POSIX AIO is great, but it lacks vectored I/O functions. This commit
fixes that shortcoming by adding aio_writev and aio_readv. They aren't
part of the standard, but they're an obvious extension. They work just
like their synchronous equivalents pwritev and preadv.
It isn't yet possible to use vectored aiocbs with lio_listio, but that
could be added in the future.
Reviewed by: jhb, kib, bcr
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D27743
- Avoid double use of "request" in a single sentence. Instead, describe
aio_sigevent as being used to request notification of the associated
operation's completion. This matches the language used to describe
aio_sigevent in aio(4).
- Simplify the prohibition on modifying buffers while requests are in
flight.
- Fix case mismatch.
- Drop note about not using stack variables. C programmers should be able
to figure out if a stack variable is safe based on the later warning
about the life cycle requirements of control blocks.
- Remove prohibition on modifying the I/O buffer for aio_fsync() since
it does not use an I/O buffer. For aio_mlock(), prohibit modifications
to the mapping (e.g. due to mprotect, munmap, mmap, etc.) but do not
prohibit modifications to the memory backing the buffer (stores into
the pages backing the buffer).
Requested by: wblock (1,2), kib (4)
Reviewed by: kib, rpokala, wblock
MFC after: 3 days
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D7462
The asynchronous I/O changes made previously result in different
behavior out of the box. Previously all AIO requests failed with
ENOSYS / SIGSYS unless aio.ko was explicitly loaded. Now, some AIO
requests complete and others ("unsafe" requests) fail with EOPNOTSUPP.
Reword the introductory paragraph in aio(4) to add a general
description of AIO before describing the vfs.aio.enable_unsafe sysctl.
Remove the ENOSYS error description from aio_fsync(2), aio_read(2),
and aio_write(2) and replace it with a description of EOPNOTSUPP.
Remove the ENOSYS error description from aio_mlock(2).
Log a message to the system log the first time a process requests an
"unsafe" AIO request that fails with EOPNOTSUPP. This is modeled on
the log message used for processes using the legacy pty devices.
Reviewed by: kib (earlier version)
MFC after: 1 week
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D7151
- Add a sigevent(3) manpage to give a general overview of the sigevent
structure and the available notification mechanisms.
- Document that AIO requests contain a nested sigevent structure that can
be used to request completion notification.
- Expand the sigevent details in other manuals to note details such as
the extra values stored in a queued signal's information or in a posted
kevent.
Reviewed by: kib
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D7122
Stop calling system calls "function calls".
Use "The .Fn system call" a-la "The .Nm utility".
When referring to a non-BSD implementation in
the HISTORY section, call syscall a function,
to be safe.
linking.
* Fix disorder in the SEE ALSO sections of aio_*(2).
* Remove unnecessary cross-references from the SEE ALSO sections of
aio_*(2); config(8), kldload(8) and kldunload(8) are cross-referenced
from aio(4).
* Remove the KERNEL OPTIONS sections from aio_*(2), now that these
pages cross-reference aio(4), which contains suitable kernel linking
reference material.
- Sort xrefs
- FreeBSD.ORG -> FreeBSD.org
- Be consistent with section names as outlines in mdoc(7)
- Other misc mdoc cleanup.
PR: doc/13144
Submitted by: Alexy M. Zelkin <phantom@cris.net>
