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I have been trying to write onto a newly created partition My partition block is /dev/sda6

I am unable to write anything onto that partition. My Corresponding fstab file is this

/dev/disk/by-id/ata-WDC_WD5000BEVT-24A0RT0_WD-WXD1EA0TV384-part7 swap                 swap       defaults              0 0
UUID=827020aa-bccf-493e-acdc-21dd8eb98639 /                    btrfs      defaults              1 1
/dev/disk/by-id/ata-WDC_WD5000BEVT-24A0RT0_WD-WXD1EA0TV384-part8 /boot                ext4       acl,user_xattr        1 2
proc                 /proc                proc       defaults              0 0
sysfs                /sys                 sysfs      noauto                0 0
debugfs              /sys/kernel/debug    debugfs    noauto                0 0
devpts               /dev/pts             devpts     mode=0620,gid=5       0 0
/dev/sda6            /home/hawk/gentoo            ext4       users,gid=users,fmask=133,dmask=022                   1 2

If I format it back to any other windows based file system such as fat I am able to both read and write

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I think your fmask option is too strict and gives no read permission on files to group and other. Set it to fmask=000 or just leave it out to get rw- permissions on all files. You shouldn't have executable permissions by default. – user13742 Mar 3 '12 at 14:25
Also, I think the gid option only accepts group id numbers, so it should read gid=100 instead. And you should add the rw option (I forgot mentioning that). – user13742 Mar 3 '12 at 14:47
No need to add rw. It's the default behaviour. It's ro that must be specified explicitly. However, users should be user. – Alexios Mar 3 '12 at 17:10

You can't; ext[234] doesn't support the uid/gid options or any other way of overriding the on disk permissions at mount time. You must set the permissions correctly on the disk as root.

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For example, after mounting as root do: chown username:groupname /home/hawk/gentoo – cpugeniusmv Apr 3 '14 at 16:32
Does this have to be done only once or everytime after the disk / partition was mounted using fstab? – DutchArjo Nov 20 '14 at 9:01
@DutchArjo, only once. The permissions and ownership are stored on disk. – psusi Nov 20 '14 at 16:34

I'm not sure if you are still facing this problem, but I agree with @htor on the unnecessary strict fmask (and dmask?) values - unless you know what you are doing. I don't have a real ext4 partition, but the following /etc/fstab entry works just fine for an ext3 partition:

/dev/sda1       /virtual        ext3    noatime,users,acl,user_xattr   1 2

One more point, looking at the mount point (/home/hawk/gentoo), it seems that you are mounting a partition that is used in a different distribution (Gentoo) onto your currently running distribution. If so, please make sure you use the gid= value that matches the corresponding group id of your user from the original distribution (Gentoo).

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