From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754461AbbCKOoT (ORCPT ); Wed, 11 Mar 2015 10:44:19 -0400 Received: from mail.kernel.org ([198.145.29.136]:53807 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753776AbbCKOoP (ORCPT ); Wed, 11 Mar 2015 10:44:15 -0400 From: anton@tuxera.com To: Al Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Anton Altaparmakov Subject: [PATCH 1/2] VFS: Add iov_iter_fault_in_multipages_readable() which is simillar to iov_iter_fault_in_readable() but differs in that it is not limited to faulting in the first iovec and instead faults in "bytes" bytes iterating over the iovecs as necessary. Date: Wed, 11 Mar 2015 10:43:31 -0400 Message-Id: <1426085012-54158-2-git-send-email-anton@tuxera.com> X-Mailer: git-send-email 1.9.3 (Apple Git-50) In-Reply-To: <1426085012-54158-1-git-send-email-anton@tuxera.com> References: <1426085012-54158-1-git-send-email-anton@tuxera.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Anton Altaparmakov Also, instead of only faulting in the first and last page of the range, all pages are faulted in. This function is needed by NTFS when it does multi page file writes. Signed-off-by: Anton Altaparmakov --- include/linux/uio.h | 1 + mm/iov_iter.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/include/linux/uio.h b/include/linux/uio.h index 07a0226..2986d5d 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -76,6 +76,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page, struct iov_iter *i, unsigned long offset, size_t bytes); void iov_iter_advance(struct iov_iter *i, size_t bytes); int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes); +int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes); size_t iov_iter_single_seg_count(const struct iov_iter *i); size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, struct iov_iter *i); diff --git a/mm/iov_iter.c b/mm/iov_iter.c index 8277320..040ad9e 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -317,6 +317,32 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) } EXPORT_SYMBOL(iov_iter_fault_in_readable); +/* + * Fault in one or more iovecs of the given iov_iter, to a maximum length of + * bytes. For each iovec, fault in each page that constitutes the iovec. + * + * Return 0 on success, or non-zero if the memory could not be accessed (i.e. + * because it is an invalid address). + */ +int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes) +{ + size_t skip = i->iov_offset; + const struct iovec *iov; + int err; + struct iovec v; + + if (!(i->type & (ITER_BVEC|ITER_KVEC))) { + iterate_iovec(i, bytes, v, iov, skip, ({ + err = fault_in_multipages_readable(v.iov_base, + v.iov_len); + if (unlikely(err)) + return err; + 0;})) + } + return 0; +} +EXPORT_SYMBOL(iov_iter_fault_in_multipages_readable); + void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, unsigned long nr_segs, size_t count) -- 1.9.3 (Apple Git-50)