Messages in this thread | | | Subject | Re: [PATCH 4.4 017/268] do d_instantiate/unlock_new_inode combinations safely | From | Ben Hutchings <> | Date | Fri, 08 Jun 2018 14:17:49 +0100 |
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On Mon, 2018-05-28 at 11:59 +0200, Greg Kroah-Hartman wrote: > 4.4-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Al Viro <viro@zeniv.linux.org.uk> > > 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. [...]
I think you missed xfs, which has a wrapper around unlock_new_inode() called xfs_finish_inode_setup(). It looks like xfs_generic_create() and xfs_vn_symlink() still need this conversion.
Ben.
-- Ben Hutchings, Software Developer Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom
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