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2017-10-12ovl: fix regression caused by exclusive upper/work dir protectionAmir Goldstein1-1/+4
commit 85fdee1eef1a9e48ad5716916677e0c5fbc781e3 upstream. Enforcing exclusive ownership on upper/work dirs caused a docker regression: https://github.com/moby/moby/issues/34672. Euan spotted the regression and pointed to the offending commit. Vivek has brought the regression to my attention and provided this reproducer: Terminal 1: mount -t overlay -o workdir=work,lowerdir=lower,upperdir=upper none merged/ Terminal 2: unshare -m Terminal 1: umount merged mount -t overlay -o workdir=work,lowerdir=lower,upperdir=upper none merged/ mount: /root/overlay-testing/merged: none already mounted or mount point busy To fix the regression, I replaced the error with an alarming warning. With index feature enabled, mount does fail, but logs a suggestion to override exclusive dir protection by disabling index. Note that index=off mount does take the inuse locks, so a concurrent index=off will issue the warning and a concurrent index=on mount will fail. Documentation was updated to reflect this change. Fixes: 2cac0c00a6cd ("ovl: get exclusive ownership on upper/work dirs") Reported-by: Euan Kemp <euank@euank.com> Reported-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-07-04ovl: document copying layers restrictions with inodes indexAmir Goldstein1-0/+34
The inodes index feature introduces a behavior change - on mount, upper root origin file handle is verified to match the lower root dir. This implies that copied layers cannot be mounted with the inodes index feature enabled, without explicitly removing the upper dir origin xattr and the index dir. The inodes index feature is required to support: - Prevent breaking hardlinks on copy up - NFS export support (upcoming) - Overlayfs snapshots (POC) Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-05-05ovl: update documentation w.r.t. constant inode numbersAmir Goldstein1-1/+8
Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16ovl: fix reStructuredText syntax errors in documentationAmir Goldstein1-3/+4
- Fix broken long line block quote - Fix missing newline before bullets list - Use correct numbered list syntax Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16ovl: redirect on rename-dirMiklos Szeredi1-2/+19
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: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16ovl: update docMiklos Szeredi1-3/+3
The quirk for file locks and leases no longer applies. Add missing info about renaming directory residing on lower layer. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-09-01ovl: update docMiklos Szeredi1-5/+3
Some of the documented quirks no longer apply. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-05-27ovl: update documentationMiklos Szeredi1-9/+0
Two "fixme" items are actually fixed now. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2015-11-11Remove email address from Documentation/filesystems/overlayfs.txtNeilBrown1-1/+2
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: NeilBrown <neilb@suse.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2015-01-08ovl: document lower layer orderingMiklos Szeredi1-2/+6
Reported-by: Fabian Sturm <fabian.sturm@aduu.de> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2014-12-13ovl: add testsuite to docsMiklos Szeredi1-0/+12
Reported-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2014-12-13ovl: support multiple lower layersMiklos Szeredi1-0/+12
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: Miklos Szeredi <mszeredi@suse.cz>
2014-11-20ovl: rename filesystem type to "overlay"Miklos Szeredi1-1/+1
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: Miklos Szeredi <mszeredi@suse.cz> Reported-by: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Andy Whitcroft <apw@canonical.com>
2014-10-24overlay: overlay filesystem documentationNeil Brown1-0/+198
Document the overlay filesystem. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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