inodes home directory

sryzdn · 06-11-2013, 11:53 PM

Hi,

when we have:

Quote:

ls -ai /

some of the output is:

Quote:

2 . ..... etc .... media ..... root .... tmp
2 .. 2 home

when we have

Quote:

ls -ai ~

some of the output is:

Quote:

2752412 .
2 ..

in "/" the inode numbers of "home", "." and ".." are the same. while the inode of "." changes in /home. I have a vague answer fr it in my mind, but I don't know why in "/" all said inodes are the same?

pan64 · 06-12-2013, 12:21 AM

what will mount say?

sryzdn · 06-13-2013, 06:51 AM

Quote:

Originally Posted by pan64

what will mount say?

here is the result of mount:

Quote:

proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel)
devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=4076932k,nr_inodes=1028433,mode=755)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,seclabel,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/net_cls type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
/dev/mapper/fedora-root on / type ext4 (rw,relatime,seclabel,data=ordered)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=35,pgrp=1,timeout=300,minproto=5,maxproto=5,direct)
configfs on /sys/kernel/config type configfs (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
mqueue on /dev/mqueue type mqueue (rw,relatime,seclabel)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,seclabel)
tmpfs on /tmp type tmpfs (rw,seclabel)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,relatime)
/dev/sda7 on /boot type ext4 (rw,relatime,seclabel,data=ordered)
/dev/mapper/fedora-home on /home type ext4 (rw,relatime,seclabel,data=ordered)
fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime)
gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=1000)
/dev/sr0 on /run/media/sryzdn/WebTemplates1 type iso9660 (ro,nosuid,nodev,relatime,uid=1000,gid=1000,iocharset=utf8,mode=0400,dmode=0500,uhelper=udisks2)
/dev/sda3 on /run/media/sryzdn/28082EC8082E953A type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096)

What does it have about the inodes of ".", ".." and "home" being the same ?!?!?!?

thedaver · 06-13-2013, 07:30 AM

"/" and "~" for the user root are NOT the same folder. Thus "." in different folders gives different inodes to "self"

chrism01 · 06-13-2013, 07:30 AM

Actually, 'df -h' would be easier to glean from.
Anyway, the top inode on a partition is '2'.
On the system root '/' I get 2 for '.' and '..', which makes sense.
(FYI inode 1 is /sys).

If you have partitions mounted direct at root '/', you'll get the same effect.
I've got a couple of extra mounts, but not mounted off '/', so the parent '..' inodes are high nums.

Code:

cd /
ls -ai

 2 .
 2 ..

 2 boot 

# low mounted partitions
cd /var/lib/libvirt
ls -ai
  2 images         2 partn_pool

cd /var/lib/libvirt/images
ls -ai
      2 .   
3933962 ..  

# which matches
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb2              70G   20G   46G  31% /
tmpfs                 3.8G  424K  3.8G   1% /dev/shm
/dev/sdb1             504M   84M  395M  18% /boot
/dev/sda6              99G   16G   78G  17% /var/lib/libvirt/images
/dev/sda8             9.9G  9.2G  201M  98% /var/lib/libvirt/partn_pool

# also
cd /boot
ls -ai
   2 .
   2 ..

Each partition has its own inode list/table, which, incidentally, is why you can't hardlink across filesystems (partitions).

HTH

jpollard · 06-13-2013, 11:23 AM

The directory structure is a tree, the parent directory contains entries for all subdirectories it contains (thus /home is a subdirectory of /).

".." is the name of the parent directory. Thus .. in the / points to the same directory as / (which is the same as the entry for ".").

In /home, the ".." entry points to the root directory /.

The "." entry in a directory represents the directory itself.

So every directory has an entry for ".." that can be different. They would be the same for all subdirectories of a given directory. All entries for "." will be different.

As every file is represented by an inode number, the inode numbers also represent the directories (directories are just files - just marked as "special"), all they really contain is an inode number, and the file name (/usr/include/bits/dirent.h for details).