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 6523B3B0AEF for ; Mon, 18 May 2026 22:31:04 +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=1779143465; cv=none; b=h276Dg8Z4Qa0WNdo6xlPx75KJ9TKP+ftRR/1xfNSyEmjZm13CfI9Ji3ZOZDZeciHD7mrAgJaGuSs3drPZIoZa5CMIWoIzWaeP7Ro4uRylXgjkq1O991UtjTGA7Q69CLPoGbntquByHC/3/P5lu1eMKbFELPResJqW78MDncKuhU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779143465; c=relaxed/simple; bh=v9qX9pDrVHgmnAQEadpynPw/iCBrNo2C6n+A4BzV/tc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EHOyKw5xoWqjYY/i7gO460jH3LjhYkYfsVmlEZOgWtxYy28JN/kAG2YPrRMlyszYxQgDKqXhl1SyyFYtYCKIkNLfN92AgRxxOt7pJrYLuASdk5f7rpPvuy0uK38NroiNGzyNui3N6umQyrVazGPk+biAbH+VJr8xePOhX9U/EEs= 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=cS2YkyJj; 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="cS2YkyJj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1779143463; 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=vcN8r0sMSJfS+kOrSGHEP+bv70A9Lsgfu7bf9ESMv5s=; b=cS2YkyJjmCKjMWHVcGMi++9EVHHM3bPJS5p/9FiTT1Cj8eegbHLEjZuOTwtKyz91ioJ0/B mCG7chHYYwlPthHf3pAwe3pEVOYN4ppkb01ezxPyBjQ/ayW4tDPzhmaQx3LM7BYZM4aKg5 W5Xb3xzViMns+EdiYAIWEMuexZq4Liw= Received: from mx-prod-mc-06.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-151-m7JavSrTOOOJ-1I2d2y8Cw-1; Mon, 18 May 2026 18:30:59 -0400 X-MC-Unique: m7JavSrTOOOJ-1I2d2y8Cw-1 X-Mimecast-MFC-AGG-ID: m7JavSrTOOOJ-1I2d2y8Cw_1779143457 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7E245180044D; Mon, 18 May 2026 22:30:56 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.44.48.33]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 334351800352; Mon, 18 May 2026 22:30:49 +0000 (UTC) From: David Howells To: Christian Brauner , Matthew Wilcox , Christoph Hellwig Cc: David Howells , Paulo Alcantara , Jens Axboe , Leon Romanovsky , Steve French , ChenXiaoSong , Marc Dionne , Eric Van Hensbergen , Dominique Martinet , Ilya Dryomov , Trond Myklebust , 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-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org Subject: [PATCH v2 05/21] Add a function to kmap one page of a multipage bio_vec Date: Mon, 18 May 2026 23:29:37 +0100 Message-ID: <20260518222959.488126-6-dhowells@redhat.com> In-Reply-To: <20260518222959.488126-1-dhowells@redhat.com> References: <20260518222959.488126-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-block@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 Acked-by: Paulo Alcantara (Red Hat) cc: Matthew Wilcox cc: Christoph Hellwig cc: Jens Axboe cc: linux-block@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- include/linux/bvec.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/bvec.h b/include/linux/bvec.h index d36dd476feda..9df4a56fef61 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -299,4 +299,21 @@ static inline phys_addr_t bvec_phys(const struct bio_vec *bvec) return page_to_phys(bvec->bv_page) + bvec->bv_offset; } +/** + * kmap_local_bvec - 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 *kmap_local_bvec(struct bio_vec *bvec, size_t offset) +{ + offset += bvec->bv_offset; + + return kmap_local_page(bvec->bv_page + offset / PAGE_SIZE) + offset % PAGE_SIZE; +} + #endif /* __LINUX_BVEC_H */