Mounting subvolumes and FS-wide mount options?

[Roman Mamedov <rm@romanrm.ru>]

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Hello,

Suppose I have in /etc/fstab:

/dev/sda2 /mnt/p2	btrfs	noatime		0	0
/dev/sda2 /home		btrfs	subvol=/home	0	0
/dev/sda2 /srv		btrfs	subvol=/srv	0	0

Now I want to add mount options like "space_cache" and "inode_cache". As far
as I understand these are FS-wide and not per subvolume. Also, changing them
once the FS has been mounted on a later subvolume mount is not allowed (?).

The question is, where to add them?

a) to the first mount in the list? Counting on the fact that it will be mounted
first (but it might be not).

b) to all of them? But that's time consuming to duplicate identical options on
each line and especially when editing them later.

Also, should I duplicate options like "noatime" and other generic options also
to all of the subvolume mounts?

I feel this is not obvious, not well-documented, and generally feels messy, so
until now I just avoided mounting individual subvolumes altogether, instead
preferring to mount the FS itself once somewhere under /mnt, and then "mount
--bind" stuff to final places where I needed it.

-- 
With respect,
Roman

~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Stallman had a printer,
with code he could not see.
So he began to tinker,
and set the software free."

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