From bb523b406c849eef8f265a07cd7f320f1f177743 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Mon, 2 Aug 2021 13:44:20 +0200 Subject: gup: Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable} Turn fault_in_pages_{readable,writeable} into versions that return the number of bytes not faulted in, similar to copy_to_user, instead of returning a non-zero value when any of the requested pages couldn't be faulted in. This supports the existing users that require all pages to be faulted in as well as new users that are happy if any pages can be faulted in. Rename the functions to fault_in_{readable,writeable} to make sure this change doesn't silently break things. Neither of these functions is entirely trivial and it doesn't seem useful to inline them, so move them to mm/gup.c. Signed-off-by: Andreas Gruenbacher --- include/linux/pagemap.h | 57 +++---------------------------------------------- 1 file changed, 3 insertions(+), 54 deletions(-) (limited to 'include/linux/pagemap.h') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 62db6b0176b9..9fe94f7a4f7e 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -733,61 +733,10 @@ int wait_on_page_private_2_killable(struct page *page); extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter); /* - * Fault everything in given userspace address range in. + * Fault in userspace address range. */ -static inline int fault_in_pages_writeable(char __user *uaddr, size_t size) -{ - char __user *end = uaddr + size - 1; - - if (unlikely(size == 0)) - return 0; - - if (unlikely(uaddr > end)) - return -EFAULT; - /* - * Writing zeroes into userspace here is OK, because we know that if - * the zero gets there, we'll be overwriting it. - */ - do { - if (unlikely(__put_user(0, uaddr) != 0)) - return -EFAULT; - uaddr += PAGE_SIZE; - } while (uaddr <= end); - - /* Check whether the range spilled into the next page. */ - if (((unsigned long)uaddr & PAGE_MASK) == - ((unsigned long)end & PAGE_MASK)) - return __put_user(0, end); - - return 0; -} - -static inline int fault_in_pages_readable(const char __user *uaddr, size_t size) -{ - volatile char c; - const char __user *end = uaddr + size - 1; - - if (unlikely(size == 0)) - return 0; - - if (unlikely(uaddr > end)) - return -EFAULT; - - do { - if (unlikely(__get_user(c, uaddr) != 0)) - return -EFAULT; - uaddr += PAGE_SIZE; - } while (uaddr <= end); - - /* Check whether the range spilled into the next page. */ - if (((unsigned long)uaddr & PAGE_MASK) == - ((unsigned long)end & PAGE_MASK)) { - return __get_user(c, end); - } - - (void)c; - return 0; -} +size_t fault_in_writeable(char __user *uaddr, size_t size); +size_t fault_in_readable(const char __user *uaddr, size_t size); int add_to_page_cache_locked(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); -- cgit From cdd591fc86e38ad3899196066219fbbd845f3162 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Mon, 5 Jul 2021 17:26:28 +0200 Subject: iov_iter: Introduce fault_in_iov_iter_writeable Introduce a new fault_in_iov_iter_writeable helper for safely faulting in an iterator for writing. Uses get_user_pages() to fault in the pages without actually writing to them, which would be destructive. We'll use fault_in_iov_iter_writeable in gfs2 once we've determined that the iterator passed to .read_iter isn't in memory. Signed-off-by: Andreas Gruenbacher --- include/linux/pagemap.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/pagemap.h') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 9fe94f7a4f7e..2f7dd14083d9 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -736,6 +736,7 @@ extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter); * Fault in userspace address range. */ size_t fault_in_writeable(char __user *uaddr, size_t size); +size_t fault_in_safe_writeable(const char __user *uaddr, size_t size); size_t fault_in_readable(const char __user *uaddr, size_t size); int add_to_page_cache_locked(struct page *page, struct address_space *mapping, -- cgit