C++ UFS_I函数代码示例

int ufs_truncate(struct inode *inode, loff_t old_i_size)
{
	struct ufs_inode_info *ufsi = UFS_I(inode);
	struct super_block *sb = inode->i_sb;
	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
	int retry, err = 0;
	
	UFSD("ENTER: ino %lu, i_size: %llu, old_i_size: %llu\n",
	     inode->i_ino, (unsigned long long)i_size_read(inode),
	     (unsigned long long)old_i_size);

	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
	      S_ISLNK(inode->i_mode)))
		return -EINVAL;
	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
		return -EPERM;

	err = ufs_alloc_lastblock(inode);

	if (err) {
		i_size_write(inode, old_i_size);
		goto out;
	}

	block_truncate_page(inode->i_mapping, inode->i_size, ufs_getfrag_block);

	lock_kernel();
	while (1) {
		retry = ufs_trunc_direct(inode);
		retry |= ufs_trunc_indirect(inode, UFS_IND_BLOCK,
					    ufs_get_direct_data_ptr(uspi, ufsi,
								    UFS_IND_BLOCK));
		retry |= ufs_trunc_dindirect(inode, UFS_IND_BLOCK + uspi->s_apb,
					     ufs_get_direct_data_ptr(uspi, ufsi,
								     UFS_DIND_BLOCK));
		retry |= ufs_trunc_tindirect (inode);
		if (!retry)
			break;
		if (IS_SYNC(inode) && (inode->i_state & I_DIRTY))
			ufs_sync_inode (inode);
		blk_run_address_space(inode->i_mapping);
		yield();
	}

	inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
	ufsi->i_lastfrag = DIRECT_FRAGMENT;
	unlock_kernel();
	mark_inode_dirty(inode);
out:
	UFSD("EXIT: err %d\n", err);
	return err;
}

static int ufs_symlink (struct inode * dir, struct dentry * dentry,
	const char * symname)
{
	struct super_block * sb = dir->i_sb;
	int err = -ENAMETOOLONG;
	unsigned l = strlen(symname)+1;
	struct inode * inode;

	if (l > sb->s_blocksize)
		goto out_notlocked;

	dquot_initialize(dir);

	lock_kernel();
	inode = ufs_new_inode(dir, S_IFLNK | S_IRWXUGO);
	err = PTR_ERR(inode);
	if (IS_ERR(inode))
		goto out;

	if (l > UFS_SB(sb)->s_uspi->s_maxsymlinklen) {
		/* slow symlink */
		inode->i_op = &ufs_symlink_inode_operations;
		inode->i_mapping->a_ops = &ufs_aops;
		err = page_symlink(inode, symname, l);
		if (err)
			goto out_fail;
	} else {
		/* fast symlink */
		inode->i_op = &ufs_fast_symlink_inode_operations;
		memcpy(UFS_I(inode)->i_u1.i_symlink, symname, l);
		inode->i_size = l-1;
	}
	mark_inode_dirty(inode);

	err = ufs_add_nondir(dentry, inode);
out:
	unlock_kernel();
out_notlocked:
	return err;

out_fail:
	inode_dec_link_count(inode);
	iput(inode);
	goto out;
}

static int ufs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
{
	struct inode *inode;
	int err;

	if (!old_valid_dev(rdev))
		return -EINVAL;

	inode = ufs_new_inode(dir, mode);
	err = PTR_ERR(inode);
	if (!IS_ERR(inode)) {
		init_special_inode(inode, mode, rdev);
		ufs_set_inode_dev(inode->i_sb, UFS_I(inode), rdev);
		mark_inode_dirty(inode);
		err = ufs_add_nondir(dentry, inode);
	}
	return err;
}

static int ufs_symlink (struct inode * dir, struct dentry * dentry,
	const char * symname)
{
	struct super_block * sb = dir->i_sb;
	int err;
	unsigned l = strlen(symname)+1;
	struct inode * inode;

	if (l > sb->s_blocksize)
		return -ENAMETOOLONG;

