On 2015-05-20 11:04 AM, Martin Pitt wrote: > Hello Iain, > > Iain Lane [2015-05-20 15:19 +0100]: >> We sometimes come across bugs where software expects to be able to >> rename files to work properly (either to atomically update, or perhaps >> to disable some functionality). This doesn't work with our read-only >> partition layout. We know how to work around this limitation by making >> code changes, for example >> >> >> https://code.launchpad.net/~seb128/whoopsie-preferences/touch-writable-image/+merge/259531 > > Indeed, I have similar hacks in systemd. Our current approach to > making writable parts of /etc via file bind mounts is hopelessly > doomed, as it breaks file system semantics like the one you mentioned. > >> to make use of a symlink into a writable directory. It's not a great >> solution, not least because we have to implement it on a case-by-case >> basis and we don't have any good way of proactively spotting the bugs - >> they typically manifest themselves by settings not being saved but >> people usually do not check for rename failures or surface these to the >> user. >> >> Can anyone think of a way to fix this class of problem and remove the >> need for us to have to go and patch code? Or at least to detect these >> rename failures (check for EROFS) and aggregate them somewhere so that >> they can be fixed. This is on touch - I'm not sure if snappy does >> anything different here. > > TBH, the only clean way that I see is to flip the whole thing around. > Keep /etc (and /var) writable, and instead deal with the things that > should *not* be modified. I. e. ship them in e. g. /usr/etc/ and > symlink/bind-mount them to /etc, or longer-term, get rid of them > completely. IMHO this would be a much saner architecture than trying > to play eternal catch-up with bugs like this and getting an > ever-growing spaghetti heap of file bind mounts which we'll never be > able to revert/change.
+1 Marc. -- Mailing list: https://launchpad.net/~ubuntu-phone Post to : [email protected] Unsubscribe : https://launchpad.net/~ubuntu-phone More help : https://help.launchpad.net/ListHelp
