Re: [RFC][PATCHES] iov_iter stuff

[Al Viro <viro@zeniv.linux.org.uk>]

On Fri, Jun 17, 2022 at 04:30:49PM -0600, Jens Axboe wrote:

> Al, looks good to me from inspection, and I ported stuffed this on top
> of -git and my 5.20 branch, and did my send/recv/recvmsg io_uring change
> on top and see a noticeable reduction there too for some benchmarking.
> Feel free to add:
> 
> Reviewed-by: Jens Axboe <axboe@kernel.dk>
> 
> to the series.
> 
> Side note - of my initial series I played with, I still have this one
> leftover that I do utilize for io_uring:
> 
> https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.20/io_uring-iter&id=a59f5c21a6eeb9506163c20aff4846dbec159f47
> 
> Doesn't make sense standalone, but I have it as a prep patch.
> 
> Can I consider your work.iov_iter stable at this point, or are you still
> planning rebasing?

Umm...  Rebasing this part - probably no; there's a fun followup to it, though,
I'm finishing the carve up & reorder at the moment.  Will post for review
tonight...

Current state:

Al Viro (43):
      No need of likely/unlikely on calls of check_copy_size()
      9p: handling Rerror without copy_from_iter_full()
      teach iomap_dio_rw() to suppress dsync
      btrfs: use IOMAP_DIO_NOSYNC
      struct file: use anonymous union member for rcuhead and llist
      iocb: delay evaluation of IS_SYNC(...) until we want to check IOCB_DSYNC
      keep iocb_flags() result cached in struct file
      copy_page_{to,from}_iter(): switch iovec variants to generic
      new iov_iter flavour - ITER_UBUF
      switch new_sync_{read,write}() to ITER_UBUF
      iov_iter_bvec_advance(): don't bother with bvec_iter
      fix short copy handling in copy_mc_pipe_to_iter()
      splice: stop abusing iov_iter_advance() to flush a pipe
      ITER_PIPE: helper for getting pipe buffer by index
      ITER_PIPE: helpers for adding pipe buffers
      ITER_PIPE: allocate buffers as we go in copy-to-pipe primitives
      ITER_PIPE: fold push_pipe() into __pipe_get_pages()
      ITER_PIPE: lose iter_head argument of __pipe_get_pages()
      ITER_PIPE: clean pipe_advance() up
      ITER_PIPE: clean iov_iter_revert()
      ITER_PIPE: cache the type of last buffer
      fold data_start() and pipe_space_for_user() together
      iov_iter_get_pages{,_alloc}(): cap the maxsize with LONG_MAX
      iov_iter_get_pages_alloc(): lift freeing pages array on failure exits into wrapper
      iov_iter_get_pages(): sanity-check arguments
      unify pipe_get_pages() and pipe_get_pages_alloc()
      unify xarray_get_pages() and xarray_get_pages_alloc()
      unify the rest of iov_iter_get_pages()/iov_iter_get_pages_alloc() guts
      ITER_XARRAY: don't open-code DIV_ROUND_UP()
      iov_iter: lift dealing with maxpages into iov_iter_get_pages()
      iov_iter: massage calling conventions for first_{iovec,bvec}_segment()
      found_iovec_segment(): just return address
      fold __pipe_get_pages() into pipe_get_pages()
      iov_iter: saner helper for page array allocation
      iov_iter: advancing variants of iov_iter_get_pages{,_alloc}()
      block: convert to advancing variants of iov_iter_get_pages{,_alloc}()
      iter_to_pipe(): switch to advancing variant of iov_iter_get_pages()
      af_alg_make_sg(): switch to advancing variant of iov_iter_get_pages()
      9p: convert to advancing variant of iov_iter_get_pages_alloc()
      ceph: switch the last caller of iov_iter_get_pages_alloc()
      get rid of non-advancing variants
      pipe_get_pages(): switch to append_pipe()
      expand those iov_iter_advance()...

 arch/powerpc/include/asm/uaccess.h |   2 +-
 arch/s390/include/asm/uaccess.h    |   4 +-
 block/bio.c                        |  15 +-
 block/blk-map.c                    |   7 +-
 block/fops.c                       |   8 +-
 crypto/af_alg.c                    |   3 +-
 crypto/algif_hash.c                |   5 +-
 drivers/nvme/target/io-cmd-file.c  |   2 +-
 drivers/vhost/scsi.c               |   4 +-
 fs/aio.c                           |   2 +-
 fs/btrfs/file.c                    |  19 +-
 fs/btrfs/inode.c                   |   3 +-
 fs/ceph/addr.c                     |   2 +-
 fs/ceph/file.c                     |   5 +-
 fs/cifs/file.c                     |   8 +-
 fs/cifs/misc.c                     |   3 +-
 fs/direct-io.c                     |   7 +-
 fs/fcntl.c                         |   1 +
 fs/file_table.c                    |  17 +-
 fs/fuse/dev.c                      |   7 +-
 fs/fuse/file.c                     |   7 +-
 fs/gfs2/file.c                     |   2 +-
 fs/io_uring.c                      |   2 +-
 fs/iomap/direct-io.c               |  21 +-
 fs/nfs/direct.c                    |   8 +-
 fs/open.c                          |   1 +
 fs/read_write.c                    |   6 +-
 fs/splice.c                        |  54 +-
 fs/zonefs/super.c                  |   2 +-
 include/linux/fs.h                 |  21 +-
 include/linux/iomap.h              |   6 +
 include/linux/pipe_fs_i.h          |  29 +-
 include/linux/uaccess.h            |   4 +-
 include/linux/uio.h                |  50 +-
 lib/iov_iter.c                     | 978 ++++++++++++++-----------------------
 mm/shmem.c                         |   2 +-
 net/9p/client.c                    | 125 +----
 net/9p/protocol.c                  |   3 +-
 net/9p/trans_virtio.c              |  37 +-
 net/core/datagram.c                |   3 +-
 net/core/skmsg.c                   |   3 +-
 net/rds/message.c                  |   3 +-
 net/tls/tls_sw.c                   |   4 +-
 43 files changed, 589 insertions(+), 906 deletions(-)