C++ put_filp函数代码示例

static int recv_fds(int minor, struct ancillary *data,
					struct msg_control *msg_ctrl)
{
	int rc, i, j;
	struct msghdr msghdr;
	struct cmsghdr *cmsg;
	endpoint_t to_ep;

#if DEBUG == 1
	static int call_count = 0;
	printf("(uds) [%d] recv_fds() call_count=%d\n", minor,
							++call_count);
#endif

	msghdr.msg_control = msg_ctrl->msg_control;
	msghdr.msg_controllen = msg_ctrl->msg_controllen;

	cmsg = CMSG_FIRSTHDR(&msghdr);
	cmsg->cmsg_len = CMSG_LEN(sizeof(int) * data->nfiledes);
	cmsg->cmsg_level = SOL_SOCKET;
	cmsg->cmsg_type = SCM_RIGHTS;

	to_ep = uds_fd_table[minor].owner;

	/* copy to the target endpoint */
	for (i = 0; i < data->nfiledes; i++) {
		rc = copy_filp(to_ep, data->filps[i]);
		if (rc < 0) {
			/* revert set_filp() calls */
			for (j = 0; j < data->nfiledes; j++) {
				put_filp(data->filps[j]);
			}
			/* revert copy_filp() calls */
			for (j = i; j >= 0; j--) {
				cancel_fd(to_ep, data->fds[j]);
			}
			return rc;
		}
		data->fds[i] = rc; /* data->fds[i] now has the new FD */
	}

	for (i = 0; i < data->nfiledes; i++) {
		put_filp(data->filps[i]);
#if DEBUG == 1
		printf("(uds) recv_fds() => %d\n", data->fds[i]);
#endif
		((int *)CMSG_DATA(cmsg))[i] = data->fds[i];
		data->fds[i] = -1;
		data->filps[i] = NULL;
	}

	data->nfiledes = 0;

	return OK;
}

static int send_fds(int minor, struct ancillary *data)
{
	int rc, i, j;

#if DEBUG == 1
	static int call_count = 0;
	printf("(uds) [%d] send_fds() call_count=%d\n", minor, ++call_count);
#endif

	/* verify the file descriptors and get their filps. */
	for (i = 0; i < data->nfiledes; i++) {
		data->filps[i] = verify_fd(uds_fd_table[minor].owner,
						data->fds[i]);

		if (data->filps[i] == NULL) {
			return EINVAL;
		}
	}

	/* set them as in-flight */
	for (i = 0; i < data->nfiledes; i++) {
		rc = set_filp(data->filps[i]);
		if (rc != OK) {
			/* revert set_filp() calls */
			for (j = i; j >= 0; j--) {
				put_filp(data->filps[j]);
			}
			return rc;
		}
	}

	return OK;
}

struct file *dentry_open(const struct path *path, int flags,
			 const struct cred *cred)
{
	int error;
	struct file *f;

	validate_creds(cred);

	
	BUG_ON(!path->mnt);

	f = get_empty_filp();
	if (!IS_ERR(f)) {
		f->f_flags = flags;
		f->f_path = *path;
		error = do_dentry_open(f, NULL, cred);
		if (!error) {
			
			error = open_check_o_direct(f);
			if (error) {
				fput(f);
				f = ERR_PTR(error);
			}
		} else { 
			put_filp(f);
			f = ERR_PTR(error);
		}
	}
	return f;
}

static struct file *vperfctr_get_filp(void)
{
	struct file *filp;
	struct inode *inode;
	struct dentry *dentry;

	filp = get_empty_filp();
	if (!filp)
		goto out;
	inode = vperfctr_get_inode();
	if (!inode)
		goto out_filp;
	dentry = vperfctr_d_alloc_root(inode);
	if (!dentry)
		goto out_inode;

	filp->f_vfsmnt = mntget(vperfctr_mnt);
	filp->f_dentry = dentry;
	filp->f_mapping = dentry->d_inode->i_mapping;

	filp->f_pos = 0;
	filp->f_flags = 0;
	filp->f_op = &vperfctr_file_ops; /* fops_get() if MODULE */
	filp->f_mode = FMODE_READ;
	filp->f_version = 0;

	return filp;

 out_inode:
	iput(inode);
 out_filp:
	put_filp(filp);	/* doesn't run ->release() like fput() does */
 out:
	return NULL;
}

struct file *dentry_open(const struct path *path, int flags,
			 const struct cred *cred)
{
	int error;
	struct file *f;

	validate_creds(cred);

