iov_iter: Define flags to qualify page extraction.

Define flags to qualify page extraction to pass into iov_iter_*_pages*()
rather than passing in FOLL_* flags.

For now only a flag to allow peer-to-peer DMA is supported.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Logan Gunthorpe <logang@deltatee.com>
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/block/bio.c b/block/bio.c
index ab59a49..b97f399 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1245,11 +1245,11 @@ static int bio_iov_add_zone_append_page(struct bio *bio, struct page *page,
  */
 static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 {
+       iov_iter_extraction_t extraction_flags = 0;
        unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
        unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
        struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
        struct page **pages = (struct page **)bv;
-       unsigned int gup_flags = 0;
        ssize_t size, left;
        unsigned len, i = 0;
        size_t offset, trim;
@@ -1264,7 +1264,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
        pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
 
        if (bio->bi_bdev && blk_queue_pci_p2pdma(bio->bi_bdev->bd_disk->queue))
-               gup_flags |= FOLL_PCI_P2PDMA;
+               extraction_flags |= ITER_ALLOW_P2PDMA;
 
        /*
         * Each segment in the iov is required to be a block size multiple.
@@ -1275,7 +1275,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
         */
        size = iov_iter_get_pages(iter, pages,
                                  UINT_MAX - bio->bi_iter.bi_size,
-                                 nr_pages, &offset, gup_flags);
+                                 nr_pages, &offset, extraction_flags);
        if (unlikely(size <= 0))
                return size ? size : -EFAULT;
 

diff --git a/block/blk-map.c b/block/blk-map.c
index 19940c9..080dd60 100644 (file)
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -265,9 +265,9 @@ static struct bio *blk_rq_map_bio_alloc(struct request *rq,
 static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
                gfp_t gfp_mask)
 {
+       iov_iter_extraction_t extraction_flags = 0;
        unsigned int max_sectors = queue_max_hw_sectors(rq->q);
        unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
-       unsigned int gup_flags = 0;
        struct bio *bio;
        int ret;
        int j;
@@ -280,7 +280,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
                return -ENOMEM;
 
        if (blk_queue_pci_p2pdma(rq->q))
-               gup_flags |= FOLL_PCI_P2PDMA;
+               extraction_flags |= ITER_ALLOW_P2PDMA;
 
        while (iov_iter_count(iter)) {
                struct page **pages, *stack_pages[UIO_FASTIOV];
@@ -291,10 +291,10 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
                if (nr_vecs <= ARRAY_SIZE(stack_pages)) {
                        pages = stack_pages;
                        bytes = iov_iter_get_pages(iter, pages, LONG_MAX,
-                                                  nr_vecs, &offs, gup_flags);
+                                                  nr_vecs, &offs, extraction_flags);
                } else {
                        bytes = iov_iter_get_pages_alloc(iter, &pages,
-                                               LONG_MAX, &offs, gup_flags);
+                                               LONG_MAX, &offs, extraction_flags);
                }
                if (unlikely(bytes <= 0)) {
                        ret = bytes ? bytes : -EFAULT;

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 9f15823..eec6ed8 100644 (file)
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -13,6 +13,8 @@
 struct page;
 struct pipe_inode_info;
 
+typedef unsigned int __bitwise iov_iter_extraction_t;
+
 struct kvec {
        void *iov_base; /* and that should *never* hold a userland pointer */
        size_t iov_len;
@@ -252,12 +254,12 @@ void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct 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);
+               iov_iter_extraction_t extraction_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);
+               iov_iter_extraction_t extraction_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);
@@ -360,4 +362,8 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
        };
 }
 
+/* Flags for iov_iter_get/extract_pages*() */
+/* Allow P2PDMA on the extracted pages */
+#define ITER_ALLOW_P2PDMA      ((__force iov_iter_extraction_t)0x01)
+
 #endif

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 47c4845..9d4949e 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1426,9 +1426,9 @@ 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 gup_flags)
+                  iov_iter_extraction_t extraction_flags)
 {
-       unsigned int n;
+       unsigned int n, gup_flags = 0;
 
        if (maxsize > i->count)
                maxsize = i->count;
@@ -1436,6 +1436,8 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
                return 0;
        if (maxsize > MAX_RW_COUNT)
                maxsize = MAX_RW_COUNT;
+       if (extraction_flags & ITER_ALLOW_P2PDMA)
+               gup_flags |= FOLL_PCI_P2PDMA;
 
        if (likely(user_backed_iter(i))) {
                unsigned long addr;
@@ -1489,14 +1491,14 @@ static ssize_t __iov_iter_get_pages_alloc(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, unsigned gup_flags)
+                  size_t *start, iov_iter_extraction_t extraction_flags)
 {
        if (!maxpages)
                return 0;
        BUG_ON(!pages);
 
        return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages,
-                                         start, gup_flags);
+                                         start, extraction_flags);
 }
 EXPORT_SYMBOL_GPL(iov_iter_get_pages);
 
@@ -1509,14 +1511,14 @@ EXPORT_SYMBOL(iov_iter_get_pages2);
 
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
                   struct page ***pages, size_t maxsize,
-                  size_t *start, unsigned gup_flags)
+                  size_t *start, iov_iter_extraction_t extraction_flags)
 {
        ssize_t len;
 
        *pages = NULL;
 
        len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start,
-                                        gup_flags);
+                                        extraction_flags);
        if (len <= 0) {
                kvfree(*pages);
                *pages = NULL;