[PATCH 0/3] implement uid and gid mount options for ext2, ext3 and ext4

[Ludwig Nussel <ludwig.nussel@suse.de>]

When using 'real' file systems on removable storage devices such as
hard disks or usb sticks people quickly face the problem that their
Linux users have different uids on different machines. Therefore one
cannot modify or even read files created on a different machine
without running chown as root or storing everything with mode 777.
Simple file systems such as vfat don't have that problem as they
don't store file ownership information and one can pass the uid
files should belong to as mount option.

The following three patches implement the uid (and gid) mount option
for ext2, ext3 and ext4 to make them actually useful on removable
media. If a file system is mounted with the uid option all files
appear to be owned by the specified uid. Only newly created files
actually end up with that uid as owner on disk though. Ownership of
existing files cannot be changed permanently if the uid option was
specified.
Optionally a second uid (diskuid) can be specified. This one is actually
written to the file system then. Useful if the filesytem is also used on a
system that does not support the uid option.

The feature can be used in two ways. Firstly via fstab by having the
admin add 'uid=useruid' in the fs_mntops column in addition to the
'user' or 'users' option. Secondly via e.g. udisks which would
automatically pass the uid of the calling user as option.

Ludwig Nussel (3):
  implement uid and gid mount options for ext2
  implement uid and gid mount options for ext3
  implement uid and gid mount options for ext4

 Documentation/filesystems/ext2.txt |    9 ++++
 Documentation/filesystems/ext3.txt |    9 ++++
 Documentation/filesystems/ext4.txt |    9 ++++
 fs/ext2/ext2.h                     |    8 +++
 fs/ext2/inode.c                    |   48 +++++++++++++-----
 fs/ext2/super.c                    |   95 +++++++++++++++++++++++++++++++++++-
 fs/ext3/ext3.h                     |    8 +++
 fs/ext3/inode.c                    |   54 ++++++++++++++------
 fs/ext3/super.c                    |   95 +++++++++++++++++++++++++++++++++++-
 fs/ext4/ext4.h                     |    4 ++
 fs/ext4/inode.c                    |   52 ++++++++++++++------
 fs/ext4/super.c                    |   87 ++++++++++++++++++++++++++++++++-
 12 Dateien geändert, 433 Zeilen hinzugefügt(+), 45 Zeilen entfernt(-)

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1.7.10.4