For user mapped IO, we do get_user_pages() upfront, and then do a
put_page() on each page at end_io time to release the page reference. In
preparation for having permanently mapped pages, add a BIO_HOLD_PAGES
flag that tells us not to release the pages, the caller will do that.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
block/bio.c | 6 ++++--
include/linux/blk_types.h | 1 +
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 03895cc0d74a..ab174bce5436 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1635,7 +1635,8 @@ static void bio_dirty_fn(struct work_struct *work)
next = bio->bi_private;
bio_set_pages_dirty(bio);
- bio_release_pages(bio);
+ if (!bio_flagged(bio, BIO_HOLD_PAGES))
+ bio_release_pages(bio);
bio_put(bio);
}
}
@@ -1651,7 +1652,8 @@ void bio_check_pages_dirty(struct bio *bio)
goto defer;
}
- bio_release_pages(bio);
+ if (!bio_flagged(bio, BIO_HOLD_PAGES))
+ bio_release_pages(bio);
bio_put(bio);
return;
defer:
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index c0ba1a038ff3..78aaf7442688 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -227,6 +227,7 @@ struct bio {
#define BIO_TRACE_COMPLETION 10 /* bio_endio() should trace the final completion
* of this bio. */
#define BIO_QUEUE_ENTERED 11 /* can use blk_queue_enter_live() */
+#define BIO_HOLD_PAGES 12 /* don't put O_DIRECT pages */
/* See BVEC_POOL_OFFSET below before adding new flags */
--
2.17.1
