lwn.git/include/linux/uio.h, branch v6.11-rc3

new helper: copy_to_iter_full()

2024-04-07T06:42:36+00:00

... and convert copy_linear_skb() to using that. Signed-off-by: Al Viro

iov_iter: get rid of 'copy_mc' flag

2024-03-06T09:52:12+00:00

This flag is only set by one single user: the magical core dumping code that looks up user pages one by one, and then writes them out using their kernel addresses (by using a BVEC_ITER). That actually ends up being a huge problem, because while we do use copy_mc_to_kernel() for this case and it is able to handle the possible machine checks involved, nothing else is really ready to handle the failures caused by the machine check. In particular, as reported by Tong Tiangen, we don't actually support fault_in_iov_iter_readable() on a machine check area. As a result, the usual logic for writing things to a file under a filesystem lock, which involves doing a copy with page faults disabled and then if that fails trying to fault pages in without holding the locks with fault_in_iov_iter_readable() does not work at all. We could decide to always just make the MC copy "succeed" (and filling the destination with zeroes), and that would then create a core dump file that just ignores any machine checks. But honestly, this single special case has been problematic before, and means that all the normal iov_iter code ends up slightly more complex and slower. See for example commit c9eec08bac96 ("iov_iter: Don't deal with iter->copy_mc in memcpy_from_iter_mc()") where David Howells re-organized the code just to avoid having to check the 'copy_mc' flags inside the inner iov_iter loops. So considering that we have exactly one user, and that one user is a non-critical special case that doesn't actually ever trigger in real life (Tong found this with manual error injection), the sane solution is to just decide that the onus on handling the machine check lines on that user instead. Ergo, do the copy_mc_to_kernel() in the core dump logic itself, copying the user data to a stable kernel page before writing it out. Fixes: f1982740f5e7 ("iov_iter: Convert iterate*() to inline funcs") Signed-off-by: Linus Torvalds Signed-off-by: Tong Tiangen Link: https://lore.kernel.org/r/20240305133336.3804360-1-tongtiangen@huawei.com Link: https://lore.kernel.org/all/4e80924d-9c85-f13a-722a-6a5d2b1c225a@huawei.com/ Tested-by: David Howells Reviewed-by: David Howells Reviewed-by: Jens Axboe Reported-by: Tong Tiangen Signed-off-by: Christian Brauner

iov_iter: replace import_single_range() with import_ubuf()

2023-12-05T10:57:37+00:00

With the removal of the 'iov' argument to import_single_range(), the two functions are now fully identical. Convert the import_single_range() callers to import_ubuf(), and remove the former fully. Signed-off-by: Jens Axboe Link: https://lore.kernel.org/r/20231204174827.1258875-3-axboe@kernel.dk Signed-off-by: Christian Brauner

iov_iter: remove unused 'iov' argument from import_single_range()

2023-12-05T10:57:34+00:00

It is entirely unused, just get rid of it. Signed-off-by: Jens Axboe Link: https://lore.kernel.org/r/20231204174827.1258875-2-axboe@kernel.dk Signed-off-by: Christian Brauner

iov_iter, net: Move hash_and_copy_to_iter() to net/

2023-10-09T07:35:14+00:00

Move hash_and_copy_to_iter() to be with its only caller in networking code. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20230925120309.1731676-13-dhowells@redhat.com cc: Alexander Viro cc: Jens Axboe cc: Christoph Hellwig cc: Christian Brauner cc: Matthew Wilcox cc: Linus Torvalds cc: David Laight cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: linux-block@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org cc: netdev@vger.kernel.org Signed-off-by: Christian Brauner

iov_iter, net: Move csum_and_copy_to/from_iter() to net/

2023-10-09T07:35:14+00:00

Move csum_and_copy_to/from_iter() to net code now that the iteration framework can be #included. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20230925120309.1731676-10-dhowells@redhat.com cc: Alexander Viro cc: Jens Axboe cc: Christoph Hellwig cc: Christian Brauner cc: Matthew Wilcox cc: Linus Torvalds cc: David Laight cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: linux-block@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org cc: netdev@vger.kernel.org Signed-off-by: Christian Brauner

iov_iter: Derive user-backedness from the iterator type

2023-09-25T12:30:28+00:00

Use the iterator type to determine whether an iterator is user-backed or not rather than using a special flag for it. Now that ITER_UBUF and ITER_IOVEC are 0 and 1, they can be checked with a single comparison. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20230925120309.1731676-7-dhowells@redhat.com cc: Alexander Viro cc: Jens Axboe cc: Christoph Hellwig cc: Christian Brauner cc: Matthew Wilcox cc: Linus Torvalds cc: David Laight cc: linux-block@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org Signed-off-by: Christian Brauner

iov_iter: Renumber ITER_* constants

2023-09-25T12:30:28+00:00

Renumber the ITER_* iterator-type constants to put things in the same order as in the iteration functions and to group user-backed iterators at the bottom. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20230925120309.1731676-6-dhowells@redhat.com cc: Alexander Viro cc: Jens Axboe cc: Christoph Hellwig cc: Christian Brauner cc: Matthew Wilcox cc: Linus Torvalds cc: David Laight cc: linux-block@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org Signed-off-by: Christian Brauner

iov_iter: Remove last_offset from iov_iter as it was for ITER_PIPE

2023-09-25T12:30:27+00:00

Now that ITER_PIPE has been removed, iov_iter::last_offset is no longer used, so remove it. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20230925120309.1731676-2-dhowells@redhat.com cc: Alexander Viro cc: Jens Axboe cc: Christoph Hellwig cc: Christian Brauner cc: Matthew Wilcox cc: Linus Torvalds cc: David Laight cc: linux-block@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org Signed-off-by: Christian Brauner

iov_iter: Add copy_folio_from_iter_atomic()

2023-07-24T22:03:58+00:00

Add a folio wrapper around copy_page_from_iter_atomic(). Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Darrick J. Wong