_inode_cache;

/* Init once constructor for the inode slab cache. */
static void ntfs_big_inode_init_once(void *foo, kmem_cache_t *cachep,
		unsigned long flags)
{
	ntfs_inode *ni = (ntfs_inode *)foo;

	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
			SLAB_CTOR_CONSTRUCTOR)
		inode_init_once(VFS_I(ni));
}

/*
 * Slab cache to optimize allocations and deallocations of attribute search
 * contexts.
 */
kmem_cache_t *ntfs_attr_ctx_cache;

/* A global default upcase table and a corresponding reference count. */
wchar_t *default_upcase = NULL;
unsigned long ntfs_nr_upcase_users = 0;

/* The number of mounted filesystems. */
unsigned long ntfs_nr_mounts = 0;

/* Driver wide semaphore. */
DECLARE_MUTEX(ntfs_lock);

static struct super_block *ntfs_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, ntfs_fill_super);
}

static struct file_system_type ntfs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "ntfs",
	.get_sb		= ntfs_get_sb,
	.kill_sb	= kill_block_super,
	.fs_flags	= FS_REQUIRES_DEV,
};

/* Stable names for the slab caches. */
static const char ntfs_attr_ctx_cache_name[] = "ntfs_attr_ctx_cache";
static const char ntfs_name_cache_name[] = "ntfs_name_cache";
static const char ntfs_inode_cache_name[] = "ntfs_inode_cache";
static const char ntfs_big_inode_cache_name[] = "ntfs_big_inode_cache";

static int __init init_ntfs_fs(void)
{
	int err = 0;

	/* This may be ugly but it results in pretty output so who cares. (-8 */
	printk(KERN_INFO "NTFS driver " NTFS_VERSION " [Flags: R/"
#ifdef NTFS_RW
			"W"
#else
			"O"
#endif
#ifdef DEBUG
			" DEBUG"
#endif
#ifdef MODULE
			" MODULE"
#endif
			"].\n");

	ntfs_debug("Debug messages are enabled.");

	ntfs_attr_ctx_cache = kmem_cache_create(ntfs_attr_ctx_cache_name,
			sizeof(attr_search_context), 0 /* offset */,
			SLAB_HWCACHE_ALIGN, NULL /* ctor */, NULL /* dtor */);
	if (!ntfs_attr_ctx_cache) {
		printk(KERN_CRIT "NTFS: Failed to create %s!\n",
				ntfs_attr_ctx_cache_name);
		goto ctx_err_out;
	}

	ntfs_name_cache = kmem_cache_create(ntfs_name_cache_name,
			(NTFS_MAX_NAME_LEN+1) * sizeof(uchar_t), 0,
			SLAB_HWCACHE_ALIGN, NULL, NULL);
	if (!ntfs_name_cache) {
		printk(KERN_CRIT "NTFS: Failed to create %s!\n",
				ntfs_name_cache_name);
		goto name_err_out;
	}

	ntfs_inode_cache = kmem_cache_create(ntfs_inode_cache_name,
			sizeof(ntfs_inode), 0,
			SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, NULL, NULL);
	if (!ntfs_inode_cache) {
		printk(KERN_CRIT "NTFS: Failed to create %s!\n",
				ntfs_inode_cache_name);
		goto inode_err_out;
	}

	ntfs_big_inode_cache = kmem_cache_create(ntfs_big_inode_cache_name,
			sizeof(big_ntfs_inode), 0,
			SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT,
			ntfs_big_inode_init_once, NULL);
	if (!ntfs_big_inode_cache) {
		printk(KERN_CRIT "NTFS: Failed to create %s!\n",
				ntfs_big_inode_cache_name);
		goto big_inode_err_out;
	}

	/* Register the ntfs sysctls. */
	err = ntfs_sysctl(1);
	if (err) {
		printk(KERN_CRIT "NTFS: Failed to register NTFS sysctls!\n");
		goto sysctl_err_out;
	}

	err = register_filesystem(&ntfs_fs_type);
	if (!err) {
		ntfs_debug("NTFS driver registered successfully.");
		return 0; /* Success! */
	}
	printk(KERN_CRIT "NTFS: Failed to register NTFS file system driver!\n");

sysctl_err_out:
	kmem_cache_destroy(ntfs_big_inode_cache);
big_inode_err_out:
	kmem_cache_destroy(ntfs_inode_cache);
inode_err_out:
	kmem_cache_destroy(ntfs_name_cache);
name_err_out:
	kmem_cache_destroy(ntfs_attr_ctx_cache);
ctx_err_out:
	if (!err) {
		printk(KERN_CRIT "NTFS: Aborting NTFS file system driver "
				"registration...\n");
		err = -ENOMEM;
	}
	return err;
}

static void __exit exit_ntfs_fs(void)
{
	int err = 0;

	ntfs_debug("Unregistering NTFS driver.");

	unregister_filesystem(&ntfs_fs_type);

	if (kmem_cache_destroy(ntfs_big_inode_cache) && (err = 1))
		printk(KERN_CRIT "NTFS: Failed to destory %s.\n",
				ntfs_big_inode_cache_name);
	if (kmem_cache_destroy(ntfs_inode_cache) && (err = 1))
		printk(KERN_CRIT "NTFS: Failed to destory %s.\n",
				ntfs_inode_cache_name);
	if (kmem_cache_destroy(ntfs_name_cache) && (err = 1))
		printk(KERN_CRIT "NTFS: Failed to destory %s.\n",
				ntfs_name_cache_name);
	if (kmem_cache_destroy(ntfs_attr_ctx_cache) && (err = 1))
		printk(KERN_CRIT "NTFS: Failed to destory %s.\n",
				ntfs_attr_ctx_cache_name);
	if (err)
		printk(KERN_CRIT "NTFS: This causes memory to leak! There is "
				"probably a BUG in the driver! Please report "
				"you saw this message to "
				"[e-mail]\n");
	/* Unregister the ntfs sysctls. */
	ntfs_sysctl(0);
}

MODULE_AUTHOR("Anton Altaparmakov <[e-mail]>");
MODULE_DESCRIPTION("NTFS 1.2/3.x driver - Copyright (c) 2001-2003 Anton Altaparmakov");
MODULE_LICENSE("GPL");
#ifdef DEBUG
MODULE_PARM(debug_msgs, "i");
MODULE_PARM_DESC(debug_msgs, "Enable debug messages.");
#endif

module_init(init_ntfs_fs)
module_exit(exit_ntfs_fs)