	inode = ufs_new_inode(dir, S_IFLNK | S_IRWXUGO);
	err = PTR_ERR(inode);
	if (IS_ERR(inode))
		return err;

	if (l > UFS_SB(sb)->s_uspi->s_maxsymlinklen) {
		/* slow symlink */
		inode->i_op = &page_symlink_inode_operations;
		inode_nohighmem(inode);
		inode->i_mapping->a_ops = &ufs_aops;
		err = page_symlink(inode, symname, l);
		if (err)
			goto out_fail;
	} else {
		/* fast symlink */
		inode->i_op = &simple_symlink_inode_operations;
		inode->i_link = (char *)UFS_I(inode)->i_u1.i_symlink;
		memcpy(inode->i_link, symname, l);
		inode->i_size = l-1;
	}
	mark_inode_dirty(inode);

	return ufs_add_nondir(dentry, inode);

out_fail:
	inode_dec_link_count(inode);
	unlock_new_inode(inode);
	iput(inode);
	return err;
}

static void ufs_i_callback(struct rcu_head *head)
{
	struct inode *inode = container_of(head, struct inode, i_rcu);
	kmem_cache_free(ufs_inode_cachep, UFS_I(inode));
}

static int ufs_trunc_direct(struct inode *inode)
{
	struct ufs_inode_info *ufsi = UFS_I(inode);
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	void *p;
	u64 frag1, frag2, frag3, frag4, block1, block2;
	unsigned frag_to_free, free_count;
	unsigned i, tmp;
	int retry;
	
	UFSD("ENTER: ino %lu\n", inode->i_ino);

	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;
	
	frag_to_free = 0;
	free_count = 0;
	retry = 0;
	
	frag1 = DIRECT_FRAGMENT;
	frag4 = min_t(u32, UFS_NDIR_FRAGMENT, ufsi->i_lastfrag);
	frag2 = ((frag1 & uspi->s_fpbmask) ? ((frag1 | uspi->s_fpbmask) + 1) : frag1);
	frag3 = frag4 & ~uspi->s_fpbmask;
	block1 = block2 = 0;
	if (frag2 > frag3) {
		frag2 = frag4;
		frag3 = frag4 = 0;
	} else if (frag2 < frag3) {
		block1 = ufs_fragstoblks (frag2);
		block2 = ufs_fragstoblks (frag3);
	}

	UFSD("ino %lu, frag1 %llu, frag2 %llu, block1 %llu, block2 %llu,"
	     " frag3 %llu, frag4 %llu\n", inode->i_ino,
	     (unsigned long long)frag1, (unsigned long long)frag2,
	     (unsigned long long)block1, (unsigned long long)block2,
	     (unsigned long long)frag3, (unsigned long long)frag4);

	if (frag1 >= frag2)
		goto next1;		

	/*
	 * Free first free fragments
	 */
	p = ufs_get_direct_data_ptr(uspi, ufsi, ufs_fragstoblks(frag1));
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp )
		ufs_panic (sb, "ufs_trunc_direct", "internal error");
	frag2 -= frag1;
	frag1 = ufs_fragnum (frag1);

	ufs_free_fragments(inode, tmp + frag1, frag2);
	mark_inode_dirty(inode);
	frag_to_free = tmp + frag1;

next1:
	/*
	 * Free whole blocks
	 */
	for (i = block1 ; i < block2; i++) {
		p = ufs_get_direct_data_ptr(uspi, ufsi, i);
		tmp = ufs_data_ptr_to_cpu(sb, p);
		if (!tmp)
			continue;
		ufs_data_ptr_clear(uspi, p);

		if (free_count == 0) {
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		} else if (free_count > 0 && frag_to_free == tmp - free_count)
			free_count += uspi->s_fpb;
		else {
			ufs_free_blocks (inode, frag_to_free, free_count);
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		}
		mark_inode_dirty(inode);
	}
	
	if (free_count > 0)
		ufs_free_blocks (inode, frag_to_free, free_count);

	if (frag3 >= frag4)
		goto next3;

