leases: fix write-open/read-lease race (f3c7691e) · Commits · 戴 / test

In setlease, we use i_writecount to decide whether we can give out a read lease. In open, we break leases before incrementing i_writecount. There is therefore a window between the break lease and the i_writecount increment when setlease could add a new read lease. This would leave us with a simultaneous write open and read lease, which shouldn't happen. Signed-off-by:

J. Bruce Fields <bfields@redhat.com> Signed-off-by:

Christoph Hellwig <hch@lst.de>

fs/namei.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -2035,10 +2035,7 @@ static int may_open(struct path *path, int acc_mode, int flag)
		if (flag & O_NOATIME && !inode_owner_or_capable(inode))
		return -EPERM;

		/*
		* Ensure there are no outstanding leases on the file.
		*/
		return break_lease(inode, flag);
		return 0;
		}

		static int handle_truncate(struct file *filp)

fs/open.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -685,6 +685,10 @@ static struct file __dentry_open(struct dentry dentry, struct vfsmount *mnt,
		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) {

Admin message