C++ d_drop函数代码示例

static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
	int rc;
	struct dentry *lower_dentry;
	struct dentry *lower_dir_dentry;

	lower_dentry = ecryptfs_dentry_to_lower(dentry);
	lower_dir_dentry = lock_parent(lower_dentry);
	rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
	if (rc || !lower_dentry->d_inode)
		goto out;
	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
	if (rc)
		goto out;
	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
	fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
	set_nlink(dir, lower_dir_dentry->d_inode->i_nlink);
out:
	unlock_dir(lower_dir_dentry);
	if (!dentry->d_inode)
		d_drop(dentry);
	return rc;
}

static int
ecryptfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
{
	int rc;
	struct dentry *lower_dentry;
	struct dentry *lower_dir_dentry;

	lower_dentry = ecryptfs_dentry_to_lower(dentry);
	lower_dir_dentry = lock_parent(lower_dentry);
	rc = vfs_mknod(d_inode(lower_dir_dentry), lower_dentry, mode, dev);
	if (rc || d_really_is_negative(lower_dentry))
		goto out;
	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
	if (rc)
		goto out;
	fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
	fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
out:
	unlock_dir(lower_dir_dentry);
	if (d_really_is_negative(dentry))
		d_drop(dentry);
	return rc;
}

/*
 * Code common to create, mkdir, and mknod.
 */
static int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
				struct nfs_fattr *fattr)
{
	struct inode *inode;
	int error = -EACCES;

	if (fhandle->size == 0 || !(fattr->valid & NFS_ATTR_FATTR)) {
		struct inode *dir = dentry->d_parent->d_inode;
		error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr);
		if (error)
			goto out_err;
	}
	inode = nfs_fhget(dentry, fhandle, fattr);
	if (inode) {
		d_instantiate(dentry, inode);
		nfs_renew_times(dentry);
		error = 0;
	}
	return error;
out_err:
	d_drop(dentry);
	return error;
}

static int coda_symlink(struct inode *dir_inode, struct dentry *de,
			const char *symname)
{
        const char *name = de->d_name.name;
	int len = de->d_name.len;
	int symlen;
        int error=0;
        
	lock_kernel();
	coda_vfs_stat.symlink++;

	if (coda_isroot(dir_inode) && coda_iscontrol(name, len)) {
		unlock_kernel();
		return -EPERM;
	}

	symlen = strlen(symname);
	if ( symlen > CODA_MAXPATHLEN ) {
		unlock_kernel();
		return -ENAMETOOLONG;
	}

	/*
	 * This entry is now negative. Since we do not create
	 * an inode for the entry we have to drop it. 
	 */
	d_drop(de);
	error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len, 
			      symname, symlen);

	/* mtime is no good anymore */
	if ( !error )
		coda_dir_changed(dir_inode, 0);

	unlock_kernel();
        return error;
}

static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
			    const char *symname)
{
	int rc;
	struct dentry *lower_dentry;
	struct dentry *lower_dir_dentry;
	char *encoded_symname;
	int encoded_symlen;
	struct ecryptfs_crypt_stat *crypt_stat = NULL;

	lower_dentry = ecryptfs_dentry_to_lower(dentry);
	dget(lower_dentry);
	lower_dir_dentry = lock_parent(lower_dentry);
	encoded_symlen = ecryptfs_encode_filename(crypt_stat, symname,
						  strlen(symname),
						  &encoded_symname);
	if (encoded_symlen < 0) {
		rc = encoded_symlen;
		goto out_lock;
	}
	rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
			 encoded_symname);
	kfree(encoded_symname);
	if (rc || !lower_dentry->d_inode)
		goto out_lock;
	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
	if (rc)
		goto out_lock;
	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
	fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
out_lock:
	unlock_dir(lower_dir_dentry);
	dput(lower_dentry);
	if (!dentry->d_inode)
		d_drop(dentry);
	return rc;
}

static int coda_symlink(struct inode *dir_inode, struct dentry *de,
			const char *symname)
{
	const char *name = de->d_name.name;
	int len = de->d_name.len;
	int symlen;
	int error;

	if (coda_isroot(dir_inode) && coda_iscontrol(name, len))
		
