implement not double-caching for reads from vnode-backed md devices.
Use VOP_ADVISE() similarly instead of !IO_DIRECT unsimilarly for writes.
Add a "cache" option to mdconfig to allow changing the default of not
caching.
This depends on a recent commit to fix VOP_ADVISE(). A previous version
had optimizations for sequential i/o's (merge the i/o's and only uncache
for discontiguous i/o's and for full blocks), but optimizations and
knowledge of block boundaries belong in VOP_ADVISE(). Read-ahead should
also be handled better, by supporting it in md and discarding it in
VOP_ADVISE().
POSIX_FADV_DONTNEED is ignored by zfs, but so is IO_DIRECT.
POSIX_FADV_DONTNEED works better than IO_DIRECT if it is not ignored,
since it only discards from the buffer cache immediately, while
IO_DIRECT also discards from the page cache immediately.
IO_DIRECT was not used for writes since it was claimed to be too slow,
but most of the slowness for writes is from doing them synchronously by
default. Non-synchronous writes still deadlock in many cases.
IO_DIRECT only has a special implementation for ffs reads with DIRECTIO
configured. Otherwise, if it is not ignored than it uses the buffer and
page caches normally except for discarding everything after each i/o,
and then it has much the same overheads as POSIX_FADV_DONTNEED. The
overheads for reading with ffs and DIRECTIO were similar in tests of md.
Reviewed by: kib
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
No functional change intended.
This feature comes from the fact that we rely memory-backed md(4)
in our build process heavily. However, if the build goes haywire
the allocated resources (i.e. swap and memory-backed md(4)'s) need
to be purged. It is extremely useful to have ability to attach
arbitrary labels to each of the virtual disks so that they can
be identified and GC'ed if neecessary.
MFC after: 4 weeks
Differential Revision: https://reviews.freebsd.org/D10457
Add -o [no]verify option to mdconfig (and document in man page.)
Implement GEOM attribute MNT::verified to ask md if the backing vnode is
verified.
Check for MNT::verified in cd9660 mount to flag the mount as MNT_VERIFIED if
the underlying device has been verified.
Reviewed by: rwatson
Approved by: sjg (mentor)
Obtained from: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D2902
meta-data, copy it into the softc structure.
When returning md(4) device details to the caller, include the file name in
any MD_PRELOAD type devices if it is set (first character is not NUL.)
In mdconfig, for "preload" type md(4) devices, if there is file config
available, print it in the file column of the output.
Reviewed by: brooks
Approved by: sjg (mentor)
MFC after: 1 month
Sponsored by: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D9529
1. "-u N" specified, no -f, and mdN found,
2. no -u, "-f /pathname" specified, and mdN associated with /pathname found,
3. "-u N" specified, "-f /pathname" specified, and both of them found,
4. "-l" specified and no -f,
5. "-l" specified, "-f /pathname" specified, and /pathname found.
otherwise return -1.
Spotted by: Julian H. Stacey
specified, only md(4) devices which have the specified file as backing
store are displayed.
- Use MD_NAME instead of "md".
- Use _PATH_DEV instead of "/dev/".
MFC after: 1 week
- The feature is dangerous because the kernel code didn't check
validity of the memory address provided from user space.
- It seems that mdconfig(8) never really supported attaching preloaded
memory disks.
- Preloaded memory disks are automatically attached during md(4)
initialization. Thus there shouldn't be much use for the feature.
PR: kern/169683
Discussed on: freebsd-hackers
by removing the ordering requirements and adding more descriptive error
messages; it also makes it more readable and maintainable.
Sponsored by: The FreeBSD Foundation
"mdconfig -f file", I decided that it would be easier to make mdconfig
DWIM than to teach my fingers to type the correct command line.
MFC after: 3 weeks
- Constify geom_config_get() name argument.
- Add void keyword for usage().
- Initialize mdunit to NULL.
- Don't call md_prthumanval() at all if length is NULL.
Approved by: trasz (mentor)
device number at creation time with -u option. Together with XMLizing
mdconfig(8), I broke this functionality.
This change is temporary. Complete fix will be commited soon.
Approved by: cognet (mentor)
a problem with listing large number of md(4) devices. Either 'list' or
'query' mode uses XML.
Additionally, new functionality was introduced. It's possible to pass
multiple devices to -u:
# ./mdconfig -l -u md0,md1
Approved by: cognet (mentor)
kernel is in the order the devices were made, which is not useful to
the user. Also, remove the "%d more" test since the kernel does not
return the complete count in md_pad[0] (maybe it should?).
Submitted by: Wojciech A. Koszek
device be created read+write, check to see if the backing store is read only
through the use of the access(2) system call. If this check fails returning
EACCES, EPERM or EROFS then gracefully downgrade the access to read only. Also
print a warning message to stderr, informing the user that the access mode
they requested is not available.
This behavior used to be handled by md(4) but was changed in revision 1.154
Discussed with: pjd, phk, Dario Freni <saturnero at freesbie dot org>
Reviewed by: phk
show file name for 'mdconfig -l -u <x>' command.
This allows to preserve API/ABI compatibility with version 0 (that's why
I changed version number back to 0) and will allow to merge this change
to RELENG_5.
MFC after: 5 days
