The branch main has been updated by rmacklem:
URL:
https://cgit.FreeBSD.org/src/commit/?id=3a6c62e69597b012589e1f2f5465747e37ab0f13
commit 3a6c62e69597b012589e1f2f5465747e37ab0f13
Author: Rick Macklem <rmack...@freebsd.org>
AuthorDate: 2025-08-07 21:12:37 +0000
Commit: Rick Macklem <rmack...@freebsd.org>
CommitDate: 2025-08-07 21:12:37 +0000
named_attribute.7: Add an explanation for a quirk
I thought I would be able to come up with a
ZFS patch to avoid the possibility of there
being two attributes with the same name for
a file. This can only occur if the two attributes
are created when xattr=sa and xattr=dir respectively.
I have not been able to fix this, so this patch
documents this quirk.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D51751
---
share/man/man7/named_attribute.7 | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)
diff --git a/share/man/man7/named_attribute.7 b/share/man/man7/named_attribute.7
index 4080dfce2fab..a0599ef71496 100644
--- a/share/man/man7/named_attribute.7
+++ b/share/man/man7/named_attribute.7
@@ -3,7 +3,7 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
-.Dd July 20, 2025
+.Dd August 5, 2025
.Dt NAMED_ATTRIBUTE 7
.Os
.Sh NAME
@@ -153,6 +153,31 @@ property to
will make the attribute(s) visible as both named attributes
and via
.Xr extattr 2 .
+.It
+For ZFS, it is also possible to create two attributes with the same
+name by creating one when the ZFS
+.Dv xattr
+property is set to
+.Dq sa
+and then creating another one with the same name after the ZFS
+property
+.Dv xattr
+has been changed to
+.Dq dir .
+The one created when the ZFS
+.Dv xattr
+property is set to
+.Dq sa
+may be removed via
+.Xr rmextattr 8 .
+.It
+To avoid these issues for ZFS, it is strongly recommended that the ZFS
+property
+.Dv xattr
+be set to
+.Dq dir
+as soon as the file system is created, if named attributes
+are to be used on the file system.
.El
.Pp
The named attribute mechanism/system call interface provides certain
@@ -288,7 +313,8 @@ enters the named attribute directory for the file object
.Xr truncate 2 ,
.Xr unlinkat 2 ,
.Xr write 2 ,
-.Xr zfsprops 7
+.Xr zfsprops 7 ,
+.Xr rmextattr 8
.Sh HISTORY
This interface first appeared in
.Fx 15.0 .