	/*
	 * Free last free fragments
	 */
	p = ufs_get_direct_data_ptr(uspi, ufsi, ufs_fragstoblks(frag3));
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp )
		ufs_panic(sb, "ufs_truncate_direct", "internal error");
	frag4 = ufs_fragnum (frag4);
	ufs_data_ptr_clear(uspi, p);

	ufs_free_fragments (inode, tmp, frag4);
	mark_inode_dirty(inode);
 next3:

//.........这里部分代码省略.........

static void ufs_destroy_inode(struct inode *inode)
{
    kmem_cache_free(ufs_inode_cachep, UFS_I(inode));
}

/*
 * There are two policies for allocating an inode.  If the new inode is
 * a directory, then a forward search is made for a block group with both
 * free space and a low directory-to-inode ratio; if that fails, then of
 * the groups with above-average free space, that group with the fewest
 * directories already is chosen.
 *
 * For other inodes, search forward from the parent directory's block
 * group to find a free inode.
 */
struct inode * ufs_new_inode(struct inode * dir, int mode)
{
    struct super_block * sb;
    struct ufs_sb_info * sbi;
    struct ufs_sb_private_info * uspi;
    struct ufs_super_block_first * usb1;
    struct ufs_cg_private_info * ucpi;
    struct ufs_cylinder_group * ucg;
    struct inode * inode;
    unsigned cg, bit, i, j, start;
    struct ufs_inode_info *ufsi;
    int err = -ENOSPC;

    UFSD("ENTER\n");
    
    /* Cannot create files in a deleted directory */
    if (!dir || !dir->i_nlink)
        return ERR_PTR(-EPERM);
    sb = dir->i_sb;
    inode = new_inode(sb);
    if (!inode)
        return ERR_PTR(-ENOMEM);
    ufsi = UFS_I(inode);
    sbi = UFS_SB(sb);
    uspi = sbi->s_uspi;
    usb1 = ubh_get_usb_first(uspi);

    lock_super (sb);

    /*
     * Try to place the inode in its parent directory
     */
    i = ufs_inotocg(dir->i_ino);
    if (sbi->fs_cs(i).cs_nifree) {
        cg = i;
        goto cg_found;
    }

    /*
     * Use a quadratic hash to find a group with a free inode
     */
    for ( j = 1; j < uspi->s_ncg; j <<= 1 ) {
        i += j;
        if (i >= uspi->s_ncg)
            i -= uspi->s_ncg;
        if (sbi->fs_cs(i).cs_nifree) {
            cg = i;
            goto cg_found;
        }
    }

    /*
     * That failed: try linear search for a free inode
     */
    i = ufs_inotocg(dir->i_ino) + 1;
    for (j = 2; j < uspi->s_ncg; j++) {
        i++;
        if (i >= uspi->s_ncg)
            i = 0;
        if (sbi->fs_cs(i).cs_nifree) {
            cg = i;
            goto cg_found;
        }
    }

    goto failed;

cg_found:
    ucpi = ufs_load_cylinder (sb, cg);
    if (!ucpi) {
        err = -EIO;
        goto failed;
    }
    ucg = ubh_get_ucg(UCPI_UBH(ucpi));
    if (!ufs_cg_chkmagic(sb, ucg)) 
        ufs_panic (sb, "ufs_new_inode", "internal error, bad cg magic number");

    start = ucpi->c_irotor;
    bit = ubh_find_next_zero_bit (UCPI_UBH(ucpi), ucpi->c_iusedoff, uspi->s_ipg, start);
    if (!(bit < uspi->s_ipg)) {
        bit = ubh_find_first_zero_bit (UCPI_UBH(ucpi), ucpi->c_iusedoff, start);
        if (!(bit < start)) {
            ufs_error (sb, "ufs_new_inode",
                "cylinder group %u corrupted - error in inode bitmap\n", cg);
            err = -EIO;
            goto failed;
        }
    }
    UFSD("start = %u, bit = %u, ipg = %u\n", start, bit, uspi->s_ipg);
    if (ubh_isclr (UCPI_UBH(ucpi), ucpi->c_iusedoff, bit))
//.........这里部分代码省略.........

