Generic, per-fs and per-dev defaults in fstab?

Generic, per-fs and per-dev defaults in fstab?

[Linda A. Walsh]

Split this off from previous note (different subject, though
forgot to change previous subject line fully! *arg*).


As another matter of being user friendly, why can't specify a defaults
line for all mounts with the option of per-type defaults taking precedence:

default   *     defaults     defaults,x-'"mostly for completeness"'
default   xfs   defaults     logbsize=256k,largeio,nodiratime
/dev/sdf  xfs   defaults     su=64k,sw=256k
...
-------------

fs-type specific mounts would be applied after global
defaults, and in the 3rd line, what I am trying
to allow for (some way to tell any future space
managers to pay attention to the above alignment --
i.e. mkfs would be sure to set such params for xfs,
lvm and partition managers _could_ both use that information
to align layout.... etc.  Obviously the work /util would
have to come over time, but setting up a standard place
for such information is necessary -- and the file-system table
seems like a logical place to describe file-volume and filesystem details.

THE main purpose behind defaults -- is to apply to interactively made 
mounts,
so a user can have some set of defaults they want to, by default,
be applied when they use a mount command interactively.
(It can save on typing when working w/multiple temporary mounts & 
filesystems).

Re: Generic, per-fs and per-dev defaults in fstab?

[Karel Zak]

On Wed, Aug 06, 2014 at 03:59:27PM -0700, Linda A. Walsh wrote:
> Split this off from previous note (different subject, though
> forgot to change previous subject line fully! *arg*).
> 
> 
> As another matter of being user friendly, why can't specify a defaults
> line for all mounts with the option of per-type defaults taking precedence:
> 
> default   *     defaults     defaults,x-'"mostly for completeness"'
> default   xfs   defaults     logbsize=256k,largeio,nodiratime
> /dev/sdf  xfs   defaults     su=64k,sw=256k
> ...
> -------------
> 
> fs-type specific mounts would be applied after global
> defaults, and in the 3rd line, what I am trying

Well, the problem is that fstab is de-facto standard. If you want to
change semantic than you have to fix all programs that follow fstab
setting. The file is no private mount(8) config file.

The old idea is to use per-filesystem config files where you can
specify default mount options. We use this concept for NFS. But again,
such setting is invisible for many utils etc.

IMHO the best is the extN way. It means to store the default setting to 
filesystem superblock, see 

 # tune2fs -l /dev/sda4 | grep 'Default mount options'
 Default mount options:    user_xattr acl

   Karel


-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com