Getcwd() incorrectly returning ENOENT
From Linux NFS
Revision as of 17:26, 22 October 2010 by Amschuma
- Kernel version: 2.6.30, 2.6.31, 2.6.32-rc5
- bug 14541
- Reported by: Daniel J Blueman
- Fixed by:
- Caused by race condition that appeared in a65318bf3afc93ce49227e849d213799b072c5fd
- To observe the change to user-level behaviour (after the reproducer commands):
- this impacts userspace and causes varying levels of failure, which often are benign, but can break applications
- it's impossible to build an Ubuntu/Debian kernel over NFS4 since 2.6.30-rc.
$ sudo bash # apt-get install build-essential # apt-get build-dep apt # mount server:/ /mnt -tnfs4 && cd /mnt # apt-get source apt # cd apt-0.7.23.1ubuntu2 # ./configure && make -> "getcwd: No such file or directory"
- This problem was caused by commit a65318bf3afc93ce49227e849d213799b072c5fd
commit a65318bf3afc93ce49227e849d213799b072c5fd Author: Trond Myklebust <Trond.Myklebust@netapp.com> Date: Wed Mar 11 14:10:28 2009 -0400 NFSv4: Simplify some cache consistency post-op GETATTRs Certain asynchronous operations such as write() do not expect (or care) that other metadata such as the file owner, mode, acls, ... change. All they want to do is update and/or check the change attribute, ctime, and mtime. By skipping the file owner and group update, we also avoid having to do a potential idmapper upcall for these asynchronous RPC calls. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
- This problem was fixed by commit 96d25e532234bec1a1989e6e1baf702d43a78b0d
commit 96d25e532234bec1a1989e6e1baf702d43a78b0d Author: Trond Myklebust <Trond.Myklebust@netapp.com> Date: Wed Nov 11 16:15:42 2009 +0900 NFSv4: Fix a cache validation bug which causes getcwd() to return ENOENT Changeset a65318bf3afc93ce49227e849d213799b072c5fd (NFSv4: Simplify some cache consistency post-op GETATTRs) incorrectly changed the getattr bitmap for readdir(). This causes the readdir() function to fail to return a fileid/inode number, which again exposed a bug in the NFS readdir code that causes spurious ENOENT errors to appear in applications (see http://bugzilla.kernel.org/show_bug.cgi?id=14541). The immediate band aid is to revert the incorrect bitmap change, but more long term, we should change the NFS readdir code to cope with the fact that NFSv4 servers are not required to support fileids/inode numbers. Reported-by: Daniel J Blueman <email@example.com> Cc: firstname.lastname@example.org Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>