On Fri, Sep 29, 2023 at 07:44:09AM +0300, Amir Goldstein wrote: > On Fri, Sep 29, 2023 at 4:08 AM Ryan Hendrickson > <ryan.hendrickson@xxxxxxxxxxxx> wrote: > > > > Up to and including kernel 6.4.15, it was possible to have commas in > > the lowerdir/upperdir/workdir paths used by overlayfs, provided they were > > escaped with backslashes: > > > > mkdir /tmp/test-lower, /tmp/test-upper /tmp/test-work /tmp/test > > mount -t overlay overlay -o 'lowerdir=/tmp/test-lower\,,upperdir=/tmp/test-upper,workdir=/tmp/test-work' /tmp/test > > > > In 6.5.2 and 6.5.5, this no longer works; dmesg reports that overlayfs > > can't resolve '/tmp/test-lower' (without the comma). > > > > I see that there is a commit between the 6.4 and 6.5 lines titled [ovl: > > port to new mount api][1]. I haven't compiled a kernel before and after > > this commit to verify, but based on the code it deletes I strongly suspect > > that it, or if not then one of the ovl commits committed on the same day, > > is responsible for this change. > > > > [1]: https://github.com/torvalds/linux/commit/1784fbc2ed9c888ea4e895f30a53207ed7ee8208 > > > > That's a good guess. > It helps to CC the author of the patch in this case ;-) > > > Does this count as a regression? > > "used to work, does not work now" is pretty close to a dictionary > definition of a regression :) > > The question is whether we should fix it. > The rule of thumb is that if users complain than we need to fix it, > but it's a corner case and if the only users that complained are willing > to work around the problem (hint hint) then we may not need to fix it. It would be nice to have this fixed. A more general question: will you commit on keeping the escaping stable from now on or do we have to expect changes at any point in the future? In that case we would just reject any string contianing characters that need escaping. > > I can't find documentation for this > > escaping feature anywhere, even as it pertains to the non-comma characters > > '\\' and ':' (which, I've tested, can still be escaped as expected), so > > perhaps it was never properly supported? But a search for escaping commas > > in overlayfs turns up resources like [this post][2], suggesting that there > > are others who figured this out and expect it to work. > > > > [2]: https://unix.stackexchange.com/a/552640 > > > > Is there a new way to escape commas for overlayfs options? > > > > Deferring the question to Christian. > > Thanks, > Amir.