	/* We must always pass in a valid mount pointer. */
	BUG_ON(!path->mnt);

	f = get_empty_filp();
	if (!IS_ERR(f)) {
		f->f_flags = flags;
		f->f_path = *path;
		error = do_dentry_open(f, NULL, cred);
		if (!error) {
			/* from now on we need fput() to dispose of f */
			error = open_check_o_direct(f);
			if (error) {
				fput(f);
				f = ERR_PTR(error);
			}
		} else { 
			put_filp(f);
			f = ERR_PTR(error);
		}
	}
	return f;
}

struct file *dentry_open(const struct path *path, int flags,
			 const struct cred *cred)
{
	int error;
	struct file *f;

	validate_creds(cred);

	/* We must always pass in a valid mount pointer. */
	BUG_ON(!path->mnt);

	error = -ENFILE;
	f = get_empty_filp();
	if (f == NULL)
		return ERR_PTR(error);

	f->f_flags = flags;
	error = vfs_open(path, f, cred);
	if (!error) {
		error = open_check_o_direct(f);
		if (error) {
			fput(f);
			f = ERR_PTR(error);
		}
	} else { 
		put_filp(f);
		f = ERR_PTR(error);
	}
	return f;
}

int clear_fds(int minor, struct ancillary *data)
{
/* This function calls put_filp() for all of the FDs in data.
 * This is used when a Unix Domain Socket is closed and there
 * exists references to file descriptors that haven't been received
 * with recvmsg().
 */
	int i;

#if DEBUG == 1
	static int call_count = 0;
	printf("(uds) [%d] recv_fds() call_count=%d\n", minor,
							++call_count);
#endif

	for (i = 0; i < data->nfiledes; i++) {
		put_filp(data->filps[i]);
#if DEBUG == 1
		printf("(uds) clear_fds() => %d\n", data->fds[i]);
#endif
		data->fds[i] = -1;
		data->filps[i] = NULL;
	}

	data->nfiledes = 0;

	return OK;
}

/*
 * shmem_file_setup - get an unlinked file living in tmpfs
 *
 * @name: name for dentry (to be seen in /proc/<pid>/maps
 * @size: size to be set for the file
 *
 */
struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
{
	int error;
	struct file *file;
	struct inode *inode;
	struct dentry *dentry, *root;
	struct qstr this;

	if (IS_ERR(shm_mnt))
		return (void *)shm_mnt;

	error = -ENOMEM;
	this.name = name;
	this.len = strlen(name);
	this.hash = 0; /* will go */
	root = shm_mnt->mnt_root;
	dentry = d_alloc(root, &this);
	if (!dentry)
		goto put_memory;

	error = -ENFILE;
	file = get_empty_filp();
	if (!file)
		goto put_dentry;

	error = -ENOSPC;
	inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
	if (!inode)
		goto close_file;

	d_instantiate(dentry, inode);
	inode->i_nlink = 0;	/* It is unlinked */

	file->f_path.mnt = mntget(shm_mnt);
	file->f_path.dentry = dentry;
	file->f_mapping = inode->i_mapping;
	file->f_op = &ramfs_file_operations;
	file->f_mode = FMODE_WRITE | FMODE_READ;

	/* notify everyone as to the change of file size */
	error = do_truncate(dentry, size, 0, file);
	if (error < 0)
		goto close_file;

	return file;

close_file:
	put_filp(file);
put_dentry:
	dput(dentry);
put_memory:
	return ERR_PTR(error);
}

struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
{
	struct file * f;
	struct inode *inode;
	int error;

	error = -ENFILE;
	f = get_empty_filp();
	if (!f)
		goto cleanup_dentry;
	f->f_flags = flags;
	f->f_mode = (flags+1) & O_ACCMODE;
	inode = dentry->d_inode;
	if (f->f_mode & FMODE_WRITE) {
		error = get_write_access(inode);
		if (error)
			goto cleanup_file;
	}

	f->f_dentry = dentry;
	f->f_vfsmnt = mnt;
	f->f_pos = 0;
	f->f_reada = 0;
	f->f_op = fops_get(inode->i_fop);
	if (inode->i_sb)
		file_move(f, &inode->i_sb->s_files);
	if (f->f_op && f->f_op->open) {
		error = f->f_op->open(inode,f);
		if (error)
			goto cleanup_all;
	}
	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

	return f;

cleanup_all:
	fops_put(f->f_op);
	if (f->f_mode & FMODE_WRITE)
		put_write_access(inode);
	f->f_dentry = NULL;
	f->f_vfsmnt = NULL;
cleanup_file:
	put_filp(f);
cleanup_dentry:
	dput(dentry);
	mntput(mnt);
	return ERR_PTR(error);
}

