get_user_pages() call in aio_setup_ring() is useless these days. We create all ringbuffer the pages in page cache using find_or_create_page() anyway so we can just use the pointers we get from this function instead of having to look them up via user address space.
CC: [email protected] CC: [email protected] CC: Alexander Viro <[email protected]> CC: Benjamin LaHaise <[email protected]> Signed-off-by: Jan Kara <[email protected]> --- fs/aio.c | 48 +++++++++++++++++------------------------------- 1 file changed, 17 insertions(+), 31 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 6b868f0e0c4c..a14a33027990 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -269,9 +269,21 @@ static int aio_setup_ring(struct kioctx *ctx) file->f_inode->i_mapping->a_ops = &aio_ctx_aops; file->f_inode->i_mapping->private_data = ctx; file->f_inode->i_size = PAGE_SIZE * (loff_t)nr_pages; + ctx->aio_ring_file = file; + nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) + / sizeof(struct io_event); + + ctx->ring_pages = ctx->internal_pages; + if (nr_pages > AIO_RING_PAGES) { + ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *), + GFP_KERNEL); + if (!ctx->ring_pages) + return -ENOMEM; + } for (i = 0; i < nr_pages; i++) { struct page *page; + page = find_or_create_page(file->f_inode->i_mapping, i, GFP_HIGHUSER | __GFP_ZERO); if (!page) @@ -281,19 +293,13 @@ static int aio_setup_ring(struct kioctx *ctx) SetPageUptodate(page); SetPageDirty(page); unlock_page(page); + ctx->ring_pages[i] = page; } - ctx->aio_ring_file = file; - nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) - / sizeof(struct io_event); - - ctx->ring_pages = ctx->internal_pages; - if (nr_pages > AIO_RING_PAGES) { - ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *), - GFP_KERNEL); - if (!ctx->ring_pages) - return -ENOMEM; + ctx->nr_pages = i; + if (unlikely(ctx->nr_pages != nr_pages)) { + aio_free_ring(ctx); + return -EAGAIN; } - ctx->mmap_size = nr_pages * PAGE_SIZE; pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size); @@ -309,28 +315,8 @@ static int aio_setup_ring(struct kioctx *ctx) } pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base); - - /* We must do this while still holding mmap_sem for write, as we - * need to be protected against userspace attempting to mremap() - * or munmap() the ring buffer. - */ - ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages, - 1, 0, ctx->ring_pages, NULL); - - /* Dropping the reference here is safe as the page cache will hold - * onto the pages for us. It is also required so that page migration - * can unmap the pages and get the right reference count. - */ - for (i = 0; i < ctx->nr_pages; i++) - put_page(ctx->ring_pages[i]); - up_write(&mm->mmap_sem); - if (unlikely(ctx->nr_pages != nr_pages)) { - aio_free_ring(ctx); - return -EAGAIN; - } - ctx->user_id = ctx->mmap_base; ctx->nr_events = nr_events; /* trusted copy */ -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
