Commit 1027abe8 authored by Al Viro's avatar Al Viro
Browse files

[PATCH] merge locate_fd() and get_unused_fd() 



	New primitive: alloc_fd(start, flags).  get_unused_fd() and
get_unused_fd_flags() become wrappers on top of it.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent a1bc6eb4

fs/fcntl.c

+14 −73
Original line number Diff line number Diff line
@@ -49,73 +49,6 @@ static int get_close_on_exec(unsigned int fd) 
	return res;

}



/*

 * locate_fd finds a free file descriptor in the open_fds fdset,

 * expanding the fd arrays if necessary.  Must be called with the

 * file_lock held for write.

 */



static int locate_fd(unsigned int orig_start, int cloexec)

{

	struct files_struct *files = current->files;

	unsigned int newfd;

	unsigned int start;

	int error;

	struct fdtable *fdt;



	spin_lock(&files->file_lock);

repeat:

	fdt = files_fdtable(files);

	/*

	 * Someone might have closed fd's in the range

	 * orig_start..fdt->next_fd

	 */

	start = orig_start;

	if (start < files->next_fd)

		start = files->next_fd;



	newfd = start;

	if (start < fdt->max_fds)

		newfd = find_next_zero_bit(fdt->open_fds->fds_bits,

					   fdt->max_fds, start);



	error = expand_files(files, newfd);

	if (error < 0)

		goto out;



	/*

	 * If we needed to expand the fs array we

	 * might have blocked - try again.

	 */

	if (error)

		goto repeat;



	if (start <= files->next_fd)

		files->next_fd = newfd + 1;



	FD_SET(newfd, fdt->open_fds);

	if (cloexec)

		FD_SET(newfd, fdt->close_on_exec);

	else

		FD_CLR(newfd, fdt->close_on_exec);

	error = newfd;



out:

	spin_unlock(&files->file_lock);

	return error;

}



static int dupfd(struct file *file, unsigned int start, int cloexec)

{

	int fd = locate_fd(start, cloexec);

	if (fd >= 0)

		fd_install(fd, file);

	else

		fput(file);



	return fd;

}



asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)

{

	int err = -EBADF;
@@ -196,8 +129,13 @@ asmlinkage long sys_dup(unsigned int fildes) 
	int ret = -EBADF;

	struct file *file = fget(fildes);



	if (file)

		ret = dupfd(file, 0, 0);

	if (file) {

		ret = get_unused_fd();

		if (ret >= 0)

			fd_install(ret, file);

		else

			fput(file);

	}

	return ret;

}
@@ -322,8 +260,11 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 
	case F_DUPFD_CLOEXEC:

		if (arg >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)

			break;

		err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);

		if (err >= 0) {

			get_file(filp);

		err = dupfd(filp, arg, cmd == F_DUPFD_CLOEXEC);

			fd_install(err, filp);

		}

		break;

	case F_GETFD:

		err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;

fs/file.c

+61 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
 *  Manage the dynamic fd arrays in the process files_struct.

 */



#include <linux/module.h>

#include <linux/fs.h>

#include <linux/mm.h>

#include <linux/time.h>
@@ -432,3 +433,63 @@ struct files_struct init_files = { 
	},

	.file_lock	= __SPIN_LOCK_UNLOCKED(init_task.file_lock),

};



/*

 * allocate a file descriptor, mark it busy.

 */

int alloc_fd(unsigned start, unsigned flags)

{

	struct files_struct *files = current->files;

	unsigned int fd;

	int error;

	struct fdtable *fdt;



	spin_lock(&files->file_lock);

repeat:

	fdt = files_fdtable(files);

	fd = start;

	if (fd < files->next_fd)

		fd = files->next_fd;



	if (fd < fdt->max_fds)

		fd = find_next_zero_bit(fdt->open_fds->fds_bits,

					   fdt->max_fds, fd);



	error = expand_files(files, fd);

	if (error < 0)

		goto out;



	/*

	 * If we needed to expand the fs array we

	 * might have blocked - try again.

	 */

	if (error)

		goto repeat;



	if (start <= files->next_fd)

		files->next_fd = fd + 1;



	FD_SET(fd, fdt->open_fds);

	if (flags & O_CLOEXEC)

		FD_SET(fd, fdt->close_on_exec);

	else

		FD_CLR(fd, fdt->close_on_exec);

	error = fd;

#if 1

	/* Sanity check */

	if (rcu_dereference(fdt->fd[fd]) != NULL) {

		printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);

		rcu_assign_pointer(fdt->fd[fd], NULL);

	}

#endif



out:

	spin_unlock(&files->file_lock);

	return error;

}



int get_unused_fd(void)

{

	return alloc_fd(0, 0);

}

EXPORT_SYMBOL(get_unused_fd);

fs/open.c

+0 −56
Original line number Diff line number Diff line
@@ -963,62 +963,6 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags) 
}

EXPORT_SYMBOL(dentry_open);



/*

 * Find an empty file descriptor entry, and mark it busy.

 */

int get_unused_fd_flags(int flags)

{

	struct files_struct * files = current->files;

	int fd, error;

	struct fdtable *fdt;



	spin_lock(&files->file_lock);



repeat:

	fdt = files_fdtable(files);

	fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds,

				files->next_fd);



	/* Do we need to expand the fd array or fd set?  */

	error = expand_files(files, fd);

	if (error < 0)

		goto out;



	if (error) {

		/*

	 	 * If we needed to expand the fs array we

		 * might have blocked - try again.

		 */

		goto repeat;

	}



	FD_SET(fd, fdt->open_fds);

	if (flags & O_CLOEXEC)

		FD_SET(fd, fdt->close_on_exec);

	else

		FD_CLR(fd, fdt->close_on_exec);

	files->next_fd = fd + 1;

#if 1

	/* Sanity check */

	if (fdt->fd[fd] != NULL) {

		printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);

		fdt->fd[fd] = NULL;

	}

#endif

	error = fd;



out:

	spin_unlock(&files->file_lock);

	return error;

}



int get_unused_fd(void)

{

	return get_unused_fd_flags(0);

}



EXPORT_SYMBOL(get_unused_fd);



static void __put_unused_fd(struct files_struct *files, unsigned int fd)

{

	struct fdtable *fdt = files_fdtable(files);

include/linux/file.h

+2 −1
Original line number Diff line number Diff line
@@ -34,8 +34,9 @@ extern struct file *fget(unsigned int fd); 
extern struct file *fget_light(unsigned int fd, int *fput_needed);

extern void set_close_on_exec(unsigned int fd, int flag);

extern void put_filp(struct file *);

extern int alloc_fd(unsigned start, unsigned flags);

extern int get_unused_fd(void);

extern int get_unused_fd_flags(int flags);

#define get_unused_fd_flags(flags) alloc_fd(0, (flags))

extern void put_unused_fd(unsigned int fd);



extern void fd_install(unsigned int fd, struct file *file);