Bug 892291

Summary: guestmount: link() incorrectly returns ENOENT, when it should be EXDEV
Product: Red Hat Enterprise Linux 6 Reporter: Colin Walters <walters>
Component: libguestfsAssignee: Richard W.M. Jones <rjones>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 6.4CC: bfan, leiwang, wshi
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: libguestfs-1.20.9-5.el6 Doc Type: Bug Fix
Doc Text:
Cause: Creating a hard link when using guestmount. Consequence: If creating the hard link fails, the wrong error was returned. This could result in applications failing, or failing to print the correct error message (making diagnosis of the true causes of problems difficult). Fix: Error handling in guestmount has been rewritten. Result: Correct errors are returned to guestmount users.
Story Points: ---
Clone Of:
: 895905 (view as bug list) Environment:
Last Closed: 2013-11-20 23:42:32 EST Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On: 895905, 958183    
Bug Blocks:    

Description Colin Walters 2013-01-06 06:11:32 EST
Description of problem:

My project ostree uses hardlinks extensively; I have a bit of code which tries link() and falls back to a copy if it gets EXDEV.

Unfortunately, something in the guestmount/fuse/kernel chain is giving me ENOENT, when it should be EXDEV.  I've added a workaround to ostree, but this is suboptimal.

Version-Release number of selected component (if applicable):

libguestfs-1.16.34-2.el6.x86_64
fuse-2.8.3-4.el6.x86_64
kernel-2.6.32-350.el6.x86_64


How reproducible:

Always.

Steps to Reproduce:
1. guestmount --rw -o allow_root --pid-file guestmount.pid -a test.img -m /dev/sda3 -m /dev/sda1:/boot mnt
2. cd mnt
3. touch foo
4. ln foo boot/foo
 
Actual results:

ENOENT

Expected results:

EXDEV
Comment 2 RHEL Product and Program Management 2013-01-11 01:47:31 EST
This request was not resolved in time for the current release.
Red Hat invites you to ask your support representative to
propose this request, if still desired, for consideration in
the next release of Red Hat Enterprise Linux.
Comment 3 Richard W.M. Jones 2013-01-21 09:50:21 EST
Unfortunately this missed RHEL 6.4.  However it's a fairly
serious bug as it turns out.  The full description, along
with patches, is here:

https://bugzilla.redhat.com/show_bug.cgi?id=895905#c4
Comment 5 Richard W.M. Jones 2013-04-11 13:55:00 EDT
Fix included in upstream libguestfs 1.16.35.
Comment 6 Richard W.M. Jones 2013-06-28 06:55:04 EDT
This is fixed by the rebase (bug 958183).
Comment 11 bfan 2013-09-18 02:19:35 EDT
Reproduced with libguestfs-1.16.34-1.el6.x86_64

# mkdir mountpoint
# guestmount --rw -o allow_root --pid-file guestmount.pid -a RHEL-Server-6.0-32-hvm.raw -m /dev/vg_dhcp669266/lv_root -m /dev/sda1:/boot mountpoint
# cd mountpoint/
# touch foo
# ln foo boot/foo
ln: creating hard link `boot/foo' => `foo': No such file or directory

Give error "No such file or directory"
Comment 12 bfan 2013-10-21 03:53:25 EDT
Verified with libguestfs-1.20.11-2.el6.x86_64


[root@dhcp-9-42]# guestmount --rw -o allow_root --pid-file guestmount.pid -a RHEL-Server-6.0-32-hvm.raw -m /dev/vg_dhcp669266/lv_root -m /dev/sda1:/boot mountpoint
[root@dhcp-9-42]# cd mountpoint/
[root@dhcp-9-42 mountpoint]# touch foo
[root@dhcp-9-42 mountpoint]# ln foo boot/foo
ln: creating hard link `boot/foo' => `foo': Invalid cross-device link


Check the errno
[root@dhcp-9-42 mountpoint]# cat /usr/include/asm-generic/errno-base.h | grep EXDEV
#define	EXDEV		18	/* Cross-device link */


So, change the status to verified.
Comment 14 errata-xmlrpc 2013-11-20 23:42:32 EST
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.

http://rhn.redhat.com/errata/RHSA-2013-1536.html