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[71.255.240.10]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-87fc48a8bc4sm89004146d6.7.2025.10.28.19.13.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Oct 2025 19:13:58 -0700 (PDT) Received: from secra.localdomain (localhost [127.0.0.1]) by secra.localdomain (8.18.1/8.18.1) with ESMTP id 59T2DwFD085957; Tue, 28 Oct 2025 22:13:58 -0400 Received: (from secra@localhost) by secra.localdomain (8.18.1/8.18.1/Submit) id 59T2Dw3B085956; Tue, 28 Oct 2025 22:13:58 -0400 From: Wes Gibbs To: linux-man@vger.kernel.org Cc: mtk.manpages@gmail.com, colomar.alejandro@gmail.com, bigeasy@linutronix.de, Wes Gibbs Subject: [PATCH v2] Subject: copy_file_range.2: glibc no longer provides fallback after 2.30 Date: Tue, 28 Oct 2025 22:13:48 -0400 Message-ID: <20251029021348.85946-1-wg21908@gmail.com> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-man@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Update the documentation to note that glibc no longer provides a user-space fallback for copy_file_range() when the system call is not available, as of glibc 2.30. Applications must now handle ENOSYS themselves. Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=220489 Signed-off-by: Wes Gibbs --- man/man2/copy_file_range.2 | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/man/man2/copy_file_range.2 b/man/man2/copy_file_range.2 index e9e9e9945..5146c0d11 100644 --- a/man/man2/copy_file_range.2 +++ b/man/man2/copy_file_range.2 @@ -202,10 +202,16 @@ that was also backported to earlier stable kernels. .SH STANDARDS Linux, GNU. .SH HISTORY -Linux 4.5, -but glibc 2.27 provides a user-space -emulation when it is not available. +Linux 4.5. +Before glibc 2.30, the glibc wrapper function provided a user-space +fallback implementation when the kernel did not implement this +system call. Since glibc 2.30, that fallback has been removed; the +function now fails with ENOSYS if the kernel lacks support for +.BR copy_file_range (). +.\" Fallback introduced in glibc 2.27: .\" https://sourceware.org/git/?p=glibc.git;a=commit;f=posix/unistd.h;h=bad7a0c81f501fbbcc79af9eaa4b8254441c4a1f +.\" Fallback removed in glibc 2.30: +.\" https://sourceware.org/git/?p=glibc.git;a=commit;h=50c6ee3e74e08b8205f18dfb2830e9ec1bcf2ad4 .SH NOTES If .I fd_in -- 2.48.1