C++ drop_nlink函数代码示例

void
zfsctl_dir_destroy(void *ptr)
{
	zfsvfs_t *zfsvfs = NULL;
   
	ASSERT(ptr);
	zfsvfs = (zfsvfs_t *) ptr;
	drop_nlink(LZFS_VTOI(zfsvfs->z_ctldir));
	mutex_destroy(&(zfsvfs->z_ctldir->v_lock));
}

static int hpfs_rmdir(struct inode *dir, struct dentry *dentry)
{
	const unsigned char *name = dentry->d_name.name;
	unsigned len = dentry->d_name.len;
	struct quad_buffer_head qbh;
	struct hpfs_dirent *de;
	struct inode *inode = dentry->d_inode;
	dnode_secno dno;
	int n_items = 0;
	int err;
	int r;

	hpfs_adjust_length(name, &len);
	hpfs_lock(dir->i_sb);
	err = -ENOENT;
	de = map_dirent(dir, hpfs_i(dir)->i_dno, name, len, &dno, &qbh);
	if (!de)
		goto out;

	err = -EPERM;
	if (de->first)
		goto out1;

	err = -ENOTDIR;
	if (!de->directory)
		goto out1;

	hpfs_count_dnodes(dir->i_sb, hpfs_i(inode)->i_dno, NULL, NULL, &n_items);
	err = -ENOTEMPTY;
	if (n_items)
		goto out1;

	r = hpfs_remove_dirent(dir, dno, de, &qbh, 1);
	switch (r) {
	case 1:
		hpfs_error(dir->i_sb, "there was error when removing dirent");
		err = -EFSERROR;
		break;
	case 2:
		err = -ENOSPC;
		break;
	default:
		drop_nlink(dir);
		clear_nlink(inode);
		err = 0;
	}
	goto out;
out1:
	hpfs_brelse4(&qbh);
out:
	if (!err)
		hpfs_update_directory_times(dir);
	hpfs_unlock(dir->i_sb);
	return err;
}

static ssize_t efivarfs_file_write(struct file *file,
		const char __user *userbuf, size_t count, loff_t *ppos)
{
	struct efivar_entry *var = file->private_data;
	void *data;
	u32 attributes;
	struct inode *inode = file->f_mapping->host;
	unsigned long datasize = count - sizeof(attributes);
	ssize_t bytes = 0;
	bool set = false;

	if (count < sizeof(attributes))
		return -EINVAL;

	if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
		return -EFAULT;

	if (attributes & ~(EFI_VARIABLE_MASK))
		return -EINVAL;

	data = kmalloc(datasize, GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	if (copy_from_user(data, userbuf + sizeof(attributes), datasize)) {
		bytes = -EFAULT;
		goto out;
	}

	bytes = efivar_entry_set_get_size(var, attributes, &datasize,
					  data, &set);
	if (!set && bytes) {
		if (bytes == -ENOENT)
			bytes = -EIO;
		goto out;
	}

	if (bytes == -ENOENT) {
		drop_nlink(inode);
		d_delete(file->f_dentry);
		dput(file->f_dentry);
	} else {
		mutex_lock(&inode->i_mutex);
		i_size_write(inode, datasize + sizeof(attributes));
		mutex_unlock(&inode->i_mutex);
	}

	bytes = count;

out:
	kfree(data);

	return bytes;
}

static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
{
	struct efivar_entry *var = dentry->d_inode->i_private;

	if (efivar_entry_delete(var))
		return -EINVAL;

	drop_nlink(dentry->d_inode);
	dput(dentry);
	return 0;
};

/**
 *	sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
 *	@sd: target sysfs_dirent
 *
 *	Drop dentry for @sd.  @sd must have been unlinked from its
 *	parent on entry to this function such that it can't be looked
 *	up anymore.
 *
 *	@sd->s_dentry which is protected with sysfs_assoc_lock points
 *	to the currently associated dentry but we're not holding a
 *	reference to it and racing with dput().  Grab dcache_lock and
 *	verify dentry before dropping it.  If @sd->s_dentry is NULL or
 *	dput() beats us, no need to bother.
 */
static void sysfs_drop_dentry(struct sysfs_dirent *sd)
{
	struct dentry *dentry = NULL;
	struct inode *inode;

	/* We're not holding a reference to ->s_dentry dentry but the
	 * field will stay valid as long as sysfs_assoc_lock is held.
	 */
	spin_lock(&sysfs_assoc_lock);
	spin_lock(&dcache_lock);

