From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C2A44D954B for ; Wed, 30 Sep 2026 12:53:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790772806; cv=none; b=ajxUwfCQABrzYg6Bzm5pCFFAktTwSshXnGWjPVS+pUHfuIUikmjIy5LBY2GVEl+3zsTe2MXBUG6EKzJeCF1tgyCR1bHSCTX9bdeJAZ0ipTYPunxH4TOL+2/+5iNI4X7FyqkGg5KSQP/2yNC06MjfaKLBsIXPTIcF1QWUjjM80+Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790772806; c=relaxed/simple; bh=FFbefN2Y4qRJn5vswr2Uy9xuWqjQECbgHAQFP+xEhfc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o77cbfgRZjO3XFu4Rv5CqZ62fx8Ikul4Zb3nAH9suWzRpv/IH7YLcOo4OcXNawDiPnpBm501HGPhdzeoagPbX13nHSn6XVpQbe2yUTuw45ey3qiu9PHy7C45j6c5SXXTWpKfOXBOi5QV9d9+v8z/EbQ/DKGTYtJd/5snK+BKUJA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=M1NlFJWX; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="M1NlFJWX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1790772796; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TrGq5iY6/w2n25N0igq41iNBSv1Z7z5H/VJULRFdP7Y=; b=M1NlFJWXXjCYXC5b98ksPGUe7rsivuPMQ4Og91+kJi+ctP88ckn/Lg1iTttkByxFBQHODB bpOXUwaK0Jn7R11b5PK9YOVcmgfMWnOXarpQXm2ZGxFN/MN3lNS4QHuhTvyVYXSeJLrAyT KUiEHa+AeCxi4m/sr5Xok1xiH0I7j8w= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-583--1saaqWWPBOqK-NNFMlbfg-1; Wed, 30 Sep 2026 08:53:10 -0400 X-MC-Unique: -1saaqWWPBOqK-NNFMlbfg-1 X-Mimecast-MFC-AGG-ID: -1saaqWWPBOqK-NNFMlbfg_1790772788 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8309718A5C7F; Wed, 30 Sep 2026 12:53:06 +0000 (UTC) Received: from warthog.com (unknown [10.44.32.54]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id CA49C1800361; Wed, 30 Sep 2026 12:52:59 +0000 (UTC) From: David Howells To: Christian Brauner Cc: David Howells , Paulo Alcantara , Matthew Wilcox , Namjae Jeon , Marc Dionne , Stefan Metzmacher , Eric Van Hensbergen , Dominique Martinet , Ilya Dryomov , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jens Axboe , Christoph Hellwig , linux-block@vger.kernel.org Subject: [PATCH v14 01/10] Add a function to kmap one page of a multipage bio_vec Date: Wed, 30 Sep 2026 13:52:36 +0100 Message-ID: <20260930125247.3232130-2-dhowells@redhat.com> In-Reply-To: <20260930125247.3232130-1-dhowells@redhat.com> References: <20260930125247.3232130-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Add a function to kmap one page of a multipage bio_vec by offset (which is added to the offset in the bio_vec internally). The caller is responsible for calculating how much of the page is then available. Signed-off-by: David Howells Reviewed-by: Paulo Alcantara (Red Hat) cc: Matthew Wilcox cc: Jens Axboe cc: Christoph Hellwig cc: linux-block@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- include/linux/bvec.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/include/linux/bvec.h b/include/linux/bvec.h index fc566ee1c1ff..df9ce860e787 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -343,4 +343,22 @@ static inline phys_addr_t bvec_phys(const struct bio_vec *bvec) return page_to_phys(bvec->bv_page) + bvec->bv_offset; } +/** + * bvec_kmap_partial - Map part of a bvec into the kernel virtual address space + * @bvec: bvec to map + * @offset: Offset into bvec + * + * Map the page containing the byte at @offset into the kernel virtual address + * space. The caller is responsible for making sure this doesn't overrun. + * + * Call kunmap_local on the returned address to unmap. + */ +static inline void *bvec_kmap_partial(struct bio_vec *bvec, size_t offset) +{ + offset += bvec->bv_offset; + + return kmap_local_page(bvec->bv_page + (offset >> PAGE_SHIFT)) + + (offset & ~PAGE_MASK); +} + #endif /* __LINUX_BVEC_H */