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From:   David Howells <dhowells@redhat.com>
To:     Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>
Cc:     David Howells <dhowells@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
        Jeff Layton <jlayton@kernel.org>,
        Logan Gunthorpe <logang@deltatee.com>,
        linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: [PATCH v7 4/8] block: Rename BIO_NO_PAGE_REF to BIO_PAGE_REFFED and invert the meaning
Date:   Fri, 20 Jan 2023 17:55:52 +0000
Message-Id: <20230120175556.3556978-5-dhowells@redhat.com>
In-Reply-To: <20230120175556.3556978-1-dhowells@redhat.com>
References: <20230120175556.3556978-1-dhowells@redhat.com>
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Rename BIO_NO_PAGE_REF to BIO_PAGE_REFFED and invert the meaning.  In a
following patch I intend to add a BIO_PAGE_PINNED flag to indicate that the
page needs unpinning and this way both flags have the same logic.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Jan Kara <jack@suse.cz>
cc: Matthew Wilcox <willy@infradead.org>
cc: Logan Gunthorpe <logang@deltatee.com>
cc: linux-block@vger.kernel.org
Link: https://lore.kernel.org/r/167305166150.1521586.10220949115402059720.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/167344730802.2425628.14034153595667416149.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/167391054631.2311931.7588488803802952158.stgit@warthog.procyon.org.uk/ # v6
---

Notes:
    ver #5)
     - Split from patch that uses iov_iter_extract_pages().

 block/bio.c               | 9 ++++++++-
 fs/iomap/direct-io.c      | 1 -
 include/linux/bio.h       | 2 +-
 include/linux/blk_types.h | 2 +-
 4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 6a6c73d14bfd..cfe11f4799d1 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -243,6 +243,10 @@ static void bio_free(struct bio *bio)
  * Users of this function have their own bio allocation. Subsequently,
  * they must remember to pair any call to bio_init() with bio_uninit()
  * when IO has completed, or when the bio is released.
+ *
+ * We set the initial assumption that pages attached to the bio will be
+ * released with put_page() by setting BIO_PAGE_REFFED; if the pages
+ * should not be put, this flag should be cleared.
  */
 void bio_init(struct bio *bio, struct block_device *bdev, struct bio_vec *table,
 	      unsigned short max_vecs, blk_opf_t opf)
@@ -274,6 +278,7 @@ void bio_init(struct bio *bio, struct block_device *bdev, struct bio_vec *table,
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 	bio->bi_integrity = NULL;
 #endif
+	bio_set_flag(bio, BIO_PAGE_REFFED);
 	bio->bi_vcnt = 0;
 
 	atomic_set(&bio->__bi_remaining, 1);
@@ -302,6 +307,7 @@ void bio_reset(struct bio *bio, struct block_device *bdev, blk_opf_t opf)
 {
 	bio_uninit(bio);
 	memset(bio, 0, BIO_RESET_BYTES);
+	bio_set_flag(bio, BIO_PAGE_REFFED);
 	atomic_set(&bio->__bi_remaining, 1);
 	bio->bi_bdev = bdev;
 	if (bio->bi_bdev)
@@ -812,6 +818,7 @@ EXPORT_SYMBOL(bio_put);
 static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp)
 {
 	bio_set_flag(bio, BIO_CLONED);
+	bio_clear_flag(bio, BIO_PAGE_REFFED);
 	bio->bi_ioprio = bio_src->bi_ioprio;
 	bio->bi_iter = bio_src->bi_iter;
 
@@ -1198,7 +1205,7 @@ 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_clear_flag(bio, BIO_PAGE_REFFED);
 	bio_set_flag(bio, BIO_CLONED);
 }
 
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 9804714b1751..c0e75900e754 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -202,7 +202,6 @@ static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
 	bio->bi_private = dio;
 	bio->bi_end_io = iomap_dio_bio_end_io;
 
-	get_page(page);
 	__bio_add_page(bio, page, len, 0);
 	iomap_dio_submit_bio(iter, dio, bio, pos);
 }
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 22078a28d7cb..63bfd91793f9 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -482,7 +482,7 @@ void zero_fill_bio(struct bio *bio);
 
 static inline void bio_release_pages(struct bio *bio, bool mark_dirty)
 {
-	if (!bio_flagged(bio, BIO_NO_PAGE_REF))
+	if (bio_flagged(bio, BIO_PAGE_REFFED))
 		__bio_release_pages(bio, mark_dirty);
 }
 
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 99be590f952f..86711fb0534a 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -318,7 +318,7 @@ struct bio {
  * bio flags
  */
 enum {
-	BIO_NO_PAGE_REF,	/* don't put release vec pages */
+	BIO_PAGE_REFFED,	/* Pages need refs putting (equivalent to FOLL_GET) */
 	BIO_CLONED,		/* doesn't own data */
 	BIO_BOUNCED,		/* bio is a bounce bio */
 	BIO_QUIET,		/* Make BIO Quiet */