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. > 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.
