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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>
This commit is contained in:
David Howells 2023-01-19 12:47:23 +00:00 committed by Steve French
parent 33b3b04154
commit f62e52d127
4 changed files with 23 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
block/bio.c
View File

@ -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;

8
block/blk-map.c
View File

@ -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;

10
include/linux/uio.h
View File

@ -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

14
lib/iov_iter.c
View File

@ -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;