Bug 517650

Summary:	ext4 allows ro->rw transitions of filesystems w/ features that can't be mounted rw
Product:	Red Hat Enterprise Linux 6	Reporter:	Eric Sandeen <esandeen>
Component:	kernel	Assignee:	Eric Sandeen <esandeen>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Igor Zhang <yugzhang>
Severity:	medium	Docs Contact:
Priority:	low
Version:	6.0	CC:	dwu, snagar, yugzhang
Target Milestone:	rc	Keywords:	FutureFeature
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel-2.6.32-1.el6	Doc Type:	Enhancement
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2010-11-15 14:24:27 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Eric Sandeen 2009-08-15 16:44:39 UTC

Many checks in ext4_fill_super are checking for ro-compat features etc - for example, HUGE_FILES filesystems are denied rw mounts on a 32-bit box w/o LBD.

However, these tests aren't enforced on a ro->rw remount transition.  This could potentially be bad, esp. as the normal boot process does a remount in this manner.

The tests probably need to be moved to a separate helper function that can be called by both the mount & remount paths.  And in any case, ext4_fill_super could use some refactoring at 676 lines.

Comment 2 Eric Sandeen 2009-08-16 22:10:46 UTC

Sent a patch upstream for this:

http://marc.info/?l=linux-ext4&m=125045416001117&w=2

Comment 3 Eric Sandeen 2009-09-25 15:35:16 UTC

Upstream now:

commit a13fb1a4533f26c1e2b0204d5283b696689645af
Author: Eric Sandeen <sandeen>
Date:   Tue Aug 18 00:20:23 2009 -0400

    ext4: Add feature set check helper for mount & remount paths
    
    A user reported that although his root ext4 filesystem was mounting
    fine, other filesystems would not mount, with the:
    
    "Filesystem with huge files cannot be mounted RDWR without CONFIG_LBDAF"
    
    error on his 32-bit box built without CONFIG_LBDAF.  This is because
    the test at mount time for this situation was not being re-checked
    on remount, and the normal boot process makes an ro->rw transition,
    so this was being missed.
    
    Refactor to make a common helper function to test the filesystem
    features against the type of mount request (RO vs. RW) so that we
    stay consistent.
    
    Addresses Red-Hat-Bugzilla: #517650
    
    Signed-off-by: Eric Sandeen <sandeen>
    Signed-off-by: "Theodore Ts'o" <tytso>

Comment 4 Eric Sandeen 2009-12-01 22:59:10 UTC

The patch in comment #3 is in 2.6.32, so setting MODIFIED.

Comment 6 Igor Zhang 2010-09-30 08:59:01 UTC

Sanity Check in kernel-2.6.32-73.el6 and the code is there actually.

Comment 7 releng-rhel@redhat.com 2010-11-15 14:24:27 UTC

Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.