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Wed, 08 Jul 2026 05:34:51 -0400 X-MC-Unique: 1jWkn7APP-qkLQEIcXgpAg-1 X-Mimecast-MFC-AGG-ID: 1jWkn7APP-qkLQEIcXgpAg_1783503290 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 391EB1956068; Wed, 8 Jul 2026 09:34:50 +0000 (UTC) Received: from oxygen.redhat.com (unknown [10.44.33.242]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id EAC481955F43; Wed, 8 Jul 2026 09:34:48 +0000 (UTC) From: Giuseppe Scrivano To: linux-erofs@lists.ozlabs.org Cc: linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org Subject: [PATCH 0/2] erofs: fd-based source and backing file introspection Date: Wed, 8 Jul 2026 11:34:25 +0200 Message-ID: <20260708093446.3370200-1-gscrivan@redhat.com> X-Mailing-List: linux-erofs@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-MFC-PROC-ID: GImxKb9qCB-aecL2leZxVNHYVG5-CZuIpL4TdvOky3k_1783503290 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true This series adds two features to erofs for file-backed mounts: 1. Accept a source file descriptor via fsconfig(FSCONFIG_SET_FD, "source", NULL, fd) as an alternative to a path string. This is useful when the backing file isn't reachable by path in the caller's mount namespace. For example, composefs reusing an already-mounted erofs image's backing file. 2. Add an EROFS_IOC_GET_SOURCE_FD ioctl that returns a file descriptor to the backing image file. This allows userspace to retrieve the backing file from an existing erofs mount without needing to know or parse the original source path. Giuseppe Scrivano (2): erofs: accept source file descriptor via fsconfig erofs: add ioctl to retrieve the backing source file descriptor fs/erofs/inode.c | 25 +++++++++++++++++++++++++ fs/erofs/super.c | 36 +++++++++++++++++++++++++----------- include/uapi/linux/erofs.h | 9 +++++++++ 3 files changed, 59 insertions(+), 11 deletions(-) create mode 100644 include/uapi/linux/erofs.h -- 2.55.0