On Thu, Dec 17, 2020 at 1:07 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>
> On Thu, Dec 17, 2020 at 6:22 PM Michael Labriola
*snip*
> > On Thu, Dec 17, 2020 at 7:00 AM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> > Thanks, Amir. I didn't have CONFIG_DYNAMIC_DEBUG enabled, so
>
> I honestly don't expect to find much in the existing overlay debug prints
> but you never know..
> I suspect you will have to add debug prints to find the problem.
Ok, here goes. I had to setup a new virtual machine that doesn't use
overlayfs for its root filesystem because turning on dynamic debug
gave way too much output for a nice controlled test. It's exhibiting
the same behavior as my previous tests (5.8 good, 5.9 bad). The is
with a freshly compiled 5.9.15 w/ CONFIG_OVERLAY_FS_XINO_AUTO turned
off and CONFIG_DYNAMIC_DEBUG turned on. Here's what we get:
echo "file fs/overlayfs/* +p" > /sys/kernel/debug/dynamic_debug/control
mount borky2.sqsh t
mount -t tmpfs tmp tt
mkdir -p tt/upper/{upper,work}
mount -t overlay -o \
lowerdir=t,upperdir=tt/upper/upper,workdir=tt/upper/work blarg ttt
[ 164.505193] overlayfs: mkdir(work/work, 040000) = 0
[ 164.505204] overlayfs: tmpfile(work/work, 0100000) = 0
[ 164.505209] overlayfs: create(work/#3, 0100000) = 0
[ 164.505210] overlayfs: rename(work/#3, work/#4, 0x4)
[ 164.505216] overlayfs: unlink(work/#3) = 0
[ 164.505217] overlayfs: unlink(work/#4) = 0
[ 164.505221] overlayfs: setxattr(work/work,
"trusted.overlay.opaque", "0", 1, 0x0) = 0
touch ttt/FOO
touch: cannot touch 'ttt/FOO': No data available
[ 191.919498] overlayfs: setxattr(upper/upper,
"trusted.overlay.impure", "y", 1, 0x0) = 0
[ 191.919523] overlayfs: tmpfile(work/work, 0100644) = 0
[ 191.919788] overlayfs: tmpfile(work/work, 0100644) = 0
That give you any hints? I'll start reading through the overlayfs
code. I've never actually looked at it, so I'll be planting printk
calls at random. ;-)
--
Michael D Labriola
21 Rip Van Winkle Cir
Warwick, RI 02886
401-316-9844 (cell)