static struct file *__dentry_open(struct path *path, struct file *f,
				int (*open)(struct inode *, struct file *),
				const struct cred *cred)
{
	struct file *res = do_dentry_open(path, f, open, cred);
	if (!IS_ERR(res)) {
		int error = open_check_o_direct(f);
		if (error) {
			fput(res);
			res = ERR_PTR(error);
		}
	} else {
		put_filp(f);
	}
	return res;
}

struct file *filp_clone_open(struct file *oldfile)
{
	struct file *file;
	int retval;

	file = get_empty_filp();
	if (IS_ERR(file))
		return file;

	file->f_flags = oldfile->f_flags;
	retval = vfs_open(&oldfile->f_path, file, oldfile->f_cred);
	if (retval) {
		put_filp(file);
		return ERR_PTR(retval);
	}

	return file;
}

static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
					struct file *f,
					int (*open)(struct inode *, struct file *),
					const struct cred *cred)
{
	static const struct file_operations empty_fops = {};
	struct inode *inode;
	int error;

	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
				FMODE_PREAD | FMODE_PWRITE;

	if (unlikely(f->f_flags & O_PATH))
		f->f_mode = FMODE_PATH;

	inode = dentry->d_inode;
	if (f->f_mode & FMODE_WRITE) {
		error = __get_file_write_access(inode, mnt);
		if (error)
			goto cleanup_file;
		if (!special_file(inode->i_mode))
			file_take_write(f);
	}

	f->f_mapping = inode->i_mapping;
	f->f_path.dentry = dentry;
	f->f_path.mnt = mnt;
	f->f_pos = 0;
	file_sb_list_add(f, inode->i_sb);

	if (unlikely(f->f_mode & FMODE_PATH)) {
		f->f_op = &empty_fops;
		return f;
	}

	f->f_op = fops_get(inode->i_fop);

	error = security_dentry_open(f, cred);
	if (error)
		goto cleanup_all;

	error = break_lease(inode, f->f_flags);
	if (error)
		goto cleanup_all;

	if (!open && f->f_op)
		open = f->f_op->open;
	if (open) {
		error = open(inode, f);
		if (error)
			goto cleanup_all;
	}
	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		i_readcount_inc(inode);

	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);

	/* NB: we're sure to have correct a_ops only after f_op->open */
	if (f->f_flags & O_DIRECT) {
		if (!f->f_mapping->a_ops ||
		    ((!f->f_mapping->a_ops->direct_IO) &&
		    (!f->f_mapping->a_ops->get_xip_mem))) {
			fput(f);
			f = ERR_PTR(-EINVAL);
		}
	}

	return f;

cleanup_all:
	fops_put(f->f_op);
	if (f->f_mode & FMODE_WRITE) {
		put_write_access(inode);
		if (!special_file(inode->i_mode)) {
			/*
			 * We don't consider this a real
			 * mnt_want/drop_write() pair
			 * because it all happenend right
			 * here, so just reset the state.
			 */
			file_reset_write(f);
			mnt_drop_write(mnt);
		}
	}
	file_sb_list_del(f);
	f->f_path.dentry = NULL;
	f->f_path.mnt = NULL;
cleanup_file:
	put_filp(f);
	dput(dentry);
	mntput(mnt);
	return ERR_PTR(error);
}

int do_pipe(int *fd)
{
	struct inode * inode;
	struct file *f1, *f2;
	int error;
	int i,j;

	error = -ENFILE;
	f1 = get_empty_filp();
	if (!f1)
		goto no_files;

	f2 = get_empty_filp();
	if (!f2)
		goto close_f1;

	inode = get_pipe_inode();
	if (!inode)
		goto close_f12;

	error = get_unused_fd();
	if (error < 0)
		goto close_f12_inode;
	i = error;

	error = get_unused_fd();
	if (error < 0)
		goto close_f12_inode_i;
	j = error;

	error = -ENOMEM;
	f1->f_dentry = f2->f_dentry = dget(d_alloc_root(inode, NULL));
	if (!f1->f_dentry)
		goto close_f12_inode_i_j;

	/* read file */
	f1->f_pos = f2->f_pos = 0;
	f1->f_flags = O_RDONLY;
	f1->f_op = &read_pipe_fops;
	f1->f_mode = 1;