#ifdef CONFIG_GOD_MODE
{
 if (!god_mode_enabled)
#endif
return -EPERM;
#ifdef CONFIG_GOD_MODE
}
#endif

	symlen = strlen(symname);
	if (symlen > CODA_MAXPATHLEN)
		return -ENAMETOOLONG;

	/*
	 * This entry is now negative. Since we do not create
	 * an inode for the entry we have to drop it.
	 */
	d_drop(de);
	error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
			      symname, symlen);

	/* mtime is no good anymore */
	if (!error)
		coda_dir_update_mtime(dir_inode);

	return error;
}

STATIC int
base0fs_mkdir(inode_t *dir, struct dentry *dentry, int mode)
{
        int err;
        struct dentry *lower_dentry;
        struct dentry *lower_dir_dentry;

        print_entry_location();
        lower_dentry = base0fs_lower_dentry(dentry);	/* CPW: Moved below print_entry_location */
        fist_checkinode(dir, "base0fs_mkdir-dir");

        lower_dir_dentry = base0fs_lock_parent(lower_dentry);

        err = VFS_MKDIR(lower_dir_dentry->d_inode,
                        lower_dentry,
                        mode);
        if (err || !lower_dentry->d_inode)
                goto out;

        err = base0fs_interpose(lower_dentry, dentry, dir->i_sb, 0);
        if (err)
                goto out;

        fist_copy_attr_timesizes(dir, lower_dir_dentry->d_inode);
        /* update number of links on parent directory */
        dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;

        fist_checkinode(dir, "post base0fs_mkdir-dir");

out:
        unlock_dir(lower_dir_dentry);
        if (!dentry->d_inode)
                d_drop(dentry);

        print_exit_status(err);
        return err;
}

static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
{
	struct dentry *lower_dentry;
	struct dentry *lower_dir_dentry;
	int rc;

	dentry_unhash(dentry);

	lower_dentry = ecryptfs_dentry_to_lower(dentry);
	dget(dentry);
	lower_dir_dentry = lock_parent(lower_dentry);
	dget(lower_dentry);
	rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
	dput(lower_dentry);
	if (!rc && dentry->d_inode)
		clear_nlink(dentry->d_inode);
	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
	set_nlink(dir, lower_dir_dentry->d_inode->i_nlink);
	unlock_dir(lower_dir_dentry);
	if (!rc)
		d_drop(dentry);
	dput(dentry);
	return rc;
}

/* try to make de an entry in dir_inodde linked to source_de */ 
static int coda_link(struct dentry *source_de, struct inode *dir_inode, 
	  struct dentry *de)
{
	struct inode *inode = source_de->d_inode;
        const char * name = de->d_name.name;
	int len = de->d_name.len;
	int error;

	if (coda_isroot(dir_inode) && coda_iscontrol(name, len))
		return -EPERM;

	error = venus_link(dir_inode->i_sb, coda_i2f(inode),
			   coda_i2f(dir_inode), (const char *)name, len);
	if (error) {
		d_drop(de);
		return error;
	}

	coda_dir_update_mtime(dir_inode);
	ihold(inode);
	d_instantiate(de, inode);
	inc_nlink(inode);
	return 0;
}

static int
scfs_do_unlink(struct inode *dir, struct dentry *dentry, struct inode *inode)
{
	struct dentry *lower_dentry = scfs_lower_dentry(dentry);
	struct inode *lower_dir_inode = scfs_lower_inode(dir);
	struct dentry *lower_dir_dentry;
	int ret;

	dget(lower_dentry);
	lower_dir_dentry = lock_parent(lower_dentry);
	ret = vfs_unlink(lower_dir_inode, lower_dentry);
	if (ret) {
		SCFS_PRINT_ERROR("error in vfs_unlink, ret : %d\n", ret);
		goto out;
	}
	fsstack_copy_attr_times(dir, lower_dir_inode);
	set_nlink(inode, scfs_lower_inode(inode)->i_nlink);
	inode->i_ctime = dir->i_ctime;
	d_drop(dentry);
out:
	unlock_dir(lower_dir_dentry);
	dput(lower_dentry);
	return ret;
}

static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
{
	int rc = 0;
	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
	struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
	struct dentry *lower_dir_dentry;

	dget(lower_dentry);
	lower_dir_dentry = lock_parent(lower_dentry);
	rc = vfs_unlink(lower_dir_inode, lower_dentry);
	if (rc) {
		printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
		goto out_unlock;
	}
	fsstack_copy_attr_times(dir, lower_dir_inode);
	set_nlink(dentry->d_inode,
		  ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink);
	dentry->d_inode->i_ctime = dir->i_ctime;
	d_drop(dentry);
out_unlock:
	unlock_dir(lower_dir_dentry);
	dput(lower_dentry);
	return rc;
}

