On 2022-10-24 19:14, Chaitanya Kulkarni wrote:

On 10/21/22 10:41, Logan Gunthorpe wrote:

quoted

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@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
  include/linux/uio.h |  6 ++++++
  lib/iov_iter.c      | 32 ++++++++++++++++++++++++--------
  2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 2e3134b14ffd..9ede533ce64c 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h

@@ -247,8 +247,14 @@ 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(struct iov_iter *i, struct page **pages,
+		size_t maxsize, unsigned maxpages, size_t *start,
+		unsigned gup_flags);
  ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
  			size_t maxsize, unsigned maxpages, size_t *start);
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
+		struct page ***pages, size_t maxsize, size_t *start,
+		unsigned gup_flags);
  ssize_t iov_iter_get_pages_alloc2(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 c3ca28ca68a6..53efad017f3c 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c

@@ -1430,7 +1430,8 @@ static struct page *first_bvec_segment(const struct iov_iter *i,
  
  static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
  		   struct page ***pages, size_t maxsize,
-		   unsigned int maxpages, size_t *start)
+		   unsigned int maxpages, size_t *start,
+		   unsigned int gup_flags)
  {
  	unsigned int n;
  

@@ -1442,7 +1443,6 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
  		maxsize = MAX_RW_COUNT;
  
  	if (likely(user_backed_iter(i))) {
-		unsigned int gup_flags = 0;
  		unsigned long addr;
  		int res;
  

@@ -1492,33 +1492,49 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
  	return -EFAULT;
  }
  
-ssize_t iov_iter_get_pages2(struct iov_iter *i,
+ssize_t iov_iter_get_pages(struct iov_iter *i,
  		   struct page **pages, size_t maxsize, unsigned maxpages,
-		   size_t *start)
+		   size_t *start, unsigned gup_flags)
  {
  	if (!maxpages)
  		return 0;
  	BUG_ON(!pages);
  
-	return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start);
+	return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages,
+					  start, gup_flags);
+}
+EXPORT_SYMBOL_GPL(iov_iter_get_pages);
+
+ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
+		size_t maxsize, unsigned maxpages, size_t *start)
+{
+	return iov_iter_get_pages(i, pages, maxsize, maxpages, start, 0);
  }
  EXPORT_SYMBOL(iov_iter_get_pages2);
  
-ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i,
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
  		   struct page ***pages, size_t maxsize,
-		   size_t *start)
+		   size_t *start, unsigned gup_flags)
  {
  	ssize_t len;
  
  	*pages = NULL;
  
-	len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start);
+	len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start,
+					 gup_flags);
  	if (len <= 0) {
  		kvfree(*pages);
  		*pages = NULL;
  	}
  	return len;
  }
+EXPORT_SYMBOL_GPL(iov_iter_get_pages_alloc);
+
+ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i,
+		struct page ***pages, size_t maxsize, size_t *start)
+{
+	return iov_iter_get_pages_alloc(i, pages, maxsize, start, 0);
+}
  EXPORT_SYMBOL(iov_iter_get_pages_alloc2);

Just one minor question why not make following functions
EXPORT_SYMBOL_GPL() ?

1. iov_iter_get_pages2()
2. iov_iter_get_pages_alloc2()

They previously were not GPL, so I didn't think that should be changed
in this patch.

Thanks for the review!

Logan