	/* drop dentry if it's there and dput() didn't kill it yet */
	if (sd->s_dentry && sd->s_dentry->d_inode) {
		dentry = dget_locked(sd->s_dentry);
		spin_lock(&dentry->d_lock);
		__d_drop(dentry);
		spin_unlock(&dentry->d_lock);
	}

	spin_unlock(&dcache_lock);
	spin_unlock(&sysfs_assoc_lock);

	/* dentries for shadowed inodes are pinned, unpin */
	if (dentry && sysfs_is_shadowed_inode(dentry->d_inode))
		dput(dentry);
	dput(dentry);

	/* adjust nlink and update timestamp */
	inode = ilookup(sysfs_sb, sd->s_ino);
	if (inode) {
		mutex_lock(&inode->i_mutex);

		inode->i_ctime = CURRENT_TIME;
		drop_nlink(inode);
		if (sysfs_type(sd) == SYSFS_DIR)
			drop_nlink(inode);

		mutex_unlock(&inode->i_mutex);
		iput(inode);
	}
}

static int hfsplus_unlink(struct inode *dir, struct dentry *dentry)
{
	struct super_block *sb = dir->i_sb;
	struct inode *inode = dentry->d_inode;
	struct qstr str;
	char name[32];
	u32 cnid;
	int res;

	if (HFSPLUS_IS_RSRC(inode))
		return -EPERM;

	cnid = (u32)(unsigned long)dentry->d_fsdata;
	if (inode->i_ino == cnid &&
	    atomic_read(&HFSPLUS_I(inode).opencnt)) {
		str.name = name;
		str.len = sprintf(name, "temp%lu", inode->i_ino);
		res = hfsplus_rename_cat(inode->i_ino,
					 dir, &dentry->d_name,
					 HFSPLUS_SB(sb).hidden_dir, &str);
		if (!res)
			inode->i_flags |= S_DEAD;
		return res;
	}
	res = hfsplus_delete_cat(cnid, dir, &dentry->d_name);
	if (res)
		return res;

	if (inode->i_nlink > 0)
		drop_nlink(inode);
	if (inode->i_ino == cnid)
		clear_nlink(inode);
	if (!inode->i_nlink) {
		if (inode->i_ino != cnid) {
			HFSPLUS_SB(sb).file_count--;
			if (!atomic_read(&HFSPLUS_I(inode).opencnt)) {
				res = hfsplus_delete_cat(inode->i_ino,
							 HFSPLUS_SB(sb).hidden_dir,
							 NULL);
				if (!res)
					hfsplus_delete_inode(inode);
			} else
				inode->i_flags |= S_DEAD;
		} else
			hfsplus_delete_inode(inode);
	} else
		HFSPLUS_SB(sb).file_count--;
	inode->i_ctime = CURRENT_TIME_SEC;
	mark_inode_dirty(inode);

	return res;
}

/**
 *	sysfs_remove_one - remove sysfs_dirent from parent
 *	@acxt: addrm context to use
 *	@sd: sysfs_dirent to be added
 *
 *	Mark @sd removed and drop nlink of parent inode if @sd is a
 *	directory.  @sd is NOT unlinked from the children list of the
 *	parent.  The caller is repsonsible for removing @sd from the
 *	children list before calling this function.
 *
 *	This function should be called between calls to
 *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
 *	passed the same @acxt as passed to sysfs_addrm_start().
 *
 *	LOCKING:
 *	Determined by sysfs_addrm_start().
 */
void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
{
	BUG_ON(sd->s_sibling || (sd->s_flags & SYSFS_FLAG_REMOVED));

	sd->s_flags |= SYSFS_FLAG_REMOVED;
	sd->s_sibling = acxt->removed;
	acxt->removed = sd;

	if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
		drop_nlink(acxt->parent_inode);

	acxt->cnt++;
}

/* destruction routines: unlink, rmdir */
static int coda_unlink(struct inode *dir, struct dentry *de)
{
        int error;
	const char *name = de->d_name.name;
	int len = de->d_name.len;

	error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
	if (error)
		return error;

	coda_dir_update_mtime(dir);
	drop_nlink(de->d_inode);
	return 0;
}

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

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

	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
	if (err)
		return err;

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

	/* slow symlink */
	inode->i_op = &nilfs_symlink_inode_operations;
	inode_nohighmem(inode);
	inode->i_mapping->a_ops = &nilfs_aops;
	err = page_symlink(inode, symname, l);
	if (err)
		goto out_fail;