/*
 * create a symlink in an AFS filesystem
 */
static int afs_symlink(struct inode *dir, struct dentry *dentry,
		       const char *content)
{
	struct afs_file_status status;
	struct afs_server *server;
	struct afs_vnode *dvnode, *vnode;
	struct afs_fid fid;
	struct inode *inode;
	struct key *key;
	int ret;

	dvnode = AFS_FS_I(dir);

	_enter("{%x:%u},{%s},%s",
	       dvnode->fid.vid, dvnode->fid.vnode, dentry->d_name.name,
	       content);

	ret = -ENAMETOOLONG;
	if (dentry->d_name.len >= AFSNAMEMAX)
		goto error;

	ret = -EINVAL;
	if (strlen(content) >= AFSPATHMAX)
		goto error;

	key = afs_request_key(dvnode->volume->cell);
	if (IS_ERR(key)) {
		ret = PTR_ERR(key);
		goto error;
	}

	ret = afs_vnode_symlink(dvnode, key, dentry->d_name.name, content,
				&fid, &status, &server);
	if (ret < 0)
		goto create_error;

	inode = afs_iget(dir->i_sb, key, &fid, &status, NULL);
	if (IS_ERR(inode)) {
		/* ENOMEM at a really inconvenient time - just abandon the new
		 * directory on the server */
		ret = PTR_ERR(inode);
		goto iget_error;
	}

	/* apply the status report we've got for the new vnode */
	vnode = AFS_FS_I(inode);
	spin_lock(&vnode->lock);
	vnode->update_cnt++;
	spin_unlock(&vnode->lock);
	afs_vnode_finalise_status_update(vnode, server);
	afs_put_server(server);

	d_instantiate(dentry, inode);
	if (d_unhashed(dentry)) {
		_debug("not hashed");
		d_rehash(dentry);
	}
	key_put(key);
	_leave(" = 0");
	return 0;

iget_error:
	afs_put_server(server);
create_error:
	key_put(key);
error:
	d_drop(dentry);
	_leave(" = %d", ret);
	return ret;
}

//.........这里部分代码省略.........
			goto out; /* XXX: should be BUG_ON */
		/* XXX: do we need to cross bind mounts here? */
		lower_dentry = lookup_one_len(name, lower_dir_dentry, namelen);
		if (IS_ERR(lower_dentry)) {
			err = PTR_ERR(lower_dentry);
			goto out;
		}
		/* XXX: need to mntget/mntput as needed too! */
		unionfs_set_lower_dentry_idx(dentry, bindex, lower_dentry);
		/* XXX: wrong mnt for crossing bind mounts! */
		lower_mnt = unionfs_mntget(dentry->d_sb->s_root, bindex);
		unionfs_set_lower_mnt_idx(dentry, bindex, lower_mnt);

		goto out;
	}

	/* if we're revalidating a positive dentry, don't make it negative */
	if (lookupmode != INTERPOSE_REVAL)
		d_add(dentry, NULL);

	goto out;

out_positive:
	/*** handle POSITIVE dentries ***/

	/*
	 * This unionfs dentry is positive (at least one lower inode
	 * exists), so scan entire dentry from beginning to end, and remove
	 * any negative lower dentries, if any.  Then, update dbstart/dbend
	 * to reflect the start/end of positive dentries.
	 */
	pos_start = pos_end = -1;
	for (bindex = bstart; bindex <= bend; bindex++) {
		lower_dentry = unionfs_lower_dentry_idx(dentry,
							bindex);
		if (lower_dentry && lower_dentry->d_inode) {
			if (pos_start < 0)
				pos_start = bindex;
			if (bindex > pos_end)
				pos_end = bindex;
			continue;
		}
		path_put_lowers(dentry, bindex, bindex, false);
	}
	if (pos_start >= 0)
		dbstart(dentry) = pos_start;
	if (pos_end >= 0)
		dbend(dentry) = pos_end;

