linux-kernel - [PATCH v7 15/21] iov_iter: introduce iov_iter_get_pages_[alloc

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Date:   Wed, 15 Jun 2022 10:12:27 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-block@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-mm@...ck.org, iommu@...ts.linux-foundation.org
Cc:     Stephen Bates <sbates@...thlin.com>,
        Christoph Hellwig <hch@....de>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Christian König <christian.koenig@....com>,
        John Hubbard <jhubbard@...dia.com>,
        Don Dutile <ddutile@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Minturn Dave B <dave.b.minturn@...el.com>,
        Jason Ekstrand <jason@...kstrand.net>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Xiong Jianxin <jianxin.xiong@...el.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Robin Murphy <robin.murphy@....com>,
        Martin Oliveira <martin.oliveira@...eticom.com>,
        Chaitanya Kulkarni <ckulkarnilinux@...il.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v7 15/21] iov_iter: introduce iov_iter_get_pages_[alloc_]flags()

Add iov_iter_get_pages_flags() and iov_iter_get_pages_alloc_flags()
which take a flags argument that is passed to get_user_pages_fast().

This is so that FOLL_PCI_P2PDMA can be passed when appropriate.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 include/linux/uio.h |  6 ++++++
 lib/iov_iter.c      | 25 +++++++++++++++++++------
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 739285fe5a2f..ddf9e4cf4a59 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -232,8 +232,14 @@ void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode
 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
 		     loff_t start, size_t count);
+ssize_t iov_iter_get_pages_flags(struct iov_iter *i, struct page **pages,
+		size_t maxsize, unsigned maxpages, size_t *start,
+		unsigned int gup_flags);
 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 			size_t maxsize, unsigned maxpages, size_t *start);
+ssize_t iov_iter_get_pages_alloc_flags(struct iov_iter *i,
+		struct page ***pages, size_t maxsize, size_t *start,
+		unsigned int gup_flags);
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 			size_t maxsize, size_t *start);
 int iov_iter_npages(const struct iov_iter *i, int maxpages);
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 6dd5330f7a99..9bf6e3af5120 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1515,9 +1515,9 @@ static struct page *first_bvec_segment(const struct iov_iter *i,
 	return page;
 }
 
-ssize_t iov_iter_get_pages(struct iov_iter *i,
+ssize_t iov_iter_get_pages_flags(struct iov_iter *i,
 		   struct page **pages, size_t maxsize, unsigned maxpages,
-		   size_t *start)
+		   size_t *start, unsigned int gup_flags)
 {
 	size_t len;
 	int n, res;
@@ -1528,7 +1528,6 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
 		return 0;
 
 	if (likely(iter_is_iovec(i))) {
-		unsigned int gup_flags = 0;
 		unsigned long addr;
 
 		if (iov_iter_rw(i) != WRITE)
@@ -1558,6 +1557,13 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
 		return iter_xarray_get_pages(i, pages, maxsize, maxpages, start);
 	return -EFAULT;
 }
+EXPORT_SYMBOL_GPL(iov_iter_get_pages_flags);
+
+ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
+			   size_t maxsize, unsigned maxpages, size_t *start)
+{
+	return iov_iter_get_pages_flags(i, pages, maxsize, maxpages, start, 0);
+}
 EXPORT_SYMBOL(iov_iter_get_pages);
 
 static struct page **get_pages_array(size_t n)
@@ -1640,9 +1646,9 @@ static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
 	return actual;
 }
 
-ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
+ssize_t iov_iter_get_pages_alloc_flags(struct iov_iter *i,
 		   struct page ***pages, size_t maxsize,
-		   size_t *start)
+		   size_t *start, unsigned int gup_flags)
 {
 	struct page **p;
 	size_t len;
@@ -1654,7 +1660,6 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		return 0;
 
 	if (likely(iter_is_iovec(i))) {
-		unsigned int gup_flags = 0;
 		unsigned long addr;
 
 		if (iov_iter_rw(i) != WRITE)
@@ -1667,6 +1672,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		p = get_pages_array(n);
 		if (!p)
 			return -ENOMEM;
+
 		res = get_user_pages_fast(addr, n, gup_flags, p);
 		if (unlikely(res <= 0)) {
 			kvfree(p);
@@ -1694,6 +1700,13 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		return iter_xarray_get_pages_alloc(i, pages, maxsize, start);
 	return -EFAULT;
 }
+EXPORT_SYMBOL_GPL(iov_iter_get_pages_alloc_flags);
+
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
+				 size_t maxsize, size_t *start)
+{
+	return iov_iter_get_pages_alloc_flags(i, pages, maxsize, start, 0);
+}
 EXPORT_SYMBOL(iov_iter_get_pages_alloc);
 
 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
-- 
2.30.2