** Also affects: linux (Ubuntu Vivid)
Importance: Undecided
Status: New
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1479468
Title:
OverlayFS: Wrong mnt_id and path reported in /proc
Status in linux package in Ubuntu:
New
Status in linux source package in Vivid:
New
Bug description:
I am running Ubuntu Vivid (3.19.0-22-generic #22-Ubuntu SMP Tue Jun 16
17:15:15 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux). There are two
issues in OverlayFS as follows:
1. /proc/<pid>/fdinfo/<fd> reports wrong mnt_id (non-existent in
/proc/<pid>/mountinfo)
2. /proc/<pid>/fd/<fd> shows incorrect path for the symlink target
These problems can be easily reproduced with the shell script below.
Fortunately, both problems have been fixed in the upstream's master
branch of the kernel via the following commits:
torvalds 4.0: 155e35d4d VFS: Introduce inode-getting helpers for
layered/unioned fs environments
torvalds 4.0: df1a085af VFS: Add a fallthrough flag for marking virtual
dentries
torvalds 4.2-rc2: f25801ee4 overlay: Call ovl_drop_write() earlier in
ovl_dentry_open()
torvalds 4.2-rc2: 4bacc9c92 overlayfs: Make f_path always point to the
overlay and f_inode to the underlay
torvalds 4.2-rc2: 9391dd00d fix a braino in ovl_d_select_inode()
(The commit df1a085af may technically not be needed but it prevents a
conflict when applying 4bacc9c92.)
Simple script to reproduce the problem:
#!/bin/bash
set -eu
ERROR=0
setup() {
setup_mount
start_python > /dev/null 2>&1 &
BASH_PID=$!
PYTHON_PID=$(ps -C python | awk '/python/ { print $1 }')
sleep 1
}
setup_mount() {
mkdir overlay_test
cd overlay_test
mkdir a b c z
sudo mount -t overlay -o lowerdir=a,upperdir=b,workdir=c overlayfs z
}
start_python() {
python << EOF
import time
fd = open("z/file", "w")
time.sleep(10)
EOF
}
check_path() {
WD=$(pwd)
if ! ls -l /proc/$PYTHON_PID/fd | grep -qw "$WD/z/file"; then
ERROR=1
echo "ERROR! expected $WD/z/file"
set -x
ls -l /proc/$PYTHON_PID/fd
set +x
fi
}
check_mnt_id() {
FDINFO_MNT_ID=$(awk '/mnt_id:/ { print $2 }' /proc/$PYTHON_PID/fdinfo/3)
MOUNTINFO_MNT_ID=$(awk '/overlayfs/ { print $1 }' /proc/self/mountinfo)
if [[ $FDINFO_MNT_ID -ne $MOUNTINFO_MNT_ID ]]; then
ERROR=1
echo "ERROR! mnt_id $FDINFO_MNT_ID not in /proc/self/mountinfo"
set -x
cat /proc/$PYTHON_PID/fdinfo/3
cat /proc/self/mountinfo
set +x
fi
}
finish() {
kill -INT $PYTHON_PID > /dev/null 2>&1
sudo umount z
cd $ORIG_WD
rm -rf overlay_test
}
main() {
ORIG_WD=$(pwd)
setup
check_path
check_mnt_id
finish
[[ $ERROR -eq 0 ]] && echo "OverlayFS looks good."
}
main
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1479468/+subscriptions
--
Mailing list: https://launchpad.net/~kernel-packages
Post to : kernel-packages@lists.launchpad.net
Unsubscribe : https://launchpad.net/~kernel-packages
More help : https://help.launchpad.net/ListHelp
