sysfs_attr_init() is required to make lockdep happy for dynamically
allocated sysfs attributes. This fixed #8868 on Fedora 29 running
kernel-debug.

This requirement was introduced in 2.6.34.
See include/linux/sysfs.h for what it actually does.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Closes #8868 
Closes #8884

When iterating over a ZAP object, we're almost always certain to iterate
over the entire object. If there are multiple leaf blocks, we can
realize a performance win by issuing reads for all the leaf blocks in
parallel when the iteration begins.

For example, if we have 10,000 snapshots, "zfs destroy -nv
pool/fs@1%9999" can take 30 minutes when the cache is cold. This change
provides a >3x performance improvement, by issuing the reads for all ~64
blocks of each ZAP object in parallel.

Reviewed-by: Andreas Dilger <andreas.dilger@whamcloud.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
External-issue: DLPX-58347
Closes #8862

Sometimes the target ARC size is reduced to arc_c_min, which impacts
performance.  We've seen this happen as part of the random_reads
performance regression test, where the ARC size is reduced before the
reads test starts which impacts how long it takes for system to reach
good IOPS performance.

We call arc_reduce_target_size when arc_reap_cb_check() returns TRUE,
and arc_available_memory() is less than arc_c>>arc_shrink_shift.

However, arc_available_memory() could easily be low, even when arc_c is
low, because we can have tons of unused bufs in the abd kmem cache. This
would be especially true just after the DMU requests a bunch of stuff be
evicted from the ARC (e.g. due to "zpool export").

To fix this, the ARC should reduce arc_c by the requested amount, not
all the way down to arc_size (or arc_c_min), which can be very small.

Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
External-issue: DLPX-59431
Closes #8864

Fix typo in vdev_raidz_math.c

Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brad Forschinger <github@bnjf.id.au>
Closes #8875 
Closes #8880

Those function may be useful to pass fileargs connections around.

Let's change the unsigned arguments to the signed one, but let's don't
change pointers to the array notation.

Requested by:	pjd

asserted. Some development boards for example will reset on DTR,
and some radio interfaces will transmit on RTS.

This patch allows "stty -f /dev/ttyu9.init -rtsdtr" to prevent
RTS and DTR from being asserted on open(), allowing these devices
to be used without problems.

Reviewed by:    imp
Differential Revision:  https://reviews.freebsd.org/D20031

r348783 changed the behavior of the kernel mappings and broke booting on G5.

- Split the kernel mapping logic out so that the case where we are
running from the wrong memory space is handled using identity
mappings, and the case where we are not using a DMAP is handled by
forcibly mapping the kernel into the dmap range as intended by
r348783.

Reported by:	Mikael Urankar
Reviewed by:	luporl
Approved by:	jhibbits (mentor)
Differential Revision:	https://reviews.freebsd.org/D20608