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Date: Mon, 07 Jan 2008 12:17:30 +0900 From: Ian Kent <raven@...maw.net> To: linux-kernel@...r.kernel.org Subject: umount -l <path>, getcwd and /proc/<pid>/cwd inconsistent 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@...en ~]$ 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@...en ~]$ cd /mnt/auto [raven@...en auto]$ pwd /mnt/auto [raven@...en auto]$ ps PID TTY TIME CMD 5435 pts/2 00:00:00 bash 5543 pts/2 00:00:00 ps [raven@...en 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@...en 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@...en auto]$ pwd /mnt/auto [raven@...en auto]$ ls -ld /proc/5435/cwd lrwxrwxrwx 1 raven raven 0 2008-01-07 11:57 /proc/5435/cwd -> [raven@...en auto]$ Ian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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