ufs: Fix possible deadlock when looking up directories
authorJan Kara <jack@suse.cz>
Tue, 2 Jun 2015 09:26:34 +0000 (11:26 +0200)
committerAl Viro <viro@zeniv.linux.org.uk>
Tue, 16 Jun 2015 06:08:12 +0000 (02:08 -0400)
commit514d748f69c97a51a2645eb198ac5c6218f22ff9
tree62b4f0f249c523eaba9fe4b8ce407782922a5b11
parent12ecbb4b1d765a5076920999298d9625439dbe58
ufs: Fix possible deadlock when looking up directories

Commit e4502c63f56aeca88 (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: e4502c63f56aeca887ced37f24e0def1ef11cec8
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>
fs/ufs/namei.c