Current code returns EXDEV when a directory would need to be copied up to
move.  We could copy up the directory tree in this case, but there's
another, simpler solution: point to old lower directory from moved upper
directory.

This is achieved with a "trusted.overlay.redirect" xattr storing the path
relative to the root of the overlay.  After such attribute has been set,
the directory can be moved without further actions required.

This is a backward incompatible feature, old kernels won't be able to
correctly mount an overlay containing redirected directories.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

The quirk for file locks and leases no longer applies.

Add missing info about renaming directory residing on lower layer.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Some of the documented quirks no longer apply.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Two "fixme" items are actually fixed now.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

I'm getting a surprising large number of questions about overlayfs sent
to me personally, rather than to a relevant mailing list.

So remove my email address from the documentation, and add a note
about looking in the MAINTAINERS file.
Signed-off-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Reported-by: Fabian Sturm <fabian.sturm@aduu.de> 
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Reported-by: NSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Allow "lowerdir=" option to contain multiple lower directories separated by
a colon (e.g. "lowerdir=/bin:/usr/bin").  Colon characters in filenames can
be escaped with a backslash.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Some distributions carry an "old" format of overlayfs while mainline has a
"new" format.

The distros will possibly want to keep the old overlayfs alongside the new
for compatibility reasons.

To make it possible to differentiate the two versions change the name of
the new one from "overlayfs" to "overlay".
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Reported-by: NSerge Hallyn <serge.hallyn@ubuntu.com>
Cc: Andy Whitcroft <apw@canonical.com>

Document the overlay filesystem.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>