RFR: 8262844: FileStore.supportsFileAttributeView might return false negative in case of ext3

[Brian Burkhalter]

On Wed, 3 Mar 2021 01:13:12 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Apparently as of version 11-SP3, the default file system of SLES was changed to Ext3 [1]. In [2] it is stated that
>> 
>> "The default inode size of ext3 file systems has been increased from 128 bytes to 256 bytes on SLES11, because of extended attributes / ACLs."
>> 
>> From this it may be inferred that extended attributes are enabled by default from SLES 11. One may therefore suppose that the kernel was built with configuration item CONFIG_EXT3_FS_XATTR set to Y [3].
>> 
>> [1] https://www.suse.com/releasenotes/x86_64/SUSE-SLES/11-SP3/, section 6.8
>> [2] https://www.suse.com/support/kb/doc/?id=000017683
>> [3] https://cateee.net/lkddb/web-lkddb/EXT3_FS_XATTR.html
>
> Based on testing it looks like xattr is enabled by default for ext3 file systems in Ubuntu 18.04 LTS (Linux kernel 4.15.0).

>From [1]:

       Some filesystems, such as Reiserfs (and, historically, ext2 and
       ext3), require the filesystem to be mounted with the user_xattr
       mount option in order for user extended attributes to be used.

       In the current ext2, ext3, and ext4 filesystem implementations,
       the total bytes used by the names and values of all of a file's
       extended attributes must fit in a single filesystem block ....

which reads as if extended attributes are now always supported in ext2, ext3, and ext4.

[1] https://man7.org/linux/man-pages/man7/xattr.7.html

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PR: https://git.openjdk.java.net/jdk/pull/2778