From: Ian Kent <raven@themaw.net>
To: linux-kernel@vger.kernel.org
Subject: umount -l <path>, getcwd and /proc/<pid>/cwd inconsistent
Date: Mon, 07 Jan 2008 12:17:30 +0900 [thread overview]
Message-ID: <1199675850.3156.15.camel@raven.themaw.net> (raw)
Hi all,
Could someone please help me understand what's happening with, what
looks like inconsistent behavior, between getpwd and procfs readlink.
Basically, from a bash shell, setting working directory to a mounted
directory all is fine with "pwd" and "/proc/<pid>/cwd". Following a
"umount - l" on the mount "pwd" continues to return the expected string
but "/proc/<pid>/cwd" returns an empty string.
What I'm really after is why this happens because sys_getcwd and
proc_pid_readlink appear to do essentially the same thing to get the
string.
For example:
[raven@raven ~]$ mount
/dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/mapper/VolGroup00-LogVol03 on /work type ext3 (rw)
/dev/mapper/VolGroup00-LogVol02 on /home type ext3 (rw)
/dev/mapper/VolGroup02-LogVol00 on /vmware type ext3 (rw)
/dev/sda2 on /boot type ext3 (rw)
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
shark:/export/auto on /mnt/auto type nfs (rw,addr=10.49.97.44)
[raven@raven ~]$ cd /mnt/auto
[raven@raven auto]$ pwd
/mnt/auto
[raven@raven auto]$ ps
PID TTY TIME CMD
5435 pts/2 00:00:00 bash
5543 pts/2 00:00:00 ps
[raven@raven auto]$ ls -ld /proc/5435/cwd
lrwxrwxrwx 1 raven raven 0 2008-01-07 11:57 /proc/5435/cwd -> /mnt/auto
"umount -l /mnt/auto", done elsewhere at this point.
[raven@raven auto]$ mount
/dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/mapper/VolGroup00-LogVol03 on /work type ext3 (rw)
/dev/mapper/VolGroup00-LogVol02 on /home type ext3 (rw)
/dev/mapper/VolGroup02-LogVol00 on /vmware type ext3 (rw)
/dev/sda2 on /boot type ext3 (rw)
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
[raven@raven auto]$ pwd
/mnt/auto
[raven@raven auto]$ ls -ld /proc/5435/cwd
lrwxrwxrwx 1 raven raven 0 2008-01-07 11:57 /proc/5435/cwd ->
[raven@raven auto]$
Ian
next reply other threads:[~2008-01-07 3:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-07 3:17 Ian Kent [this message]
2008-01-07 8:29 ` umount -l <path>, getcwd and /proc/<pid>/cwd inconsistent Bauke Jan Douma
2008-01-07 8:55 ` Ian Kent
2008-01-07 9:29 ` Ian Kent
2008-01-07 10:37 ` Andreas Schwab
2008-01-09 3:10 ` Ian Kent
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