From f440ea85d429e59f63d626e017403cb09d9adbdb Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 4 May 2018 08:23:01 -0400 Subject: do d_instantiate/unlock_new_inode combinations safely commit 1e2e547a93a00ebc21582c06ca3c6cfea2a309ee upstream. For anything NFS-exported we do _not_ want to unlock new inode before it has grown an alias; original set of fixes got the ordering right, but missed the nasty complication in case of lockdep being enabled - unlock_new_inode() does lockdep_annotate_inode_mutex_key(inode) which can only be done before anyone gets a chance to touch ->i_mutex. Unfortunately, flipping the order and doing unlock_new_inode() before d_instantiate() opens a window when mkdir can race with open-by-fhandle on a guessed fhandle, leading to multiple aliases for a directory inode and all the breakage that follows from that. Correct solution: a new primitive (d_instantiate_new()) combining these two in the right order - lockdep annotate, then d_instantiate(), then the rest of unlock_new_inode(). All combinations of d_instantiate() with unlock_new_inode() should be converted to that. Cc: stable@kernel.org # 2.6.29 and later Tested-by: Mike Marshall Reviewed-by: Andreas Dilger Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/ext2/namei.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'fs/ext2') diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c index e078075dc66f..aa6ec191cac0 100644 --- a/fs/ext2/namei.c +++ b/fs/ext2/namei.c @@ -41,8 +41,7 @@ static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode) { int err = ext2_add_link(dentry, inode); if (!err) { - unlock_new_inode(inode); - d_instantiate(dentry, inode); + d_instantiate_new(dentry, inode); return 0; } inode_dec_link_count(inode); @@ -269,8 +268,7 @@ static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode) if (err) goto out_fail; - unlock_new_inode(inode); - d_instantiate(dentry, inode); + d_instantiate_new(dentry, inode); out: return err; -- cgit v1.2.3