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| ID | Project | Category | View Status | Date Submitted | Last Update | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0012986 | CentOS-7 | kernel | public | 2017-03-17 16:06 | 2017-03-27 08:53 | ||||||||
| Reporter | dennisxrow | ||||||||||||
| Priority | normal | Severity | minor | Reproducibility | always | ||||||||
| Status | new | Resolution | open | ||||||||||
| Platform | OS | CentOS | OS Version | ||||||||||
| Product Version | 7.3.1611 | ||||||||||||
| Target Version | Fixed in Version | ||||||||||||
| Summary | 0012986: Stacked overlayfs: No such device or address | ||||||||||||
| Description | When overlayfs is mounted inside a overlayfs, I get a "no such device or address" error when I try to open a file. The error occured after updating the kernel from Kernel 3.10.0-327.36.3 to 3.10.0-514.6.1. | ||||||||||||
| Steps To Reproduce | # mkdir upper lower work merged # mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merged/ # cd merged # mkdir upper2 lower2 work2 merged2 # mount -t overlay overlay -olowerdir=lower2,upperdir=upper2,workdir=work2 merged2/ # cd merged2 # echo hello > test.txt bash: test.txt: No such device or address # ls test.txt # cat test.txt bash: test.txt: No such device or address | ||||||||||||
| Additional Information | It works with Kernel 3.10.0-327 I found a patch that might have something to do with our issue: https://patchwork.kernel.org/patch/9447985/ | ||||||||||||
| Tags | file system | ||||||||||||
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kabe (reporter) 2017-03-21 05:33 |
I could reproduce this. Note that overlayfs is still in TECH PREVIEW state, but RH is actively fixing bugs. Pinning down the problematic part is hard and I haven't suceeded, but I found a following upstream kernel-4.7 commit: commit 76bc8e2843b66f8205026365966b49ec6da39ae7 Author: Miklos Szeredi <mszeredi.redhat.com> Date: Fri Jul 29 12:05:24 2016 +0200 ovl: disallow overlayfs as upperdir This does not work and does not make sense. So instead of fixing it (probably not hard) just disallow. This commit disallows anything overlayfs as upper=, so the reproducing example disintegrates into # mount -t overlay overlay -olowerdir=merged/lower2,upperdir=merged/upper2,workdir=merged/work2 merged/merged2/ overlayfs: filesystem on 'merged/upper2' not supported as upperdir So, using overlayfs as upperdir will be unsupported in future kernel. RHE7's fs/overlayfs/ seems to track kernel-4.x rather than 3.x series, so RH may or may not 'fix' this by disallowing overlayfs as upper. |
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kabe (reporter) 2017-03-21 05:40 |
Using non-overlayfs as upper2 and work2 works as expected: sudo make test2 [sudo] password for kabe: rm -fr upper lower work merged mkdir upper lower work merged mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merged/ mkdir upper2 work2 mkdir merged/lower2 merged/merged2 mount -t overlay overlay -olowerdir=merged/lower2,upperdir=upper2,workdir=work2 merged/merged2/ echo hello > merged/merged2/test.txt ls -li merged/merged2 total 4 536920 -rw-r--r--. 1 root root 6 Mar 21 14:26 test.txt I know there are some corner usage cases when you can't prepare a non-overlayfs directory to mount from. |
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kabe (reporter) 2017-03-27 08:38 |
Release notes for RHEL-7.3 says: >> OverlayFS is only supported for use as a Docker graph driver. >> Its use can only be supported for container COW content, >> not for persistent storage. Any persistent storage must be placed >> on non-OverlayFS volumes to be supported. ~~~~~~~~~~~~~ >> Only default Docker configuration can be used; that is, >> one level of overlay, one lowerdir, and both lower and upper levels ~~~~~~~~~~~~~~~~~~~~ >> are on the same file system. I don't think they will extend the support for layered overlayfs since kernel upstream decided to not. |
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dennisxrow (reporter) 2017-03-27 08:53 |
Hi kabe, thank you very much for all the information! I already thought that they won't support stacked overlay any further but I couldn't find any proof for that, but the commit you provided (https://github.com/torvalds/linux/commit/76bc8e2843b66f8205026365966b49ec6da39ae7) clearly confirms that. I think we will have to look for another solution. |
| Notes |
| Issue History |
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| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2017-03-17 16:06 | dennisxrow | New Issue | |
| 2017-03-17 16:06 | dennisxrow | Tag Attached: file system | |
| 2017-03-21 05:33 | kabe | Note Added: 0028892 | |
| 2017-03-21 05:40 | kabe | Note Added: 0028893 | |
| 2017-03-27 08:38 | kabe | Note Added: 0028940 | |
| 2017-03-27 08:53 | dennisxrow | Note Added: 0028942 | |
| Issue History |