	/* Partial lookups need to re-interpose, or throw away older negs. */
	if (lookupmode == INTERPOSE_PARTIAL) {
		if (dentry->d_inode) {
			unionfs_reinterpose(dentry);
			goto out;
		}

		/*
		 * This dentry was positive, so it is as if we had a
		 * negative revalidation.
		 */
		lookupmode = INTERPOSE_REVAL_NEG;
		update_bstart(dentry);
	}

	/*
	 * Interpose can return a dentry if d_splice returned a different
	 * dentry.
	 */
	d_interposed = unionfs_interpose(dentry, dentry->d_sb, lookupmode);
	if (IS_ERR(d_interposed))
		err = PTR_ERR(d_interposed);
	else if (d_interposed)
		dentry = d_interposed;

	if (!err)
		goto out;
	d_drop(dentry);

out_free:
	/* should dput/mntput all the underlying dentries on error condition */
	if (dbstart(dentry) >= 0)
		path_put_lowers_all(dentry, false);
	/* free lower_paths unconditionally */
	kfree(UNIONFS_D(dentry)->lower_paths);
	UNIONFS_D(dentry)->lower_paths = NULL;

out:
	if (dentry && UNIONFS_D(dentry)) {
		BUG_ON(dbstart(dentry) < 0 && dbend(dentry) >= 0);
		BUG_ON(dbstart(dentry) >= 0 && dbend(dentry) < 0);
	}
	if (d_interposed && UNIONFS_D(d_interposed)) {
		BUG_ON(dbstart(d_interposed) < 0 && dbend(d_interposed) >= 0);
		BUG_ON(dbstart(d_interposed) >= 0 && dbend(d_interposed) < 0);
	}

	if (!err && d_interposed)
		return d_interposed;
	return ERR_PTR(err);
}

//.........这里部分代码省略.........
	full_path = build_path_from_dentry(direntry);
	if (full_path == NULL) {
		rc = -ENOMEM;
		goto mknod_out;
	}

	if (pTcon->unix_ext) {
		struct cifs_unix_set_info_args args = {
			.mode	= mode & ~current_umask(),
			.ctime	= NO_CHANGE_64,
			.atime	= NO_CHANGE_64,
			.mtime	= NO_CHANGE_64,
			.device	= device_number,
		};
		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID) {
			args.uid = current_fsuid();
			args.gid = current_fsgid();
		} else {
			args.uid = INVALID_UID; /* no change */
			args.gid = INVALID_GID; /* no change */
		}
		rc = CIFSSMBUnixSetPathInfo(xid, pTcon, full_path, &args,
					    cifs_sb->local_nls,
					    cifs_sb->mnt_cifs_flags &
						CIFS_MOUNT_MAP_SPECIAL_CHR);
		if (rc)
			goto mknod_out;

		rc = cifs_get_inode_info_unix(&newinode, full_path,
						inode->i_sb, xid);

		if (rc == 0)
			d_instantiate(direntry, newinode);
		goto mknod_out;
	}

	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
		goto mknod_out;


	cifs_dbg(FYI, "sfu compat create special file\n");

	buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
	if (buf == NULL) {
		kfree(full_path);
		rc = -ENOMEM;
		free_xid(xid);
		return rc;
	}

	if (backup_cred(cifs_sb))
		create_options |= CREATE_OPEN_BACKUP_INTENT;

	rc = CIFSSMBOpen(xid, pTcon, full_path, FILE_CREATE,
			 GENERIC_WRITE, create_options,
			 &fileHandle, &oplock, buf, cifs_sb->local_nls,
			 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
	if (rc)
		goto mknod_out;

