Commit 53dec2ea authored by Jens Axboe's avatar Jens Axboe
Browse files

fs: provide locked helper variant of close_fd_get_file() 



Assumes current->files->file_lock is already held on invocation. Helps
the caller check the file before removing the fd, if it needs to.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e342c807

fs/file.c

+25 −11
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ 
#include <linux/close_range.h>

#include <net/sock.h>



#include "internal.h"



unsigned int sysctl_nr_open __read_mostly = 1024*1024;

unsigned int sysctl_nr_open_min = BITS_PER_LONG;

/* our min() is unusable in constant expressions ;-/ */
@@ -732,36 +734,48 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) 
}



/*

 * variant of close_fd that gets a ref on the file for later fput.

 * The caller must ensure that filp_close() called on the file, and then

 * an fput().

 * See close_fd_get_file() below, this variant assumes current->files->file_lock

 * is held.

 */

int close_fd_get_file(unsigned int fd, struct file **res)

int __close_fd_get_file(unsigned int fd, struct file **res)

{

	struct files_struct *files = current->files;

	struct file *file;

	struct fdtable *fdt;



	spin_lock(&files->file_lock);

	fdt = files_fdtable(files);

	if (fd >= fdt->max_fds)

		goto out_unlock;

		goto out_err;

	file = fdt->fd[fd];

	if (!file)

		goto out_unlock;

		goto out_err;

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

	__put_unused_fd(files, fd);

	spin_unlock(&files->file_lock);

	get_file(file);

	*res = file;

	return 0;



out_unlock:

	spin_unlock(&files->file_lock);

out_err:

	*res = NULL;

	return -ENOENT;

}



/*

 * variant of close_fd that gets a ref on the file for later fput.

 * The caller must ensure that filp_close() called on the file, and then

 * an fput().

 */

int close_fd_get_file(unsigned int fd, struct file **res)

{

	struct files_struct *files = current->files;

	int ret;



	spin_lock(&files->file_lock);

	ret = __close_fd_get_file(fd, res);

	spin_unlock(&files->file_lock);



	return ret;

}



void do_close_on_exec(struct files_struct *files)

{

	unsigned i;

fs/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -132,6 +132,7 @@ extern struct file *do_file_open_root(struct dentry *, struct vfsmount *, 
		const char *, const struct open_flags *);

extern struct open_how build_open_how(int flags, umode_t mode);

extern int build_open_flags(const struct open_how *how, struct open_flags *op);

extern int __close_fd_get_file(unsigned int fd, struct file **res);



long do_sys_ftruncate(unsigned int fd, loff_t length, int small);

int chmod_common(const struct path *path, umode_t mode);