Partition mount problem, ext4, Mageia, questionmark, user id

[flozn]

Hey guys!

I've got some problems with my new Centos 7. Some months ago I buyed a new laptop in order to run linux (Centos) on it. Because of Centos 7 not available at this time I used Mageia first.
Now I want to use the profiles of Thunderbird and Firefox in both Linux systems. The profiles are placed in a seperate ext4 partition. Mageia is also placed in a separate ext4 partition and Centos 7 is running with xfs.

For getting access to the shared profiles I just used the /etc/fstab file of Mageia. And now the problem: in the according folders there occurs some strange permission error. The permissions of Thunderbird profile files are filled with question marks "?".
The directories in the profile folder are marked with "d" (as usual) but when trying to open a permission error occurs. In Mageia everythin works fine (and permissions are shown correctly).

The content of the /etc/fstab is :

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# Entry for /dev/sda9 :
UUID=0d5b4245-c7c2-4a73-a055-69b90a97eed0 / ext4 noatime,acl 1 1
# Entry for /dev/sda10 :
UUID=5c7b0aef-a945-4b85-9819-7ec9647d3084 /media/data ext4 user,noatime,user_xattr,exec 1 2
# Entry for /dev/sda6 :
UUID=76dc41ca-91fb-4684-85fe-08f5b78cc5f4 /media/shared ext4 user,exec,user_xattr,noatime 1 2

/media/shared and /media/data have 777 permissions on both operation systems.

Do you may have a tip for me ?
Thanks!

Cheers
Flo

[flozn]

Hello again.

Although noboby had a clue I tried and tried to get my Centos running. Finally after installing it from scratch I got the solution !
The problem of the invalid permissions is caused by different user and group id's from Mageia to Centos! My username got the id 500 in Mageia and the id 1000 in Centos. If i listed the content of a directory created in Mageia the permissions of the content were marked with "???????".
After changing my local user id and group id in Centos from 1000 to 500 everything works fine ! Therefore I had to switch to a non graphical terminal after startup (e.g. ctrl+alt+f5) execute following line:

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# usermod -u 500 flo
# groupmod -g 500 flo

For getting access to old files of the original Centos user (id 1000) I changed all owner ids to the new one:

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chown -c --from=1000 flo -R /

This line treats recursive all files of the filesystem which are owned by the old user (id 1000).

The group ids of the old files are changed with:

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chgrp flo [FILES]

Due to there is no filter for the old group id you have to define the files manually (and not recursivly over / ).

That's it . Hello Centos !

Cheers
Flo