Hi,
Al, here's some cleanup that you mentioned back in December that I got
around to (https://lkml.org/lkml/2014/12/15/28).
In summary, the rw parameter to a_ops->direct_IO() is redundant with
.type in struct iov_iter. Additionally, rw is inconsistently checked for
being a WRITE; some filesystems do rw == WRITE, others do rw & WRITE,
and others do both within the same function :) The distinction is that
swapout may OR in the ITER_BVEC flag in the rw passed to ->direct_IO(),
so the two are not equivalent (although this really only happens for
swap-over-NFS, but it's scary nonetheless). After looking through all of
these, it definitely looks like every check means for ANY write, not
just non-kernel writes.
So, the solution presented here is:
- Add a helper, iov_iter_rw(), which always returns either READ or
WRITE, no ITER_.* or REQ_.* nonsense mixed in. For consistency, the
return value is always checked for equality
- Get rid of all uses of rw in any implementations of direct_IO,
starting with the generic code
- Nuke the actual parameter and update the documentation
I decided to squish all of the filesystems together in patch 4 to avoid
inundating the mailing lists with 20+ mostly two-line patches, but I can
split those out if that's any better. Additionally, patch 1 pulls fs.h
into uio.h, which seems undesirable.
These were mostly just compile tested, with a couple of direct I/O
xfstests run on btrfs as quick sanity check, so getting some more eyes
on is probably a good thing. They should apply on top of v4.0-rc4.
Please comment away.
Thank you,
Omar Sandoval (5):
new helper: iov_iter_rw()
Remove rw from {,__,do_}blockdev_direct_IO()
Remove rw from dax_{do_,}io()
direct_IO: use iov_iter_rw() instead of rw everywhere
direct_IO: remove rw from a_ops->direct_IO()
Documentation/filesystems/Locking | 2 +-
Documentation/filesystems/vfs.txt | 2 +-
drivers/staging/lustre/lustre/llite/rw26.c | 22 ++++++++---------
fs/9p/vfs_addr.c | 2 +-
fs/affs/file.c | 9 +++----
fs/block_dev.c | 8 +++---
fs/btrfs/inode.c | 24 +++++++++---------
fs/ceph/addr.c | 3 +--
fs/cifs/file.c | 3 +--
fs/dax.c | 27 ++++++++++-----------
fs/direct-io.c | 39 ++++++++++++++----------------
fs/exofs/inode.c | 4 +--
fs/ext2/inode.c | 11 ++++-----
fs/ext3/inode.c | 14 +++++------
fs/ext4/ext4.h | 4 +--
fs/ext4/indirect.c | 25 ++++++++++---------
fs/ext4/inode.c | 28 ++++++++++-----------
fs/f2fs/data.c | 22 ++++++++---------
fs/fat/inode.c | 9 +++----
fs/fuse/file.c | 16 ++++++------
fs/gfs2/aops.c | 16 ++++++------
fs/hfs/inode.c | 8 +++---
fs/hfsplus/inode.c | 9 +++----
fs/jfs/inode.c | 8 +++---
fs/nfs/direct.c | 4 +--
fs/nilfs2/inode.c | 10 +++-----
fs/ocfs2/aops.c | 22 +++++++----------
fs/reiserfs/inode.c | 8 +++---
fs/udf/file.c | 3 +--
fs/udf/inode.c | 7 +++---
fs/xfs/xfs_aops.c | 12 ++++-----
include/linux/fs.h | 24 +++++++++---------
include/linux/nfs_fs.h | 2 +-
include/linux/uio.h | 10 ++++++++
mm/filemap.c | 4 +--
mm/page_io.c | 4 +--
36 files changed, 206 insertions(+), 219 deletions(-)
--
2.3.3
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