Messages in this thread | | | Date | Mon, 21 Jul 2008 20:02:16 +0100 | From | Al Viro <> | Subject | Re: [patch] vfs: fix vfs_rename_dir for FS_RENAME_DOES_D_MOVE filesystems |
| |
On Mon, Jul 21, 2008 at 01:41:47PM +0200, Miklos Szeredi wrote: > From: Miklos Szeredi <mszeredi@suse.cz> > > vfs_rename_dir() doesn't properly account for filesystems with > FS_RENAME_DOES_D_MOVE. If new_dentry has a target inode attached, it > unhashes the new_dentry prior to the rename() iop and rehashes it > after, but doesn't account for the possibility that rename() may have > swapped {old,new}_dentry. For FS_RENAME_DOES_D_MOVE filesystems, it > rehashes new_dentry (now the old renamed-from name, which d_move() > expected to go away), such that a subsequent lookup will find it. > > This was caught by the recently posted POSIX fstest suite, rename/10.t > test 62 (and others) on ceph. > > Fix by not rehashing the new dentry. Rehashing would only make sense > if the rename failed (which should happen extremely rarely), but we > cannot handle that case correctly 100% of the time anyway, so...
Lovely. AFAICS, that's a fallout from commit 349457ccf2592c14bdf13b6706170ae2e94931b1 Author: Mark Fasheh <mark.fasheh@oracle.com> Date: Fri Sep 8 14:22:21 2006 -0700
[PATCH] Allow file systems to manually d_move() inside of ->rename()
that had allowed that crap for directories. Note that d_rehash() used to be needed (d_move() would unhash the source otherwise) and d_move() used to be unconditional until the changeset above.
It's _probably_ OK now, but I'd really like to think about NFS behaviour. There are subtle traps in that area.
BTW, failing rename() is trivial - just have a non-empty target...
| |