linux-ext4 - Re: Inquiry: Possible built-in support for longer filenames in ext4 (beyond 256 bytes)

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Message-ID: <87pl8jzi3n.fsf@linux.intel.com>
Date: Fri, 12 Dec 2025 10:10:36 -0800
From: Andi Kleen <ak@...ux.intel.com>
To: "Theodore Tso" <tytso@....edu>
Cc: Winston Wen <wentao@...ontech.com>,  linux-ext4@...r.kernel.org
Subject: Re: Inquiry: Possible built-in support for longer filenames in ext4
 (beyond 256 bytes)

"Theodore Tso" <tytso@....edu> writes:
>
> Well, extended attributes won't work, because xattrs are associated
> with the inode, not the directory entry.  So you need to handle cases
> where the file has multiple hard links.  And if you are doing a lookup
> by long file name, there's a chicken and egg problem; you can't match
> against the full filename until you read the xattr, and you can't do
> that until you've lookup.

Perhaps you could use xattrs on the directory inode to store the longer
names, or the overflow.

One problem is that they may need to be big, exceeding xattr
limits, but perhaps some total limit on the longer file names
would be acceptable.

-Andi