Mailinglist Archive: opensuse (946 mails)

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Re: [opensuse] About relatime and lazytime
On 2017-09-27 00:03, Anton Aylward wrote:
On 26/09/17 03:27 PM, Carlos E. R. wrote:
I'm talking of Leap. 42.1 did not have it, 42.2 has it.

I'm running a notional 42.2 with 4.13.3-2.g38f3021-default
and I just tried unmounting a Reiserfs mounted FS and cli remounting it with
an
additional 'lazytime'. It is now reported to have that option -- OK.

The "lazytime" option is active by default. in Leap 42.2.

So that makes it a "mount(1)" command OK. Bt I can't see what code in could
be
in the user code that tweaks the inode. It has to be in the "mount(2)' code,
that is the kernel. It would take examining kernel source to verify. Anyone?

The activation is handled by the "mount" command. "/usr/bin/mount". Not
the kernel.

The handling is of course done by the kernel.

This was explained in a thread in the mail list some months ago.



But it fails to answer my other question which you misinterpret.

I understand that this in in-memory. The inode is not flushed just because it
has a time field updated.

It is, soon enough.


Now that makes sense in the 'preallocated" sense of a database.
What is on disk is a 'slot' in the database and the contents of the 'slot' has
changed. The allocation has not. The size has not.

Apart from that singular case the semantic get less obvious.

If I correct a spelling mistake in a document of some form, be it plain text
of
OpenOffice or HTML, that is just a character inversion such as 'hte' ->
'the'
or 'adn' -> 'and', which are remarkably common, or a spelling mistake arising
from hitting an adjacent key, such as am 'i' instead of an 'o' or vice versa,
there is no change in file length. I realise that, algorithmically, the code
could read in the whole of the file, then write out the whole of the file
(possibly renaming the old on a ".bak" if you are DEC VMS obsessed. But does
it? Should it? The _file_ *is* preallocated.
But what about files that aren't on a filesystem mounted this way?

It doesn't matter. Even if you just change a byte in a single sector of
the file, and only that sector is written, still the timestamp of the
file changes and has to be written.

In traditional unix and linux this action is more or less immediate.
With lazytime it delays.

https://lwn.net/Articles/621046/


None of that applies to my OP, is offtopic.

The subject is: If lazytime is default option, why is relatime also
default? Should we remove it? Should I report a bug?

--
Cheers / Saludos,

Carlos E. R.
(from 42.2 x86_64 "Malachite" at Telcontar)

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