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From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: linux-ext4@vger.kernel.org
Cc: tytso@mit.edu, jack@suse.com, adilger.kernel@dilger.ca,
	ktkhai@virtuozzo.com
Subject: [Q] e4defrag and append-only files
Date: Mon, 9 Dec 2019 13:54:24 +0300	[thread overview]
Message-ID: <a2b2fcf4-4b71-e78c-5a10-627097df44fb@virtuozzo.com> (raw)

Hi,

on one of production nodes I observe the situation, when many fragmented files
never become defragmented, becase of they have "a" extended attribute.
The reason is append-only file can't be open for write without O_APPEND attribute:

$lsattr a.txt
-----a--------e----- a.txt

$strace e4defrag a.txt
openat(AT_FDCWD, "a.txt", O_RDWR)       = -1 EPERM (Operation not permitted)

Simple O_APPEND passed to open() solves the situation.

The question is: can't we just do this?

Let's observe the file restrictions we may have.

"Append-only" extended attribute restriction is weaker, than RO file permissions (0444).
But RO files are being processed by e4defrag, since e4defrag runs by root, and it easily
ignores RO file permissions, while "append-only" files are always ignored by the util.
Is there a fundamental reason we must skip them?

Thanks,
Kirill

             reply	other threads:[~2019-12-09 10:54 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-09 10:54 Kirill Tkhai [this message]
2019-12-10 10:10 ` [Q] e4defrag and append-only files Jan Kara

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