** Changed in: linux (Ubuntu Vivid)
Assignee: (unassigned) => Chris J Arges (arges)
** Description changed:
+ SRU Justification:
+
+ [Impact]
+
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
+ 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
+ 2. /proc/<pid>/fd/<fd> shows incorrect path for the symlink target
+
+ [Fix]
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()
+ torvalds 4.0: 155e35d4d VFS: Introduce inode-getting helpers for
+ layered/unioned fs environments (this is already in ubuntu-vivid)
+
+ 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.)
+
+ [Test Case]
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 $1 }')
- sleep 1
+ setup_mount
+ start_python > /dev/null 2>&1 &
+ BASH_PID=$!
+ PYTHON_PID=$(ps -C python | awk '/python/ { print $1 }')
+ sleep 1
}
setup_mount() {
- mkdir overlay_test
- cd overlay_test
- mkdir a b c z
- sudo mount -t overlay -o lowerdir=a,upperdir=b,workdir=c overlayfs z
+ mkdir overlay_test
+ cd overlay_test
+ mkdir a b c z
+ sudo mount -t overlay -o lowerdir=a,upperdir=b,workdir=c overlayfs z
}
start_python() {
- python << EOF
+ python << EOF
import time
fd = open("z/file", "w")
time.sleep(10)
EOF
}
check_path() {
- WD=$(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
+ 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
+ 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
+ kill -INT $PYTHON_PID > /dev/null 2>&1
+ sudo umount z
+ cd $ORIG_WD
+ rm -rf overlay_test
}
main() {
- ORIG_WD=$(pwd)
- setup
+ ORIG_WD=$(pwd)
+ setup
- check_path
- check_mnt_id
+ check_path
+ check_mnt_id
- finish
- [[ $ERROR -eq 0 ]] && echo "OverlayFS looks good."
+ finish
+ [[ $ERROR -eq 0 ]] && echo "OverlayFS looks good."
}
main
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https://bugs.launchpad.net/bugs/1479468
Title:
OverlayFS: Wrong mnt_id and path reported in /proc
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