freebsd-nq/lib
Brian Behlendorf 1c2358c12a
Linux 5.10 compat: use iov_iter in uio structure
As of the 5.10 kernel the generic splice compatibility code has been
removed.  All filesystems are now responsible for registering a
->splice_read and ->splice_write callback to support this operation.

The good news is the VFS provided generic_file_splice_read() and
iter_file_splice_write() callbacks can be used provided the ->iter_read
and ->iter_write callback support pipes.  However, this is currently
not the case and only iovecs and bvecs (not pipes) are ever attached
to the uio structure.

This commit changes that by allowing full iov_iter structures to be
attached to uios.  Ever since the 4.9 kernel the iov_iter structure
has supported iovecs, kvecs, bvevs, and pipes so it's desirable to
pass the entire thing when possible.  In conjunction with this the
uio helper functions (i.e uiomove(), uiocopy(), etc) have been
updated to understand the new UIO_ITER type.

Note that using the kernel provided uio_iter interfaces allowed the
existing Linux specific uio handling code to be simplified.  When
there's no longer a need to support kernel's older than 4.9, then
it will be possible to remove the iovec and bvec members from the
uio structure and always use a uio_iter.  Until then we need to
maintain all of the existing types for older kernels.

Some additional refactoring and cleanup was included in this change:

- Added checks to configure to detect available iov_iter interfaces.
  Some are available all the way back to the 3.10 kernel and are used
  when available.  In particular, uio_prefaultpages() now always uses
  iov_iter_fault_in_readable() which is available for all supported
  kernels.

- The unused UIO_USERISPACE type has been removed.  It is no longer
  needed now that the uio_seg enum is platform specific.

- Moved zfs_uio.c from the zcommon.ko module to the Linux specific
  platform code for the zfs.ko module.  This gets it out of libzfs
  where it was never needed and keeps this Linux specific code out
  of the common sources.

- Removed unnecessary O_APPEND handling from zfs_iter_write(), this
  is redundant and O_APPEND is already handled in zfs_write();

Reviewed-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #11351
2020-12-18 08:48:26 -08:00
..
libavl Fixes for make dist 2020-06-26 14:20:02 -07:00
libefi pool may become suspended during device expansion 2020-09-17 20:03:10 -07:00
libicp Clean up lib dependencies 2020-07-10 14:26:00 -07:00
libnvpair Include the ABI with dist tarball 2020-11-21 10:44:52 -08:00
libshare zpool command complains about /etc/exports.d 2020-09-25 13:09:40 -07:00
libspl Linux 5.10 compat: use iov_iter in uio structure 2020-12-18 08:48:26 -08:00
libtpool Clean up lib dependencies 2020-07-10 14:26:00 -07:00
libunicode Fixes for make dist 2020-06-26 14:20:02 -07:00
libuutil Include the ABI with dist tarball 2020-11-21 10:44:52 -08:00
libzfs Linux 5.10 compat: use iov_iter in uio structure 2020-12-18 08:48:26 -08:00
libzfs_core Include the ABI with dist tarball 2020-11-21 10:44:52 -08:00
libzfsbootenv libzfsbootenv: do not depend on libnvpair 2020-11-22 15:16:42 -08:00
libzpool Linux 5.10 compat: use iov_iter in uio structure 2020-12-18 08:48:26 -08:00
libzstd Avoid symbol collision with in-kernel zstdlib 2020-08-24 12:20:41 -07:00
libzutil Fix pointer-is-uint64_t-sized assumption in the ioctl path 2020-11-10 15:53:13 -08:00
Makefile.am Library ABI tracking with abigail 2020-11-17 09:18:52 -08:00