From: "Changheun Lee" <nanich.lee@xxxxxxxxxxx>
bio size can grow up to 4GB when muli-page bvec is enabled.
but sometimes it would lead to inefficient behaviors.
in case of large chunk direct I/O, - 64MB chunk read in user space -
all pages for 64MB would be merged to a bio structure if memory address is
continued phsycally. it makes some delay to submit until merge complete.
bio max size should be limited as a proper size.
Signed-off-by: Changheun Lee <nanich.lee@xxxxxxxxxxx>
---
block/bio.c | 2 +-
include/linux/bio.h | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 1f2cc1fbe283..dbe14d675f28 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -877,7 +877,7 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page,
struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (page_is_mergeable(bv, page, len, off, same_page)) {
- if (bio->bi_iter.bi_size > UINT_MAX - len) {
+ if (bio->bi_iter.bi_size > BIO_MAX_SIZE - len) {
*same_page = false;
return false;
}
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 1edda614f7ce..0f49b354b1f6 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -20,6 +20,7 @@
#endif
#define BIO_MAX_PAGES 256
+#define BIO_MAX_SIZE (BIO_MAX_PAGES * PAGE_SIZE)
#define bio_prio(bio) (bio)->bi_ioprio
#define bio_set_prio(bio, prio) ((bio)->bi_ioprio = prio)
@@ -113,7 +114,7 @@ static inline bool bio_full(struct bio *bio, unsigned len)
if (bio->bi_vcnt >= bio->bi_max_vecs)
return true;
- if (bio->bi_iter.bi_size > UINT_MAX - len)
+ if (bio->bi_iter.bi_size > BIO_MAX_SIZE - len)
return true;
return false;
--
2.28.0
