diff options
Diffstat (limited to 'block/bio.c')
| -rw-r--r-- | block/bio.c | 48 |
1 files changed, 28 insertions, 20 deletions
diff --git a/block/bio.c b/block/bio.c index 71a78d9fb8b7..716510ecd7ff 100644 --- a/block/bio.c +++ b/block/bio.c @@ -849,20 +849,14 @@ static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter) size = bio_add_page(bio, bv->bv_page, len, bv->bv_offset + iter->iov_offset); if (size == len) { - struct page *page; - int i; + if (!bio_flagged(bio, BIO_NO_PAGE_REF)) { + struct page *page; + int i; + + mp_bvec_for_each_page(page, bv, i) + get_page(page); + } - /* - * For the normal O_DIRECT case, we could skip grabbing this - * reference and then not have to put them again when IO - * completes. But this breaks some in-kernel users, like - * splicing to/from a loop device, where we release the pipe - * pages unconditionally. If we can fix that case, we can - * get rid of the get here and the need to call - * bio_release_pages() at IO completion time. - */ - mp_bvec_for_each_page(page, bv, i) - get_page(page); iov_iter_advance(iter, size); return 0; } @@ -925,10 +919,12 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) * This takes either an iterator pointing to user memory, or one pointing to * kernel pages (BVEC iterator). If we're adding user pages, we pin them and * map them into the kernel. On IO completion, the caller should put those - * pages. For now, when adding kernel pages, we still grab a reference to the - * page. This isn't strictly needed for the common case, but some call paths - * end up releasing pages from eg a pipe and we can't easily control these. - * See comment in __bio_iov_bvec_add_pages(). + * pages. If we're adding kernel pages, and the caller told us it's safe to + * do so, we just have to add the pages to the bio directly. We don't grab an + * extra reference to those pages (the user should already have that), and we + * don't put the page on IO completion. The caller needs to check if the bio is + * flagged BIO_NO_PAGE_REF on IO completion. If it isn't, then pages should be + * released. * * The function tries, but does not guarantee, to pin as many pages as * fit into the bio, or are requested in *iter, whatever is smaller. If @@ -940,6 +936,13 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) const bool is_bvec = iov_iter_is_bvec(iter); unsigned short orig_vcnt = bio->bi_vcnt; + /* + * If this is a BVEC iter, then the pages are kernel pages. Don't + * release them on IO completion, if the caller asked us to. + */ + if (is_bvec && iov_iter_bvec_no_ref(iter)) + bio_set_flag(bio, BIO_NO_PAGE_REF); + do { int ret; @@ -1295,8 +1298,11 @@ struct bio *bio_copy_user_iov(struct request_queue *q, } } - if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes) + if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes) { + if (!map_data) + __free_page(page); break; + } len -= bytes; offset = 0; @@ -1696,7 +1702,8 @@ 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_NO_PAGE_REF)) + bio_release_pages(bio); bio_put(bio); } } @@ -1713,7 +1720,8 @@ void bio_check_pages_dirty(struct bio *bio) goto defer; } - bio_release_pages(bio); + if (!bio_flagged(bio, BIO_NO_PAGE_REF)) + bio_release_pages(bio); bio_put(bio); return; defer: |