path: root/Documentation
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authorAl Viro <viro@zeniv.linux.org.uk>2015-02-20 04:58:52 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2015-02-20 04:58:52 -0500
commitce7b9facdf43b42fb95bdff9069aefeddb7d0a69 (patch)
treedb49cfb72630e88172b51e586acfa9ddb22b5dc1 /Documentation
parenta95104fd3393080e8bcca348f51996f5f0f5ccb6 (diff)
parent4330397e4e8a662f36d101659e2a59ce32e76ff4 (diff)
Merge branch 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs into for-next
Diffstat (limited to 'Documentation')
1 files changed, 28 insertions, 0 deletions
diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt
index a27c950ece61..6db0e5d1da07 100644
--- a/Documentation/filesystems/overlayfs.txt
+++ b/Documentation/filesystems/overlayfs.txt
@@ -159,6 +159,22 @@ overlay filesystem (though an operation on the name of the file such as
rename or unlink will of course be noticed and handled).
+Multiple lower layers
+Multiple lower layers can now be given using the the colon (":") as a
+separator character between the directory names. For example:
+ mount -t overlay overlay -olowerdir=/lower1:/lower2:/lower3 /merged
+As the example shows, "upperdir=" and "workdir=" may be omitted. In
+that case the overlay will be read-only.
+The specified lower directories will be stacked beginning from the
+rightmost one and going left. In the above example lower1 will be the
+top, lower2 the middle and lower3 the bottom layer.
Non-standard behavior
@@ -196,3 +212,15 @@ Changes to the underlying filesystems while part of a mounted overlay
filesystem are not allowed. If the underlying filesystem is changed,
the behavior of the overlay is undefined, though it will not result in
a crash or deadlock.
+There's testsuite developed by David Howells at:
+ git://git.infradead.org/users/dhowells/unionmount-testsuite.git
+Run as root:
+ # cd unionmount-testsuite
+ # ./run --ov

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