diff options
author | Al Viro <viro@zeniv.linux.org.uk> | 2018-05-04 15:23:01 +0300 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2018-05-11 22:36:37 +0300 |
commit | 1e2e547a93a00ebc21582c06ca3c6cfea2a309ee (patch) | |
tree | e31468774e0543997a15daa0409ef79a02d1438c /fs/ext4 | |
parent | d7760d638b140d53c6390a2fbee9b06460b43e9e (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/ext4')
-rw-r--r-- | fs/ext4/namei.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index b1f21e3a0763..4a09063ce1d2 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -2411,8 +2411,7 @@ static int ext4_add_nondir(handle_t *handle, int err = ext4_add_entry(handle, dentry, inode); if (!err) { ext4_mark_inode_dirty(handle, inode); - unlock_new_inode(inode); - d_instantiate(dentry, inode); + d_instantiate_new(dentry, inode); return 0; } drop_nlink(inode); @@ -2651,8 +2650,7 @@ out_clear_inode: err = ext4_mark_inode_dirty(handle, dir); if (err) goto out_clear_inode; - unlock_new_inode(inode); - d_instantiate(dentry, inode); + d_instantiate_new(dentry, inode); if (IS_DIRSYNC(dir)) ext4_handle_sync(handle); |