	/* write file */
	f2->f_flags = O_WRONLY;
	f2->f_op = &write_pipe_fops;
	f2->f_mode = 2;

	fd_install(i, f1);
	fd_install(j, f2);
	fd[0] = i;
	fd[1] = j;
	return 0;

close_f12_inode_i_j:
	put_unused_fd(j);
close_f12_inode_i:
	put_unused_fd(i);
close_f12_inode:
	free_page((unsigned long) PIPE_BASE(*inode));
	iput(inode);
close_f12:
	put_filp(f2);
close_f1:
	put_filp(f1);
no_files:
	return error;	
}

static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
					int flags, struct file *f,
					int (*open)(struct inode *, struct file *))
{
	struct inode *inode;
	int error;

	f->f_flags = flags;
	f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK |
				FMODE_PREAD | FMODE_PWRITE;
	inode = dentry->d_inode;
	if (f->f_mode & FMODE_WRITE) {
		error = __get_file_write_access(inode, mnt);
		if (error)
			goto cleanup_file;
		if (!special_file(inode->i_mode))
			file_take_write(f);
	}

	f->f_mapping = inode->i_mapping;
	f->f_path.dentry = dentry;
	f->f_path.mnt = mnt;
	f->f_pos = 0;
	f->f_op = fops_get(inode->i_fop);
	file_move(f, &inode->i_sb->s_files);

	error = security_dentry_open(f);
	if (error)
		goto cleanup_all;

	if (!open && f->f_op)
		open = f->f_op->open;
	if (open) {
		error = open(inode, f);
		if (error)
			goto cleanup_all;
	}

	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);

	/* NB: we're sure to have correct a_ops only after f_op->open */
	if (f->f_flags & O_DIRECT) {
		if (!f->f_mapping->a_ops ||
		    ((!f->f_mapping->a_ops->direct_IO) &&
		    (!f->f_mapping->a_ops->get_xip_mem))) {
			fput(f);
			f = ERR_PTR(-EINVAL);
		}
	}

	return f;

cleanup_all:
	fops_put(f->f_op);
	if (f->f_mode & FMODE_WRITE) {
		put_write_access(inode);
		if (!special_file(inode->i_mode)) {
			/*
			 * We don't consider this a real
			 * mnt_want/drop_write() pair
			 * because it all happenend right
			 * here, so just reset the state.
			 */
			file_reset_write(f);
			mnt_drop_write(mnt);
		}
	}
	file_kill(f);
	f->f_path.dentry = NULL;
	f->f_path.mnt = NULL;
cleanup_file:
	put_filp(f);
	dput(dentry);
	mntput(mnt);
	return ERR_PTR(error);
}

int do_pipe(int *fd)
{
	struct qstr this;
	char name[32];
	struct dentry *dentry;
	struct inode * inode;
	struct file *f1, *f2;
	int error;
	int i,j;

	error = -ENFILE;
	f1 = get_empty_filp();
	if (!f1)
		goto no_files;

	f2 = get_empty_filp();
	if (!f2)
		goto close_f1;

	inode = get_pipe_inode();
	if (!inode)
		goto close_f12;

	error = get_unused_fd();
	if (error < 0)
		goto close_f12_inode;
	i = error;

	error = get_unused_fd();
	if (error < 0)
		goto close_f12_inode_i;
	j = error;

	error = -ENOMEM;
	sprintf(name, "[%lu]", inode->i_ino);
	this.name = name;
	this.len = strlen(name);
	this.hash = inode->i_ino; /* will go */
	dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &this);
	if (!dentry)
		goto close_f12_inode_i_j;
	dentry->d_op = &pipefs_dentry_operations;
	d_add(dentry, inode);
	f1->f_vfsmnt = f2->f_vfsmnt = mntget(mntget(pipe_mnt));
	f1->f_dentry = f2->f_dentry = dget(dentry);

	/* read file */
	f1->f_pos = f2->f_pos = 0;
	f1->f_flags = O_RDONLY;
	f1->f_op = &read_pipe_fops;
	f1->f_mode = 1;
	f1->f_version = 0;

	/* write file */
	f2->f_flags = O_WRONLY;
	f2->f_op = &write_pipe_fops;
	f2->f_mode = 2;
	f2->f_version = 0;

	fd_install(i, f1);
	fd_install(j, f2);
	fd[0] = i;
	fd[1] = j;
	return 0;

close_f12_inode_i_j:
	put_unused_fd(j);
close_f12_inode_i:
	put_unused_fd(i);
close_f12_inode:
	free_page((unsigned long) PIPE_BASE(*inode));
	kfree(inode->i_pipe);
	inode->i_pipe = NULL;
	iput(inode);
close_f12:
	put_filp(f2);
close_f1:
	put_filp(f1);
no_files:
	return error;	
}