Re: [PATCH v9 5/8] block: Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED with inverted logic

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On 1/24/23 09:01, David Howells wrote:
From: Christoph Hellwig <hch@xxxxxx>

Replace BIO_NO_PAGE_REF with a BIO_PAGE_REFFED flag that has the inverted
meaning is only set when a page reference has been acquired that needs to
be released by bio_release_pages().

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
cc: Jens Axboe <axboe@xxxxxxxxx>
cc: Jan Kara <jack@xxxxxxx>
cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
cc: linux-block@xxxxxxxxxxxxxxx
---

Notes:
     ver #8)
      - Don't default to BIO_PAGE_REFFED [hch].
ver #5)
      - Split from patch that uses iov_iter_extract_pages().

  block/bio.c               | 2 +-
  block/blk-map.c           | 1 +
  fs/direct-io.c            | 2 ++
  fs/iomap/direct-io.c      | 1 -
  include/linux/bio.h       | 2 +-
  include/linux/blk_types.h | 2 +-
  6 files changed, 6 insertions(+), 4 deletions(-)

One documentation nit below, but either way,

Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>


diff --git a/block/bio.c b/block/bio.c
index 683444e6b711..851c23641a0d 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1198,7 +1198,6 @@ void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter)
  	bio->bi_io_vec = (struct bio_vec *)iter->bvec;
  	bio->bi_iter.bi_bvec_done = iter->iov_offset;
  	bio->bi_iter.bi_size = size;
-	bio_set_flag(bio, BIO_NO_PAGE_REF);
  	bio_set_flag(bio, BIO_CLONED);
  }
@@ -1343,6 +1342,7 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
  		return 0;
  	}
+ bio_set_flag(bio, BIO_PAGE_REFFED);
  	do {
  		ret = __bio_iov_iter_get_pages(bio, iter);
  	} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
diff --git a/block/blk-map.c b/block/blk-map.c
index 7db52ad5b2d0..0e2b0a861ba3 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -282,6 +282,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
  	if (blk_queue_pci_p2pdma(rq->q))
  		extraction_flags |= ITER_ALLOW_P2PDMA;
+ bio_set_flag(bio, BIO_PAGE_REFFED);
  	while (iov_iter_count(iter)) {
  		struct page **pages, *stack_pages[UIO_FASTIOV];
  		ssize_t bytes;
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 03d381377ae1..07810465fc9d 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -403,6 +403,8 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
  		bio->bi_end_io = dio_bio_end_aio;
  	else
  		bio->bi_end_io = dio_bio_end_io;
+	/* for now require references for all pages */

Maybe just delete this comment?

thanks,
--
John Hubbard
NVIDIA



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