/*
 * There are two policies for allocating an inode.  If the new inode is
 * a directory, then a forward search is made for a block group with both
 * free space and a low directory-to-inode ratio; if that fails, then of
 * the groups with above-average free space, that group with the fewest
 * directories already is chosen.
 *
 * For other inodes, search forward from the parent directory's block
 * group to find a free inode.
 */
struct inode * ufs_new_inode(struct inode * dir, int mode)
{
	struct super_block * sb;
	struct ufs_sb_info * sbi;
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_cg_private_info * ucpi;
	struct ufs_cylinder_group * ucg;
	struct inode * inode;
	unsigned cg, bit, i, j, start;
	struct ufs_inode_info *ufsi;

	UFSD(("ENTER\n"))
	
	/* Cannot create files in a deleted directory */
	if (!dir || !dir->i_nlink)
		return ERR_PTR(-EPERM);
	sb = dir->i_sb;
	inode = new_inode(sb);
	if (!inode)
		return ERR_PTR(-ENOMEM);
	ufsi = UFS_I(inode);
	sbi = UFS_SB(sb);
	uspi = sbi->s_uspi;
	usb1 = ubh_get_usb_first(USPI_UBH);

	lock_super (sb);

	/*
	 * Try to place the inode in its parent directory
	 */
	i = ufs_inotocg(dir->i_ino);
	if (sbi->fs_cs(i).cs_nifree) {
		cg = i;
		goto cg_found;
	}

	/*
	 * Use a quadratic hash to find a group with a free inode
	 */
	for ( j = 1; j < uspi->s_ncg; j <<= 1 ) {
		i += j;
		if (i >= uspi->s_ncg)
			i -= uspi->s_ncg;
		if (sbi->fs_cs(i).cs_nifree) {
			cg = i;
			goto cg_found;
		}
	}

	/*
	 * That failed: try linear search for a free inode
	 */
	i = ufs_inotocg(dir->i_ino) + 1;
	for (j = 2; j < uspi->s_ncg; j++) {
		i++;
		if (i >= uspi->s_ncg)
			i = 0;
		if (sbi->fs_cs(i).cs_nifree) {
			cg = i;
			goto cg_found;
		}
	}
	
	goto failed;

cg_found:
	ucpi = ufs_load_cylinder (sb, cg);
	if (!ucpi)
		goto failed;
	ucg = ubh_get_ucg(UCPI_UBH);
	if (!ufs_cg_chkmagic(sb, ucg)) 
		ufs_panic (sb, "ufs_new_inode", "internal error, bad cg magic number");

	start = ucpi->c_irotor;
	bit = ubh_find_next_zero_bit (UCPI_UBH, ucpi->c_iusedoff, uspi->s_ipg, start);
	if (!(bit < uspi->s_ipg)) {
		bit = ubh_find_first_zero_bit (UCPI_UBH, ucpi->c_iusedoff, start);
		if (!(bit < start)) {
			ufs_error (sb, "ufs_new_inode",
			    "cylinder group %u corrupted - error in inode bitmap\n", cg);
			goto failed;
		}
	}
	UFSD(("start = %u, bit = %u, ipg = %u\n", start, bit, uspi->s_ipg))
	if (ubh_isclr (UCPI_UBH, ucpi->c_iusedoff, bit))
		ubh_setbit (UCPI_UBH, ucpi->c_iusedoff, bit);
	else {
		ufs_panic (sb, "ufs_new_inode", "internal error");
		goto failed;
//.........这里部分代码省略.........

static void ufs_i_callback(struct rcu_head *head)
{
	struct inode *inode = container_of(head, struct inode, i_rcu);
	INIT_LIST_HEAD(&inode->i_dentry);
	kmem_cache_free(ufs_inode_cachep, UFS_I(inode));
}

static void *ufs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	struct ufs_inode_info *p = UFS_I(dentry->d_inode);
	nd_set_link(nd, (char*)p->i_u1.i_symlink);
	return NULL;
}