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 73A843AF64B for ; Mon, 18 May 2026 22:31:05 +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=1779143466; cv=none; b=KL5SqloVjsYkr9RhZYY/HtLgrthoNboElJ0pdZoPQ3Xqv1oh78KRz3uVt7ToHu+d93tj1emszKUaYM1cZIN4KElc3KCjuTByc2GX5RIWaqIGIV+0KKxThKuWu2jPt51DCq4TiUUihChjkFDzzG4XEDTKA81e+yqF7rtaOr4l/do= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779143466; c=relaxed/simple; bh=v9qX9pDrVHgmnAQEadpynPw/iCBrNo2C6n+A4BzV/tc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=hWldFyO6zby+/kqMkhY4igMAQrPx/msBnLCbNe9oSJESKhztHZortt5LpYdA3zzSUz7jI85qM3CZvhDm0bOB2DCDfGoOPRPsHpgceSwtN71wTaOmDUyeFWnASnf2lKYPNEF093nTen2dM5B7L3uKX8MFZ87XYzARyyJB8qDUWVY= 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=Y1xWNGFb; 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="Y1xWNGFb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1779143464; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vcN8r0sMSJfS+kOrSGHEP+bv70A9Lsgfu7bf9ESMv5s=; b=Y1xWNGFbxqfofBres9TbgCbW+DvXMMo6P4GMyVCt0gwSGRzYyg2nXHbmKMy1lACDNVN+63 TkiFhN5H77ey6xdlVgwgg4qsGAA1Qt+jysdK941DMQGRTq/1byiCNqi5vC4rvRxgjktnu5 iuOVh14MIYKl1hHt1aVI7rjC8I/+3WA= 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: netfs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: EWG3l8DCGvkJzRJIiIbeYB88BBSZHlDaolJGaHWSPtA_1779143457 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true 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 */