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Commit dfe0e09d authored by Al Viro's avatar Al Viro Committed by TARKZiM
Browse files

allow the temp files created by open() to be linked to 



O_TMPFILE | O_CREAT => linkat() with AT_SYMLINK_FOLLOW and /proc/self/fd/<n>
as oldpath (i.e. flink()) will create a link
O_TMPFILE | O_CREAT | O_EXCL => ENOENT on attempt to link those guys

Change-Id: I5e28485680c3320cd0fccc0ba1bea8b963fca7fe
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 7f0a684a

fs/inode.c

+3 −1
Original line number Diff line number Diff line
@@ -333,8 +333,10 @@ EXPORT_SYMBOL(set_nlink); 
 */

void inc_nlink(struct inode *inode)

{

	if (WARN_ON(inode->i_nlink == 0))

	if (unlikely(inode->i_nlink == 0)) {

		WARN_ON(!(inode->i_state & I_LINKABLE));

		atomic_long_dec(&inode->i_sb->s_remove_count);

	}



	inode->__i_nlink++;

}

fs/namei.c

+14 −2
Original line number Diff line number Diff line
@@ -3003,8 +3003,14 @@ static int do_tmpfile(int dfd, struct filename *pathname, 
	if (error)

		goto out2;

	error = open_check_o_direct(file);

	if (error)

	if (error) {

		fput(file);

	} else if (!(op->open_flag & O_EXCL)) {

		struct inode *inode = file_inode(file);

		spin_lock(&inode->i_lock);

		inode->i_state |= I_LINKABLE;

		spin_unlock(&inode->i_lock);

	}

out2:

	mnt_drop_write(nd->path.mnt);

out:
@@ -3726,12 +3732,18 @@ int vfs_link2(struct vfsmount *mnt, struct dentry *old_dentry, struct inode *dir 


	mutex_lock(&inode->i_mutex);

	/* Make sure we don't allow creating hardlink to an unlinked file */

	if (inode->i_nlink == 0)

	if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE))

		error =  -ENOENT;

	else if (max_links && inode->i_nlink >= max_links)

		error = -EMLINK;

	else

		error = dir->i_op->link(old_dentry, dir, new_dentry);



	if (!error && (inode->i_state & I_LINKABLE)) {

		spin_lock(&inode->i_lock);

		inode->i_state &= ~I_LINKABLE;

		spin_unlock(&inode->i_lock);

	}

	mutex_unlock(&inode->i_mutex);

	if (!error)

		fsnotify_link(dir, inode, new_dentry);

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -1771,6 +1771,7 @@ struct super_operations { 
#define I_REFERENCED		(1 << 8)

#define __I_DIO_WAKEUP		9

#define I_DIO_WAKEUP		(1 << I_DIO_WAKEUP)

#define I_LINKABLE		(1 << 10)



#define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)