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Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/overlayfs.txt | 28 |
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. + +Testsuite +--------- + +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 |