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authorAl Viro <viro@zeniv.linux.org.uk>2018-05-04 08:23:01 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2018-05-11 15:36:37 -0400
commit1e2e547a93a00ebc21582c06ca3c6cfea2a309ee (patch)
treee31468774e0543997a15daa0409ef79a02d1438c /fs/ext2/namei.c
parentd7760d638b140d53c6390a2fbee9b06460b43e9e (diff)
do d_instantiate/unlock_new_inode combinations safely
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 <hubcap@omnibond.com> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/ext2/namei.c')
-rw-r--r--fs/ext2/namei.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 55f7caadb093..152453a91877 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);
@@ -255,8 +254,7 @@ 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;