Apparently there is some kind of race in aufs kernel module code,
which leads to the errors like:
[98221.158606] aufs au_xino_create2:186:dockerd[25801]: aufs.xino create err -17
[98221.162128] aufs au_xino_set:1229:dockerd[25801]: I/O Error, failed creating xino(-17).
[98362.239085] aufs au_xino_create2:186:dockerd[6348]: aufs.xino create err -17
[98362.243860] aufs au_xino_set:1229:dockerd[6348]: I/O Error, failed creating xino(-17).
[98373.775380] aufs au_xino_create:767:dockerd[27435]: open /dev/shm/aufs.xino(-17)
[98389.015640] aufs au_xino_create2:186:dockerd[26753]: aufs.xino create err -17
[98389.018776] aufs au_xino_set:1229:dockerd[26753]: I/O Error, failed creating xino(-17).
[98424.117584] aufs au_xino_create:767:dockerd[27105]: open /dev/shm/aufs.xino(-17)
So, we have to have a lock around mount syscall.
While at it, don't call the whole Unmount() on an error path, as
it leads to bogus error from auplink flush.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
(cherry picked from commit 5cd62852fa199f272b542d828c8c5d1db427ea53)
Upstream-commit: bb4b9fe29eba57ed71d8105ec0e5dacc8e72129e
Component: engine
5ada897229