From 981f95a571e3ca20a496c0b77dbf6b06039c6648 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Fri, 19 May 2023 14:50:26 +0800 Subject: [PATCH] ublk: cleanup ublk_copy_user_pages Clean up ublk_copy_user_pages() by using iov_iter_get_pages2, and code gets simplified a lot and becomes much more readable than before. Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20230519065030.351216-4-ming.lei@redhat.com Signed-off-by: Jens Axboe --- drivers/block/ublk_drv.c | 112 +++++++++++++++++++++-------------------------- 1 file changed, 49 insertions(+), 63 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 0c8651c..afc07fa 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -412,49 +412,39 @@ static const struct block_device_operations ub_fops = { #define UBLK_MAX_PIN_PAGES 32 -struct ublk_map_data { - const struct request *rq; - unsigned long ubuf; - unsigned int len; -}; - struct ublk_io_iter { struct page *pages[UBLK_MAX_PIN_PAGES]; - unsigned pg_off; /* offset in the 1st page in pages */ - int nr_pages; /* how many page pointers in pages */ struct bio *bio; struct bvec_iter iter; }; -static inline unsigned ublk_copy_io_pages(struct ublk_io_iter *data, - unsigned max_bytes, bool to_vm) +/* return how many pages are copied */ +static void ublk_copy_io_pages(struct ublk_io_iter *data, + size_t total, size_t pg_off, int dir) { - const unsigned total = min_t(unsigned, max_bytes, - PAGE_SIZE - data->pg_off + - ((data->nr_pages - 1) << PAGE_SHIFT)); unsigned done = 0; unsigned pg_idx = 0; while (done < total) { struct bio_vec bv = bio_iter_iovec(data->bio, data->iter); - const unsigned int bytes = min3(bv.bv_len, total - done, - (unsigned)(PAGE_SIZE - data->pg_off)); + unsigned int bytes = min3(bv.bv_len, (unsigned)total - done, + (unsigned)(PAGE_SIZE - pg_off)); void *bv_buf = bvec_kmap_local(&bv); void *pg_buf = kmap_local_page(data->pages[pg_idx]); - if (to_vm) - memcpy(pg_buf + data->pg_off, bv_buf, bytes); + if (dir == ITER_DEST) + memcpy(pg_buf + pg_off, bv_buf, bytes); else - memcpy(bv_buf, pg_buf + data->pg_off, bytes); + memcpy(bv_buf, pg_buf + pg_off, bytes); kunmap_local(pg_buf); kunmap_local(bv_buf); /* advance page array */ - data->pg_off += bytes; - if (data->pg_off == PAGE_SIZE) { + pg_off += bytes; + if (pg_off == PAGE_SIZE) { pg_idx += 1; - data->pg_off = 0; + pg_off = 0; } done += bytes; @@ -468,41 +458,40 @@ static inline unsigned ublk_copy_io_pages(struct ublk_io_iter *data, data->iter = data->bio->bi_iter; } } - - return done; } -static int ublk_copy_user_pages(struct ublk_map_data *data, bool to_vm) +/* + * Copy data between request pages and io_iter, and 'offset' + * is the start point of linear offset of request. + */ +static size_t ublk_copy_user_pages(const struct request *req, + struct iov_iter *uiter, int dir) { - const unsigned int gup_flags = to_vm ? FOLL_WRITE : 0; - const unsigned long start_vm = data->ubuf; - unsigned int done = 0; struct ublk_io_iter iter = { - .pg_off = start_vm & (PAGE_SIZE - 1), - .bio = data->rq->bio, - .iter = data->rq->bio->bi_iter, + .bio = req->bio, + .iter = req->bio->bi_iter, }; - const unsigned int nr_pages = round_up(data->len + - (start_vm & (PAGE_SIZE - 1)), PAGE_SIZE) >> PAGE_SHIFT; - - while (done < nr_pages) { - const unsigned to_pin = min_t(unsigned, UBLK_MAX_PIN_PAGES, - nr_pages - done); - unsigned i, len; - - iter.nr_pages = get_user_pages_fast(start_vm + - (done << PAGE_SHIFT), to_pin, gup_flags, - iter.pages); - if (iter.nr_pages <= 0) - return done == 0 ? iter.nr_pages : done; - len = ublk_copy_io_pages(&iter, data->len, to_vm); - for (i = 0; i < iter.nr_pages; i++) { - if (to_vm) + size_t done = 0; + + while (iov_iter_count(uiter) && iter.bio) { + unsigned nr_pages; + size_t len, off; + int i; + + len = iov_iter_get_pages2(uiter, iter.pages, + iov_iter_count(uiter), + UBLK_MAX_PIN_PAGES, &off); + if (len <= 0) + return done; + + ublk_copy_io_pages(&iter, len, off, dir); + nr_pages = DIV_ROUND_UP(len + off, PAGE_SIZE); + for (i = 0; i < nr_pages; i++) { + if (dir == ITER_DEST) set_page_dirty(iter.pages[i]); put_page(iter.pages[i]); } - data->len -= len; - done += iter.nr_pages; + done += len; } return done; @@ -529,15 +518,14 @@ static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req, * context is pretty fast, see ublk_pin_user_pages */ if (ublk_need_map_req(req)) { - struct ublk_map_data data = { - .rq = req, - .ubuf = io->addr, - .len = rq_bytes, - }; + struct iov_iter iter; + struct iovec iov; + const int dir = ITER_DEST; - ublk_copy_user_pages(&data, true); + import_single_range(dir, u64_to_user_ptr(io->addr), rq_bytes, + &iov, &iter); - return rq_bytes - data.len; + return ublk_copy_user_pages(req, &iter, dir); } return rq_bytes; } @@ -549,17 +537,15 @@ static int ublk_unmap_io(const struct ublk_queue *ubq, const unsigned int rq_bytes = blk_rq_bytes(req); if (ublk_need_unmap_req(req)) { - struct ublk_map_data data = { - .rq = req, - .ubuf = io->addr, - .len = io->res, - }; + struct iov_iter iter; + struct iovec iov; + const int dir = ITER_SOURCE; WARN_ON_ONCE(io->res > rq_bytes); - ublk_copy_user_pages(&data, false); - - return io->res - data.len; + import_single_range(dir, u64_to_user_ptr(io->addr), io->res, + &iov, &iter); + return ublk_copy_user_pages(req, &iter, dir); } return rq_bytes; } -- 2.7.4