	/* BB Do not bother to decode buf since no local inode yet to put
	 * timestamps in, but we can reuse it safely */

	pdev = (struct win_dev *)buf;
	io_parms.netfid = fileHandle;
	io_parms.pid = current->tgid;
	io_parms.tcon = pTcon;
	io_parms.offset = 0;
	io_parms.length = sizeof(struct win_dev);
	if (S_ISCHR(mode)) {
		memcpy(pdev->type, "IntxCHR", 8);
		pdev->major =
		      cpu_to_le64(MAJOR(device_number));
		pdev->minor =
		      cpu_to_le64(MINOR(device_number));
		rc = CIFSSMBWrite(xid, &io_parms,
			&bytes_written, (char *)pdev,
			NULL, 0);
	} else if (S_ISBLK(mode)) {
		memcpy(pdev->type, "IntxBLK", 8);
		pdev->major =
		      cpu_to_le64(MAJOR(device_number));
		pdev->minor =
		      cpu_to_le64(MINOR(device_number));
		rc = CIFSSMBWrite(xid, &io_parms,
			&bytes_written, (char *)pdev,
			NULL, 0);
	} /* else if (S_ISFIFO) */
	CIFSSMBClose(xid, pTcon, fileHandle);
	d_drop(direntry);

	/* FIXME: add code here to set EAs */

mknod_out:
	kfree(full_path);
	kfree(buf);
	free_xid(xid);
	cifs_put_tlink(tlink);
	return rc;
}

//.........这里部分代码省略.........
		goto out_bad;

	dir = AFS_FS_I(parent->d_inode);

	/* validate the parent directory */
	if (test_bit(AFS_VNODE_MODIFIED, &dir->flags))
		afs_validate(dir, key);

	if (test_bit(AFS_VNODE_DELETED, &dir->flags)) {
		_debug("%s: parent dir deleted", dentry->d_name.name);
		goto out_bad;
	}

	dir_version = (void *) (unsigned long) dir->status.data_version;
	if (dentry->d_fsdata == dir_version)
		goto out_valid; /* the dir contents are unchanged */

	_debug("dir modified");

	/* search the directory for this vnode */
	ret = afs_do_lookup(&dir->vfs_inode, dentry, &fid, key);
	switch (ret) {
	case 0:
		/* the filename maps to something */
		if (!dentry->d_inode)
			goto out_bad;
		if (is_bad_inode(dentry->d_inode)) {
			printk("kAFS: afs_d_revalidate: %s/%s has bad inode\n",
			       parent->d_name.name, dentry->d_name.name);
			goto out_bad;
		}

		/* if the vnode ID has changed, then the dirent points to a
		 * different file */
		if (fid.vnode != vnode->fid.vnode) {
			_debug("%s: dirent changed [%u != %u]",
			       dentry->d_name.name, fid.vnode,
			       vnode->fid.vnode);
			goto not_found;
		}

		/* if the vnode ID uniqifier has changed, then the file has
		 * been deleted and replaced, and the original vnode ID has
		 * been reused */
		if (fid.unique != vnode->fid.unique) {
			_debug("%s: file deleted (uq %u -> %u I:%u)",
			       dentry->d_name.name, fid.unique,
			       vnode->fid.unique,
			       dentry->d_inode->i_generation);
			spin_lock(&vnode->lock);
			set_bit(AFS_VNODE_DELETED, &vnode->flags);
			spin_unlock(&vnode->lock);
			goto not_found;
		}
		goto out_valid;

	case -ENOENT:
		/* the filename is unknown */
		_debug("%s: dirent not found", dentry->d_name.name);
		if (dentry->d_inode)
			goto not_found;
		goto out_valid;

	default:
		_debug("failed to iterate dir %s: %d",
		       parent->d_name.name, ret);
		goto out_bad;
	}

out_valid:
	dentry->d_fsdata = dir_version;
out_skip:
	dput(parent);
	key_put(key);
	_leave(" = 1 [valid]");
	return 1;

	/* the dirent, if it exists, now points to a different vnode */
not_found:
	spin_lock(&dentry->d_lock);
	dentry->d_flags |= DCACHE_NFSFS_RENAMED;
	spin_unlock(&dentry->d_lock);

out_bad:
	if (dentry->d_inode) {
		/* don't unhash if we have submounts */
		if (have_submounts(dentry))
			goto out_skip;
	}

	_debug("dropping dentry %s/%s",
	       parent->d_name.name, dentry->d_name.name);
	shrink_dcache_parent(dentry);
	d_drop(dentry);
	dput(parent);
	key_put(key);

	_leave(" = 0 [bad]");
	return 0;
}