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| author | Amir Goldstein <amir73il@gmail.com> | 2019-07-12 15:24:34 +0300 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2019-07-16 13:23:40 +0200 |
| commit | 0be0bfd2de9dfdd2098a9c5b14bdd8f739c9165d (patch) | |
| tree | 9fdb5305b90a0baffbdd019fed86e023da52e646 /Documentation/filesystems/overlayfs.txt | |
| parent | 0ecfebd2b52404ae0c54a878c872bb93363ada36 (diff) | |
| download | lwn-0be0bfd2de9dfdd2098a9c5b14bdd8f739c9165d.tar.gz lwn-0be0bfd2de9dfdd2098a9c5b14bdd8f739c9165d.zip | |
ovl: fix regression caused by overlapping layers detection
Once upon a time, commit 2cac0c00a6cd ("ovl: get exclusive ownership on
upper/work dirs") in v4.13 added some sanity checks on overlayfs layers.
This change caused a docker regression. The root cause was mount leaks
by docker, which as far as I know, still exist.
To mitigate the regression, commit 85fdee1eef1a ("ovl: fix regression
caused by exclusive upper/work dir protection") in v4.14 turned the
mount errors into warnings for the default index=off configuration.
Recently, commit 146d62e5a586 ("ovl: detect overlapping layers") in
v5.2, re-introduced exclusive upper/work dir checks regardless of
index=off configuration.
This changes the status quo and mount leak related bug reports have
started to re-surface. Restore the status quo to fix the regressions.
To clarify, index=off does NOT relax overlapping layers check for this
ovelayfs mount. index=off only relaxes exclusive upper/work dir checks
with another overlayfs mount.
To cover the part of overlapping layers detection that used the
exclusive upper/work dir checks to detect overlap with self upper/work
dir, add a trap also on the work base dir.
Link: https://github.com/moby/moby/issues/34672
Link: https://lore.kernel.org/linux-fsdevel/20171006121405.GA32700@veci.piliscsaba.szeredi.hu/
Link: https://github.com/containers/libpod/issues/3540
Fixes: 146d62e5a586 ("ovl: detect overlapping layers")
Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Tested-by: Colin Walters <walters@verbum.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'Documentation/filesystems/overlayfs.txt')
| -rw-r--r-- | Documentation/filesystems/overlayfs.txt | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt index 1da2f1668f08..845d689e0fd7 100644 --- a/Documentation/filesystems/overlayfs.txt +++ b/Documentation/filesystems/overlayfs.txt @@ -302,7 +302,7 @@ beneath or above the path of another overlay lower layer path. Using an upper layer path and/or a workdir path that are already used by another overlay mount is not allowed and may fail with EBUSY. Using -partially overlapping paths is not allowed but will not fail with EBUSY. +partially overlapping paths is not allowed and may fail with EBUSY. If files are accessed from two overlayfs mounts which share or overlap the upper layer and/or workdir path the behavior of the overlay is undefined, though it will not result in a crash or deadlock. |