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 8281bfcbc265..a475949afd70 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1634,7 +1634,8 @@ 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);
}
}
@@ -1650,7 +1651,8 @@ 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 4845250b5ba0..e7bf29170149 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -215,6 +215,7 @@ struct bio {
/*
* bio flags
*/
+#define BIO_HOLD_PAGES 0 /* don't put O_DIRECT pages */
#define BIO_SEG_VALID 1 /* bi_phys_segments valid */
#define BIO_CLONED 2 /* doesn't own data */
#define BIO_BOUNCED 3 /* bio is a bounce bio */
--
2.17.1
