Commit 514d748f authored Jun 02, 2015 by Jan Kara Committed by Al Viro Jun 16, 2015

ufs: Fix possible deadlock when looking up directories



Commit e4502c63 (ufs: deal with nfsd/iget races) made ufs
create inodes with I_NEW flag set. However ufs_mkdir() never cleared
this flag. Thus if someone ever tried to lookup the directory by inode
number, he would deadlock waiting for I_NEW to be cleared. Luckily this
mostly happens only if the filesystem is exported over NFS since
otherwise we have the inode attached to dentry and don't look it up by
inode number. In rare cases dentry can get freed without inode being
freed and then we'd hit the deadlock even without NFS export.

Fix the problem by clearing I_NEW before instantiating new directory
inode.

Fixes: e4502c63
Reported-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 12ecbb4b

fs/ufs/namei.c

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -212,6 +212,7 @@ static int ufs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
	goto out_fail;		goto out_fail;
	unlock_ufs(dir->i_sb);		unlock_ufs(dir->i_sb);

			unlock_new_inode(inode);
	d_instantiate(dentry, inode);		d_instantiate(dentry, inode);
	out:		out:
	return err;		return err;

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