[RFC PATCH 3/7] block, fs: assert that key paths use iovecs, and nothing else
From: John Hubbard <jhubbard@nvidia.com>
Date: 2022-02-25 08:50:54
Also in:
linux-fsdevel, linux-mm, linux-xfs, lkml
Subsystem:
block layer, filesystems (vfs and infrastructure), the rest · Maintainers:
Jens Axboe, Alexander Viro, Christian Brauner, Linus Torvalds
Upcoming changes to Direct IO will change it from acquiring pages via get_user_pages_fast(), to calling pin_user_pages_fast() instead. Place a few assertions at key points, that the pages are IOVEC (user pages), to enforce the assumptions that there are no kernel or pipe or other odd variations being passed. Signed-off-by: John Hubbard <jhubbard@nvidia.com> --- block/bio.c | 4 ++++ fs/direct-io.c | 2 ++ 2 files changed, 6 insertions(+)
diff --git a/block/bio.c b/block/bio.c
index b15f5466ce08..4679d6539e2d 100644
--- a/block/bio.c
+++ b/block/bio.c@@ -1167,6 +1167,8 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2); pages += entries_left * (PAGE_PTRS_PER_BVEC - 1); + WARN_ON_ONCE(!iter_is_iovec(iter)); + size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset); if (unlikely(size <= 0)) return size ? size : -EFAULT;
@@ -1217,6 +1219,8 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter) BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2); pages += entries_left * (PAGE_PTRS_PER_BVEC - 1); + WARN_ON_ONCE(!iter_is_iovec(iter)); + size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset); if (unlikely(size <= 0)) return size ? size : -EFAULT;
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 38bca4980a1c..7dbbbfef300d 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c@@ -169,6 +169,8 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) { ssize_t ret; + WARN_ON_ONCE(!iter_is_iovec(sdio->iter)); + ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES, &sdio->from);
--
2.35.1