[PATCH v7 1/8] iov_iter: Define flags to qualify page extraction.
From: David Howells
Date: Fri Jan 20 2023 - 12:56:57 EST
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 allowed; but in future,
additional flags will be provided to indicate the I/O direction.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
cc: Jens Axboe <axboe@xxxxxxxxx>
cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
cc: linux-fsdevel@xxxxxxxxxxxxxxx
cc: linux-block@xxxxxxxxxxxxxxx
---
Notes:
ver #7)
- Don't use FOLL_* as a parameter, but rather define constants
specifically to use with iov_iter_*_pages*().
- Drop the I/O direction constants for now.
block/bio.c | 6 +++---
block/blk-map.c | 8 ++++----
include/linux/uio.h | 7 +++++--
lib/iov_iter.c | 14 ++++++++------
4 files changed, 20 insertions(+), 15 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 5f96fcae3f75..6a6c73d14bfd 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1249,7 +1249,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
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;
+ unsigned int extract_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;
+ extract_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, extract_flags);
if (unlikely(size <= 0))
return size ? size : -EFAULT;
diff --git a/block/blk-map.c b/block/blk-map.c
index 19940c978c73..bc111261fc82 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -267,7 +267,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
{
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;
+ unsigned int extract_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;
+ extract_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, extract_flags);
} else {
bytes = iov_iter_get_pages_alloc(iter, &pages,
- LONG_MAX, &offs, gup_flags);
+ LONG_MAX, &offs, extract_flags);
}
if (unlikely(bytes <= 0)) {
ret = bytes ? bytes : -EFAULT;
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 9f158238edba..46d5080314c6 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -252,12 +252,12 @@ 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);
+ unsigned extract_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);
+ unsigned extract_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 +360,7 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
};
}
+/* Flags for iov_iter_get/extract_pages*() */
+#define ITER_ALLOW_P2PDMA 0x01 /* Allow P2PDMA on the extracted pages */
+
#endif
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index f9a3ff37ecd1..fb04abe7d746 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1432,9 +1432,9 @@ 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)
+ unsigned int extract_flags)
{
- unsigned int n;
+ unsigned int n, gup_flags = 0;
if (maxsize > i->count)
maxsize = i->count;
@@ -1442,6 +1442,8 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
return 0;
if (maxsize > MAX_RW_COUNT)
maxsize = MAX_RW_COUNT;
+ if (extract_flags & ITER_ALLOW_P2PDMA)
+ gup_flags |= FOLL_PCI_P2PDMA;
if (likely(user_backed_iter(i))) {
unsigned long addr;
@@ -1495,14 +1497,14 @@ 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, unsigned extract_flags)
{
if (!maxpages)
return 0;
BUG_ON(!pages);
return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages,
- start, gup_flags);
+ start, extract_flags);
}
EXPORT_SYMBOL_GPL(iov_iter_get_pages);
@@ -1515,14 +1517,14 @@ 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, unsigned extract_flags)
{
ssize_t len;
*pages = NULL;
len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start,
- gup_flags);
+ extract_flags);
if (len <= 0) {
kvfree(*pages);
*pages = NULL;