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Subject: [PATCH 00/10] iov_iter: Add new iters and use with AFS
From:   David Howells <dhowells@redhat.com>
To:     viro@zeniv.linux.org.uk
Cc:     dhowells@redhat.com, linux-fsdevel@vger.kernel.org,
        linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org
Date:   Thu, 13 Sep 2018 16:51:35 +0100
Message-ID: <153685389564.14766.11306559824641824935.stgit@warthog.procyon.org.uk>
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Hi Al,

Here's a set of patches that adds two new iov_iter types and then makes AFS
use them to do I/O.  The iov_iter changes are:

 (1) Separate the type from the direction in the iov_iter struct and
     provide accessor functions to wrap type checking.

 (2) Renumber the type constants to be contiguous small unsigned integers,
     starting from 0 and then use switch-statements rather than if-else
     chains using bit-testing.

     Note that the compiler can optimise this better by using CMP rather
     than AND/TEST, say, as comparing integers requires fewer CMP
     instructions or can use jump tables.

 (3) Change iov_offset from size_t to loff_t.  This allows iov_offset to be
     then used as a byte offset with ITER_MAPPING and allows 4GiB and larger
     reads and writes to be proposed.

     This makes no difference on a 64-bit system, but does make a 32-bit
     compilation a bit larger.

 (4) Add an ITER_MAPPING iterator type.  This provides an iterator that
     directly accesses an address_space, and assumes that the target pages
     are in some way locked (eg. PG_lock or PG_writeback).

 (5) Add an ITER_DISCARD iterator type.  This provides an iterator that
     simply discards anything written to it.  It cannot be used as a data
     source.

The afs changes are:

 (1) Use a single ITER_MAPPING iterator to cover all the data read by a
     single FetchData RPC op.  This involves switching the operation to an
     ITER_KVEC iterator to read the status record that's transmitted after
     the data.

 (2) Use an ITER_DISCARD iterator to discard any extra data the server may
     have included that we don't want.

 (3) Use a single ITER_MAPPING iterator to cover all the data written by a
     single StoreData RPC op.

 (4) Add synchronous O_DIRECT read support.

This should also be useful for doing direct I/O from cachefiles.

The patches can be found here also:

	http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=afs-iov

David
---
David Howells (10):
      iov_iter: Separate type from direction and use accessor functions
      iov_iter: Renumber the ITER_* constants in uio.h
      iov_iter: Make count and iov_offset loff_t not size_t
      iov_iter: Add mapping and discard iterator types
      afs: Better tracing of protocol errors
      afs: Set up the iov_iter before calling afs_extract_data()
      afs: Use ITER_MAPPING for writing
      afs: Add O_DIRECT read support
      afs: Add a couple of tracepoints to log I/O errors
      afs: Don't invoke the server to read data beyond EOF


 block/bio.c                              |    2 
 drivers/block/drbd/drbd_main.c           |    2 
 drivers/block/drbd/drbd_receiver.c       |    2 
 drivers/block/loop.c                     |    9 
 drivers/block/nbd.c                      |   12 -
 drivers/isdn/mISDN/l1oip_core.c          |    3 
 drivers/misc/vmw_vmci/vmci_queue_pair.c  |    6 
 drivers/nvme/target/io-cmd-file.c        |    2 
 drivers/target/iscsi/iscsi_target_util.c |    6 
 drivers/target/target_core_file.c        |    6 
 drivers/usb/usbip/usbip_common.c         |    2 
 drivers/xen/pvcalls-back.c               |    8 
 fs/9p/vfs_addr.c                         |    4 
 fs/9p/vfs_dir.c                          |    2 
 fs/9p/xattr.c                            |    4 
 fs/afs/cmservice.c                       |   56 +--
 fs/afs/dir.c                             |  208 ++++++++---
 fs/afs/file.c                            |  262 ++++++++++----
 fs/afs/fsclient.c                        |  409 ++++++++-------------
 fs/afs/inode.c                           |    2 
 fs/afs/internal.h                        |   81 +++-
 fs/afs/mntpt.c                           |    6 
 fs/afs/rxrpc.c                           |  156 ++------
 fs/afs/server.c                          |    4 
 fs/afs/vlclient.c                        |  134 +++----
 fs/afs/volume.c                          |    2 
 fs/afs/write.c                           |  112 ++++--
 fs/block_dev.c                           |    2 
 fs/btrfs/file.c                          |    7 
 fs/ceph/file.c                           |    7 
 fs/cifs/connect.c                        |    4 
 fs/cifs/file.c                           |    4 
 fs/cifs/misc.c                           |    4 
 fs/cifs/smb2ops.c                        |    4 
 fs/cifs/smbdirect.c                      |   17 +
 fs/cifs/transport.c                      |    8 
 fs/direct-io.c                           |    2 
 fs/dlm/lowcomms.c                        |    2 
 fs/fuse/file.c                           |    2 
 fs/iomap.c                               |    2 
 fs/nfs/direct.c                          |    2 
 fs/nfsd/vfs.c                            |    4 
 fs/ocfs2/cluster/tcp.c                   |    2 
 fs/orangefs/inode.c                      |    2 
 fs/splice.c                              |    7 
 include/linux/fscache.h                  |   31 ++
 include/linux/uio.h                      |   69 ++--
 include/trace/events/afs.h               |  202 ++++++++---
 lib/iov_iter.c                           |  572 ++++++++++++++++++++++++------
 mm/filemap.c                             |    2 
 mm/page_io.c                             |    2 
 net/9p/client.c                          |    4 
 net/9p/trans_virtio.c                    |    2 
 net/bluetooth/6lowpan.c                  |    2 
 net/bluetooth/a2mp.c                     |    2 
 net/bluetooth/smp.c                      |    2 
 net/ceph/messenger.c                     |    6 
 net/netfilter/ipvs/ip_vs_sync.c          |    2 
 net/smc/smc_clc.c                        |    4 
 net/socket.c                             |    6 
 net/sunrpc/svcsock.c                     |    2 
 net/tipc/topsrv.c                        |    2 
 net/tls/tls_device.c                     |    4 
 net/tls/tls_sw.c                         |    4 
 64 files changed, 1551 insertions(+), 953 deletions(-)