Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757072AbaGVTus (ORCPT ); Tue, 22 Jul 2014 15:50:48 -0400 Received: from mga09.intel.com ([134.134.136.24]:15061 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756880AbaGVTso (ORCPT ); Tue, 22 Jul 2014 15:48:44 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,711,1400050800"; d="scan'208";a="547369321" From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Matthew Wilcox Subject: [PATCH v8 07/22] Add copy_to_iter(), copy_from_iter() and iov_iter_zero() Date: Tue, 22 Jul 2014 15:47:55 -0400 Message-Id: <02a76f478c739ad87d7d5354b0e63818ebea8541.1406058387.git.matthew.r.wilcox@intel.com> X-Mailer: git-send-email 2.0.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Matthew Wilcox For DAX, we want to be able to copy between iovecs and kernel addresses that don't necessarily have a struct page. This is a fairly simple rearrangement for bvec iters to kmap the pages outside and pass them in, but for user iovecs it gets more complicated because we might try various different ways to kmap the memory. Duplicating the existing logic works out best in this case. We need to be able to write zeroes to an iovec for reads from unwritten ranges in a file. This is performed by the new iov_iter_zero() function, again patterned after the existing code that handles iovec iterators. Signed-off-by: Matthew Wilcox --- include/linux/uio.h | 3 + mm/iov_iter.c | 237 ++++++++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 226 insertions(+), 14 deletions(-) diff --git a/include/linux/uio.h b/include/linux/uio.h index 09a7cff..86fb3e9 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -80,6 +80,9 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, struct iov_iter *i); size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, struct iov_iter *i); +size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i); +size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i); +size_t iov_iter_zero(size_t bytes, struct iov_iter *); unsigned long iov_iter_alignment(const struct iov_iter *i); void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, unsigned long nr_segs, size_t count); diff --git a/mm/iov_iter.c b/mm/iov_iter.c index 7b5dbd1..e95ed80 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -4,6 +4,96 @@ #include #include +static size_t copy_to_iter_iovec(void *from, size_t bytes, struct iov_iter *i) +{ + size_t skip, copy, left, wanted; + const struct iovec *iov; + char __user *buf; + + if (unlikely(bytes > i->count)) + bytes = i->count; + + if (unlikely(!bytes)) + return 0; + + wanted = bytes; + iov = i->iov; + skip = i->iov_offset; + buf = iov->iov_base + skip; + copy = min(bytes, iov->iov_len - skip); + + left = __copy_to_user(buf, from, copy); + copy -= left; + skip += copy; + from += copy; + bytes -= copy; + while (unlikely(!left && bytes)) { + iov++; + buf = iov->iov_base; + copy = min(bytes, iov->iov_len); + left = __copy_to_user(buf, from, copy); + copy -= left; + skip = copy; + from += copy; + bytes -= copy; + } + + if (skip == iov->iov_len) { + iov++; + skip = 0; + } + i->count -= wanted - bytes; + i->nr_segs -= iov - i->iov; + i->iov = iov; + i->iov_offset = skip; + return wanted - bytes; +} + +static size_t copy_from_iter_iovec(void *to, size_t bytes, struct iov_iter *i) +{ + size_t skip, copy, left, wanted; + const struct iovec *iov; + char __user *buf; + + if (unlikely(bytes > i->count)) + bytes = i->count; + + if (unlikely(!bytes)) + return 0; + + wanted = bytes; + iov = i->iov; + skip = i->iov_offset; + buf = iov->iov_base + skip; + copy = min(bytes, iov->iov_len - skip); + + left = __copy_from_user(to, buf, copy); + copy -= left; + skip += copy; + to += copy; + bytes -= copy; + while (unlikely(!left && bytes)) { + iov++; + buf = iov->iov_base; + copy = min(bytes, iov->iov_len); + left = __copy_from_user(to, buf, copy); + copy -= left; + skip = copy; + to += copy; + bytes -= copy; + } + + if (skip == iov->iov_len) { + iov++; + skip = 0; + } + i->count -= wanted - bytes; + i->nr_segs -= iov - i->iov; + i->iov = iov; + i->iov_offset = skip; + return wanted - bytes; +} + static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes, struct iov_iter *i) { @@ -166,6 +256,50 @@ done: return wanted - bytes; } +static size_t zero_iovec(size_t bytes, struct iov_iter *i) +{ + size_t skip, copy, left, wanted; + const struct iovec *iov; + char __user *buf; + + if (unlikely(bytes > i->count)) + bytes = i->count; + + if (unlikely(!bytes)) + return 0; + + wanted = bytes; + iov = i->iov; + skip = i->iov_offset; + buf = iov->iov_base + skip; + copy = min(bytes, iov->iov_len - skip); + + left = __clear_user(buf, copy); + copy -= left; + skip += copy; + bytes -= copy; + + while (unlikely(!left && bytes)) { + iov++; + buf = iov->iov_base; + copy = min(bytes, iov->iov_len); + left = __clear_user(buf, copy); + copy -= left; + skip = copy; + bytes -= copy; + } + + if (skip == iov->iov_len) { + iov++; + skip = 0; + } + i->count -= wanted - bytes; + i->nr_segs -= iov - i->iov; + i->iov = iov; + i->iov_offset = skip; + return wanted - bytes; +} + static size_t __iovec_copy_from_user_inatomic(char *vaddr, const struct iovec *iov, size_t base, size_t bytes) { @@ -412,12 +546,17 @@ static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t kunmap_atomic(to); } -static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t bytes, - struct iov_iter *i) +static void memzero_page(struct page *page, size_t offset, size_t len) +{ + char *addr = kmap_atomic(page); + memset(addr + offset, 0, len); + kunmap_atomic(addr); +} + +static size_t copy_to_iter_bvec(void *from, size_t bytes, struct iov_iter *i) { size_t skip, copy, wanted; const struct bio_vec *bvec; - void *kaddr, *from; if (unlikely(bytes > i->count)) bytes = i->count; @@ -430,8 +569,6 @@ static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t by skip = i->iov_offset; copy = min_t(size_t, bytes, bvec->bv_len - skip); - kaddr = kmap_atomic(page); - from = kaddr + offset; memcpy_to_page(bvec->bv_page, skip + bvec->bv_offset, from, copy); skip += copy; from += copy; @@ -444,7 +581,6 @@ static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t by from += copy; bytes -= copy; } - kunmap_atomic(kaddr); if (skip == bvec->bv_len) { bvec++; skip = 0; @@ -456,12 +592,10 @@ static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t by return wanted - bytes; } -static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t bytes, - struct iov_iter *i) +static size_t copy_from_iter_bvec(void *to, size_t bytes, struct iov_iter *i) { size_t skip, copy, wanted; const struct bio_vec *bvec; - void *kaddr, *to; if (unlikely(bytes > i->count)) bytes = i->count; @@ -473,10 +607,6 @@ static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t bvec = i->bvec; skip = i->iov_offset; - kaddr = kmap_atomic(page); - - to = kaddr + offset; - copy = min(bytes, bvec->bv_len - skip); memcpy_from_page(to, bvec->bv_page, bvec->bv_offset + skip, copy); @@ -493,7 +623,6 @@ static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t to += copy; bytes -= copy; } - kunmap_atomic(kaddr); if (skip == bvec->bv_len) { bvec++; skip = 0; @@ -505,6 +634,61 @@ static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t return wanted; } +static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, + size_t bytes, struct iov_iter *i) +{ + void *kaddr = kmap_atomic(page); + size_t wanted = copy_to_iter_bvec(kaddr + offset, bytes, i); + kunmap_atomic(kaddr); + return wanted; +} + +static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, + size_t bytes, struct iov_iter *i) +{ + void *kaddr = kmap_atomic(page); + size_t wanted = copy_from_iter_bvec(kaddr + offset, bytes, i); + kunmap_atomic(kaddr); + return wanted; +} + +static size_t zero_bvec(size_t bytes, struct iov_iter *i) +{ + size_t skip, copy, wanted; + const struct bio_vec *bvec; + + if (unlikely(bytes > i->count)) + bytes = i->count; + + if (unlikely(!bytes)) + return 0; + + wanted = bytes; + bvec = i->bvec; + skip = i->iov_offset; + copy = min_t(size_t, bytes, bvec->bv_len - skip); + + memzero_page(bvec->bv_page, skip + bvec->bv_offset, copy); + skip += copy; + bytes -= copy; + while (bytes) { + bvec++; + copy = min(bytes, (size_t)bvec->bv_len); + memzero_page(bvec->bv_page, bvec->bv_offset, copy); + skip = copy; + bytes -= copy; + } + if (skip == bvec->bv_len) { + bvec++; + skip = 0; + } + i->count -= wanted - bytes; + i->nr_segs -= bvec - i->bvec; + i->bvec = bvec; + i->iov_offset = skip; + return wanted - bytes; +} + static size_t copy_from_user_bvec(struct page *page, struct iov_iter *i, unsigned long offset, size_t bytes) { @@ -669,6 +853,31 @@ size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, } EXPORT_SYMBOL(copy_page_from_iter); +size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i) +{ + if (i->type & ITER_BVEC) + return copy_to_iter_bvec(addr, bytes, i); + else + return copy_to_iter_iovec(addr, bytes, i); +} + +size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) +{ + if (i->type & ITER_BVEC) + return copy_from_iter_bvec(addr, bytes, i); + else + return copy_from_iter_iovec(addr, bytes, i); +} + +size_t iov_iter_zero(size_t bytes, struct iov_iter *i) +{ + if (i->type & ITER_BVEC) { + return zero_bvec(bytes, i); + } else { + return zero_iovec(bytes, i); + } +} + size_t iov_iter_copy_from_user_atomic(struct page *page, struct iov_iter *i, unsigned long offset, size_t bytes) { -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/