Some snapshotters (like overlayfs or zfs) can't mount the same
directories twice. For example if the same directroy is used as an upper
directory in two mounts the kernel will output this warning:
overlayfs: upperdir is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.
And indeed accessing the files from both mounts will result in an "No
such file or directory" error.
This change introduces reference counts for the mounts, if a directory
is already mounted the mount interface will only increment the mount
counter and return the mount target effectively making sure that the
filesystem doesn't end up in an undefined behavior.
Signed-off-by: Djordje Lukic <djordje.lukic@docker.com>
(cherry picked from commit 32d58144fd)
Signed-off-by: Bjorn Neergaard <bjorn.neergaard@docker.com>
While we currently do not provide an option to specify the snapshotter to use
for individual containers (we may want to add this option in future), currently
it already is possible to configure the snapshotter in the daemon configuration,
which could (likely) cause issues when changing and restarting the daemon.
This patch updates some code-paths that have the container available to use
the snapshotter that's configured for the container (instead of the default
snapshotter configured).
There are still code-paths to be looked into, and a tracking ticket as well as
some TODO's were added for those.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Signed-off-by: Djordje Lukic <djordje.lukic@docker.com>
c8d/daemon: Mount root and fill BaseFS
This fixes things that were broken due to nil BaseFS like `docker cp`
and running a container with workdir override.
This is more of a temporary hack than a real solution.
The correct fix would be to refactor the code to make BaseFS and LayerRW
an implementation detail of the old image store implementation and use
the temporary mounts for the c8d implementation instead.
That requires more work though.
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
daemon/images: Don't unset BaseFS
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
