Bug 195113 - overlayfs documentation appears to be wrong
Summary: overlayfs documentation appears to be wrong
Status: NEW
Alias: None
Product: File System
Classification: Unclassified
Component: Other (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: fs_other
URL:
Keywords: trivial
Depends on:
Blocks:
 
Reported: 2017-03-28 03:28 UTC by bluescreen_avenger
Modified: 2020-07-02 01:10 UTC (History)
1 user (show)

See Also:
Kernel Version: 4.10
Subsystem:
Regression: No
Bisected commit-id:

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Description bluescreen_avenger 2017-03-28 03:28:51 UTC 
Hi

 
It seems that according to https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt it says

    The lower filesystem can be any filesystem supported by Linux

However there appears to be filesystems that overlayfs does NOT support (such as vfat). If I try to use a vfat file system as the lowerdir, I get
    overlayfs: filesystem on '/tmp/lower' not supported
in my dmesg.

So now I am not sure what filesystems cannot be used as a lowerdir for overlayfs.
(or what conditions I need to check for... ...in userspace)


Thanks
Comment 1 Leonard/Janis Robert König 2019-11-01 17:09:20 UTC 
I can confirm that overlayfs doesn't support vfat here either.
Comment 2 bluescreen_avenger 2020-07-02 01:10:00 UTC 
The Documentation states
"The lower filesystem can be any filesystem supported by Linux and does
not need to be writable."

But FAT doesn't work as a lower file system. The documentation should be updated so it's not misleading
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