	/* mark_inode_dirty(inode); */
	/* page_symlink() do this */

	err = nilfs_add_nondir(dentry, inode);
out:
	if (!err)
		err = nilfs_transaction_commit(dir->i_sb);
	else
		nilfs_transaction_abort(dir->i_sb);

	return err;

out_fail:
	drop_nlink(inode);
	nilfs_mark_inode_dirty(inode);
	unlock_new_inode(inode);
	iput(inode);
	goto out;
}

int yramfs_dir_unlink(struct inode *dir, struct dentry *dentry)
{
    struct inode *inode = dentry->d_inode;
    int err;

    DBG_PRINT("unlink for %s", dentry->d_name.name);
    inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
    err = yramfs_dir_remove_path(dir, dentry);
    if (err) {
        DBG_PRINT("remove path failed:%d", err);
    }
    drop_nlink(inode);
    dput(dentry);

    return 0;
}

/*
 * hfs_unlink()
 *
 * This is the unlink() entry in the inode_operations structure for
 * regular HFS directories.  The purpose is to delete an existing
 * file, given the inode for the parent directory and the name
 * (and its length) of the existing file.
 */
static int hfs_unlink(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode;
	int res;

	inode = dentry->d_inode;
	res = hfs_cat_delete(inode->i_ino, dir, &dentry->d_name);
	if (res)
		return res;

	drop_nlink(inode);
	hfs_delete_inode(inode);
	inode->i_ctime = CURRENT_TIME_SEC;
	mark_inode_dirty(inode);

	return res;
}

static int pmfs_unlink(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;
	struct super_block *sb = dir->i_sb;
	int retval = -ENOMEM;
	struct pmfs_inode *pi = pmfs_get_inode(sb, inode);
	struct pmfs_inode *pidir;
	u64 pidir_tail = 0, pi_tail = 0;
	int invalidate = 0;
	timing_t unlink_time;

	PMFS_START_TIMING(unlink_t, unlink_time);

	pidir = pmfs_get_inode(sb, dir);
	if (!pidir)
		goto out;

	pmfs_dbgv("%s: %s, ino %lu, dir %lu\n", __func__,
				dentry->d_name.name, inode->i_ino, dir->i_ino);
	retval = pmfs_remove_entry(dentry, 0, 0, &pidir_tail);
	if (retval)
		goto out;

	inode->i_ctime = dir->i_ctime;

	if (inode->i_nlink == 1)
		invalidate = 1;

	if (inode->i_nlink) {
		drop_nlink(inode);
	}

	retval = pmfs_append_link_change_entry(sb, pi, inode, 0, &pi_tail);
	if (retval)
		goto out;

	pmfs_lite_transaction_for_time_and_link(sb, pi, pidir,
					pi_tail, pidir_tail, invalidate);

	PMFS_END_TIMING(unlink_t, unlink_time);
	return 0;
out:
	pmfs_err(sb, "%s return %d\n", __func__, retval);
	PMFS_END_TIMING(unlink_t, unlink_time);
	return retval;
}

static void au_do_hide(struct dentry *dentry)
{
	struct inode *inode;

	inode = dentry->d_inode;
	if (inode) {
		if (!S_ISDIR(inode->i_mode)) {
			if (inode->i_nlink && !d_unhashed(dentry))
				drop_nlink(inode);
		} else {
			clear_nlink(inode);
			/* stop next lookup */
			inode->i_flags |= S_DEAD;
		}
		smp_mb(); /* necessary? */
	}
	d_drop(dentry);
}

static void au_do_hide(struct dentry *dentry)
{
	struct inode *inode;

	if (d_really_is_positive(dentry)) {
		inode = d_inode(dentry);
		if (!d_is_dir(dentry)) {
			if (inode->i_nlink && !d_unhashed(dentry))
				drop_nlink(inode);
		} else {
			clear_nlink(inode);
			/* stop next lookup */
			inode->i_flags |= S_DEAD;
		}
		smp_mb(); /* necessary? */
	}
	d_drop(dentry);
}

/**
 * devpts_pty_kill -- remove inode form /dev/pts/
 * @inode: inode of the slave to be removed
 *
 * This is an inverse operation of devpts_pty_new.
 */
void devpts_pty_kill(struct inode *inode)
{
	struct super_block *sb = pts_sb_from_inode(inode);
	struct dentry *root = sb->s_root;
	struct dentry *dentry;

	BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));

	mutex_lock(&root->d_inode->i_mutex);

	dentry = d_find_alias(inode);

	drop_nlink(inode);
	d_delete(dentry);
	dput(dentry);	/* d_alloc_name() in devpts_pty_new() */
	dput(dentry);		/* d_find_alias above */

	mutex_unlock(&root->d_inode->i_mutex);
}