Created attachment 709070 [details]
Description of problem:
If a filesystem is mounted read-only it is not possible to open device nodes residing on it for writing.
Version-Release number of selected component (if applicable):
kernel-2.6.32-327.el6 and up, introduced in:
Author: Eric Sandeen <email@example.com>
Date: Mon Sep 24 21:27:50 2012 -0400
[fs] Push mnt_want_write() outside of i_mutex
Steps to Reproduce:
1. prepare fs
dd if=/dev/zero of=foo bs=1M count=10
losetup -vf foo
mount /dev/loop0 /mnt
mknod /mnt/null c 1 3
2. mount fs ro: mount -o ro /dev/loop0 /mnt
3. Try to write: echo foo >> /mnt/null
zsh: read-only file system: /mnt/null
successful open + write
This behaviour makes some sense for a read-only file system. Are you looking to make a read-only root for security reasons? Is this a real issue in production or just a feature request?
Ric, we do need to be able to open devices RW even if the device node is on an RO fs. Looks like a regression from the big freeze patchset. I'll take it.
Same customer reported broken write support for file bind mounts (mount --bind file /rofs/file). This is also fixed with attached patch.
*** Bug 923778 has been marked as a duplicate of this bug. ***
*** Bug 928026 has been marked as a duplicate of this bug. ***
*** Bug 955580 has been marked as a duplicate of this bug. ***
*** Bug 957780 has been marked as a duplicate of this bug. ***
Patch(es) available on kernel-2.6.32-375.el6
I've taken the private flag off this bug, several people have run into this, several bugs have been duped to it, and there's nothing sensitive here.
*** Bug 962624 has been marked as a duplicate of this bug. ***
Created attachment 752878 [details]
the result of "sosreport -a" on NFS server
Created attachment 752879 [details]
the result of "sosreport --batch"
*** Bug 962630 has been marked as a duplicate of this bug. ***
ext2/3/4 xfs and btrfs all passed xfstests generic/306 which is the reproducer for this bug.
Set to VERIFIED.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
*** Bug 951311 has been marked as a duplicate of this bug. ***
*** Bug 951668 has been marked as a duplicate of this bug. ***